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Sample records for all-optical flip-flops based

  1. All-optical flip-flop operation based on bistability in V-cavity laser.

    PubMed

    Wu, Yingchen; Zhu, Yu; Liao, Xiaolu; Meng, Jianjun; He, Jian-Jun

    2016-06-13

    We theoretically analyzed and experimentally demonstrated an injection-locking based all-optical flip-flop memory using a simple and compact tunable V-cavity laser (VCL). A bistable region in the tuning characteristics of the VCL is employed for the flip-flop operation. The state of the VCL can be set and reset by injecting signal pulses at two different wavelengths. The pulse power for both set and reset signal is only about 1 pJ. Short response times of about 150 ps are measured for storing and erasing. PMID:27410271

  2. All-optical pseudorandom binary sequence generator with TOAD-based D flip-flops

    NASA Astrophysics Data System (ADS)

    Zoiros, K. E.; Das, M. K.; Gayen, D. K.; Maity, H. K.; Chattopadhyay, T.; Roy, J. N.

    2011-09-01

    An all-optical pseudo random binary sequence (PRBS) generator is designed using serially interconnected discrete Terahertz Optical Asymmetric Demultiplexer (TOAD)-based D flip-flops in a configuration exactly like the standard electronic setup. The performance of the circuit is evaluated through numerical simulation, which confirms its feasibility in terms of the choice of the critical parameters. The proposed scheme has been theoretically demonstrated for a 3-bit and 7-bit degree PRBS but can be extended to higher order by means of additional TOAD-based D flip-flops. Thus it can constitute an efficient solution for implementing all-optically a PRBS in an affordable, controllable and realistic manner.

  3. Optical Square-Wave Clock Generation Based on an All-Optical Flip-Flop

    SciTech Connect

    Kaplan, A.M.; Agrawal, G.P.; Maywar, D.N.

    2010-03-10

    We demonstrate optical square-wave clock generation based on an all-optical flip-flop. The bistable output power from a resonant-type semiconductor optical amplifier (SOA) is switched ON and OFF by modulating its input with its output via cross-gain modulation in a traveling-wave SOA. All active components are driven by dc currents, and the wavelength and clock frequency are selectable. A clock frequency of 3.5 MHz is demonstrated, limited by the time of flight between bulk optical components. Optical square-wave clock signals are promising for applications in photonic integrated circuits and all-optical signal processing.

  4. All-Optical Flip-Flop Operation of VCSOA

    SciTech Connect

    Kaplan, A.M.; Agrawal, G.P.; Maywar, D.N.

    2009-01-22

    An all-optical flip-flop, the memory of which is based on dispersive bistability in a single vertical cavity semiconductor optical amplifier, is demonstrated experimentally. Flip-flop control is achieved using two mechanisms: cross-phase modulation to set the flip-flop and cross-gain modulation of the holding beam within a remote SOA to reset it. Optical control signals are sub-milliwatt in power and derived from a single 5 ns, 1539 nm initial pulse. Flip-flop operation at 1542 nm is polarisation insensitive to control signals and achieved with an on-off contrast greater than 3 dB.

  5. All-optical flip-flop based on coupled SOA-PSW

    NASA Astrophysics Data System (ADS)

    Wang, Lina; Wang, Yongjun; Wu, Chen; Wang, Fu

    2016-07-01

    The semiconductor optical amplifier (SOA) has obvious advantages in all-optical signal processing, because of the simple structure, strong non-linearity, and easy integration. A variety of all-optical signal processing functions, such as all-optical wavelength conversion, all-optical logic gates and all-optical sampling, can be completed by SOA. So the SOA has been widespread concerned in the field of all-optical signal processing. Recently, the polarization rotation effect of SOA is receiving considerable interest, and many researchers have launched numerous research work utilizing this effect. In this paper, a new all-optical flip-flop structure using polarization switch (PSW) based on polarization rotation effect of SOA is presented.

  6. ZnO nanowire-based all-optical switch with Reset-Set flip-flop function

    NASA Astrophysics Data System (ADS)

    Mu, L. X.; Shi, W. S.; Zhang, T. P.; Zhang, H. Y.; Wang, Y.; She, G. W.; Gao, Y. H.; Wang, P. F.; Chang, J. C.; Lee, S. T.

    2011-04-01

    An all-optical switch with Reset-Set (RS) flip-flop function has been developed by attaching a derivative of spiropyran on the surface of zinc oxide (ZnO) Nanowire. Using UV/visible irradiation and the fluorescence of spiropyran-modified ZnO nanowire as inputs—set/reset and output, RS flip-flop function can be performed on a single ZnO nanowire or a nanowire array. The configuration of the current all-optical switch represents a potential for developing small-sized all-optical devices, which could be further exploited at higher level of integration.

  7. All-optical SR flip-flop based on SOA-MZI switches monolithically integrated on a generic InP platform

    NASA Astrophysics Data System (ADS)

    Pitris, St.; Vagionas, Ch.; Kanellos, G. T.; Kisacik, R.; Tekin, T.; Broeke, R.; Pleros, N.

    2016-03-01

    At the dawning of the exaflop era, High Performance Computers are foreseen to exploit integrated all-optical elements, to overcome the speed limitations imposed by electronic counterparts. Drawing from the well-known Memory Wall limitation, imposing a performance gap between processor and memory speeds, research has focused on developing ultra-fast latching devices and all-optical memory elements capable of delivering buffering and switching functionalities at unprecedented bit-rates. Following the master-slave configuration of electronic Flip-Flops, coupled SOA-MZI based switches have been theoretically investigated to exceed 40 Gb/s operation, provided a short coupling waveguide. However, this flip-flop architecture has been only hybridly integrated with silica-on-silicon integration technology exhibiting a total footprint of 45x12 mm2 and intra-Flip-Flop coupling waveguide of 2.5cm, limited at 5 Gb/s operation. Monolithic integration offers the possibility to fabricate multiple active and passive photonic components on a single chip at a close proximity towards, bearing promises for fast all-optical memories. Here, we present for the first time a monolithically integrated all-optical SR Flip-Flop with coupled master-slave SOA-MZI switches. The photonic chip is integrated on a 6x2 mm2 die as a part of a multi-project wafer run using library based components of a generic InP platform, fiber-pigtailed and fully packaged on a temperature controlled ceramic submount module with electrical contacts. The intra Flip-Flop coupling waveguide is 5 mm long, reducing the total footprint by two orders of magnitude. Successful flip flop functionality is evaluated at 10 Gb/s with clear open eye diagram, achieving error free operation with a power penalty of 4dB.

  8. Numerical simulation of a novel all-optical flip-flop based on a chirped nonlinear distributed feedback semiconductor laser structure using GPGPU computing

    NASA Astrophysics Data System (ADS)

    Zoweil, H.

    2015-05-01

    A novel all-optical flip-flop based on a chirped nonlinear distributed feedback laser structure is proposed. The flip-flop does not require a holding beam. The optical gain is provided by a current injection into an active layer. The nonlinear wave-guiding layer consists of a chirped phase shifted grating accompanied with a negative nonlinear refractive index coefficient that increases in magnitude along the wave-guide. In the 'OFF' state, the chirped grating does not provide the required optical feedback to start lasing. An optical pulse switches the device 'ON' by reducing the chirp due to the negative nonlinear refractive index coefficient. The reduced chirp grating provides enough feedback to sustain a laser mode. The device is switched 'OFF' by cross gain modulation. GPGPU computing allows for long simulation time of multiple SET-RESET operations. The 'ON/OFF' transitions delays are in nanoseconds time scale.

  9. All-optical flip-flop and control methods thereof

    SciTech Connect

    Maywar, Drew; Agrawal, Govind P.

    2010-03-23

    Embodiments of the invention pertain to remote optical control of holding beam-type, optical flip-flop devices, as well as to the devices themselves. All-optical SET and RE-SET control signals operate on a cw holding beam in a remote manner to vary the power of the holding beam between threshold switching values to enable flip-flop operation. Cross-gain modulation and cross-polarization modulation processes can be used to change the power of the holding beam.

  10. Ultra compact and fast All Optical Flip Flop design in photonic crystal platform

    NASA Astrophysics Data System (ADS)

    Abbasi, Amin; Noshad, Morteza; Ranjbar, Reza; Kheradmand, Reza

    2012-11-01

    In this work we present a heterostructure All Optical Flip-Flop configuration based on all optical switching with Kerr nonlinear photonic crystal. In this square-hexagonal structure, we propose three different schemes for the cavities in order to show the trade-off between switching time and triggering power. Loss in the system is reasonably low because of the perfect band gap matching at bending points where two lattices join. The proposed RS-Flip Flop has exceptional features, which make it one of the well optimized and most practical structures to be used in the all optical integrated circuits. The novel design has a fast switching action (on the order of a few picoseconds), and low input power (on the order of 100 mW). Furthermore, high contrast of the output signals for ON and OFF states, can help the easy detection or its coupling to the other devices. The structure is fascinatingly uncomplicated, which results in ultra small dimensions which make it suitable to be placed in an all optical integrated circuit. Besides, we provide a profound analytical view on the functioning of the system, as analyzed by the finite difference time domain (FDTD) method.

  11. Polarization encoded all-optical quaternary R-S flip-flop using binary latch

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay; Roy, Jitendra Nath; Chakraborty, Ajoy Kumar

    2009-04-01

    The developments of different multi-valued logic (MVL) systems have received considerable interests in recent years all over the world. In electronics, efforts have already been made to incorporate multi-valued system in logic and arithmetic data processing. But, very little efforts have been given in realization of MVL with optics. In this paper we present novel designs of certain all-optical circuits that can be used for realizing multi-valued logic functions. Polarization encoded all-optical quaternary (4-valued) R-S flip-flop is proposed and described. Two key circuits (all-optical encoder/decoder and a binary latch) are designed first. They are used to realize quaternary flip-flop in all-optical domain. Here the different quaternary logical states are represented by different polarized state of light. Terahertz Optical Asymmetric Demultiplexer (TOAD) based interferometric switch can take an important role. Computer simulation result confirming described methods and conclusion are given in this paper.

  12. New alternative approach to all-optical flip-flop with nonlinear material

    NASA Astrophysics Data System (ADS)

    Giri, Dibyendu; Das, Partha Pratima

    2010-07-01

    Due to its inherent parallelism and tremendous operational speed, optical signal is the most suitable for data processing and digital communication in various fields. Conventional electronic and opto-electronic systems are unable to fulfill this arena, because of their low speed and time delay. In the case of pure electronic flip-flop, when a switch is turned ON, there is notable propagation delay on the order of nanoseconds. For an opto-electronic flip-flop although the propagation delay time is much less than that of an electronic flip-flop (about 10 to 100 times less), there are many disadvantages. Some of these disadvantages are delay of response time due to the use of spatial light modulators, an O/E converter that does not operate at all frequencies or wavelengths, and the unavailability of such materials. An optical input encoding methodology is proposed for the performance of all-optical flip-flop operations possible for two inputs. These operations were conducted in all-optical mode and are parallel in nature. All the operations are treated with proper exploitation of some nonlinear materials.

  13. All-optical flip-flop composed of a single nonlinear passive microring coupled to two straight waveguides

    NASA Astrophysics Data System (ADS)

    Bahrampour, A. R.; Mohammad Ali Mirzaee, S.; Farman, F.; Zakeri, S. S.

    2009-02-01

    Microrings can have different hysteresis characteristics at their different resonance frequencies. They can be used as a multi-hysteresis optical component. In this paper an optical D-flip-flop circuit composed of a single nonlinear passive microring coupled to two straight waveguide based on the Kerr effect is proposed. The proposed circuit can operate as an optical digital circuit which synchronizes input DATA with the CLOCK of the circuit. A simple analytical model for hysteresis design and the transient analysis of the proposed D-flip-flop are presented. According to our model, the switching time of the flip-flop is in the order of 10 ps.

  14. Generalized Flip-Flop Input Equations Based on a Four-Valued Boolean Algebra

    NASA Technical Reports Server (NTRS)

    Tucker, Jerry H.; Tapia, Moiez A.

    1996-01-01

    A procedure is developed for obtaining generalized flip-flop input equations, and a concise method is presented for representing these equations. The procedure is based on solving a four-valued characteristic equation of the flip-flop, and can encompass flip-flops that are too complex to approach intuitively. The technique is presented using Karnaugh maps, but could easily be implemented in software.

  15. SEU Performance of TAG Based Flip Flops

    NASA Technical Reports Server (NTRS)

    Shuler, Robert L.; Kouba, Coy; O'Neill, Patrick M.

    2005-01-01

    We describe heavy ion test results for two new SEU tolerant latches based on transition nand gates, one for single rail asynchronous and the other for dual rail synchronous designs, implemented in AMI 0.5microprocess.

  16. Design, implementation and investigation of an image guide-based optical flip-flop array

    NASA Technical Reports Server (NTRS)

    Griffith, P. C.

    1987-01-01

    Presented is the design for an image guide-based optical flip-flop array created using a Hughes liquid crystal light valve and a flexible image guide in a feedback loop. This design is used to investigate the application of image guides as a communication mechanism in numerical optical computers. It is shown that image guides can be used successfully in this manner but mismatch match between the input and output fiber arrays is extremely limiting.

  17. Spectral diffusion and dipolar flip-flop in spin-based solid state quantum computers

    NASA Astrophysics Data System (ADS)

    de Sousa, Rogerio; Das Sarma, S.

    2002-03-01

    We estimate phase coherence times for spins in two quantum computer architectures, where the qubit is either an electron spin bound to a P donor impurity in Si or a GaAs quantum dot. Since the magnetic resonance line in both these systems is inhomogeneously broadened, a natural way to probe these coherence times is to measure the decay time of a two pulse spin echo envelope. Based on spin echo experiments performed on Si:P we consider three mechanisms for this decay: (1) Spin-lattice relaxation (T1 processes), (2) flip-flop between qubits mediated by dipolar interaction, and (3) spectral diffusion caused by nearby flip-flopping nuclear spins. Our estimates indicate that mechanism (3) dominates in both architectures, except for isotopically pure Si-28 samples where mechanism (2) dominates due to the fact that the line is not inhomogeneously broadened and more spin qubits can flip-flop. We acknowledge support from ARDA, DARPA and the US-ONR.

  18. A modified implementation of tristate inverter based static master-slave flip-flop with improved power-delay-area product.

    PubMed

    Singh, Kunwar; Tiwari, Satish Chandra; Gupta, Maneesha

    2014-01-01

    The paper introduces novel architectures for implementation of fully static master-slave flip-flops for low power, high performance, and high density. Based on the proposed structure, traditional C(2)MOS latch (tristate inverter/clocked inverter) based flip-flop is implemented with fewer transistors. The modified C(2)MOS based flip-flop designs mC(2)MOSff1 and mC(2)MOSff2 are realized using only sixteen transistors each while the number of clocked transistors is also reduced in case of mC(2)MOSff1. Postlayout simulations indicate that mC(2)MOSff1 flip-flop shows 12.4% improvement in PDAP (power-delay-area product) when compared with transmission gate flip-flop (TGFF) at 16X capacitive load which is considered to be the best design alternative among the conventional master-slave flip-flops. To validate the correct behaviour of the proposed design, an eight bit asynchronous counter is designed to layout level. LVS and parasitic extraction were carried out on Calibre, whereas layouts were implemented using IC station (Mentor Graphics). HSPICE simulations were used to characterize the transient response of the flip-flop designs in a 180 nm/1.8 V CMOS technology. Simulations were also performed at 130 nm, 90 nm, and 65 nm to reveal the scalability of both the designs at modern process nodes. PMID:24723808

  19. A modified implementation of tristate inverter based static master-slave flip-flop with improved power-delay-area product.

    PubMed

    Singh, Kunwar; Tiwari, Satish Chandra; Gupta, Maneesha

    2014-01-01

    The paper introduces novel architectures for implementation of fully static master-slave flip-flops for low power, high performance, and high density. Based on the proposed structure, traditional C(2)MOS latch (tristate inverter/clocked inverter) based flip-flop is implemented with fewer transistors. The modified C(2)MOS based flip-flop designs mC(2)MOSff1 and mC(2)MOSff2 are realized using only sixteen transistors each while the number of clocked transistors is also reduced in case of mC(2)MOSff1. Postlayout simulations indicate that mC(2)MOSff1 flip-flop shows 12.4% improvement in PDAP (power-delay-area product) when compared with transmission gate flip-flop (TGFF) at 16X capacitive load which is considered to be the best design alternative among the conventional master-slave flip-flops. To validate the correct behaviour of the proposed design, an eight bit asynchronous counter is designed to layout level. LVS and parasitic extraction were carried out on Calibre, whereas layouts were implemented using IC station (Mentor Graphics). HSPICE simulations were used to characterize the transient response of the flip-flop designs in a 180 nm/1.8 V CMOS technology. Simulations were also performed at 130 nm, 90 nm, and 65 nm to reveal the scalability of both the designs at modern process nodes.

  20. Flip-Flop Digital Modulator

    NASA Technical Reports Server (NTRS)

    Eno, R. F.

    1984-01-01

    Clock switched on and off in response to data signal. Flip-flop modulator generates square-wave carrier frequency that is half clock frequency and turns carrier on and off. Final demodulator output logical inverse of data input.

  1. Single-transistor-clocked flip-flop

    DOEpatents

    Zhao, Peiyi; Darwish, Tarek; Bayoumi, Magdy

    2005-08-30

    The invention provides a low power, high performance flip-flop. The flip-flop uses only one clocked transistor. The single clocked transistor is shared by the first and second branches of the device. A pulse generator produces a clock pulse to trigger the flip-flop. In one preferred embodiment the device can be made as a static explicit pulsed flip-flop which employs only two clocked transistors.

  2. Flip-flops of FK Comae Berenices

    NASA Astrophysics Data System (ADS)

    Hackman, T.; Pelt, J.; Mantere, M. J.; Jetsu, L.; Korhonen, H.; Granzer, T.; Kajatkari, P.; Lehtinen, J.; Strassmeier, K. G.

    2013-05-01

    Context.FK Comae Berenices is a rapidly rotating magnetically active star, the light curve of which is modulated by cool spots on its surface. It was the first star where the "flip-flop" phenomenon was discovered. Since then, flip-flops in the spot activity have been reported in many other stars. Follow-up studies with increasing length have shown, however, that the phenomenon is more complex than was thought right after its discovery. Aims: Therefore, it is of interest to perform a more thorough study of the evolution of the spot activity in FK Com. In this study, we analyse 15 years of photometric observations with two different time series analysis methods, with a special emphasis on detecting flip-flop type events from the data. Methods: We apply the continuous period search and carrier fit methods on long-term standard Johnson-Cousins V-observations from the years 1995-2010. The observations were carried out with two automated photometric telescopes, Phoenix-10 and Amadeus T7 located in Arizona. Results: We identify complex phase behaviour in 6 of the 15 analysed data segments. We identify five flip-flop events and two cases of phase jumps, where the phase shift is Δφ < 0.4. In addition we see two mergers of spot regions and two cases where the apparent phase shifts are caused by spot regions drifting with respect to each other. Furthermore we detect variations in the rotation period corresponding to a differential rotation coefficient of |k| > 0.031. Conclusions: The flip-flop cannot be interpreted as a single phenomenon, where the main activity jumps from one active longitude to another. In some of our cases the phase shifts can be explained by differential rotation: two spot regions move with different angular velocity and even pass each other. Comparison between the methods show that the carrier fit utility is better in retrieving slow evolution especially from a low amplitude light curve, while the continuous period search is more sensitive in case of

  3. Flip-flop logic circuit based on fully solution-processed organic thin film transistor devices with reduced variations in electrical performance

    NASA Astrophysics Data System (ADS)

    Takeda, Yasunori; Yoshimura, Yudai; Adib, Faiz Adi Ezarudin Bin; Kumaki, Daisuke; Fukuda, Kenjiro; Tokito, Shizuo

    2015-04-01

    Organic reset-set (RS) flip-flop logic circuits based on pseudo-CMOS inverters have been fabricated using full solution processing at a relatively low process temperatures of 150 °C or less. The work function for printed silver electrodes was increased from 4.7 to 5.4 eV through surface modification with a self-assembled monolayer (SAM) material. A bottom-gate, bottom-contact organic thin-film transistor (OTFT) device using a solution-processable small-molecular semiconductor material exhibited field-effect mobility of 0.40 cm2 V-1 s-1 in the saturation region and a threshold voltage (VTH) of -2.4 V in ambient air operation conditions. In order to reduce the variations in mobility and VTH, we designed a circuit with six transistors arranged in parallel, in order to average out their electrical characteristics. As a result, we have succeeded in reducing these variations without changing the absolute values of the mobility and VTH. The fabricated RS flip-flop circuits were functioned well and exhibited short delay times of 3.5 ms at a supply voltage of 20 V.

  4. Integrated silicon flip-flop sensors

    NASA Astrophysics Data System (ADS)

    Lian, Weijian

    1989-12-01

    A thesis on a class of silicon sensors (input transducers) called flip-flop sensors is presented. An understanding of the operating principles of the flip-flop sensor with a subsequent development of analytical expressions to describe its characteristics is given. The implementation of the flip-flop sensor in a standard IC (integrated circuit) process was investigated and sensor characteristics were measured through experiments. Application of the sensors in sensor arrays is described. A design of a sense amplifier is introduced and several methods in which the array can be operated are analyzed.

  5. Gas-Sensing Flip-Flop Circuits

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G.; Blaes, Brent R.; Williams, Roger; Ryan, Margaret A.

    1995-01-01

    Gas-sensing integrated circuits consisting largely of modified static random-access memories (SRAMs) undergoing development, building on experience gained in use of modified SRAMs as radiation sensors. Each SRAM memory cell includes flip-flop circuit; sensors exploit metastable state that lies between two stable states (corresponding to binary logic states) of flip-flop circuit. Voltages of metastable states vary with exposures of gas-sensitive resistors.

  6. Flip-flop resolving time test circuit

    NASA Technical Reports Server (NTRS)

    Rosenberger, F.; Chaney, T. J.

    1982-01-01

    Integrated circuit (IC) flip-flop resolving time parameters are measured by wafer probing, without need of dicing or bonding, throught the incorporation of test structures on an IC together with the flip-flop to be measured. Several delays that are fabricated as part of the test circuit, including a voltage-controlled delay with a resolution of a few picosecs, are calibrated as part of the test procedure by integrating them into, and out of, the delay path of a ring oscillator. Each of the delay values is calculated by subtracting the period of the ring oscillator with the delay omitted from the period with the delay included. The delay measurement technique is sufficiently general for other applications. The technique is illustrated for the case of the flip-flop parameters of a 5-micron feature size NMOS circuit.

  7. Comparison of all optical forwarding packet architectures

    NASA Astrophysics Data System (ADS)

    Farhat, Rim; Farhat, Amel; Menif, Mourad

    2016-04-01

    In this paper two all optical packet forwarding architectures based on non linear effect in semiconductor optical amplifier in Mach-Zehnder configuration SOA-MZI are studied. The first architecture consist in combing flip flop functionality with the AND logic functionality in the same unit. Error free operation at 40 Gbps for two cascaded nodes is achieved. In the second architecture two separated units namely the flip flop and the AND logic gate are used. 100 Gbps bit rate is reached. At 40 Gbps error free operation is achieved for three cascaded nodes.

  8. Few Drugs Display Flip-Flop Pharmacokinetics and These Are Primarily Associated with Classes 3 and 4 of the BDDCS

    PubMed Central

    Garrison, Kimberly L.; Sahin, Selma; Benet, Leslie Z.

    2015-01-01

    Purpose To determine the number of drugs exhibiting flip-flop pharmacokinetics following oral dosing from immediate release dosage forms and if they exhibit a common characteristic that may be predicted based on BDDCS classification. Method The literature was searched for drugs displaying flip-flop kinetics (i.e. absorption half-life larger than elimination half-life) in mammals in PubMed, via internet search engines and reviewing drug pharmacokinetic data. Results Twenty two drugs were identified as displaying flip-flop kinetics in humans (13 drugs), rat (9 drugs), monkey (3 drugs), horse (2 drugs), and/or rabbit (2 drugs). Nineteen of the 22 drugs exhibiting flip-flop kinetics were BDDCS Classes 3 and 4. One of the three exceptions, meclofenamic acid (Class 2), was identified in the horse however it would not exhibit flip-flop kinetics in humans where the oral dosing terminal half-life is 1.4 hr. The second, carvedilol, can be explained based on solubility issues, but the third sapropterin dihydrochloride (nominally Class 1) requires further consideration. Conclusion The few drugs displaying oral flip-flop kinetics in humans are predominantly BDDCS Classes 3 and 4. New molecular entities predicted to be BDDCS Classes 3 and 4 could be liable to exhibit flip-flop kinetics when the elimination half life is short and should be suspected to be substrates for intestinal transporters. PMID:26010239

  9. Few Drugs Display Flip-Flop Pharmacokinetics and These Are Primarily Associated with Classes 3 and 4 of the BDDCS.

    PubMed

    Garrison, Kimberly L; Sahin, Selma; Benet, Leslie Z

    2015-09-01

    This study was conducted to determine the number of drugs exhibiting flip-flop pharmacokinetics following oral (p.o.) dosing from immediate-release dosage forms and if they exhibit a common characteristic that may be predicted based on BDDCS classification. The literature was searched for drugs displaying flip-flop kinetics (i.e., absorption half-life larger than elimination half-life) in mammals in PubMed, via internet search engines and reviewing drug pharmacokinetic data. Twenty two drugs were identified as displaying flip-flop kinetics in humans (13 drugs), rat (nine drugs), monkey (three drugs), horse (two drugs), and/or rabbit (two drugs). Nineteen of the 22 drugs exhibiting flip-flop kinetics were BDDCS Classes 3 and 4. One of the three exceptions, meclofenamic acid (Class 2), was identified in the horse; however, it would not exhibit flip-flop kinetics in humans where the p.o. dosing terminal half-life is 1.4 h. The second, carvedilol, can be explained based on solubility issues, but the third sapropterin dihydrochloride (nominally Class 1) requires further consideration. The few drugs displaying p.o. flip-flop kinetics in humans are predominantly BDDCS Classes 3 and 4. New molecular entities predicted to be BDDCS Classes 3 and 4 could be liable to exhibit flip-flop kinetics when the elimination half life is short and should be suspected to be substrates for intestinal transporters.

  10. Flip-flopping binary black holes.

    PubMed

    Lousto, Carlos O; Healy, James

    2015-04-10

    We study binary spinning black holes to display the long term individual spin dynamics. We perform a full numerical simulation starting at an initial proper separation of d≈25M between equal mass holes and evolve them down to merger for nearly 48 orbits, 3 precession cycles, and half of a flip-flop cycle. The simulation lasts for t=20 000M and displays a total change in the orientation of the spin of one of the black holes from an initial alignment with the orbital angular momentum to a complete antialignment after half of a flip-flop cycle. We compare this evolution with an integration of the 3.5 post-Newtonian equations of motion and spin evolution to show that this process continuously flip flops the spin during the lifetime of the binary until merger. We also provide lower order analytic expressions for the maximum flip-flop angle and frequency. We discuss the effects this dynamics may have on spin growth in accreting binaries and on the observational consequences for galactic and supermassive binary black holes.

  11. Flip-flopping binary black holes.

    PubMed

    Lousto, Carlos O; Healy, James

    2015-04-10

    We study binary spinning black holes to display the long term individual spin dynamics. We perform a full numerical simulation starting at an initial proper separation of d≈25M between equal mass holes and evolve them down to merger for nearly 48 orbits, 3 precession cycles, and half of a flip-flop cycle. The simulation lasts for t=20 000M and displays a total change in the orientation of the spin of one of the black holes from an initial alignment with the orbital angular momentum to a complete antialignment after half of a flip-flop cycle. We compare this evolution with an integration of the 3.5 post-Newtonian equations of motion and spin evolution to show that this process continuously flip flops the spin during the lifetime of the binary until merger. We also provide lower order analytic expressions for the maximum flip-flop angle and frequency. We discuss the effects this dynamics may have on spin growth in accreting binaries and on the observational consequences for galactic and supermassive binary black holes. PMID:25910104

  12. Tonal Flip-Flop in Chinese Dialects.

    ERIC Educational Resources Information Center

    Yue-Hashimoto, Anne O.

    1986-01-01

    Tonal "flip-flop" (reversal of pitch value in which a direct exchange of value between two items is necessarily involved) can be found in a significant number of modern Chinese dialects, where an opposite pitch pattern is observed for the traditional Yin/Yang dichotomy of tones. (Author/CB)

  13. The first close-up of the ``flip-flop'' phenomenon in a single star

    NASA Astrophysics Data System (ADS)

    Korhonen, H.; Berdyugina, S. V.; Strassmeier, K. G.; Tuominen, I.

    2001-11-01

    We present temperature maps of the active late-type giant FK Com which exhibit the first imagining record of the ``flip-flop'' phenomenon in a single star. The phenomenon, in which the main part of the spot activity shifts 180° in longitude, discovered a decade ago in FK Com, was reported later also in a number of RS CVn binaries and a single young dwarf. With the surface images obtained right before and after the ``flip-flop'', we clearly show that the ``flip-flop'' phenomenon in FK Com is caused by changing the relative strengths of the spot groups at the two active longitudes, with no actual spot movements across the stellar surface, i.e. exactly as it happens in other active stars. Based on the observations obtained at the Kitt Peak National Observatory, USA; the Automatic Photometric Telescope, Phoenix 10, Arizona, USA; the Nordic Optical Telescope, Observatorio Roque de los Muchachos, La Palma, Canary Islands, Spain.

  14. Direct Measurement of the Flip-Flop Rate of Electron Spins in the Solid State

    NASA Astrophysics Data System (ADS)

    Dikarov, Ekaterina; Zgadzai, Oleg; Artzi, Yaron; Blank, Aharon

    2016-10-01

    Electron spins in solids have a central role in many current and future spin-based devices, ranging from sensitive sensors to quantum computers. Many of these apparatuses rely on the formation of well-defined spin structures (e.g., a 2D array) with controlled and well-characterized spin-spin interactions. While being essential for device operation, these interactions can also result in undesirable effects, such as decoherence. Arguably, the most important pure quantum interaction that causes decoherence is known as the "flip-flop" process, where two interacting spins interchange their quantum state. Currently, for electron spins, the rate of this process can only be estimated theoretically, or measured indirectly, under limiting assumptions and approximations, via spin-relaxation data. This work experimentally demonstrates how the flip-flop rate can be directly and accurately measured by examining spin-diffusion processes in the solid state for physically fixed spins. Under such terms, diffusion can occur only through this flip-flop-mediated quantum-state exchange and not via actual spatial motion. Our approach is implemented on two types of samples, phosphorus-doped 28Si and nitrogen vacancies in diamond, both of which are significantly relevant to quantum sensors and information processing. However, while the results for the former sample are conclusive and reveal a flip-flop rate of approximately 12.3 Hz, for the latter sample only an upper limit of approximately 0.2 Hz for this rate can be estimated.

  15. A SEU-Hard Flip-Flop for Antifuse FPGAs

    NASA Technical Reports Server (NTRS)

    Katz, R.; Wang, J. J.; McCollum, J.; Cronquist, B.; Chan, R.; Yu, D.; Kleyner, I.; Day, John H. (Technical Monitor)

    2001-01-01

    A single event upset (SEU)-hardened flip-flop has been designed and developed for antifuse Field Programmable Gate Array (FPGA) application. Design and application issues, testability, test methods, simulation, and results are discussed.

  16. A Simple Voltage Controlled Oscillator Using Bootstrap Circuits and NOR-RS Flip Flop

    NASA Astrophysics Data System (ADS)

    Chaikla, Amphawan; Pongswatd, Sawai; Sasaki, Hirofumi; Fujimoto, Kuniaki; Yahara, Mitsutoshi

    This paper presents a simple and successful design for a voltage controlled oscillator. The proposed circuit is based on the use of two identical bootstrap circuits and a NOR-RS Flip Flop to generate wide-tunable sawtooth and square waves. Increasing control voltage linearly increases the output oscillation frequency. Experimental results verifying the performances of the proposed circuit are in agreement with the calculated values.

  17. Active Longitudes and Flip-Flops in Binary Stars

    NASA Astrophysics Data System (ADS)

    Korhonen, Heidi; Järvinen, Silva P.

    2007-08-01

    In many active stars the spots concentrate on two permanent active longitudes which are 180 degrees apart. In some of these stars the dominant part of the spot activity changes the longitude every few years. This so-called flip-flop phenomenon was first reported in the early 1990's in the single, late type giant FK Com. Since then flip-flops have been reported also on binary stars, young solar type stars and the Sun itself. Even though this phenomenon has been detected on many different kinds of active stars, still less than ten stars are known to exhibit this effect. Therefore no statistically significant correlation between the stellar parameters and the flip-flop phenomenon can be carried out. Here we present results from investigation where we have studied the long-term photometry of several magnetically active RS CVn binaries to see whether or not they show permanent active longitudes and the flip-flop phenomenon. We find that it is very common for the active regions to occur on permanent active longitudes, and some of these stars also show clear flip-flop phenomenon.

  18. Unstable flip-flopping spinning binary black holes

    NASA Astrophysics Data System (ADS)

    Lousto, Carlos O.; Healy, James

    2016-06-01

    We provide a unified description of the flip-flop and the antialignment instability effects in spinning black hole binaries in terms of real and imaginary flip-flop frequencies. We find that this instability is only effective for mass ratios 0.5

  19. Effect of flip-flop motion on dielectric spectra of highly ordered liquid crystals

    NASA Astrophysics Data System (ADS)

    Osiecka, N.; Massalska-Arodź, M.; Galewski, Z.; Chłedowska, K.; Bąk, A.

    2015-11-01

    This paper presents studies of dielectric response of chosen Schiff bases, which have similar molecular structures with different isomerizations of an azomethine bridging group, alkyloxy chain length with n =5 or n =6 carbon atoms, and a bromine or chlorine halogen terminal atom. Significant differences in the values of the maximum of dielectric absorption related to flip-flop molecular jumps in hexagonal smectic-BCry phases have been found despite small differences of molecular dipole moments in these substances. This phenomenon is discussed in relation to the possibilities of the creation of dimers and to steric factors favoring motions.

  20. Effect of flip-flop motion on dielectric spectra of highly ordered liquid crystals.

    PubMed

    Osiecka, N; Massalska-Arodź, M; Galewski, Z; Chłędowska, K; Bąk, A

    2015-11-01

    This paper presents studies of dielectric response of chosen Schiff bases, which have similar molecular structures with different isomerizations of an azomethine bridging group, alkyloxy chain length with n=5 or n=6 carbon atoms, and a bromine or chlorine halogen terminal atom. Significant differences in the values of the maximum of dielectric absorption related to flip-flop molecular jumps in hexagonal smectic-B(Cry) phases have been found despite small differences of molecular dipole moments in these substances. This phenomenon is discussed in relation to the possibilities of the creation of dimers and to steric factors favoring motions.

  1. Development of phased twin flip-flop jets

    NASA Technical Reports Server (NTRS)

    Raman, Ganesh; Rice, Edward J.

    1993-01-01

    The flip-flop nozzle is a device that can produce an oscillating jet flow without any moving parts. There is now a renewed interest in such nozzles due to their potential for use as excitation devices in practical applications. An experiment aimed at developing twin flip-flop jets that operate at prescribed frequencies and phase differences was performed. The phasing was achieved using two different nozzle interconnection schemes. In one configuration the two jets flapped in-phase and in another they flapped out-of-phase with respect to each other. In either configuration the frequencies of oscillation of both jets were equal. When one of the jets was run at a constant high velocity and the velocity of the second jet was increased gradually, the higher velocity jet determined the frequency of oscillation of both jets. The two flip-flop jet configurations described could be used to excite a primary jet flow in either an anti-symmetric (sinuous) or a symmetric (varicose) mode.

  2. Design and fabrication of a monolithic two-mode optical flip-flop

    NASA Astrophysics Data System (ADS)

    Jian, Bin

    1997-05-01

    As the information revolution unfolds, there is an explosive growth in transmission bandwidth requirement. It is in turn spurring research efforts around the world to develop new technologies to handle the bandwidth required by the burgeoning multimedia services. Electronic switching systems will be insufficient to handle the huge information flux of future video-based information services, which is why researchers around the world have been actively investigating photonic switching, processing, and control technologies. Photonic technology is widely recognized as the ultimate solution to the communication bandwidth needs of future generations of communications networks. This thesis is part of this global effort. We focus on a particularly promising optical memory device, the two-mode optical flip-flop, which could be a fundamental building block of future switching systems. The operating principles of the flip-flop are laser gain-quenching and saturable absorption. The device can be readily integrated with other photonic circuit elements. We have explored ways to add new functionality to photonic integrated circuits through the use of dry- etched laser facets and waveguides. Research was conducted to improve the existing fabrication process for semiconductor laser devices. A streamlined high- performance fabrication process was obtained. Next, we present a theoretical and experimental study of the tapered waveguide amplifier structure in the two-mode bistable laser. This study may lead to a new class of optical bistability. Finally we describe a detailed investigation of the corner reflector array laser, in which the diffraction principle is demonstrated to be an important and pervasive concept in the design of unguided photonic integrated circuits. The new corner reflector array laser design and the enhanced microfabrication process have led to tremendous improvements in the performance of the two-mode optical flip-flop. Room temperature, CW operation of such a

  3. Asynchronous inputs and flip-flop metastability in the CLAS trigger at CEBAF

    SciTech Connect

    Doughty, D.C. Jr.; Lemon, S. ); Bonneau, P. )

    1993-08-01

    The impact of flip-flop metastability on the pipelined trigger for the CLAS detector at CEBAF has been studied. The authors find that the newest ECL flip-flops (ECLinPS) are much faster than older families (10H) at resolving the metastable condition. This will allow their use in systems with asynchronous inputs without an extra stage of synchronizing flip-flops.

  4. Asynchronous inputs and flip-flop metastability in the CLAS trigger at CEBAF

    SciTech Connect

    Dave Doughty; S. Lemon; P. Bonneau

    1992-10-01

    The impact of flip-flop metastability on the pipelined trigger for the CLAS detector at CEBAF (Continuous Electron Beam Accelerator Facility) has been studied. It is found that the newest ECL (emitter coupled logic) flip-flops (ECLinPS) are much faster than older families at resolving the metastable condition. This will allow their use in systems with asynchronous inputs without an extra stage of synchronizing flip-flops.

  5. Phospholipid Flip-flop Modulated by Transmembrane Peptides WALP and Melittin

    PubMed Central

    Anglin, Timothy C.; Brown, Krystal L.; Conboy, John C.

    2010-01-01

    Select transmembrane proteins found in biogenic membranes are known to facilitate rapid bidirectional flip-flop of lipids between the membrane leaflets, while others have no little or no effect. The particular characteristics which determine the extent to which a protein will facilitate flip-flop are still unknown. To determine if the relative polarity of the transmembrane protein segment influences its capacity for facilitation of flip-flop, we have studied lipid flip-flop dynamics for bilayers containing the peptides WALP23 and melittin. WALP23 is used as a model hydrophobic peptide, while melittin consists of both hydrophobic and hydrophilic residues. Sum-frequency vibrational spectroscopy (SFVS) was used to characterize the bilayers and determine the kinetics of flip-flop for the lipid component, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), within the mixed bilayers. The kinetics data were utilized to determine the activation thermodynamics for DSPC flip-flop in the presence of the peptides. Melittin was found to significantly reduce the free energy barrier to DSPC flip-flop when incorporated into the bilayer at 1 mol%, while incorporation of WALP23 at the same concentration led to a more modest reduction of the free energy barrier. The possible mechanisms by which these peptides facilitate flip-flop are analyzed and discussed in terms of the observed activation thermodynamics. PMID:19508895

  6. Flip-Flop Recovery System for sounding rocket payloads

    NASA Technical Reports Server (NTRS)

    Flores, A., Jr.

    1986-01-01

    The design, development, and testing of the Flip-Flop Recovery System, which protects sensitive forward-mounted instruments from ground impact during sounding rocket payload recovery operations, are discussed. The system was originally developed to reduce the impact damage to the expensive gold-plated forward-mounted spectrometers in two existing Taurus-Orion rocket payloads. The concept of the recovery system is simple: the payload is flipped over end-for-end at a predetermined time just after parachute deployment, thus minimizing the risk of damage to the sensitive forward portion of the payload from ground impact.

  7. Flip-flop pharmacokinetics – delivering a reversal of disposition: challenges and opportunities during drug development

    PubMed Central

    Yáñez, Jaime A; Remsberg, Connie M; Sayre, Casey L; Forrest, M Laird; Davies, Neal M

    2011-01-01

    Flip-flop pharmacokinetics is a phenomenon often encountered with extravascularly administered drugs. Occurrence of flip-flop spans preclinical to human studies. The purpose of this article is to analyze both the pharmacokinetic interpretation errors and opportunities underlying the presence of flip-flop pharmacokinetics during drug development. Flip-flop occurs when the rate of absorption is slower than the rate of elimination. If it is not recognized, it can create difficulties in the acquisition and interpretation of pharmacokinetic parameters. When flip-flop is expected or discovered, a longer duration of sampling may be necessary in order to avoid overestimation of fraction of dose absorbed. Common culprits of flip-flop disposition are modified dosage formulations; however, formulation characteristics such as the drug chemical entities themselves or the incorporated excipients can also cause the phenomenon. Yet another contributing factor is the physiological makeup of the extravascular site of administration. In this article, these causes of flip-flop pharmacokinetics are discussed with incorporation of relevant examples and the implications for drug development outlined. PMID:21837267

  8. Photo-induced flip-flop of membrane markers monitored by SHG microscopy

    NASA Astrophysics Data System (ADS)

    Pons, Thomas; Mertz, Jerome

    2003-10-01

    Photoisomerization properties of amphiphilic stilbazolium markers are used to provoke photo-induced flip-flop in model lipid bilayer membranes. The flip-flop mechanism and dynamics are determined using simultaneous two-photon excited fluorescence and second harmonic generation microscopy. In absence of illumination, trans- is the dominant conformation, however when an illumination pulse is applied to the membrane markers, photo-induced isomerization provokes a significant increase in the cis- population, whose flip-flop rate was determined to be at least a thousand times greater than that for the trans- marker. Following the illumination pulse, all markers rapidly relax to the trans-conformation.

  9. Rapid flip-flop motions of diacylglycerol and ceramide in phospholipid bilayers

    NASA Astrophysics Data System (ADS)

    Ogushi, Fumiko; Ishitsuka, Reiko; Kobayashi, Toshihide; Sugita, Yuji

    2012-01-01

    We have investigated flip-flop motions of diacylglycerol and ceramide in phospholipid bilayers using coarse-grained molecular dynamics simulations. In the simulations, flip-flop motions of diacylglycerol and ceramide in the DAPC membrane are slower than cholesterol. Rates correlate with the number of unsaturated bonds in the membrane phospholipids and hence with fluidity of membranes. These findings qualitatively agree with corresponding experimental data. Statistical analysis of the trajectories suggests that flip-flop can be approximated as a Poisson process. The rate of the transverse movement is influenced by depth of the polar head group in the membrane and extent of interaction with water.

  10. UVP Measurements on Periodic Flow in a Flip-Flop Jet Nozzle

    NASA Astrophysics Data System (ADS)

    Funaki, Jiro; Matsuda, Hiroyuki; Inoue, Tatsuya; Tanigawa, Hirochika; Hirata, Katsuya

    This research deals with the switching mechanism of a flip-flop jet nozzle with a connecting tube, being based on the measurements of pressure in two chambers, velocity in the connecting tube and velocity distribution between two inside walls of the nozzle, i.e., reattachment walls. The authors particularly focus upon the details of switching flow field inside the nozzle, using a ultrasound-velocity-profile monitor (UVP monitor). As a result, two re-circulating flows, viz., two vortical structures, are shown on both side walls inside the nozzle. By means of the simultaneous observation of chamber pressures and connecting-tube velocity with UVP results, we show a coherent scenario of the jet-oscillation phenomenon in concern.

  11. On the fly all-optical packet switching based on hybrid WDM/OCDMA labeling scheme

    NASA Astrophysics Data System (ADS)

    Brahmi, Houssem; Giannoulis, Giannis; Menif, Mourad; Katopodis, Vasilis; Kalavrouziotis, Dimitrios; Kouloumentas, Christos; Groumas, Panos; Kanakis, Giannis; Stamatiadis, Christos; Avramopoulos, Hercules; Erasme, Didier

    2014-02-01

    We introduce a novel design of an all-optical packet routing node that allows for the selection and forwarding of optical packets based on the routing information contained in hybrid wavelength division multiplexing/optical code division multiple access (WDM/OCDMA) labels. A stripping paradigm of optical code-label is adopted. The router is built around an optical-code gate that consists in an optical flip-flop controlled by two fiber Bragg grating correlators and is combined with a Mach-Zehnder interferometer (MZI)-based forwarding gate. We experimentally verify the proof-of-principle operation of the proposed self-routing node under NRZ and OCDMA packet traffic conditions. The successful switching of elastic NRZ payload at 40 Gb/s controlled by DS-OCDMA coded labels and the forwarding operation of encoded data using EQC codes are presented. Proper auto-correlation functions are obtained with higher than 8.1 dB contrast ratio, suitable to efficiently trigger the latching device with a contrast ratio of 11.6 dB and switching times below 3.8 ns. Error-free operation is achieved with 1.5 dB penalty for 40 Gb/s NRZ data and with 2.1 dB penalty for DS-OCDMA packets. The scheme can further be applied to large-scale optical packet switching networks by exploiting efficient optical coders allocated at different WDM channels.

  12. Optical flip-flops and sequential logic circuits using a liquid crystal light valve

    NASA Technical Reports Server (NTRS)

    Fatehi, M. T.; Collins, S. A., Jr.; Wasmundt, K. C.

    1984-01-01

    This paper is concerned with the application of optics to digital computing. A Hughes liquid crystal light valve is used as an active optical element where a weak light beam can control a strong light beam with either a positive or negative gain characteristic. With this device as the central element the ability to produce bistable states from which different types of flip-flop can be implemented is demonstrated. In this paper, some general comments are first presented on digital computing as applied to optics. This is followed by a discussion of optical implementation of various types of flip-flop. These flip-flops are then used in the design of optical equivalents to a few simple sequential circuits such as shift registers and accumulators. As a typical sequential machine, a schematic layout for an optical binary temporal integrator is presented. Finally, a suggested experimental configuration for an optical master-slave flip-flop array is given.

  13. The flip-flop nozzle extended to supersonic flows

    NASA Technical Reports Server (NTRS)

    Raman, Ganesh; Hailye, Michael; Rice, Edward J.

    1992-01-01

    An experiment studying a fluidically oscillated rectangular jet flow was conducted. The Mach number was varied over a range from low subsonic to supersonic. Unsteady velocity and pressure measurements were made using hot wires and piezoresistive pressure transducers. In addition smoke flow visualization using high speed photography was used to document the oscillation of the jet. For the subsonic flip-flop jet it was found that the apparent time-mean widening of the jet was not accompanied by an increase in mass flux. It was found that it is possible to extend the operation of these devices to supersonic flows. Most of the measurements were made for a fixed nozzle geometry for which the oscillations ceased at a fully expanded Mach number of 1.58. By varying the nozzle geometry this limitation was overcome and operation was extended to Mach 1.8. The streamwise velocity perturbation levels produced by this device were much higher than the perturbation levels that could be produced using conventional excitation sources such as acoustic drivers. In view of this ability to produce high amplitudes, the potential for using small scale fluidically oscillated jet as an unsteady excitation source for the control of shear flows in full scale practical applications seems promising.

  14. The flip flop nozzle extended to supersonic flows

    NASA Technical Reports Server (NTRS)

    Raman, Ganesh; Hailye, Michael; Rice, Edward J.

    1992-01-01

    An experiment studying a fluidically oscillated rectangular jet flow was conducted. The Mach number was varied over a range from low subsonic to supersonic. Unsteady velocity and pressure measurements were made using hot wires and piezoresistive pressure transducers. In addition smoke flow visualization using high speed photography was used to document the oscillation of the jet. For the subsonic flip-flop jet it was found that the apparent time-mean widening of the jet was not accompanied by an increase in mass flux. It was found that it is possible to extend the operation of these devices to supersonic flows. Most of the measurements were made for a fixed nozzle geometry for which the oscillations ceased at a fully expanded Mach number of 1.58. By varying the nozzle geometry this limitation was overcome and operation was extended to Mach 1.8. The streamwise velocity perturbation levels produced by this device were much higher than the perturbation levels that could be produced using conventional excitation sources such as acoustic drivers. In view of this ability to produce high amplitudes, the potential for using small scale fluidically oscillated jet as an unsteady excitation source for the control of shear flows in full scale practical applications seems promising.

  15. Shock-induced poration, cholesterol flip-flop and small interfering RNA transfection in a phospholipid membrane: Multimillion atom, microsecond molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Choubey, Amit

    Biological cell membranes provide mechanical stability to cells and understanding their structure, dynamics and mechanics are important biophysics problems. Experiments coupled with computational methods such as molecular dynamics (MD) have provided insight into the physics of membranes. We use long-time and large-scale MD simulations to study the structure, dynamics and mechanical behavior of membranes. We investigate shock-induced collapse of nanobubbles in water using MD simulations based on a reactive force field. We observe a focused jet at the onset of bubble shrinkage and a secondary shock wave upon bubble collapse. The jet length scales linearly with the nanobubble radius, as observed in experiments on micron-to-millimeter size bubbles. Shock induces dramatic structural changes, including an ice-VII-like structural motif at a particle velocity of 1 km/s. The incipient ice VII formation and the calculated Hugoniot curve are in good agreement with experimental results. We also investigate molecular mechanisms of poration in lipid bilayers due to shock-induced collapse of nanobubbles. Our multimillion-atom MD simulations reveal that the jet impact generates shear flow of water on bilayer leaflets and pressure gradients across them. This transiently enhances the bilayer permeability by creating nanopores through which water molecules translocate rapidly across the bilayer. Effects of nanobubble size and temperature on the porosity of lipid bilayers are examined. The second research project focuses on cholesterol (CHOL) dynamics in phospholipid bilayers. Several experimental and computational studies have been performed on lipid bilayers consisting of dipalmitoylphosphatidylcholine (DPPC) and CHOL molecules. CHOL interleaflet transport (flip-flop) plays an important role in interleaflet coupling and determining CHOL flip-flop rate has been elusive. Various studies report that the rate ranges between milliseconds to seconds. We calculate CHOL flip-flop rates by

  16. The components of an optical RS flip-flop for an integrated optical processor

    NASA Astrophysics Data System (ADS)

    Parker, Michael A.; Libby, Stuart I.; Swanson, Paul D.

    1992-07-01

    This report discusses the design, fabrication and test of an optical RS Flip-Flop as an integrated optical memory element. The Flip-Flop has three GaAs-AlGaAs heterostructure lasers with total internal reflection mirrors. A main laser incorporates a saturable absorber to develop the bistable output characteristics. A pump laser bleaches the absorber to set the logic 1 state. A third laser quenches the main laser to reset the device to logic 0. Experiments and data for the laser quenching and bistability are presented.

  17. Evaluation of flip-flop jet nozzles for use as practical excitation devices

    NASA Technical Reports Server (NTRS)

    Raman, Ganesh; Rice, Edward J.; Cornelius, David M.

    1994-01-01

    This paper describes the flowfield characteristics of the flip-flop jet nozzle and the potential for using this nozzle as a practical excitation device. It appears from the existing body of published information that there is a lack of data on the parameters affecting the operation of such nozzles and on the mechanism of operation of these nozzles. An attempt is made in the present work to study the important parameters affecting the operation and performance of a flip-flop jet nozzle. Measurements were carried out to systematically assess the effect of varying the nozzle pressure ratio (NPR) as well as the length and volume of the feedback tube on the frequency of oscillation of this device. Flow visualization was used to obtain a better understanding of the jet flowfield and of the processes occurring within the feedback tube. The frequency of oscillation of the flip-flop jet depended significantly on the feedback tube length and volume as well as on the nozzle pressure ratio. In contrast, the coherent velocity perturbation levels did not depend on the above mentioned parameters. The data presented in this paper would be useful for modeling such flip-flop excitation devices that are potentially useful for controlling practical shear flows.

  18. Structural Basis for Flip-Flop Action of Thiamin Pyrophosphate-Dependent Enzymes Revealed by Human Pyruvate Dehydrogenase

    NASA Technical Reports Server (NTRS)

    Dominiak, Paulina; Ciszak, Ewa M.; Korotchkina, Lioubov; Sidhu, Sukhdeep; Patel, Mulchand

    2003-01-01

    Thiamin pyrophosphate (TPP), the biologically active form of vitamin BI, is a cofactor of enzymes catalyzing reactions involving the cleavage of a carbon-carbon bond adjacent to an oxo group. TPP-dependent enzymes show a common mechanism of TPP activation by: (1) forming the ionic N-H...O(sup -) hydrogen bonding between the N1' atom of the aminopirymidine ring of the coenzyme and intrinsic gamma-carboxylate group of glutamate and (2) imposing an "active" V-conformation that brings the N4' atom of the aminopirymidine to the distance required for the intramolecular C-H.. .N hydrogen bonding with the thiazolium C2 atom. Within these two hydrogen bonds that rapidly exchange protons, protonation of the N1' atom is strictly coordinated with the deprotonation of the 4' -amino group and eventually abstraction of the proton from C2. The human pyruvate dehydrogenase Elp, component of human pyruvate dehydrogenase complex, catalyzes the irreversible decarboxylation of the pyruvate followed by the reductive acetylation of the lipoyl group of dihydrolipoyl acyltransferase. Elp is alpha(sub 2)beta(sub2)-heterotetrameric with a molecular mass of I54 kDa, which has two catalytic sites, each providing TPP and magnesium ion as cofactors and each formed on the interface between the PP and PYR domains. The dynamic nonequivalence of two otherwise chemically equivalent catalytic sites has been observed and the flip-flop mechanism was suggested, according to which two active sites affect each other and in which different steps of the catalytic reaction are performed in each of the sites at any given moment. Based on specific futures of human pyruvate dehydrogenase including rigid and flexible connections between domains that bind the cofactor we propose a mechanistic model for the flip-flop action of this enzyme. We postulate that the dynamic protein environment drives the exchange of tautomers in the 4' -aminopyrimidine ring of the cofactor through a concerted shuttl-like motion of

  19. State retention flip flop architectures with different tradeoffs using crystalline indium gallium zinc oxide transistors implemented in a 32-bit normally-off microprocessor

    NASA Astrophysics Data System (ADS)

    Sjökvist, Niclas; Ohmaru, Takuro; Isobe, Atsuo; Tsutsui, Naoaki; Tamura, Hikaru; Uesugi, Wataru; Ishizu, Takahiko; Onuki, Tatsuya; Ohshima, Kazuaki; Matsuzaki, Takanori; Mimura, Hidetoshi; Hirose, Atsushi; Suzuki, Yasutaka; Ieda, Yoshinori; Atsumi, Tomoaki; Shionoiri, Yutaka; Kato, Kiyoshi; Goto, Gensuke; Koyama, Jun; Fujita, Masahiro; Yamazaki, Shunpei

    2014-01-01

    As leakage power continues to increase when transistor sizes are downscaled, it becomes increasingly hard to achieve low power consumption in modern chips. Normally-off processors use state-retention and non-volatile circuits to make power gating more efficient with less static power. In this paper, we propose two novel state-retention flip-flop designs based on a parallel and series retention circuit architectures utilizing crystalline indium gallium zinc oxide transistors, which can achieve state retention with zero static power. To demonstrate the application of these different designs, they are implemented in a 32-bit normally-off microprocessor with an energy break-even time of 1.47 µs for the parallel type design and 0.93 µs for the series type design, at a clock frequency of 15 MHz. We show that decreasing the power supply duty cycle to 0.9%, the average current of the processor core can be decreased by over 99% using either type of flip-flop.

  20. Structural Model for the Flip-Flop Action in Thiamin Pyrophosphate-Dependent Human Pyruvate Dehydrogenase

    NASA Technical Reports Server (NTRS)

    Ciszak, Ewa; Dominiak, Paulina

    2003-01-01

    The derivative of vitamin B1 thiamin pyrophosphate (TPP) is a cofactor of enzymes performing catalysis in pathways of energy production, including (i) decarboxylation of alpha-keto acids followed by (ii) transketolation. These enzymes have shown a common mechanism of TPP activation by imposing an active V-conformation of this coenzyme that brings the N4 atom of the aminopyrimidine ring to the distance required for the intramolecular C-H N hydrogen-bonding with the C2- atom of the thiazolium ring. The reactive C2 atom of TPP is the nucleophile that attacks the carbonyl carbon of different substrates used by the TPP-dependent enzymes. The structure of the heterotetrameric human pyruvate dehydrogenase (Elp) recently determined in our laboratory (1) revealed the association pattern of the subunits and the specifics of two chemically equivalent cofactor binding sites. Dynamic nonequivalence of these two cofactor sites directs the flip-flop action of this enzyme, depending upon which two active sites effect each other (2). The crystal structure derived from the holo-form of Elp provided the basis for the model of the flip-flop action of Elp in which different steps of the catalytic reaction are performed in each of the two cofactor sites at any given moment, where these steps are governed by the concerted shuttle-like motion of the subunits. It is further proposed that balancing a hydrogen-bond network and related cofactor geometry determine the continuity of catalytic events.

  1. Nanoparticle permeation induces water penetration, ion transport, and lipid flip-flop.

    PubMed

    Song, Bo; Yuan, Huajun; Pham, Sydney V; Jameson, Cynthia J; Murad, Sohail

    2012-12-11

    Nanoparticles are generally considered excellent candidates for targeted drug delivery. However, ion leakage and cytotoxicity induced by nanoparticle permeation is a potential problem in such drug delivery schemes because of the toxic effect of many ions. In this study, we have carried out a series of coarse-grained molecular dynamics simulations to investigate the water penetration, ion transport, and lipid molecule flip-flop in a protein-free phospholipid bilayer membrane during nanoparticle permeation. The effect of ion concentration gradient, pressure differential across the membrane, nanoparticle size, and permeation velocity have been examined in this work. Some conclusions from our studies include (1) The number of water molecules in the interior of the membrane during the nanoparticle permeation increases with the nanoparticle size and the pressure differential across the membrane but is unaffected by the nanoparticle permeation velocity or the ion concentration gradient. (2) Ion transport is sensitive to the size of nanoparticle as well as the ion concentration gradient between two sides of the membrane; no anion/cation selectivity is observed for small nanoparticle permeation, while anions are preferentially translocated through the membrane when the size of nanoparticle is large enough. (3) Incidences of lipid molecule flip-flop increases with the size of nanoparticle and ion concentration gradient and decreases with the pressure differential and the nanoparticle permeation velocity.

  2. Practical applications of digital integrated circuits. Part 2: Minimization techniques, code conversion, flip-flops, and asynchronous circuits

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Here, the 7400 line of transistor to transistor logic (TTL) devices is emphasized almost exclusively where hardware is concerned. However, it should be pointed out that the logic theory contained herein applies to all hardware. Binary numbers, simplification of logic circuits, code conversion circuits, basic flip-flop theory, details about series 54/7400, and asynchronous circuits are discussed.

  3. Coupled Flip-Flop Model for REM Sleep Regulation in the Rat

    PubMed Central

    Dunmyre, Justin R.; Mashour, George A.; Booth, Victoria

    2014-01-01

    Recent experimental studies investigating the neuronal regulation of rapid eye movement (REM) sleep have identified mutually inhibitory synaptic projections among REM sleep-promoting (REM-on) and REM sleep-inhibiting (REM-off) neuronal populations that act to maintain the REM sleep state and control its onset and offset. The control mechanism of mutually inhibitory synaptic interactions mirrors the proposed flip-flop switch for sleep-wake regulation consisting of mutually inhibitory synaptic projections between wake- and sleep-promoting neuronal populations. While a number of synaptic projections have been identified between these REM-on/REM-off populations and wake/sleep-promoting populations, the specific interactions that govern behavioral state transitions have not been completely determined. Using a minimal mathematical model, we investigated behavioral state transition dynamics dictated by a system of coupled flip-flops, one to control transitions between wake and sleep states, and another to control transitions into and out of REM sleep. The model describes the neurotransmitter-mediated inhibitory interactions between a wake- and sleep-promoting population, and between a REM-on and REM-off population. We proposed interactions between the wake/sleep and REM-on/REM-off flip-flops to replicate the behavioral state statistics and probabilities of behavioral state transitions measured from experimental recordings of rat sleep under ad libitum conditions and after 24 h of REM sleep deprivation. Reliable transitions from REM sleep to wake, as dictated by the data, indicated the necessity of an excitatory projection from the REM-on population to the wake-promoting population. To replicate the increase in REM-wake-REM transitions observed after 24 h REM sleep deprivation required that this excitatory projection promote transient activation of the wake-promoting population. Obtaining the reliable wake-nonREM sleep transitions observed in the data required that

  4. Coupled flip-flop model for REM sleep regulation in the rat.

    PubMed

    Dunmyre, Justin R; Mashour, George A; Booth, Victoria

    2014-01-01

    Recent experimental studies investigating the neuronal regulation of rapid eye movement (REM) sleep have identified mutually inhibitory synaptic projections among REM sleep-promoting (REM-on) and REM sleep-inhibiting (REM-off) neuronal populations that act to maintain the REM sleep state and control its onset and offset. The control mechanism of mutually inhibitory synaptic interactions mirrors the proposed flip-flop switch for sleep-wake regulation consisting of mutually inhibitory synaptic projections between wake- and sleep-promoting neuronal populations. While a number of synaptic projections have been identified between these REM-on/REM-off populations and wake/sleep-promoting populations, the specific interactions that govern behavioral state transitions have not been completely determined. Using a minimal mathematical model, we investigated behavioral state transition dynamics dictated by a system of coupled flip-flops, one to control transitions between wake and sleep states, and another to control transitions into and out of REM sleep. The model describes the neurotransmitter-mediated inhibitory interactions between a wake- and sleep-promoting population, and between a REM-on and REM-off population. We proposed interactions between the wake/sleep and REM-on/REM-off flip-flops to replicate the behavioral state statistics and probabilities of behavioral state transitions measured from experimental recordings of rat sleep under ad libitum conditions and after 24 h of REM sleep deprivation. Reliable transitions from REM sleep to wake, as dictated by the data, indicated the necessity of an excitatory projection from the REM-on population to the wake-promoting population. To replicate the increase in REM-wake-REM transitions observed after 24 h REM sleep deprivation required that this excitatory projection promote transient activation of the wake-promoting population. Obtaining the reliable wake-nonREM sleep transitions observed in the data required that

  5. High magnetic field induced spin flip/flop behavior and magnetic phase diagram of CuFe{sub 1−x}Ga{sub x}O{sub 2}

    SciTech Connect

    Shi, L.R.; Xia, Z.C.; Jin, Z.; Wei, M.; Huang, J.W.; Chen, B.R.; Xiao, L.X.; Zuo, H.K.; Ouyang, Z.W.

    2014-11-15

    The structure and magnetic properties of non-magnetic Ga{sup 3+} ion doped CuFe{sub 1−x}Ga{sub x}O{sub 2} (x=0, 0.03, and 0.05) single crystal samples were investigated. X-ray diffraction patterns analysis confirms that the samples are single-phase crystallizing. Doping effect on the magnetic behavior of the ground state and the field-induced spin flip/flop transitions were detected. The transition temperatures and critical magnetic fields of the spin flip/flop, as well as the magnetic hysteresis directly depend on the Ga{sup 3+} doping level. Such doping effects may associate with the competition between dilution effect (partial release of spin frustration) and the induced local magnetic moment, which is the result of the changed magnetic coupling both inter- and intra-planes of Fe ions. Based on the experimental results, the effects of Ga{sup 3+} doping on the spin flip/flop behavior and a detailed high field magnetic diagram were assumed. - Graphical abstract: Temperature dependence of the critical fields for CuFe{sub 1−x}Ga{sub x}O{sub 2} (x=0, 0.03, 0.05). (a) and (b) The magnetic field's parallel and perpendicular cases respectively. In which, the square, circle and triangular represent x=0, 0.03 and 0.05 respectively. - Highlights: • Single crystal samples of CuFe{sub 1−x}Ga{sub x}O{sub 2} (x=0, 0.03 and 0.05) were grown. • Magnetic field dependence of magnetization was measured in pulsed high magnetic field up to 54 T with different temperatures. • The magnetic field induced multi-step-like transitions were observed in all the single crystal samples. • A detailed magnetic diagram was assumed based on the experimental results.

  6. Type II secretory phospholipase A2 binds to ischemic flip-flopped cardiomyocytes and subsequently induces cell death.

    PubMed

    Nijmeijer, R; Willemsen, M; Meijer, C J L M; Visser, C A; Verheijen, R H; Gottlieb, R A; Hack, C E; Niessen, H W M

    2003-11-01

    Type II secretory phospholipase A2 (sPLA2) is a cardiovascular risk factor. We recently found depositions of sPLA2 in the necrotic center of infarcted human myocardium and normally appearing cardiomyocytes adjacent to the border zone. The consequences of binding of sPLA2 to ischemic cardiomyocytes are not known. To explore a potential effect of sPLA2 on ischemic cardiomyocytes at a cellular level we used an in vitro model. The cardiomyocyte cell line H9c2 or adult cardiomyocytes were isolated from rabbits that were incubated with sPLA2 in the presence of metabolic inhibitors to mimic ischemia-reperfusion conditions. Cell viability was established with the use of annexin V and propidium iodide or 7-aminoactinomycin D. Metabolic inhibition induced an increase of the number of flip-flopped cells, including a population that did not stain with propidium iodide and that was caspase-3 negative. sPLA2 bound to the flip-flopped cells, including those negative for caspase-3. sPLA2 binding induced cell death in these latter cells. In addition, sPLA2 potentiated the binding of C-reactive protein (CRP) to these cells. We conclude that by binding to flip-flopped cardiomyocytes, including those that are caspase-3 negative and presumably reversibly injured, sPLA2 may induce cell death and tag these cells with CRP.

  7. Ferroelectricity and polarity control in solid-state flip-flop supramolecular rotators

    NASA Astrophysics Data System (ADS)

    Akutagawa, Tomoyuki; Koshinaka, Hiroyuki; Sato, Daisuke; Takeda, Sadamu; Noro, Shin-Ichiro; Takahashi, Hiroyuki; Kumai, Reiji; Tokura, Yoshinori; Nakamura, Takayoshi

    2009-04-01

    Molecular rotation has attracted much attention with respect to the development of artificial molecular motors, in an attempt to mimic the intelligent and useful functions of biological molecular motors. Random motion of molecular rotators-for example the 180∘ flip-flop motion of a rotatory unit-causes a rotation of the local structure. Here, we show that such motion is controllable using an external electric field and demonstrate how such molecular rotators can be used as polarization rotation units in ferroelectric molecules. In particular, m-fluoroanilinium forms a hydrogen-bonding assembly with dibenzo[18]crown-6, which was introduced as the counter cation of [Ni(dmit)2]- anions (dmit2-=2-thioxo-1,3-dithiole-4,5-dithiolate). The supramolecular rotator of m-fluoroanilinium exhibited dipole rotation by the application of an electric field, and the crystal showed a ferroelectric transition at 348K. These findings will open up new strategies for ferroelectric molecules where a chemically designed dipole unit enables control of the nature of the ferroelectric transition temperature.

  8. Hemispherical and Longitudinal Asymmetries in the Heliospheric Magnetic Field: Flip-flops of a Bashful Ballerina

    NASA Astrophysics Data System (ADS)

    Hiltula, T.; Mursula, K.

    2004-12-01

    Several studies during many decennia have studied possible longitudinal and hemispherical asymmetries in various forms of solar activity. E.g., there are well known periods when one of the solar hemispheres has dominated the other in sunspot numbers, flare occurrence or some other form of solar activity. However, the solar asymmetries have not been found to be very conclusive, or to form any clear systematical patterns (e.g., relation to solar cycle). On the contrary, recent studies of similar longitudinal and hemispherical asymmetries in the heliospheric magnetic field have shown a very clear and systematic behaviour. E.g., it was found recently that the dominance of the two HMF sectors experiences an oscillation with a period of about 3.2 years. This new flip-flop periodicity in the heliospheric magnetic field is most likely related to a similar periodicity recently found in sunspots. Also, it has recently been found that the HMF sector coming from the northern solar hemisphere systematically dominates at 1AU during solar minimum times. This leads to a persistent southward shift or coning of the heliospheric current sheet at these times that can be picturesquely described by the concept of a Bashful Ballerina. This result also implies that the Sun has a large-scale quadrupole magnetic moment. Here we review these recent developments concerning the longitudinal and hemispherical asymmetries in the heliospheric magnetic field and study their inter-connection.

  9. On the Motions of an Oscillating System Under the Influence of Flip-Flop Controls

    NASA Technical Reports Server (NTRS)

    Fluegge-Lotz, I.; Klotter, K.

    1949-01-01

    So-called flip-flop controls (also called "on-off-course controls") are frequently preferred to continuous controls because of their simple construction. Thus they are used also for the steering control of airplanes. Such a body possesses-even if one thinks, for instance, only of the symmetric longitudinal motion - three degrees of freedom so that a study of its motions under the influence of an intermittent control is at least lengthy. Thus, it is suggested that an investigation of the basic effect of such a control first be made on a system with one degree of freedom. Furthermore, we limit ourselves in the resent report to the investigation of an "ideal" control where the control surface immediately obeys the command given by the "steering control function". Thus the oscillation properties of the control surface and the defects in linkage, sensing element, and mixing device are, at first, neglected. As long as the deviations from the "ideal" control may be neglected in practice, also the motion of the control surface takes place at the heat of the motion of the principal system. The aim of our investigation is to obtain a survey of the influence of the system and control coefficients on the damping behavior which is to be attained.

  10. Quantum random flip-flop and its applications in random frequency synthesis and true random number generation.

    PubMed

    Stipčević, Mario

    2016-03-01

    In this work, a new type of elementary logic circuit, named random flip-flop (RFF), is proposed, experimentally realized, and studied. Unlike conventional Boolean logic circuits whose action is deterministic and highly reproducible, the action of a RFF is intentionally made maximally unpredictable and, in the proposed realization, derived from a fundamentally random process of emission and detection of light quanta. We demonstrate novel applications of RFF in randomness preserving frequency division, random frequency synthesis, and random number generation. Possible usages of these applications in the information and communication technology, cryptographic hardware, and testing equipment are discussed. PMID:27036825

  11. Quantum random flip-flop and its applications in random frequency synthesis and true random number generation.

    PubMed

    Stipčević, Mario

    2016-03-01

    In this work, a new type of elementary logic circuit, named random flip-flop (RFF), is proposed, experimentally realized, and studied. Unlike conventional Boolean logic circuits whose action is deterministic and highly reproducible, the action of a RFF is intentionally made maximally unpredictable and, in the proposed realization, derived from a fundamentally random process of emission and detection of light quanta. We demonstrate novel applications of RFF in randomness preserving frequency division, random frequency synthesis, and random number generation. Possible usages of these applications in the information and communication technology, cryptographic hardware, and testing equipment are discussed.

  12. Spontaneous changes in contact angle of water and oil on novel flip-flop-type hydrophobic multilayer coatings

    NASA Astrophysics Data System (ADS)

    Kawamura, Go; Ema, Tomoyuki; Sakamoto, Hisatoshi; Wei, Xing; Muto, Hiroyuki; Matsuda, Atsunori

    2014-04-01

    Multilayer structures composed of poly(allylamine hydrochloride) (PAH) and Nafion were fabricated on glass substrates by layer-by-layer assembly. Some of the multilayers demonstrated spontaneous changes in contact angle of water and oil due to flip-flop movements of free sulfo groups in the Nafion layer, and the multilayers eventually possessed water repellency in air and oil repellency in water. The repellencies were enhanced by applying primer layers that were formed using SiO2 fine particles to increase surface roughness. Compared to typical hydrophobic and oleophobic surfaces, the multilayers showed practical levels for a use as soil release coatings.

  13. Quantum random flip-flop and its applications in random frequency synthesis and true random number generation

    NASA Astrophysics Data System (ADS)

    Stipčević, Mario

    2016-03-01

    In this work, a new type of elementary logic circuit, named random flip-flop (RFF), is proposed, experimentally realized, and studied. Unlike conventional Boolean logic circuits whose action is deterministic and highly reproducible, the action of a RFF is intentionally made maximally unpredictable and, in the proposed realization, derived from a fundamentally random process of emission and detection of light quanta. We demonstrate novel applications of RFF in randomness preserving frequency division, random frequency synthesis, and random number generation. Possible usages of these applications in the information and communication technology, cryptographic hardware, and testing equipment are discussed.

  14. All-optical controlling based on nonlinear graphene plasmonic waveguides.

    PubMed

    Li, Jian; Tao, Jin; Chen, Zan Hui; Huang, Xu Guang

    2016-09-19

    We give the effective refractive index of graphene plasmonic waveguides with both linear and nonlinear effects based on the nonlinear cross-phase modulation, and address the effects of photo-induced refractive index change and absorption change. A non-resonant all-optical nonlinear graphene plasmonic switch with an ultra-compact size of 0.25 μm2 is proposed and numerically analyzed based on the dynamics of the photo-induced absorption change. The results show that the all-optical graphene plasmonic switch can realize a broad bandwidth over 5 THz, a potentially very high switching speed and an extinction ratio of 18.14 dB with the electric amplitude of the pump light of 1.5 × 107 V/m at the signal frequency of 28 THz. Our study could provide a possibility for future all-optical highly integrated optical components. PMID:27661951

  15. All-optical depth coloring based on directional gating.

    PubMed

    Lim, Sungjin; Kim, Mugeon; Hahn, Joonku

    2016-09-19

    In non-contacting depth extraction there are several issues, such as the accuracy and the measurement speed. In the issue of the measurement speed, the computation cost for image processing is significant. We present an all-optical depth extraction method by coloring objects according to their depth. Our system is operated fully optically and both encoding and decoding processes are optically performed. Therefore, all-optical depth coloring has a distinct advantage to extract the depth information in real time without any computation cost. We invent a directional gating method to extract the points from the object which are positioned at the same distance. Based on this method, the objects look painted by different colors according to the distance when the objects are observed through our system. In this paper, we demonstrate the all-optical depth coloring system and verify the feasibility of our method. PMID:27661875

  16. All-optical pseudorandom bit sequences generator based on TOADs

    NASA Astrophysics Data System (ADS)

    Sun, Zhenchao; Wang, Zhi; Wu, Chongqing; Wang, Fu; Li, Qiang

    2016-03-01

    A scheme for all-optical pseudorandom bit sequences (PRBS) generator is demonstrated with optical logic gate 'XNOR' and all-optical wavelength converter based on cascaded Tera-Hertz Optical Asymmetric Demultiplexer (TOADs). Its feasibility is verified by generation of return-to-zero on-off keying (RZ-OOK) 263-1 PRBS at the speed of 1 Gb/s with 10% duty radio. The high randomness of ultra-long cycle PRBS is validated by successfully passing the standard benchmark test.

  17. Effect of thong style flip-flops on children’s barefoot walking and jogging kinematics

    PubMed Central

    2013-01-01

    Background Thong style flip-flops are a popular form of footwear for children. Health professionals relate the wearing of thongs to foot pathology and deformity despite the lack of quantitative evidence to support or refute the benefits or disadvantages of children wearing thongs. The purpose of this study was to compare the effect of thong footwear on children’s barefoot three dimensional foot kinematics during walking and jogging. Methods Thirteen healthy children (age 10.3 ± 1.6 SD years) were recruited from the metropolitan area of Sydney Australia following a national press release. Kinematic data were recorded at 200 Hz using a 14 camera motion analysis system (Cortex, Motion Analysis Corporation, Santa Rosa, USA) and simultaneous ground reaction force were measured using a force platform (Model 9281B, Kistler, Winterthur, Switzerland). A three-segment foot model was used to describe three dimensional ankle, midfoot and one dimensional hallux kinematics during the stance sub-phases of contact, midstance and propulsion. Results Thongs resulted in increased ankle dorsiflexion during contact (by 10.9°, p; = 0.005 walk and by 8.1°, p; = 0.005 jog); increased midfoot plantarflexion during midstance (by 5.0°, p; = 0.037 jog) and propulsion (by 6.7°, p; = 0.044 walk and by 5.4°, p;= 0.020 jog); increased midfoot inversion during contact (by 3.8°, p;= 0.042 jog) and reduced hallux dorsiflexion during walking 10% prior to heel strike (by 6.5°, p; = 0.005) at heel strike (by 4.9°, p; = 0.031) and 10% post toe-off (by 10.7°, p; = 0.001). Conclusions Ankle dorsiflexion during the contact phase of walking and jogging, combined with reduced hallux dorsiflexion during walking, suggests a mechanism to retain the thong during weight acceptance. Greater midfoot plantarflexion throughout midstance while walking and throughout midstance and propulsion while jogging may indicate a gripping action to sustain the thong during stance. While these compensations exist

  18. Delay-Compensation Flip-Flop with In-situ Error Monitoring for Low-Power and Timing-Error-Tolerant Circuit Design

    NASA Astrophysics Data System (ADS)

    Hirose, Kenichiro; Manzawa, Yasuo; Goshima, Masahiro; Sakai, Shuichi

    2008-04-01

    With the continuous downscaling of transistors, process variation and power consumption have become major issues. Dynamic voltage and frequency scaling (DVFS) with in-situ timing-error monitoring is an effective method that addresses both issues. However, the conventional implementations of this method, which are mainly based on duplicated circuits, have some implementation-specific constraints. In this paper, the authors propose a delay-compensation flip-flop (DCFF) that does not use duplicated circuit components. It monitors timing errors by directly checking the transient timings of signals. The DCFF adjusts the rising-edge timings of the clock to avoid timing errors and compensates the timing margins between successive stages. Simulations using simulation program with integrated circuit emphasis (SPICE) indicated that the DCFF can operate in a wider supply voltage range than the conventional implementation of DVFS with in-situ timing-error monitoring. A 2.5 ×2.5 mm2 test chip was designed by using a 0.18 µm 5-metal process. An essential circuit component of the DCFF was implemented using semi-custom gate-array chips and its operation was verified. Although more detailed and varied simulations and actual measurements are required as future work, DCFFs can be effectively applied to process-variation tolerance and low-power computation and to optimize the design margin and resolve the false-path problem.

  19. Structural Basis for Flip-Flop Action of Thiamin Pyrophosphate-dependent Enzymes Revealed by Human Pyruvate Dehydrogenase

    NASA Technical Reports Server (NTRS)

    Ciszak, Ewa M.; Korotchkina, Lioubov G.; Dominiak, Paulina M.; Sidhu, Sukdeep; Patel, Mulchand S.

    2003-01-01

    The derivative of vitamin B1, thiamin pyrophosphate, is a cofactor of enzymes performing catalysis in pathways of energy production. In alpha (sub 2) beta (sub 2)-heterotetrameric human pyruvate dehydrogenase, this cofactor is used to cleave the C(sup alpha) -C(=O) bond of pyruvate followed by reductive acetyl transfer to lipoyl-dihydrolipoamide acetyltransferase. The dynamic nonequivalence of two, otherwise chemically equivalent, catalytic sites has not yet been understood. To understand the mechanism of action of this enzyme, we determined the crystal structure of the holo-form of human pyruvate dehydrogenase at 1.95-Angstrom resolution. We propose a model for the flip-flop action of this enzyme through a concerted approximately 2-Angstrom shuttle-like motion of its heterodimers. Similarity of thiamin pyrophosphate binding in human pyruvate dehydrogenase with functionally related enzymes suggests that this newly defined shuttle-like motion of domains is common to the family of thiamin pyrophosphate-dependent enzymes.

  20. Fabrication and voltage divider operation of a T flip-flop using high-Tc interface-engineered Josephson junctions

    NASA Astrophysics Data System (ADS)

    Kim, Jun Ho; Hyeob Kim, Sang; Sung, Gun Yong

    2002-09-01

    We designed and fabricated a rapid-single-flux-quantum T flip-flop (TFF) with high-Tc interface-engineered Josephson junctions. Y1Ba2Cu3O7-d and Sr2AlTaO6 were deposited for the superconducting layer and the insulating layer, respectively. The Josephson junction was formed through an interface treatment process using Ar ion milling and vacuum annealing. We simulated a TFF circuit and designed a physical layout using WRspice and Xic. The fabricated TFF has a minimum junction width of 3 μm. Through the measurement of the voltage divider operation, the maximum operation frequency was estimated to be 53 GHz at 22 K and 106 GHz at 12 K.

  1. All-optical optoacoustic microscope based on wideband pulse interferometry.

    PubMed

    Wissmeyer, Georg; Soliman, Dominik; Shnaiderman, Rami; Rosenthal, Amir; Ntziachristos, Vasilis

    2016-05-01

    Optical and optoacoustic (photoacoustic) microscopy have been recently joined in hybrid implementations that resolve extended tissue contrast compared to each modality alone. Nevertheless, the application of the hybrid technique is limited by the requirement to combine an optical objective with ultrasound detection collecting signal from the same micro-volume. We present an all-optical optoacoustic microscope based on a pi-phase-shifted fiber Bragg grating (π-FBG) with coherence-restored pulsed interferometry (CRPI) used as the interrogation method. The sensor offers an ultra-small footprint and achieved higher sensitivity over piezoelectric transducers of similar size. We characterize the spectral bandwidth of the ultrasound detector and interrogate the imaging performance on phantoms and tissues. We show the first optoacoustic images of biological specimen recorded with π-FBG sensors. We discuss the potential uses of π-FBG sensors based on CRPI. PMID:27128047

  2. All-optical reservoir computer based on saturation of absorption.

    PubMed

    Dejonckheere, Antoine; Duport, François; Smerieri, Anteo; Fang, Li; Oudar, Jean-Louis; Haelterman, Marc; Massar, Serge

    2014-05-01

    Reservoir computing is a new bio-inspired computation paradigm. It exploits a dynamical system driven by a time-dependent input to carry out computation. For efficient information processing, only a few parameters of the reservoir needs to be tuned, which makes it a promising framework for hardware implementation. Recently, electronic, opto-electronic and all-optical experimental reservoir computers were reported. In those implementations, the nonlinear response of the reservoir is provided by active devices such as optoelectronic modulators or optical amplifiers. By contrast, we propose here the first reservoir computer based on a fully passive nonlinearity, namely the saturable absorption of a semiconductor mirror. Our experimental setup constitutes an important step towards the development of ultrafast low-consumption analog computers. PMID:24921786

  3. All-optical reservoir computer based on saturation of absorption.

    PubMed

    Dejonckheere, Antoine; Duport, François; Smerieri, Anteo; Fang, Li; Oudar, Jean-Louis; Haelterman, Marc; Massar, Serge

    2014-05-01

    Reservoir computing is a new bio-inspired computation paradigm. It exploits a dynamical system driven by a time-dependent input to carry out computation. For efficient information processing, only a few parameters of the reservoir needs to be tuned, which makes it a promising framework for hardware implementation. Recently, electronic, opto-electronic and all-optical experimental reservoir computers were reported. In those implementations, the nonlinear response of the reservoir is provided by active devices such as optoelectronic modulators or optical amplifiers. By contrast, we propose here the first reservoir computer based on a fully passive nonlinearity, namely the saturable absorption of a semiconductor mirror. Our experimental setup constitutes an important step towards the development of ultrafast low-consumption analog computers.

  4. Graphene based All-Optical Spatial Terahertz Modulator

    PubMed Central

    Wen, Qi-Ye; Tian, Wei; Mao, Qi; Chen, Zhi; Liu, Wei-Wei; Yang, Qing-Hui; Sanderson, Matthew; Zhang, Huai-Wu

    2014-01-01

    We demonstrate an all-optical terahertz modulator based on single-layer graphene on germanium (GOG), which can be driven by a 1.55 μm CW laser with a low-level photodoping power. Both the static and dynamic THz transmission modulation experiments were carried out. A spectrally wide-band modulation of the THz transmission is obtained in a frequency range from 0.25 to 1 THz, and a modulation depth of 94% can be achieved if proper pump power is applied. The modulation speed of the modulator was measured to be ~200 KHz using a 340 GHz carrier. A theoretical model is proposed for the modulator and the calculation results indicate that the enhanced THz modulation is mainly due to the third order nonlinear effect in the optical conductivity of the graphene monolayer. PMID:25491194

  5. Structural Basis for Flip-Flop Action of Thiamin-Dependent Enzymes Revealed by Crystal Structure of Human Pyruvate Dehydrogenase

    NASA Technical Reports Server (NTRS)

    Ciszak, Ewa; Korotchkina, Lioubov G.; Dominiak, Paulina M.; Sidhu, Sukdeep; Patel, Mulchand S.

    2003-01-01

    The biologically active derivative of vitamin B1; thiamin pyrophosphate; is used as cofactor by many enzymes that perform a wide range of catalytic functions in the pathways of energy production. In alpha2beta2-heterotetrameric human pyruvate dehydrogenase, the first catalytic component enzyme of human pyruvate dehydrogenase complex, this cofactor is used to cleave the C(sup alpha)-C(=0) bond of pyruvate followed by reductive acetyl transfer to lipoyl-dihydrolipoamide acetyltransferase, the second catalytic component of the complex. The dynamic nonequivalence of two, otherwise chemically equivalent, catalytic sites have puzzled researchers from earlier functional studies of this enzyme. In order to gain insight into the mechanism of action of this enzyme, we determined the crystal structure of the holoform of human pyruvate dehydrogenase at 1.958, resolution. We propose a kinetic model for the flip-flop action of this enzyme through the concerted approx. 2A, shuttle-like motion of the heterodimers. The similarity of thiamin pyrophosphate binding in human pyruvate dehydrogenase and other functionally related enzymes suggests this newly defined mechanism of shuttle-like motion of domains to be common for the family of thiamin pyrophosphate-dependent enzymes.

  6. Computational simulation of a gene regulatory network implementing an extendable synchronous single-input delay flip-flop.

    PubMed

    Hoteit, Imad; Kharma, Nawwaf; Varin, Luc

    2012-07-01

    We present a detailed and extendable design of the first synchronous single-input delay flip-flop implemented as a gene regulatory network in Escherichia coli (E. coli). The device, which we call the BioD, has one data input (transacting RNA), one clock input (far-red light) and an output that reports the state of the device using green fluorescent protein (GFP). The proposed design builds on Gardner's toggle switch, to provide a more sophisticated device that can be synchronized with other devices within the same cell, and which requires only one data input. We provide a mathematical model of the system and simulation results. The results show that the device behaves in line with desired functionality. Further, we discuss the constraints of the design, which pertain to ranges of parameter values. The BioD is extended via the addition of an update function and input and output interfaces. The result is the BioFSM, which constitutes a synchronous and modular finite state machine, which uses an update function to change its state, stored in the BioD. The BioFSM uses its input and output interfaces for inter-cellular communications. This opens the door to the design of a circular cellular automata (the BioCell), which is envisioned as a number of communicating E. coli colonies, each made of clones of one BioFSM.

  7. Nanophotonic technologies for innovative all- optical signal processor using photonic crystals and quantum dots

    SciTech Connect

    Sugimoto, Y.; Ikeda, N.; Ozaki, N.; Watanabe, Y.; Asakawa, K.; Ohkouchi, S.; Nakamura, S.

    2009-06-29

    GaAs-based two-dimensional photonic crystal (2DPC) slab waveguides (WGs) and InAs quantum dots (QDs) were developed for key photonic device structures in the future. An ultrasmall and ultrafast symmetrical Mach-Zehnder (SMZ)-type all-optical switch (PC-SMZ) and an optical flip-flop device (PC-FF) have been developed based on these nanophotonic structures for an ultrafast digital photonic network. To realize these devices, two important techniques were developed. One is a new simulation method, i.e., topology optimization method of 2DPC WGs with wide/flat bandwidth, high transmittance and low reflectivity. Another is a new selective-area-growth method, i.e., metal-mask molecular beam epitaxy method of InAs QDs. This technique contributes to achieving high-density and highly uniform InAs QDs in a desired area such as an optical nonlinearity-induced phase shift arm in the PC-FF. Furthermore, as a unique site-controlled QD technique, a nano-jet probe method is also developed for positioning QDs at the centre of the optical nonlinearity-induced phase shift arm.

  8. A simple and effective theory for all-optical helicity-dependent spin switching

    NASA Astrophysics Data System (ADS)

    Zhang, Guoping; Bai, Yihua; George, Thomas F.

    All-optical helicity-dependent spin switching (AOS) represents a new frontier in magnetic recording technology, where a single ultrafast laser pulse, without any assistance from an external magnetic field, can permanently switch spin within a few hundred femtoseconds. By contrast, the existing theory does rely on an artificial magnetic field to switch spins. Here we develop a microscopic spin switch theory, free of any artificial field, and demonstrate unambiguously that both circularly and linearly polarized lights can switch spins faithfully. Our theory is based on the Hookean theory, but includes two new elements: spin-orbit coupling and exchange interaction. We predict that left (right) circularly polarized light only flips (flops) spin, a symmetry constraint that strongly favors ferrimagnetic orderings over ferromagnetic ones, with the allowable exchange interaction within 10 meV, consistent with all prior theories. The effect of the laser amplitude is highly nonlinear: If it is too weak, AOS does not occur, but if too strong, the spin cants; a compromise between them produces a narrow spin reversal window as observed experimentally. We envision that our model can be easily extended to describe spin frustrated systems and multiferroics, where the light-spin interaction Supported by the U.S. Department of Energy under Contract No. DE-FG02-06ER46304 and the National Energy Research Scientific Computing Center.

  9. Corticosteroid-binding globulin (CBG) reactive centre loop antibodies and surface plasmon resonance interrogate the proposed heat dependent "flip-flop" mechanism of human CBG.

    PubMed

    Lewis, John G; Fredericks, Rayleen; Fee, Conan J; Elder, Peter A

    2016-04-01

    Corticosteroid-binding globulin (CBG) is the predominant carrier of cortisol in circulation and is a non-inhibitory member of the serpin superfamily of serine protease inhibitors. In the stressed or "S" conformation, CBG possesses an intact exposed reactive centre loop (RCL) that can be irreversibly cleaved by elastase released from activated human neutrophils whereupon it adopts a relaxed or "R" conformation. The latter conformation has decreased affinity for cortisol, allowing the release of the majority of cortisol at sites of inflammation. Recently there has been speculation that mild increments in heat such as found in pyrexia (39-40°C) may also induce a reversible "flip-flop" of the RCL into the body of the protein structure, without cleavage, facilitating a reversible temperature-dependent release of cortisol. Here we raised a new monoclonal antibody to the RCL of human CBG and used this in concert with an existing RCL antibody and show by surface plasma resonance that, at temperatures up to 40°C, the RCL of purified CBG and the RCL of CBG in intact plasma is accessible to these two antibodies. Together, the epitopes of these antibodies span 11 consecutive amino acids (STGVTLNLTSK) of the 18 residues of the RCL. This adequate antibody cover of the RCL sequence leads to the conclusion that the proposed temperature-dependent "flip-flop" of the RCL of CBG is doubtful.

  10. Corticosteroid-binding globulin (CBG) reactive centre loop antibodies and surface plasmon resonance interrogate the proposed heat dependent "flip-flop" mechanism of human CBG.

    PubMed

    Lewis, John G; Fredericks, Rayleen; Fee, Conan J; Elder, Peter A

    2016-04-01

    Corticosteroid-binding globulin (CBG) is the predominant carrier of cortisol in circulation and is a non-inhibitory member of the serpin superfamily of serine protease inhibitors. In the stressed or "S" conformation, CBG possesses an intact exposed reactive centre loop (RCL) that can be irreversibly cleaved by elastase released from activated human neutrophils whereupon it adopts a relaxed or "R" conformation. The latter conformation has decreased affinity for cortisol, allowing the release of the majority of cortisol at sites of inflammation. Recently there has been speculation that mild increments in heat such as found in pyrexia (39-40°C) may also induce a reversible "flip-flop" of the RCL into the body of the protein structure, without cleavage, facilitating a reversible temperature-dependent release of cortisol. Here we raised a new monoclonal antibody to the RCL of human CBG and used this in concert with an existing RCL antibody and show by surface plasma resonance that, at temperatures up to 40°C, the RCL of purified CBG and the RCL of CBG in intact plasma is accessible to these two antibodies. Together, the epitopes of these antibodies span 11 consecutive amino acids (STGVTLNLTSK) of the 18 residues of the RCL. This adequate antibody cover of the RCL sequence leads to the conclusion that the proposed temperature-dependent "flip-flop" of the RCL of CBG is doubtful. PMID:26829559

  11. Structural Basis for "Flip-Flop" Action of Human Pyruvate Dehydrogenase

    NASA Technical Reports Server (NTRS)

    Ciszak, Ewa; Korotchkina, Lioubov; Dominiak, Paulina; Sidhu, Sukhdeep; Patel, Mulchand

    2003-01-01

    The derivative of vitamin B1, thiamin pyrophosphate is a cofactor of pyruvate dehydrogenase, a component enzyme of the mitochondrial pyruvate dehydrogenase multienzyme complex that plays a major role in directing energy metabolism in the cell. This cofactor is used to cleave the C(sup alpha)-C(=O) bond of pyruvate followed by reductive acetyl transfer to lipoyl-dihydrolipoamide acetyltransferase. In alpha(sub 2)beta(sub 2)-tetrameric human pyruvate dehydrogenase, there are two cofactor binding sites, each of them being a center of independently conducted, although highly coordinated enzymatic reactions. The dynamic nonequivalence of two, otherwise chemically equivalent, catalytic sites can now be understood based on the recently determined crystal structure of the holo-form of human pyruvate dehydrogenase at 1.95A resolution. The structure of pyruvate dehydrogenase was determined using a combination of MAD phasing and molecular replacement followed by rounds of torsion-angles molecular-dynamics simulated-annealing refinement. The final pyruvate dehydrogenase structure included coordinates for all protein amino acids two cofactor molecules, two magnesium and two potassium ions, and 742 water molecules. The structure was refined to R = 0.202 and R(sub free) = 0.244. Our structural analysis of the enzyme folding and domain assembly identified a simple mechanism of this protein motion required for the conduct of catalytic action.

  12. Chemogenetic E-MAP in Saccharomyces cerevisiae for Identification of Membrane Transporters Operating Lipid Flip Flop.

    PubMed

    Vazquez, Hector M; Vionnet, Christine; Roubaty, Carole; Mallela, Shamroop K; Schneiter, Roger; Conzelmann, Andreas

    2016-07-01

    While most yeast enzymes for the biosynthesis of glycerophospholipids, sphingolipids and ergosterol are known, genes for several postulated transporters allowing the flopping of biosynthetic intermediates and newly made lipids from the cytosolic to the lumenal side of the membrane are still not identified. An E-MAP measuring the growth of 142'108 double mutants generated by systematically crossing 543 hypomorphic or deletion alleles in genes encoding multispan membrane proteins, both on media with or without an inhibitor of fatty acid synthesis, was generated. Flc proteins, represented by 4 homologous genes encoding presumed FAD or calcium transporters of the ER, have a severe depression of sphingolipid biosynthesis and elevated detergent sensitivity of the ER. FLC1, FLC2 and FLC3 are redundant in granting a common function, which remains essential even when the severe cell wall defect of flc mutants is compensated by osmotic support. Biochemical characterization of some other genetic interactions shows that Cst26 is the enzyme mainly responsible for the introduction of saturated very long chain fatty acids into phosphatidylinositol and that the GPI lipid remodelase Cwh43, responsible for introducing ceramides into GPI anchors having a C26:0 fatty acid in sn-2 of the glycerol moiety can also use lyso-GPI protein anchors and various base resistant lipids as substrates. Furthermore, we observe that adjacent deletions in several chromosomal regions show strong negative genetic interactions with a single gene on another chromosome suggesting the presence of undeclared suppressor mutations in certain chromosomal regions that need to be identified in order to yield meaningful E-map data. PMID:27462707

  13. Chemogenetic E-MAP in Saccharomyces cerevisiae for Identification of Membrane Transporters Operating Lipid Flip Flop

    PubMed Central

    Vazquez, Hector M.; Vionnet, Christine; Roubaty, Carole; Mallela, Shamroop k.; Schneiter, Roger; Conzelmann, Andreas

    2016-01-01

    While most yeast enzymes for the biosynthesis of glycerophospholipids, sphingolipids and ergosterol are known, genes for several postulated transporters allowing the flopping of biosynthetic intermediates and newly made lipids from the cytosolic to the lumenal side of the membrane are still not identified. An E-MAP measuring the growth of 142'108 double mutants generated by systematically crossing 543 hypomorphic or deletion alleles in genes encoding multispan membrane proteins, both on media with or without an inhibitor of fatty acid synthesis, was generated. Flc proteins, represented by 4 homologous genes encoding presumed FAD or calcium transporters of the ER, have a severe depression of sphingolipid biosynthesis and elevated detergent sensitivity of the ER. FLC1, FLC2 and FLC3 are redundant in granting a common function, which remains essential even when the severe cell wall defect of flc mutants is compensated by osmotic support. Biochemical characterization of some other genetic interactions shows that Cst26 is the enzyme mainly responsible for the introduction of saturated very long chain fatty acids into phosphatidylinositol and that the GPI lipid remodelase Cwh43, responsible for introducing ceramides into GPI anchors having a C26:0 fatty acid in sn-2 of the glycerol moiety can also use lyso-GPI protein anchors and various base resistant lipids as substrates. Furthermore, we observe that adjacent deletions in several chromosomal regions show strong negative genetic interactions with a single gene on another chromosome suggesting the presence of undeclared suppressor mutations in certain chromosomal regions that need to be identified in order to yield meaningful E-map data. PMID:27462707

  14. Photonic-crystal-based all-optical NOT logic gate.

    PubMed

    Singh, Brahm Raj; Rawal, Swati

    2015-12-01

    In the present paper, we have utilized the concept of photonic crystals for the implementation of an optical NOT gate inverter. The designed structure has a hexagonal arrangement of silicon rods in air substrate. The logic function is based on the phenomenon of the existence of the photonic bandgap and resulting guided modes in defect photonic crystal waveguides. We have plotted the transmission, extinction ratio, and tolerance analysis graphs for the structure, and it has been observed that the maximum output is obtained for a telecom wavelength of 1.554 μm. Dispersion curves are obtained using the plane wave expansion method, and the transmission is simulated using the finite element method. The proposed structure is applicable for photonic integrated circuits due to its simple structure and clear operating principle.

  15. Novel type of linear mitochondrial genomes with dual flip-flop inversion system in apicomplexan parasites, Babesia microti and Babesia rodhaini

    PubMed Central

    2012-01-01

    Background Mitochondrial (mt) genomes vary considerably in size, structure and gene content. The mt genomes of the phylum Apicomplexa, which includes important human pathogens such as the malaria parasite Plasmodium, also show marked diversity of structure. Plasmodium has a concatenated linear mt genome of the smallest size (6-kb); Babesia and Theileria have a linear monomeric mt genome (6.5-kb to 8.2-kb) with terminal inverted repeats; Eimeria, which is distantly related to Plasmodium and Babesia/Theileria, possesses a mt genome (6.2-kb) with a concatemeric form similar to that of Plasmodium; Cryptosporidium, the earliest branching lineage within the phylum Apicomplexa, has no mt genome. We are interested in the evolutionary origin of linear mt genomes of Babesia/Theileria, and have investigated mt genome structures in members of archaeopiroplasmid, a lineage branched off earlier from Babesia/Theileria. Results The complete mt genomes of archaeopiroplasmid parasites, Babesia microti and Babesia rodhaini, were sequenced. The mt genomes of B. microti (11.1-kb) and B. rodhaini (6.9-kb) possess two pairs of unique inverted repeats, IR-A and IR-B. Flip-flop inversions between two IR-As and between two IR-Bs appear to generate four distinct genome structures that are present at an equi-molar ratio. An individual parasite contained multiple mt genome structures, with 20 copies and 2 – 3 copies per haploid nuclear genome in B. microti and B. rodhaini, respectively. Conclusion We found a novel linear monomeric mt genome structure of B. microti and B. rhodhaini equipped with dual flip-flop inversion system, by which four distinct genome structures are readily generated. To our knowledge, this study is the first to report the presence of two pairs of distinct IR sequences within a monomeric linear mt genome. The present finding provides insight into further understanding of evolution of mt genome structure. PMID:23151128

  16. All-Optical Terahertz Optical Asymmetric Demultiplexer (toad) Based Binary Comparator:. a Proposal

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay

    Comparator determines whether a number is greater than, equals to or less than another number. It plays a significant role in fast central processing unit in all-optical scheme. In all-optical scheme here 1-bit binary comparator is proposed and described by Terahertz Optical Asymmetric Demultiplexer (TOAD) based interferometric switch. Simulation result by Mathcad-7 is also given. Cascading technique of building up the n-bit binary comparator with this 1-bit comparator block is also proposed here.

  17. All-optical virtual private network and ONUs communication in optical OFDM-based PON system.

    PubMed

    Zhang, Chongfu; Huang, Jian; Chen, Chen; Qiu, Kun

    2011-11-21

    We propose and demonstrate a novel scheme, which enables all-optical virtual private network (VPN) and all-optical optical network units (ONUs) inter-communications in optical orthogonal frequency-division multiplexing-based passive optical network (OFDM-PON) system using the subcarrier bands allocation for the first time (to our knowledge). We consider the intra-VPN and inter-VPN communications which correspond to two different cases: VPN communication among ONUs in one group and in different groups. The proposed scheme can provide the enhanced security and a more flexible configuration for VPN users compared to the VPN in WDM-PON or TDM-PON systems. The all-optical VPN and inter-ONU communications at 10-Gbit/s with 16 quadrature amplitude modulation (16 QAM) for the proposed optical OFDM-PON system are demonstrated. These results verify that the proposed scheme is feasible.

  18. All-optical buffer based on temporal cavity solitons operating at 10 Gb/s

    NASA Astrophysics Data System (ADS)

    Jang, Jae K.; Erkintalo, Miro; Schröder, Jochen; Eggleton, Benjamin J.; Murdoch, Stuart G.; Coen, Stéphane

    2016-10-01

    We demonstrate the operation of an all-optical buffer based on temporal cavity solitons stored in a nonlinear passive fiber ring resonator. Unwanted acoustic interactions between neighboring solitons are suppressed by modulating the phase of the external laser driving the cavity. A new locking scheme is presented that allows the buffer to operate with an arbitrarily large number of cavity solitons in the loop. Experimentally, we are able to demonstrate the storage of 4536 bits of data, written all-optically into the fiber ring at 10 Gb/s, for 1 minute.

  19. Interplay of Packing and Flip-flop in Local Bilayer Deformation. How Phosphatidylglycerol Could Rescue Mitochondrial Function in a Cardiolipin-deficient Yeast Mutant

    PubMed Central

    Khalifat, Nada; Rahimi, Mohammad; Bitbol, Anne-Florence; Seigneuret, Michel; Fournier, Jean-Baptiste; Puff, Nicolas; Arroyo, Marino; Angelova, Miglena I.

    2014-01-01

    In a previous work, we have shown that a spatially localized transmembrane pH gradient, produced by acid micro-injection near the external side of cardiolipin-containing giant unilamellar vesicles, leads to the formation of tubules that retract after the dissipation of this gradient. These tubules have morphologies similar to mitochondrial cristae. The tubulation effect is attributable to direct phospholipid packing modification in the outer leaflet, that is promoted by protonation of cardiolipin headgroups. In this study, we compare the case of cardiolipin-containing giant unilamellar vesicles with that of giant unilamellar vesicles that contain phosphatidylglycerol (PG). Local acidification also promotes formation of tubules in the latter. However, compared with cardiolipin-containing giant unilamellar vesicles the tubules are longer, exhibit a visible pearling, and have a much longer lifetime after acid micro-injection is stopped. We attribute these differences to an additional mechanism that increases monolayer surface imbalance, namely inward PG flip-flop promoted by the local transmembrane pH gradient. Simulations using a fully nonlinear membrane model as well as geometrical calculations are in agreement with this hypothesis. Interestingly, among yeast mutants deficient in cardiolipin biosynthesis, only the crd1-null mutant, which accumulates phosphatidylglycerol, displays significant mitochondrial activity. Our work provides a possible explanation of such a property and further emphasizes the salient role of specific lipids in mitochondrial function. PMID:25140423

  20. All-optical multibit address recognition at 20 Gb/s based on TOAD

    NASA Astrophysics Data System (ADS)

    Yan, Yumei; Wu, Jian; Lin, Jintong

    2005-04-01

    All-optical multibit address recognition at 20 Gb/s is demonstrated based on a special AND logic of terahertz optical asymmetric demultiplexer (TOAD). The semiconductor optical amplifier (SOA) used in the TOAD is biased at transparency status to accelerate the gain recovery. This is the highest bit rate that multibit address recognition is demonstrated with SOA-based interferometer. The experimental results show low pattern dependency. With this method, address recognition can be performed without separating address and payload beforehand.

  1. A 2*4 all optical decoder switch based on photonic crystal ring resonators

    NASA Astrophysics Data System (ADS)

    Alipour-Banaei, Hamed; Mehdizadeh, Farhad; Serajmohammadi, Somaye; Hassangholizadeh-Kashtiban, Mahdi

    2015-03-01

    Based on photonic crystal ring resonators and nonlinear Kerr effect in this paper, we proposed a 2*4 all optical decoder switch. Our proposed structure has two logic input ports and one bias input port. This decoder switch has four output ports. Via these two logic input ports, we control the bias signal to transfer toward which output port. We employed numerical methods such as plane wave expansion and finite difference time domain methods for analyzing the proposed structure.

  2. All-optically driven system in ultrasonic wave-based structural health monitoring

    NASA Astrophysics Data System (ADS)

    Bi, Siwen; Wu, Nan; Zhou, Jingcheng; Zhang, Haifeng; Wang, Xingwei

    2016-04-01

    Ultrasonic wave based structural health monitoring (SHM) is an innovative method for nondestructive detection and an area of growing interest. This is due to high demands for wireless detection in the field of structural engineering. Through optically exciting and detecting ultrasonic waves, electrical wire connections can be avoided, and non-contact SHM can be achieved. With the combination of piezoelectric transducer (PZT) (which possesses high heat resistance) and the noncontact detection, this system has a broad range of applications, even in extreme conditions. This paper reports an all-optically driven SHM system. The resonant frequencies of the PZT transducers are sensitive to a variety of structural damages. Experimental results have verified the feasibility of the all-optically driven SHM system.

  3. All-optical NOR and NAND gates based on photonic crystal ring resonator

    NASA Astrophysics Data System (ADS)

    Bao, Junjie; Xiao, Jun; Fan, Lin; Li, Xiaoxu; Hai, Yunfei; Zhang, Tong; Yang, Chunbo

    2014-10-01

    We report a new configuration of all-optical logic gates based on two-dimensional (2D) square lattice photonic crystals (PCs) composed of silicon (Si) rods in Silica (SiO2). The proposed device is composed of cross-shaped waveguide and two photonic crystal ring resonators (PCRRs) without nonlinear materials and optical amplifiers. The gate has been simulated and analyzed by finite difference time domain (FDTD) and plane wave expansion (PWE) methods. The simulation results show that the proposed all-optical logic gates could really function as NOR and NAND logic gates. This new device can potentially be used in large-scale optical integration and on-chip photonic logic integrated circuits.

  4. All-optical repetition rate multiplication of pseudorandom bit sequences based on cascaded TOADs

    NASA Astrophysics Data System (ADS)

    Sun, Zhenchao; Wang, Zhi; Wu, Chongqing; Wang, Fu; Li, Qiang

    2016-03-01

    A scheme for all-optical repetition rate multiplication of pseudorandom bit sequences (PRBS) is demonstrated with all-optical wavelength conversion and optical logic gate 'OR' based on cascaded Tera-Hertz Optical Asymmetric Demultiplexers (TOADs). Its feasibility is verified by multiplication experiments from 500 Mb/s to 4 Gb/s for 23-1 PRBS and from 1 Gb/s to 4 Gb/s for 27-1 PRBS. This scheme can be employed for rate multiplication for much longer cycle PRBS at much higher bit rate over 40 Gb/s when the time-delay, the loss and the dispersion of the optical delay line are all precisely managed. The upper limit of bit rate will be restricted by the recovery time of semiconductor optical amplifier (SOA) finally.

  5. 10Gbit/s all-optical NRZ to RZ conversion based on TOAD

    NASA Astrophysics Data System (ADS)

    Yan, Yumei; Yin, Lina; Zhou, Yunfeng; Liu, Guoming; Wu, Jian; Lin, Jintong

    2006-01-01

    Future network will include wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM) technologies. All-optical format conversion between their respective preferable data formats, non-return-to-zero (NRZ) and return-to-zero (RZ), may become an important technology. In this paper, 10Gbit/s all-optical NRZ-to-RZ conversion is demonstrated based on terahertz optical asymmetric demultiplexer (TOAD) using clock all-optically recovered from the NRZ signal for the first time. The clock component is enhanced in an SOA and the pseudo-return-to-zero (PRZ) signal is filtered. The PRZ signal is input into an injection mode-locked fiber ring laser for clock recovery. The recovered clock and the NRZ signal are input into TOAD as pump signal and probe signal, respectively, and format conversion is performed. The quality of the converted RZ signal is determined by that of the recovered clock and the NRZ signal, whereas hardly influenced by gain recovery time of the SOA. In the experimental demonstration, the obtained RZ signal has an extinction ratio of 8.7dB and low pattern dependency. After conversion, the spectrum broadens obviously and shows multimode structure with spectrum interval of 0.08nm, which matches with the bit rate 10Gbit/s. Furthermore, this format conversion method has some tolerance on the pattern dependency of the clock signal.

  6. All-optical arithmetic unit with the help of terahertz-optical-asymmetric-demultiplexer-based tree architecture

    NASA Astrophysics Data System (ADS)

    Gayen, Dilip Kumar; Nath Roy, Jitendra

    2008-03-01

    An all-optical arithmetic unit with the help of terahertz-optical-asymmetric-demultiplexer (TOAD)-based tree architecture is proposed. We describe the all-optical arithmetic unit by using a set of all-optical multiplexer, all-optical full-adder, and optical switch. The all-optical arithmetic unit can be used to perform a fast central processor unit using optical hardware components. We have tried to exploit the advantages of both optical tree architecture and TOAD-based switch to design an integrated all-optical circuit that can perform binary addition, addition with carry, subtract with borrow, subtract (2's complement), double, increment, decrement, and transfer operations.

  7. All-optical 2-bit header recognition and packet switching using polarization bistable VCSELs.

    PubMed

    Hayashi, Daisuke; Nakao, Kazuya; Katayama, Takeo; Kawaguchi, Hitoshi

    2015-04-01

    We propose and evaluate an all-optical 2-bit header recognition and packet switching method using two 1.55-µm polarization bistable vertical-cavity surface-emitting lasers (VCSELs) and three optical switches. Polarization bistable VCSELs acted as flip-flop devices by using AND-gate operations of the header and set pulses, together with the reset pulses. Optical packets including 40-Gb/s non-return-to-zero pseudo-random bit-sequence payloads were successfully sent to one of four ports according to the state of two bits in the headers with a 4-bit 500-Mb/s return-to-zero format. The input pulse powers were 17.2 to 31.8 dB lower than the VCSEL output power. We also examined an extension of this method to multi-bit header recognition and packet switching.

  8. All optical wavelength multicaster and regenerator based on four-mode phase-sensitive parametric mixer.

    PubMed

    Liu, Lan; Temprana, Eduardo; Ataie, Vahid; Wiberg, Andreas O J; Kuo, Bill P-P; Myslivets, Evgeny; Alic, Nikola; Radic, Stojan

    2015-11-30

    Four-mode phase-sensitive (4MPS) process has been employed in a parametric mixer based wavelength multicaster, enhancing the multicasting conversion efficiency and signal-to-noise ratio. In addition, the 4MPS parametric multicaster is an outstanding candidate for all-optical regeneration, owing to its inherent capabilities to clamp amplitude fluctuations by the saturated parametric effect and to squeeze phase distortions by the phase sensitive process. The investigation in this paper focuses on the 4MPS multicaster operated in the saturation gain regime, including theoretical simulations and experimental demonstrations on amplitude and phase noise regeneration over 20 multicasting signal copies. PMID:26698727

  9. Nanoresonator Enabled Ultrafast All-optical Terahertz Switching Based on Vanadium Dioxide Thin Film

    NASA Astrophysics Data System (ADS)

    Kyoung, J. S.; Choi, S. B.; Kim, H. S.; Kim, B. J.; Ahn, Y. H.; Kim, H. T.; Kim, D. S.

    2011-12-01

    We demonstrate nanoresonator enabled ultrafast all-optical switching of terahertz transmission based on phase transition of vanadium dioxide (VO2) thin film. Nanoresonators, nm-width slot antenna patterns on the gold layer, are fabricated on the VO2 films. Without nanoresonators, THz wave shows negligible change through bare VO2 film even though optical pumping exists, while about 20 percents switching ratio is clearly seen with nanoresonator patterns on the VO2. The switching time is in a few hundreds femtosecond time scales.

  10. Ultrafast all-optical NOR gate based on semiconductor optical amplifier and fiber delay interferometer.

    PubMed

    Xu, Jing; Zhang, Xinliang; Liu, Deming; Huang, Dexiu

    2006-10-30

    An ultrafast all-optical logic NOR gate based on a semiconductor optical amplifier (SOA) and a fiber delay interferometer (FDI) is presented. For high-speed input return-to-zero (RZ) signal, nonreturn-to-zero (NRZ) switching windows which satisfy Boolean NOR operation can be formed by properly choosing the delay time and the phase shift of FDI. 40Gb/s NOR operation has been demonstrated successfully with low control optical power. The factors that degrade the NOR operation have been discussed.

  11. Ultrafast all-optical NOR gate based on semiconductor optical amplifier and fiber delay interferometer

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Zhang, Xinliang; Liu, Deming; Huang, Dexiu

    2006-10-01

    An ultrafast all-optical logic NOR gate based on a semiconductor optical amplifier (SOA) and a fiber delay interferometer (FDI) is presented. For high-speed input return-to-zero (RZ) signal, nonreturn-to-zero (NRZ) switching windows which satisfy Boolean NOR operation can be formed by properly choosing the delay time and the phase shift of FDI. 40Gb/s NOR operation has been demonstrated successfully with low control optical power. The factors that degrade the NOR operation have been discussed.

  12. Photonic crystal-based all-optical on-chip sensor.

    PubMed

    Liu, Y; Salemink, H W M

    2012-08-27

    In this paper we demonstrate a sensor based on a two-dimensional photonic crystal cavity structure. Design, theoretical simulations, fabrication and experiments are shown to illustrate the working principle of this device. Sensitivity of our sensor is determined by observing the shift of resonant wavelength of the photonic crystal cavity as a function of the refractive index variation of the analyte. By experimentally infiltrating solutions of water and ethanol through an elastomeric micro-fluidic channel, we have confirmed that our all-optical sensor achieves a sensitivity of 460 nm/RIU. PMID:23037043

  13. Design and analysis of an all-optical Demultiplexer based on photonic crystals

    NASA Astrophysics Data System (ADS)

    Goodarzi, K.; Mir, A.

    2015-01-01

    An all-optical 1of 2 De-multiplexer (D-mux) based on silicon rods in the air, created by two dimensional square lattice photonic crystals (PCs), is proposed and demonstrated. The device operation is because of line and point defects and phase difference between input beams that created by point defects. The device has a selection line, S, an input data port, A, and three output data ports, Q0, Q1 and Q2. Photonic band gap (PBG) calculation is done by plane wave expansion (PWE) method and electrical field distribution (EFD) in the device by finite difference time domain (FDTD) method. Power levels lower than "0.25P0" is considered as "0" logic value and higher than "0.4P0" as "1" logic value. When S = 0, the data of port A, is directed to Q0 and when S = 1, is directed to Q1. Moreover, one of the output ports, Q1 or Q2, can be used as an AND logic gate. The device is applicable for all-optical processors and integrated circuit.

  14. Design of SOA-MZI based all-optical programmable logic device (PLD)

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay; Roy, Jitendra Nath

    2010-06-01

    Photon being the ultimate unit of information with unmatched speed and with data package in a signal of zero mass, the techniques of computing with light may provide a way out of the limitations of computational speed and complexity inherent in electronics computing. Information processing with photon as information carrying signal has shown a high level potentiality through the researches in last few decades. The driving force behind this evolution has been the utilization of interferometric configurations that employ a semiconductor optical amplifier (SOA) as the nonlinear element in combination with cross-phase modulation to achieve switching by means of light. Here, in this paper we present an all-optical circuit of programmable logic device (PLD) with the help of SOA-MZI (Mach-Zehnder interferometer) based optical tree-structured splitter. Numerical simulation result confirming described method is reported here. This paper also explains the applicability of this scheme to perform logical and arithmetic operations in all-optical domain.

  15. Design of an All-Optical Network Based on LCoS Technologies

    NASA Astrophysics Data System (ADS)

    Cheng, Yuh-Jiuh; Shiau, Yhi

    2016-06-01

    In this paper, an all-optical network composed of the ROADMs (reconfigurable optical add-drop multiplexer), L2/L3 optical packet switches, and the fiber optical cross-connection for fiber scheduling and measurement based on LCoS (liquid crystal on silicon) technologies is proposed. The L2/L3 optical packet switches are designed with optical output buffers. Only the header of optical packets is converted to electronic signals to control the wavelength of input ports and the packet payloads can be transparently destined to their output ports. An optical output buffer is designed to queue the packets when more than one incoming packet should reach to the same destination output port. For preserving service-packet sequencing and fairness of routing sequence, a priority scheme and a round-robin algorithm are adopted at the optical output buffer. The wavelength of input ports is designed for routing incoming packets using LCoS technologies. Finally, the proposed OFS (optical flow switch) with input buffers can quickly transfer the big data to the output ports and the main purpose of the OFS is to reduce the number of wavelength reflections. The all-optical content delivery network is comprised of the OFSs for a large amount of audio and video data transmissions in the future.

  16. Complete all-optical processing polarization-based binary logic gates and optical processors.

    PubMed

    Zaghloul, Y A; Zaghloul, A R M

    2006-10-16

    We present a complete all-optical-processing polarization-based binary-logic system, by which any logic gate or processor can be implemented. Following the new polarization-based logic presented in [Opt. Express 14, 7253 (2006)], we develop a new parallel processing technique that allows for the creation of all-optical-processing gates that produce a unique output either logic 1 or 0 only once in a truth table, and those that do not. This representation allows for the implementation of simple unforced OR, AND, XOR, XNOR, inverter, and more importantly NAND and NOR gates that can be used independently to represent any Boolean expression or function. In addition, the concept of a generalized gate is presented which opens the door for reconfigurable optical processors and programmable optical logic gates. Furthermore, the new design is completely compatible with the old one presented in [Opt. Express 14, 7253 (2006)], and with current semiconductor based devices. The gates can be cascaded, where the information is always on the laser beam. The polarization of the beam, and not its intensity, carries the information. The new methodology allows for the creation of multiple-input-multiple-output processors that implement, by itself, any Boolean function, such as specialized or non-specialized microprocessors. Three all-optical architectures are presented: orthoparallel optical logic architecture for all known and unknown binary gates, singlebranch architecture for only XOR and XNOR gates, and the railroad (RR) architecture for polarization optical processors (POP). All the control inputs are applied simultaneously leading to a single time lag which leads to a very-fast and glitch-immune POP. A simple and easy-to-follow step-by-step algorithm is provided for the POP, and design reduction methodologies are briefly discussed. The algorithm lends itself systematically to software programming and computer-assisted design. As examples, designs of all binary gates, multiple

  17. Multiperiodicity, modulations and flip-flops in variable star light curves. II. Analysis of II Pegasus photometry during 1979-2010

    NASA Astrophysics Data System (ADS)

    Lindborg, M.; Mantere, M. J.; Olspert, N.; Pelt, J.; Hackman, T.; Henry, G. W.; Jetsu, L.; Strassmeier, K. G.

    2013-11-01

    Aims: According to previously published Doppler images of the magnetically active primary giant component of the RS CVn binary II Peg, the surface of the star was dominated by one single active longitude that was clearly drifting in the rotational frame of the binary system during 1994-2002; later imaging for 2004-2010, however, showed decreased and chaotic spot activity, with no signs of the drift pattern. Here we set out to investigate from a more extensive photometric dataset whether this drift is a persistent phenomenon, in which case it could be caused either by an azimuthal dynamo wave or be an indication that the binary system's orbital synchronization is still incomplete. On a differentially rotating stellar surface, spot structures preferentially on a certain latitude band could also cause such a drift, the disruption of which could arise from the change of the preferred spot latitude. Methods: We analyzed the datasets using the carrier fit (CF) method, which is especially suitable for analyzing time series in which a fast clocking frequency (such as the rotation of the star) is modulated with a slower process (such as the stellar activity cycle). Results: We combined all collected photometric data into one single data set and analyzed it with the CF method. We confirm the previously published results that the spot activity has been dominated by one primary spotted region almost through the entire data set and also confirm a persistent, nearly linear drift. Disruptions of the linear trend and complicated phase behavior are also seen, but the period analysis reveals a rather stable periodicity with Pspot = 6.71054d ± 0.00005d. After removing the linear trend from the data, we identified several abrupt phase jumps, three of which are analyzed in more detail with the CF method. These phase jumps closely resemble what is called a flip-flop event, but the new spot configurations do not persist for longer than a few months in most cases. Conclusions: There is

  18. Flip flops, dress clothes, and no coat: clothing barriers to children's physical activity in child-care centers identified from a qualitative study

    PubMed Central

    2009-01-01

    Background Three-quarters of 3-6 year-old children in the U.S. spend time in childcare; many spend most of their waking hours in these settings. Daily physical activity offers numerous health benefits, but activity levels vary widely across centers. This study was undertaken to explore reasons why physical activity levels may vary. The purpose of this paper is to summarize an unexpected finding that child-care providers cited was a key barrier to children's physical activity. Methods Nine focus groups with 49 child-care providers (55% black) from 34 centers (including inner-city, suburban, Head Start and Montessori) were conducted in Cincinnati, OH. Three independent raters analyzed verbatim transcripts for themes. Several techniques were used to increase credibility of findings, including interviews with 13 caregivers. Results Two major themes about clothing were: 1) children's clothing was a barrier to children's physical activity in child-care, and 2) clothing choices were a significant source of conflict between parents and child-care providers. Inappropriate clothing items included: no coat/hat/gloves in the wintertime, flip flops or sandals, dress/expensive clothes, jewelry, and clothes that were either too loose or too tight. Child-care providers explained that unless there were enough extra coats at the center, a single child without a coat could prevent the entire class from going outside. Caregivers suggested several reasons why parents may dress their child inappropriately, including forgetfulness, a rushed morning routine, limited income to buy clothes, a child's preference for a favorite item, and parents not understanding the importance of outdoor play. Several child-care providers favored specific policies prohibiting inappropriate clothing, as many reported limited success with verbal or written reminders to bring appropriate clothing. Conclusion Inappropriate clothing may be an important barrier to children's physical activity in child

  19. Deterministic character of all-optical magnetization switching in GdFe-based ferrimagnetic alloys

    NASA Astrophysics Data System (ADS)

    Le Guyader, L.; El Moussaoui, S.; Buzzi, M.; Savoini, M.; Tsukamoto, A.; Itoh, A.; Kirilyuk, A.; Rasing, Th.; Nolting, F.; Kimel, A. V.

    2016-04-01

    Using photoemission electron microscopy with x-ray magnetic circular dichroism as a contrast mechanism, new insights into the all-optical magnetization switching (AOS) phenomenon in GdFe-based rare-earth transition-metal ferrimagnetic alloys are provided. From a sequence of static images taken after single linearly polarized laser pulse excitation, the repeatability of AOS can be quantified with a correlation coefficient. It is found that low coercivity enables thermally activated domain-wall motion, limiting in turn the repeatability of the switching. Time-resolved measurements of the magnetization dynamics reveal that while AOS occurs below and above the magnetization compensation temperature TM, it is not observed in GdFe samples where TM is absent. Finally, AOS is experimentally demonstrated against an applied magnetic field of up to 180 mT.

  20. Vortex-based all-optical manipulation of stored light at low light levels.

    PubMed

    Zhao, Lu

    2015-11-16

    We exploit the giant cross-Kerr nonlinearity of electromagnetically induced transparency (EIT) system in ultracold atoms to implement vortex-based multimode manipulation of stored light at low light levels. Using image-bearing signal light fields with angular intensity profiles, sinusoidal grating structures with phase-only modulation can be azimuthally imprinted on the stored probe light field, where the nonlinear absorption loss can be ignored. Upon retrieval of the probe light, collinearly superimposed vortex modes can be generated in the far field. Considering the finite size of atomic gas, the Fraunhofer diffraction patterns of the retrieved probe fields and their spiral spectra are numerically investigated, where the diffracted vortex modes can be efficiently controlled by tuning the weak signal fields. Our studies not only exhibit a fundamental diffraction phenomenon with angular grating structures in EIT system, but also provide a fascinating opportunity to realize multidimensional quantum information processing for stored light in an all-optical manner. PMID:26698464

  1. High efficiency all-optical diode based on photonic crystal waveguide

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Liu, Yun-Feng; Li, Shu-Jing; He, Xing-Dao

    2016-06-01

    A high efficiency all-optical diode based on photonic crystal (PC) waveguide has been proposed and numerically investigated by finite-difference time-domain (FDTD) method. The structure is asymmetrically coupled by a Fano cavity containing nonlinear Kerr medium and a F-P cavity in PC waveguide. Because of interference between two cavities, Fano peak and F-P peak can both appear in transmission spectra. Working wavelength is set between the two peaks and approaching to Fano peak. For forward launch with suitable light intensity, nonlinear Kerr effect of micro-cavity can be excited. It would result in red shift of Fano peak and achieving forward transmission. But due to the asymmetric design, backward launch need stronger incidence light to excite Kerr effect. This design has many advantages, including high maximum transmittance (>90%), high transmittance contrast ratio, low power threshold, short response time (picosecond level), ease of integration.

  2. Expanded all-optical programmable logic array based on multi-input/output canonical logic units.

    PubMed

    Lei, Lei; Dong, Jianji; Zou, Bingrong; Wu, Zhao; Dong, Wenchan; Zhang, Xinliang

    2014-04-21

    We present an expanded all-optical programmable logic array (O-PLA) using multi-input and multi-output canonical logic units (CLUs) generation. Based on four-wave mixing (FWM) in highly nonlinear fiber (HNLF), two-input and three-input CLUs are simultaneously achieved in five different channels with an operation speed of 40 Gb/s. Clear temporal waveforms and wide open eye diagrams are successfully observed. The effectiveness of the scheme is validated by extinction ratio and optical signal-to-noise ratio measurements. The computing capacity, defined as the total amount of logic functions achieved by the O-PLA, is discussed in detail. For a three-input O-PLA, the computing capacity of the expanded CLUs-PLA is more than two times as large as that of the standard CLUs-PLA, and this multiple will increase to more than three and a half as the idlers are individually independent.

  3. Ultrafast all-optical arithmetic logic based on hydrogenated amorphous silicon microring resonators

    NASA Astrophysics Data System (ADS)

    Gostimirovic, Dusan; Ye, Winnie N.

    2016-03-01

    For decades, the semiconductor industry has been steadily shrinking transistor sizes to fit more performance into a single silicon-based integrated chip. This technology has become the driving force for advances in education, transportation, and health, among others. However, transistor sizes are quickly approaching their physical limits (channel lengths are now only a few silicon atoms in length), and Moore's law will likely soon be brought to a stand-still despite many unique attempts to keep it going (FinFETs, high-k dielectrics, etc.). This technology must then be pushed further by exploring (almost) entirely new methodologies. Given the explosive growth of optical-based long-haul telecommunications, we look to apply the use of high-speed optics as a substitute to the digital model; where slow, lossy, and noisy metal interconnections act as a major bottleneck to performance. We combine the (nonlinear) optical Kerr effect with a single add-drop microring resonator to perform the fundamental AND-XOR logical operations of a half adder, by all-optical means. This process is also applied to subtraction, higher-order addition, and the realization of an all-optical arithmetic logic unit (ALU). The rings use hydrogenated amorphous silicon as a material with superior nonlinear properties to crystalline silicon, while still maintaining CMOS-compatibility and the many benefits that come with it (low cost, ease of fabrication, etc.). Our method allows for multi-gigabit-per-second data rates while maintaining simplicity and spatial minimalism in design for high-capacity manufacturing potential.

  4. All-optical fiber anemometer based on laser heated fiber Bragg gratings.

    PubMed

    Gao, Shaorui; Zhang, A Ping; Tam, Hwa-Yaw; Cho, L H; Lu, Chao

    2011-05-23

    A fiber-optic anemometer based on fiber Bragg gratings (FBGs) is presented. A short section of cobalt-doped fiber was utilized to make a fiber-based "hot wire" for wind speed measurement. Fiber Bragg gratings (FBGs) were fabricated in the cobalt-doped fiber using 193 nm laser pulses to serve as localized temperature sensors. A miniature all-optical fiber anemometer is constructed by using two FBGs to determine the dynamic thermal equilibrium between the laser heating and air flow cooling through monitoring the FBGs' central wavelengths. It was demonstrated that the sensitivity of the sensor can be adjusted through the power of pump laser or the coating on the FBG. Experimental results reveal that the proposed FBG-based anemometer exhibits very good performance for wind speed measurement. The resolution of the FBG-based anemometer is about 0.012 m/s for wind speed range between 2.0 m/s and 8.0 m/s.

  5. A reconfigurable all-optical VPN based on XGM effect of SOA in WDM PON

    NASA Astrophysics Data System (ADS)

    Hu, Xiaofeng; Zhang, Liang; Cao, Pan; Wang, Tao; Su, Yikai

    2010-12-01

    We propose and experimentally demonstrate a reconfigurable all-optical VPN scheme enabling intercommunications among different ONUs in a WDM PON. Reconfiguration is realized by dynamically setting wavelength conversion of optical VPN signal using a SOA in the OLT.

  6. High contrast all-optical logic gates based on 2D nonlinear photonic crystal

    NASA Astrophysics Data System (ADS)

    Mohebbi, Zahra; Nozhat, Najmeh; Emami, Farzin

    2015-11-01

    We have proposed the all optical XOR, XNOR, NAND and NOT logic gates based on two-dimensional (2D) photonic crystals (PCs). In all structures the nonlinear Kerr effect has been used. The gates function is based on the destructive interference of the input signals. The phase difference between the input signals has been caused by the different signal travelling paths. To demonstrate the performance of the XNOR, NOT, and NAND gates a control port has been added to the structure. The gates have been operated at the frequency of 0.341(c/a) where 'a' and 'c' are the lattice constant and the speed of light in vacuum, respectively. Due to the maximum required input power of P0 = 277 (mW /μm2) for the XOR, NOT, and XNOR gates and P0 = 554 (mW /μm2) for the NAND gates, and the high contrast ratio of at least 20 dB between the ON and OFF states, these logic gates are applicable for real time communications. Simulations are based on the finite-difference time-domain (FDTD) numerical method.

  7. Design of all-optical multi-level regenerators based on Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Kong, Xiangjian; Wu, Baojian; Zhou, Xingyu; Wan, Qingyao; Jiang, Shanglong; Wen, Feng; Qiu, Kun

    2016-12-01

    We propose a design method for all-optical multi-level regenerators by mimicking the normalized power transfer function (PTF) in the first-order approximation to the ideal step-like PTF, in which a key step is to appropriately select the amplitude and phase conditions of Mach-Zehnder-interferometer (MZI)-based regenerators. As an example, we describe the design process of the self-phase-modulation (SPM)-based MZI regenerator constructed by a section of nonlinear fiber and an optical phase shifter (OPS). It is shown that the parameter of reference power level (RPL) can be regarded as the upper limit of input power, which is useful for the measure of the multi-level regeneration performance. The number of regenerative power levels increases with the RPL parameter. For 4-level pulse amplitude modulated (4PAM) optical signals degraded by the Gaussian noises with the standard deviation of 0.02, the SPM-based MZI regenerator has an average noise reduction ratio (NRR) of 6.5 dB, better than that of 1st-order regenerator by about 5 dB.

  8. Proposal of all-optical sensor based on nonlinear MMI coupler for multi-purpose usage

    NASA Astrophysics Data System (ADS)

    Tajaldini, M.; MatJafri, M. Z.

    2015-10-01

    In this study, we propose an all-optical sensor based on consideration the nonlinear effects on modal propagation and output intensity based on ultra-compact nonlinear multimode interference (NLMMI) coupler. The sensor can be tuned to highest sensitivity in the wavelength and refractive index ranges sufficient to detect water- soluble chemical, air pollutions, and heart operation. The results indicate high output sensitivity to input wavelength. This sensitivity guides us to propose a wave sensor both transverse and longitudinal waves such as acoustic and light wave, when an external wave interacts with input waveguide. For instance, this sensor can be implemented by long input that inserted in the land, then any wave could detected from earth. The visible changes of intensity at output facet in various surrounding layer refractive index show the high sensitivity to the refractive index of surrounding layer that is foundation of introducing a sensor. Also, the results show the high distinguished changes on modal expansion and output throat distribution in various refractive indices of surrounding layer.

  9. All-optical digital 4 × 2 encoder based on 2D photonic crystal ring resonators

    NASA Astrophysics Data System (ADS)

    Moniem, Tamer A.

    2016-04-01

    The photonic crystals draw significant attention to build all-optical logic devices and are considered one of the solutions for the opto-electronic bottleneck via speed and size. The paper presents a novel optical 4 × 2 encoder based on 2D square lattice photonic crystals of silicon rods. The main realization of optical encoder is based on the photonic crystal ring resonator NOR gates. The proposed structure has four logic input ports, two output ports, and two bias input port. The photonic crystal structure has a square lattice of silicon rods with a refractive index of 3.39 in air. The structure has lattice constant 'a' equal to 630 nm and bandgap range from 0.32 to 044. The total size of the proposed 4 × 2 encoder is equal to 35 μm × 35 μm. The simulation results using the dimensional finite difference time domain and Plane Wave Expansion methods confirm the operation and the feasibility of the proposed optical encoder for ultrafast optical digital circuits.

  10. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal.

    PubMed

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-08-05

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature 'prototype' PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits.

  11. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal

    PubMed Central

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-01-01

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature ‘prototype’ PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits. PMID:27491391

  12. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal

    NASA Astrophysics Data System (ADS)

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-08-01

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature ‘prototype’ PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits.

  13. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal.

    PubMed

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-01-01

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature 'prototype' PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits. PMID:27491391

  14. Design of photonic crystal-based all-optical AND gate using T-shaped waveguide

    NASA Astrophysics Data System (ADS)

    haq Shaik, Enaul; Rangaswamy, Nakkeeran

    2016-05-01

    We present a new configuration of all-optical AND gate based on two-dimensional photonic crystal composed of Si rods in air. Two AND gate structures with and without probe input are proposed. The proposed structures are designed with T-shaped waveguide without using nonlinear materials and optical amplifiers. The performance of the proposed AND gate structures is analyzed and simulated by plane-wave expansion and finite difference time domain methods. The AND gate without probe input needs only one T-shaped waveguide, whereas the AND gate with probe input needs two T-shaped waveguides. The former AND gate offers a bit rate of 6.26 Tbps with a contrast ratio of 5.74 dB, whereas the latter AND gate offers a bit rate of 3.58 Tbps whose contrast ratio is 9.66 dB. It can be expected that these small size T-shaped structures are suitable for large-scale integration and can potentially be used in on-chip photonic integrated circuits.

  15. A New All-Optical Imaging Scheme based on QWIP technology

    NASA Astrophysics Data System (ADS)

    Zeng, Debing; Chen, Gang; Martini, Rainer

    2006-03-01

    Infrared imaging applications have gained increasing interest over the recent decades due to favorable light propagation, night imaging as well as chemical sensing applications. However, the scalability of the existing techniques towards high resolution in the multi-megapixel range is one of the major challenges in today's IR imaging technologies. Here we present an alternative solution using an all-optical wavelength conversion scheme. QWIP has been successfully proven their potential in IR imaging applications. Yet the fundamental conversion process from IR light to electric current has been one of the major restrictions in such system. To overcome this problem we propose the use of an all-optical conversion scheme, which utilizes an interband resonant optical NIR beam to probe the electrical population of the QW structure. In this methodology the incident MIR radiation changes the occupation of the QWs, which in turn influences the NIR transmission. Hence the irradiated MIR images can be probed by spatially resolved measurement of the NIR transmission, as has been demonstrated by Nada et al. for all-optical switching purposes. In this talk we present an implementation scheme of the all-optical QWIP readout technique together with theoretical calculations of the sensitivity of the proposed device and its temperature dependence. First experimental results will be presented also. The Authors thankfully acknowledge financial support by US Army, Picatinny Arsenal.

  16. All-optical polarization control and noise cleaning based on a nonlinear lossless polarizer

    NASA Astrophysics Data System (ADS)

    Barozzi, Matteo; Vannucci, Armando; Picchi, Giorgio

    2015-01-01

    We propose an all-optical fiber-based device able to accomplish both polarization control and OSNR enhancement of an amplitude modulated optical signal, affected by unpolarized additive white Gaussian noise, at the same time. The proposed noise cleaning device is made of a nonlinear lossless polarizer (NLP), that performs polarization control, followed by an ideal polarizing filter that removes the orthogonally polarized half of additive noise. The NLP transforms every input signal polarization into a unique, well defined output polarization (without any loss of signal energy) and its task is to impose a signal polarization aligned with the transparent eigenstate of the polarizing filter. In order to effectively control the polarization of the modulated signal, we show that two different NLP configurations (with counter- or co-propagating pump laser) are needed, as a function of the signal polarization coherence time. The NLP is designed so that polarization attraction is effective only on the "noiseless" (i.e., information-bearing) component of the signal and not on noise, that remains unpolarized at the NLP output. Hence, the proposed device is able to discriminate signal power (that is preserved) from in-band noise power (that is partly suppressed). Since signal repolarization is detrimental if applied to polarization-multiplexed formats, the noise cleaner application is limited here to "legacy" links, with 10 Gb/s OOK modulation, still representing the most common format in deployed networks. By employing the appropriate NLP configurations, we obtain an OSNR gain close to 3dB. Furthermore, we show how the achievable OSNR gain can be estimated theoretically.

  17. Chip-integrated all-optical 4-bit Gray code generation based on silicon microring resonators.

    PubMed

    Liu, Li; Dong, Jianji; Zhang, Xinliang

    2015-08-10

    We propose and experimentally demonstrate a 4-port passive encoder for 4-bit Gray code on pure silicon platform. The operation principle for this device is the thermo-optic (TO) effect in silicon microring resonator (MRR) whose transmission spectrum could be shifted by injecting strong light power. Therefore, the output powers of both the through-port and drop-port of the MRR could be controllable and switchable. Two threshold powers are defined to decide the port output code of bit "0" or "1". By combining two independent resonant wavelengths of two MRRs and adjusting their powers in a certain order, all-optical 4-bit Gray code generation has been successfully demonstrated. The proposed integrated device is competent in on-chip all-optical communication and optical interconnection systems with significant advantages, such as simple operation, compact size, economical fabrication process and great scalability.

  18. All-optical time-delay relay based on a bacteriorhodopsin film.

    PubMed

    Chen, Guiying; Yuan, Yizhe; Zhang, Chunping; Yang, Guan; Tian, Jian Guo; Xu, Tang; Song, Q W

    2006-05-15

    Using the property of dynamic complementary suppression modulated transmission of bacteriorhodopsin film, we propose and demonstrate an all-optical time-delay relay in an incoherent light system. The relay can last for a certain amount of time after the switch function of turn off (or turn on) is activated. Furthermore, the delay time can be adjusted by changing the lifetime of the M state and the intensities of blue and yellow beams.

  19. Photonic-chip-based all-optical ultra-wideband pulse generation via XPM and birefringence in a chalcogenide waveguide.

    PubMed

    Tan, Kang; Marpaung, David; Pant, Ravi; Gao, Feng; Li, Enbang; Wang, Jian; Choi, Duk-Yong; Madden, Steve; Luther-Davies, Barry; Sun, Junqiang; Eggleton, Benjamin J

    2013-01-28

    We report a photonic-chip-based scheme for all-optical ultra-wideband (UWB) pulse generation using a novel all-optical differentiator that exploits cross-phase modulation and birefringence in an As₂S₃ chalcogenide rib waveguide. Polarity-switchable UWB monocycles and doublets were simultaneously obtained with single optical carrier operation. Moreover, transmission over 40-km fiber of the generated UWB doublets is demonstrated with good dispersion tolerance. These results indicate that the proposed approach has potential applications in multi-shape, multi-modulation and long-distance UWB-over-fiber communication systems.

  20. Proposed new approach to design all optical AND gate using plasmonic based Mach-Zehnder interferometer for high speed communication

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Singh, Lokendra

    2016-04-01

    The limitation of conventional electronics is mitigated by all optical integrated circuits which have potential of high speed computing and information processing. In this work, an all optical AND gate using optical Kerr effect and optical bistability of a plasmonic based Mach-Zehnder interferometer (MZI) is proposed. An MZI is capable for switching of light according to the intensities of optical input signal. The paper constitutes with mathematical formulation of device and its study is verified using finite difference time domain (FDTD) method.

  1. All-Optical NAND Gate Based on Nonlinear Photonic Crystal Ring Resonators

    NASA Astrophysics Data System (ADS)

    Serajmohammadi, Somaye

    2016-06-01

    In this paper we proposed a new design for all-optical NAND gate. By combining nonlinear Kerr effect with photonic crystal ring resonators first we designed a structure, whose optical behavior can be controlled via input power intensity. The switching power threshold obtained for this structure equal to 1 kW/μm2. For designing the proposed optical logic gate we employed two resonant rings with the same structures, both rings at the logic gates were designed such that their resonant wavelength be at λ=1,550 nm. Every proposed logic gate has one bias and two logic input ports.

  2. Phase-sensitive fiber-based parametric all-optical switch.

    PubMed

    Parra-Cetina, Josué; Kumpera, Aleš; Karlsson, Magnus; Andrekson, Peter A

    2015-12-28

    We experimentally demonstrate, for the first time, an all-optical switch in a phase-sensitive fiber optic parametric amplifier operated in saturation. We study the effect of phase variation of the signal and idler waves on the pump power depletion. By changing the phase of a 0.9 mW signal/idler pair wave by π/2 rad, a pump power extinction ratio of 30.4 dB is achieved. Static and dynamic characterizations are also performed and time domain results presented. PMID:26832007

  3. All-optical encryption based on interleaved waveband switching modulation for optical network security.

    PubMed

    Fok, Mable P; Prucnal, Paul R

    2009-05-01

    All-optical encryption for optical code-division multiple-access systems with interleaved waveband-switching modulation is experimentally demonstrated. The scheme explores dual-pump four-wave mixing in a 35 cm highly nonlinear bismuth oxide fiber to achieve XOR operation of the plaintext and the encryption key. Bit 0 and bit 1 of the encrypted data are represented by two different wavebands. Unlike on-off keying encryption methods, the encrypted data in this approach has the same intensity for both bit 0 and bit 1. Thus no plaintext or ciphertext signatures are observed.

  4. All-optical multiplexing schemes for multiple access networks based on wavelet packet filter banks

    NASA Astrophysics Data System (ADS)

    Cincotti, Gabriella; Svaluto Moreolo, Michela; Neri, Alessandro

    2004-08-01

    All optical architectures for Wavelet Packet Division Multiplexing (WPDM) are presented, that can be used in multiple access networks to increase the number of simultaneous users. Wavelet waveform coding spreads data signals both in time and frequency domains, with a large capacity improvement with respect to standard Optical-Code Division Multiple Access (O-CDMA) systems. In addition, the orthogonal property of the wavelet atoms ensures low InterSymbol Interference (ISI) and Multiple Access Interference (MAI) noises. To exploit the large bandwidth capacity of optical fibres, the Optical-Electrical-Optical (O-E-O) conversion is completely avoided, and we designed an all optical system that realizes the WPDM fully in the optical domain. A single Planar Lightwave Circuit (PLC) device multiplies/demultiplies N different users and a diffractive or an integrated optical device performs the waveform coding/decoding. The Wavelet Packet (WP) encoder/decoder is realized as a tree of lattice-form delay-line filters, and can be integrated on a single device along with the optical waveform modulator, resulting in a compact planar optical system. In addition, we show that different choices of WP encoders/decoders are possible to further enhance the system performances.

  5. All-Optical Micro Motors Based on Moving Gratings in Photosensitive Media

    NASA Technical Reports Server (NTRS)

    Curley, M.; Sarkisov, S. S.; Fields, A.; Smith, C.; Kukhtarev, N.; Kulishov, M. B.; Adamovsky, G. (Technical Monitor)

    2000-01-01

    An all-optical micro motor with a rotor driven by a traveling wave of surface deformation of a stator being in contact with the rotor is being studied. Instead of an ultrasonic wave produced by an electrically driven piezoelectric actuator as in ultrasonic motors, the wave is a result of a photo induced surface deformation of a photosensitive material produced by a traveling holographic grating. Two phase modulated coherent optical beams generate the grating. Several types of photosensitive materials are studied such as photorefractive crystals, photosensitive piezoelectric ceramics, and side-chain liquid crystalline polyesters. In order to be considered as a possible candidate for micro motors, the material should exhibit surface deformation produced by moving grating of the order of 10 micron. Deformations produced by static holographic gratings are studied in photorefractive crystals of LiNbO3 using high vertical resolution surface profilometer Dektak 3 and surface interferometer WYKO. An experimental set-up with moving grating has been developed. The set-up uses a two-beam interferometry configuration with one beam being reflected by a thin mirror mounted on a loud speaker. A ramp voltage signal generator drives the speaker. Changing voltage, polarity, and frequency of the signal can easily generate vibrating gratings or moving gratings in both directions. A vibrating grating has been applied to a photorefractive crystal of BSO controlled by an external electric field of the order of 104 V/cm. We have additionally studied effects of moving grating interaction with light absorbing fluids such as solutions of 2,9,16,23-Tetrakis(phenylthio)-29H, 31 Hphthalocyanine in chlorobenzene in capillary tubes. The purpose of using a liquid is to show that the moving gratings can force a liquid to shift. The interaction of a single low power focused laser beam at 633 nm with such fluid produced an intensive circular motion, which also might be applied to all-optical micro

  6. 7x 40 Gb/s base-rate RZ all-optical broadcasting utilizing an electroabsorption modulator.

    PubMed

    Xu, L; Chi, N; Yvind, K; Christiansen, L; Oxenløwe, L; Mørk, J; Jeppesen, P; Hanberg, J

    2004-02-01

    We experimentally demonstrate all-optical broadcasting through simultaneous 7 x 40 Gb/s base-rate wavelength conversion in RZ format based on cross absorption modulation in an electroabsorption modulator. In this experiment the original intensity-modulated information is successfully duplicated onto seven wavelengths that comply with the ITU-T proposal. The advantages of the proposed wavelength conversion scheme are also discussed.

  7. All-optical cross-bar network architecture using TOAD based interferometric switch and designing of reconfigurable logic unit

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay

    2011-12-01

    The design of all-optical 2 × 2 Terahertz Optical Asymmetric Demultiplexer (TOAD) based interferometric switch is proposed and described in this manuscript. Numerical simulation has been done to achieve the performance of the switch. Using this 2 × 2 TOAD based switch, cross-bar network architecture is designed. A reconfigurable logic unit is also proposed in this manuscript, which can perform 16-Boolean logical operations.

  8. All-optical switching based on nonradiative effects in doped fibers

    NASA Astrophysics Data System (ADS)

    Davis, Monica Karin

    1999-10-01

    Doped fibers are used for many purposes in fiber-optic communications and fiber sensors. These applications rely on the stimulated electronic transitions of dopant ions to produce a desired effect, such as gain (erbium doped fiber amplifiers and fiber lasers), refractive index modulation (switching) or absorption (fiber attenuators). In most devices it is advantageous to use short doped fiber lengths containing large numbers of dopant ions. However, high dopant concentrations are often accompanied by significant nonradiative decay processes that produce other effects, either beneficial or undesirable. The understanding of these nonradiative processes is critical to most doped fiber devices. In this dissertation we report the first comprehensive study of the effects of nonradiative processes in optically pumped, highly doped fibers. We have developed a new method to measure the size and relative abundance of clusters in rare-earth-doped fibers. This enables us to predict the extent of nonradiative, heat-producing processes in these fibers. We have also developed analytical and numerical models to quantify the dynamic evolution of the temperature profile in the fiber and to predict the thermal phase modulation in the fiber due to this temperature increase. Ours is the first analysis to fully describe the thermal effects created in doped fibers in both the single short pump pulse regime and the continuous pumping regime, as well as in intermediate modes of operation. We have designed methods to determine the presence and extent of nonradiative decay mechanisms and to differentiate them from nonlinear optical effects. We present this analysis and experimental verification of our model using high concentration cobalt- and vanadium- doped fibers. Finally, we have expanded the number of configurations available for all-optical switching by developing both the analysis of the pumped nonlinear directional coupler (PNLDC) and the analysis of the self- terminating Sagnac loop

  9. All-optical NRZ wavelength conversion based on a single hybrid III-V/Si SOA and optical filtering.

    PubMed

    Wu, Yingchen; Huang, Qiangsheng; Keyvaninia, Shahram; Katumba, Andrew; Zhang, Jing; Xie, Weiqiang; Morthier, Geert; He, Jian-Jun; Roelkens, Gunther

    2016-09-01

    We demonstrate all-optical wavelength conversion (AOWC) of non-return-to-zero (NRZ) signal based on cross-gain modulation in a single heterogeneously integrated III-V-on-silicon semiconductor optical amplifier (SOA) with an optical bandpass filter. The SOA is 500 μm long and consumes less than 250 mW electrical power. We experimentally demonstrate 12.5 Gb/s and 40 Gb/s AOWC for both wavelength up and down conversion. PMID:27607638

  10. Fast all-optical nuclear spin echo technique based on EIT

    NASA Astrophysics Data System (ADS)

    Walther, Andreas; Nilsson, Adam N.; Li, Qian; Rippe, Lars; Kröll, Stefan

    2016-08-01

    We demonstrate an all-optical Raman spin echo technique, using electromagnetically induced transparency (EIT) to create the pulses required for a spin echo sequence: initialization, pi-rotation, and readout. The first pulse of the sequence induces coherence directly from a mixed state, and the technique is used to measure the nuclear spin coherence of an inhomogeneously broadened ensemble of rare-earth ions (Pr3 +) in a crystal. The rephasing pi-rotation is shown to offer an advantage of combining the rephasing action with the operation of a phase gate, particularly useful in e.g. dynamic decoupling sequences. In contrast to many previous experiments the sequence does not require any preparatory hole burning, which greatly shortens the total duration of the sequence. The effect of the different pulses is characterized by quantum state tomography and compared with simulations. We demonstrate two applications of the technique: compensating the magnetic field across our sample by monitoring T2 reductions from stray magnetic fields, and measuring coherence times at temperatures up to 11 K, where standard preparation techniques are difficult to implement. We explore the potential of the technique, in particular for systems with much shorter T2, and other possible applications.

  11. Fast all-optical nuclear spin echo technique based on EIT

    NASA Astrophysics Data System (ADS)

    Walther, Andreas; Nilsson, Adam N.; Li, Qian; Rippe, Lars; Kröll, Stefan

    2016-08-01

    We demonstrate an all-optical Raman spin echo technique, using electromagnetically induced transparency (EIT) to create the pulses required for a spin echo sequence: initialization, pi-rotation, and readout. The first pulse of the sequence induces coherence directly from a mixed state, and the technique is used to measure the nuclear spin coherence of an inhomogeneously broadened ensemble of rare-earth ions (Pr3 +) in a crystal. The rephasing pi-rotation is shown to offer an advantage of combining the rephasing action with the operation of a phase gate, particularly useful in e.g. dynamic decoupling sequences. In contrast to many previous experiments the sequence does not require any preparatory hole burning, which greatly shortens the total duration of the sequence. The effect of the different pulses is characterized by quantum state tomography and compared with simulations. We demonstrate two applications of the technique: compensating the magnetic field across our sample by monitoring T 2 reductions from stray magnetic fields, and measuring coherence times at temperatures up to 11 K, where standard preparation techniques are difficult to implement. We explore the potential of the technique, in particular for systems with much shorter T 2, and other possible applications.

  12. Asynchronous, all-optical signal processing based on the self-frequency shift of a gigahertz Raman soliton.

    PubMed

    Kato, Masao; Fujiura, Kazuo; Kurihara, Takashi

    2005-03-10

    Ultrafast asynchronous all-optical signal processing is experimentally demonstrated. It is based on the intensity-dependent, self-frequency shift of a gigahertz Raman soliton. We demonstrate error-free, asynchronous, all-optical, bit-by-bit, self-signal recognition and demultiplexing from contended optical packets without use of an optical buffer, control pulse, or bit-phase synchronization. Fourfold, contended, 9.95-Gbit/s optical packets are transmitted through a conventional repeater span of 80 km and simultaneously demultiplexed to multiwavelength 9.95-Gbit/s optical packets with 0.5-dB processing sensitivity. Furthermore, we successfully accomplish demultiplexing from overlapping signals in contended optical packets with better than 3-dB recognition sensitivity. We confirm the capability of realizing a 3x cascade operation from bit-error-rate measurements.

  13. All-Optical Micro Motors Based on Moving Gratings in Photosensitive Media

    NASA Technical Reports Server (NTRS)

    Curley, M.; Sarkisov, S. S.; Fields, A.; Smith, C.; Kukhtarev, N.; Kulishov, M. B.; Adamovsky, Grigory

    2001-01-01

    An all-optical micromotor with a rotor driven by a traveling wave of surface deformation of a stator being in contact with the rotor is being studied. Instead of an ultrasonic wave produced by an electrically driven piezoelectric actuator as in ultrasonic motors, the wave is a result of a photo-induced surface deformation of a photosensitive material produced by an incident radiation. A thin piezoelectric polymer will deform more easily LiNbO3 or metal when irradiated with light. The type of photosensitive material studied are piezoelectric polymers with and without coatings for connecting electrodes. In order to be considered as a possible candidate for micromotors, the material should exhibit surface deformation produced by a laser beam of the order of 10 microns. This is compared to the deformations produced by static holographic gratings studied in photorefractive crystals of LiNbO3 using high vertical resolution surface profilometer Dektak 3 and surface interferometer WYKO. An experimental setup showing the oscillations has been developed. The setup uses a chopped beam from an Argon ion laser to produce the deformation while a probe beam is reflected by the thin film into a fiber which is then detected on an oscilloscope. A ramp voltage signal generator will drive the piezoelectric film in another experiment to determine the resonance of the film. A current is generated when light is incident upon the film and this current can be measured. The reverse process has already been demonstrated in other piezoelectric actuators. Changing voltage, polarity, and frequency of the signal can easily generate vibrations similar to those when light is incident on the film. This can be compared to the effects of laser interaction with light absorbing fluids such as solutions of 2,9,16,23-Tetrakis(phenylthio)-29H, 31 H-phthalocyanine in chlorobenzene in capillary tubes, The possibility of using a liquid with the piezoelectric film would be a novel idea for a micromotor since

  14. A novel 40-Gb/s all-optical inverted wavelength converter based on a modified terahertz optical asymmetric demultiplexer

    NASA Astrophysics Data System (ADS)

    Huang, Xuetian; Ye, Peida; Zhang, Min; Wang, Ling

    2004-12-01

    A novel scheme for all-optical inverted wavelength conversion with 40-Gb/s pseudorandom bit sequences (PRBSs) based on a modified terahertz optical asymmetric demultiplexer (TOAD) is proposed. The performance of the proposed wavelength converter is analyzed in term of extinction ratio (ER) through numerical simulations. For a typical ER of 10 dB, some key characteristic parameters of the semiconductor optical amplifier (SOA) are designed. With the properly designed parameters, a high quality eye diagram is achievable, indicating that the amplitude fluctuation of the output signal is effectively reduced.

  15. A novel all-optical label processing for OPS networks based on multiple OOC sequences from multiple-groups OOC

    NASA Astrophysics Data System (ADS)

    Qiu, Kun; Zhang, Chongfu; Ling, Yun; Wang, Yibo

    2007-11-01

    This paper proposes an all-optical label processing scheme using multiple optical orthogonal codes sequences (MOOCS) for optical packet switching (OPS) (MOOCS-OPS) networks, for the first time to the best of our knowledge. In this scheme, the multiple optical orthogonal codes (MOOC) from multiple-groups optical orthogonal codes (MGOOC) are permuted and combined to obtain the MOOCS for the optical labels, which are used to effectively enlarge the capacity of available optical codes for optical labels. The optical label processing (OLP) schemes are reviewed and analyzed, the principles of MOOCS-based optical labels for OPS networks are given, and analyzed, then the MOOCS-OPS topology and the key realization units of the MOOCS-based optical label packets are studied in detail, respectively. The performances of this novel all-optical label processing technology are analyzed, the corresponding simulation is performed. These analysis and results show that the proposed scheme can overcome the lack of available optical orthogonal codes (OOC)-based optical labels due to the limited number of single OOC for optical label with the short code length, and indicate that the MOOCS-OPS scheme is feasible.

  16. A compact, high-performance all optical atomic clock based on telecom lasers

    NASA Astrophysics Data System (ADS)

    Burke, John H.; Lemke, Nathan D.; Phelps, Gretchen R.; Martin, Kyle W.

    2016-03-01

    We discuss an optical atomic clock based on a two-photon transition at 778 nm in rubidium. In particular, we discuss the fundamental limitations to the short-term stability of a system based on a commercial C-band telecom laser as opposed to a near infrared laser. We show that this system is fundamentally capable of besting a hydrogen MASER in frequency stability and size.

  17. Implementation of sequential logic circuits using the Mach-Zehnder interferometer structure based on electro-optic effect

    NASA Astrophysics Data System (ADS)

    Kumar Raghuwanshi, Sanjeev; Kumar, Ajay; Chen, Nan-Kuang

    2014-12-01

    The electro-optic effect is one of the most important phenomena in Mach-Zehnder (MZI) interferometer structure. The Mach-Zehnder interferometer structure working on the principle of electro-optic effect behaves as the powerful optical switching device. The paper contains the discussion of electro-optic effect based MZI structure. The proper feedback mechanism with the delay unit provides the responses of optical clocked D flip-flop. The paper includes the detailed mathematical description of optical clocked D flip-flops with the MATLAB simulation result. Based on the proposed optical D-flip flop, it is possible to construct some sequential circuits such as synchronous shift registers and ripple counters. Finally, the paper includes the detailed discussion of optical sequential circuits such as synchronous shift register and ripple counter and its implementation using the MATLAB simulation. However, the concept of proposed optical clocked D flip-flop is implemented using the OptiBPM software for the proper verification of the discussed schemes. The Basic building block structures are analyzed to check the optimum performance parameters such as crosstalk, power imbalance, extinction ratio and transition losses, in order to obtain the appropriate Ti-thickness and switching voltage.

  18. All-optical atomic magnetometers based on nonlinear magneto-optical rotation with amplitude modulated light

    NASA Astrophysics Data System (ADS)

    Pustelny, Szymon; Wojciechowski, Adam; Kotyrba, Mateusz; Sycz, Krystian; Zachorowski, Jerzy; Gawlik, Wojciech; Cingoz, Arman; Leefer, Nathan; Higbie, James M.; Corsini, Eric; Ledbetter, Micah P.; Rochester, Simon M.; Sushkov, Alexander O.; Budker, Dmitry

    2007-03-01

    We demonstrate a magnetometric technique based on nonlinear magneto-optical rotation using amplitude modulated light. The magnetometers can be operated in either open-loop (typical nonlinear magneto-optical rotation with amplitude-modulated light) or closed-loop (self-oscillating) modes. The latter mode is particularly well suited for conditions where the magnetic field is changing by large amounts over a relatively short timescale.

  19. A novel burst-mode all-optical wavelength converter based on gain-clamping structure

    NASA Astrophysics Data System (ADS)

    Zhao, B.; Ke, C. J.; Zhao, Y.; Liu, D. M.

    2011-02-01

    A novel gain-clamped wavelength converter (GCWC) is proposed to make the hybrid TDM-WDM PON architecture based on wavelength conversion feasible, and its operation principle is also demonstrated. The power budget of this network is measured to identify the architecture can support 4096 users who share 40Gbit/s accessing capacity on a single trunk fiber. And optical power equalization functionality and burst transparency characteristic of GCWC is experimentally evaluated, and the results show that the GCWC makes burst signals from different transmitters with up to 5 dB dynamic range equalized and is transparency for burst signals.

  20. All-optical photochromic spatial light modulators based on photoinduced electron transfer in rigid matrices

    NASA Technical Reports Server (NTRS)

    Beratan, David N. (Inventor); Perry, Joseph W. (Inventor)

    1991-01-01

    A single material (not a multi-element structure) spatial light modulator may be written to, as well as read out from, using light. The device has tailorable rise and hold times dependent on the composition and concentration of the molecular species used as the active components. The spatial resolution of this device is limited only by light diffraction as in volume holograms. The device may function as a two-dimensional mask (transmission or reflection) or as a three-dimensional volume holographic medium. This device, based on optically-induced electron transfer, is able to perform incoherent to coherent image conversion or wavelength conversion over a wide spectral range (ultraviolet, visible, or near-infrared regions).

  1. All optical controlled-NOT gate based on an exciton-polariton circuit

    NASA Astrophysics Data System (ADS)

    Solnyshkov, D. D.; Bleu, O.; Malpuech, G.

    2015-07-01

    We propose an implementation of a CNOT gate for quantum computing based on a patterned microcavity polariton system, which can be manufactured using the modern technological facilities. The qubits are encoded in the spin-coherent polariton states. The structure consists of two wire cavities oriented at 45° with a micropillar between them. The polariton spin rotates due to the Longitudinal-Transverse splitting between polarization eigenstates in the wires. In the pillar, the optically generated circularly polarized polariton macrooccupied state plays the role of the control qubit. Because of the spin-anisotropic polariton interaction, it induces an effective magnetic field along the Z-direction with a sign depending on the qubit value.

  2. All optical OFDM transmission systems

    NASA Astrophysics Data System (ADS)

    Rhee, June-Koo K.; Lim, Seong-Jin; Kserawi, Malaz

    2011-12-01

    All-optical OFDM data transmission opens up a new realm of advanced optical transmission at extreme data rates, as subcarriers are multiplexed and demultiplexed by all optical discrete Fourier transforms (DFT). This paper reviews the principles of all optical OFDM transmission and its system application techniques, providing the generic ideas and the practical implementation issues to achieve 100Gbps or higher data rates with a spectral efficiency of 1 bps/Hz or better. This paper also include discussions on all-optical OFDM implementation variants such as an AWG-based OFDM multiplexer and demultiplexer, a receiver design without optical sampling, a transmitter design with frequency-locked cw lasers, an OFDM cyclic prefix designs, and a chromatic dispersion mitigation technique.

  3. Integrated all-optical logic and arithmetic operations with the help of a TOAD-based interferometer device--alternative approach

    NASA Astrophysics Data System (ADS)

    Nath Roy, Jitendra; Gayen, Dilip Kumar

    2007-08-01

    Interferometric devices have drawn a great interest in all-optical signal processing for their high-speed photonic activity. The nonlinear optical loop mirror provides a major support to optical switching based all-optical logic and algebraic operations. The gate based on the terahertz optical asymmetric demultiplexer (TOAD) has added new momentum in this field. Optical tree architecture (OTA) plays a significant role in the optical interconnecting network. We have tried to exploit the advantages of both OTA- and TOAD-based switches. We have proposed a TOAD-based tree architecture, a new and alternative scheme, for integrated all-optical logic and arithmetic operations.

  4. A novel all-optical label processing based on multiple optical orthogonal codes sequences for optical packet switching networks

    NASA Astrophysics Data System (ADS)

    Zhang, Chongfu; Qiu, Kun; Xu, Bo; Ling, Yun

    2008-05-01

    This paper proposes an all-optical label processing scheme that uses the multiple optical orthogonal codes sequences (MOOCS)-based optical label for optical packet switching (OPS) (MOOCS-OPS) networks. In this scheme, each MOOCS is a permutation or combination of the multiple optical orthogonal codes (MOOC) selected from the multiple-groups optical orthogonal codes (MGOOC). Following a comparison of different optical label processing (OLP) schemes, the principles of MOOCS-OPS network are given and analyzed. Firstly, theoretical analyses are used to prove that MOOCS is able to greatly enlarge the number of available optical labels when compared to the previous single optical orthogonal code (SOOC) for OPS (SOOC-OPS) network. Then, the key units of the MOOCS-based optical label packets, including optical packet generation, optical label erasing, optical label extraction and optical label rewriting etc., are given and studied. These results are used to verify that the proposed MOOCS-OPS scheme is feasible.

  5. All-optical logical gates based on pump-induced resonant nonlinearity in an erbium-doped fiber coupler.

    PubMed

    Li, Qiliang; Zhang, Zhen; Li, Dongqiang; Zhu, Mengyun; Tang, Xianghong; Li, Shuqin

    2014-12-01

    In this paper, we theoretically investigate all-optical logical gates based on the pump-induced resonant nonlinearity in an erbium-doped fiber coupler. The resonant nonlinearity yielded by the optical transitions between the (4)I(15/2) states and (4)I(13/2) states in Er(3+) induces the refractive index to change, which leads to switching between two output ports. First, we do a study on the switching performance, and calculate the extinction ratio (Xratio) of the device. Second, using the Xratio, we obtain the truth tables of the device. The results reveal that compared with other undoped nonlinear couplers, the erbium-doped fiber coupler can drop the switching threshold power. We also obtain different logic gates and logic operations in the cases of the same phase and different phase of two initial signals by changing the pump power.

  6. A new design procedure for all-optical photonic crystal logic gates and functions based on threshold logic

    NASA Astrophysics Data System (ADS)

    Sharifi, Hojjat; Hamidi, Seyyedeh Mehri; Navi, Keivan

    2016-07-01

    In this paper, a general method is proposed to design all-optical photonic crystal logic gates and functions based on threshold logic concept that have regular pattern in inputs. In our proposed structure, a photonic crystal junction is cascaded by a threshold power level detector. Additionally, a novel mechanism is introduced to shift the threshold power level for designing different logic gates and functions. The finite difference time domain and plane wave expansion methods are used to evaluate the proposed structures. The proposed gates and functions occupy an area less than 150 μm2 and also, the maximum power required for the switching mechanism is 15 μW. The inputs and output in the mentioned gates and functions are homogeneous and they can operate with a bit rate of about 500 Gbits/s.

  7. All-optical logic gates based on cross phase modulation effect in a phase-shifted grating.

    PubMed

    Li, Qiliang; Song, Junfeng; Chen, Xin; Bi, Meihua; Hu, Miao; Li, Shuqin

    2016-09-01

    In this paper, we perform a theoretical study of the all-optical logic gates based on the techniques of cross phase modulation (XPM) in a phase-shifted grating. Here the pumps are used to control the switching of a weak continuous wave (cw). In order to understand the transferring process of the information from the pump light to the cw light, we first study the switching characteristic of the device. Then, by changing the combination between two pumps, in a fiber grating with zero phase shift we have realized NOT, AND, and NAND gates, and in a phase-shifted grating with the phase shift π, the other various logic operations can be realized such as NAND gates and OR gates; when selecting Δφ=3/2π, we can realize XOR gates and XNOR gates. Thus the change of the phase shift of the phase-shifted grating will yield various logic gates. PMID:27607262

  8. Performance analysis of an all-optical logic gate based on a single I/Q modulator with direct detection.

    PubMed

    Zhai, Yaxue; Tang, Xianfeng; Zhang, Xiaoguang; Xi, Lixia; Zhang, Wenbo

    2016-09-01

    This paper investigates the performance of an all-optical logic gate scheme based on a single in-phase and quadrature (I/Q) modulator with direct detection. The proposed scheme of an all-optical logic gate is simple, high speed, and easily reconfigured to realize 24 logic states by adjusting bias voltages, peak-to-peak voltages of the driven RF signals, and the phase shift. As the scheme to realize logic gates is based on the irregular use of a commercially available I/Q modulator and laser source, a specialized logic gate system including a laser, I/Q modulator, and driven RF module should be optimally designed to obtain the best performance. With the system's extinction ratio (ER) and Q-factor as metrics, the performance of the proposed logic gate scheme is analyzed theoretically and numerically in this paper. We first give a new theoretical model of the I/Q modulator. Next, taking the OR gate as an example, the simulations are carried out to analyze performance under the influence of some key factors in the system. Results show that the extinction ratio of the whole system is affected by the phase shift between the two arms of the I/Q modulator and the extinction ratios of two Mach-Zehnder modulators (MZMs), while Q-factor is further influenced by the output power of the laser and the insertion loss of the MZMs in the I/Q modulator. For an I/Q modulator with MZMs having an extinction ratio of 20 dB, the minimum laser output power to obtain a system's ER higher than 16 dB is 3 dBm, while in order to obtain a Q-factor higher than 6, the output power of the laser must not be <10  dBm. PMID:27607252

  9. Fixed weight Hopfield Neural Network based on optical implementation of all-optical MZI-XNOR logic gate

    NASA Astrophysics Data System (ADS)

    Nugamesh Mutter, Kussay; Mat Jafri, Mohd Zubir; Abdul Aziz, Azlan

    2010-05-01

    Many researches are conducted to improve Hopfield Neural Network (HNN) performance especially for speed and memory capacity in different approaches. However, there is still a significant scope of developing HNN using Optical Logic Gates. We propose here a new model of HNN based on all-optical XNOR logic gates for real time color image recognition. Firstly, we improved HNN toward optimum learning and converging operations. We considered each unipolar image as a set of small blocks of 3-pixels as vectors for HNN. This enables to save large number of images in the net with best reaching into global minima, and because there are only eight fixed states of weights so that only single iteration performed to construct a vector with stable state at minimum energy. HNN is useless in dealing with data not in bipolar representation. Therefore, HNN failed to work with color images. In RGB bands each represents different values of brightness, for d-bit RGB image it is simply consists of d-layers of unipolar. Each layer is as a single unipolar image for HNN. In addition, the weight matrices with stability of unity at the diagonal perform clear converging in comparison with no self-connecting architecture. Synchronously, each matrix-matrix multiplication operation would run optically in the second part, since we propose an array of all-optical XOR gates, which uses Mach-Zehnder Interferometer (MZI) for neurons setup and a controlling system to distribute timely signals with inverting to achieve XNOR function. The primary operation and simulation of the proposal HNN is demonstrated.

  10. Revisiting 2D Lattice Based Spin Flip-Flop Ising Model: Magnetic Properties of a Thin Film and Its Temperature Dependence

    ERIC Educational Resources Information Center

    Singh, Satya Pal

    2014-01-01

    This paper presents a brief review of Ising's work done in 1925 for one dimensional spin chain with periodic boundary condition. Ising observed that no phase transition occurred at finite temperature in one dimension. He erroneously generalized his views in higher dimensions but that was not true. In 1941 Kramer and Wannier obtained…

  11. All-optical analog comparator.

    PubMed

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Zhao, Dongliang; Zhao, Yongpeng; Wang, Yuncai

    2016-01-01

    An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical '1' or '0' by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures. Our results show that the all-optical comparator is very well suited for true AO-ADCs, enabling the whole digital conversion from an analog optical signal (continuous-time signal or discrete pulse signal) to a binary representation totally in the optical domain. In particular, this all-optical analog comparator possesses a low threshold power (several mW), high extinction ratio (up to 40 dB), fast operation rate (of the order of tens of Gb/s) and a step-like transfer function.

  12. All-optical analog comparator

    NASA Astrophysics Data System (ADS)

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Zhao, Dongliang; Zhao, Yongpeng; Wang, Yuncai

    2016-08-01

    An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical ‘1’ or ‘0’ by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures. Our results show that the all-optical comparator is very well suited for true AO-ADCs, enabling the whole digital conversion from an analog optical signal (continuous-time signal or discrete pulse signal) to a binary representation totally in the optical domain. In particular, this all-optical analog comparator possesses a low threshold power (several mW), high extinction ratio (up to 40 dB), fast operation rate (of the order of tens of Gb/s) and a step-like transfer function.

  13. All-optical analog comparator

    PubMed Central

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Zhao, Dongliang; Zhao, Yongpeng; Wang, Yuncai

    2016-01-01

    An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical ‘1’ or ‘0’ by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures. Our results show that the all-optical comparator is very well suited for true AO-ADCs, enabling the whole digital conversion from an analog optical signal (continuous-time signal or discrete pulse signal) to a binary representation totally in the optical domain. In particular, this all-optical analog comparator possesses a low threshold power (several mW), high extinction ratio (up to 40 dB), fast operation rate (of the order of tens of Gb/s) and a step-like transfer function. PMID:27550874

  14. All-optical analog comparator.

    PubMed

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Zhao, Dongliang; Zhao, Yongpeng; Wang, Yuncai

    2016-01-01

    An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical '1' or '0' by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures. Our results show that the all-optical comparator is very well suited for true AO-ADCs, enabling the whole digital conversion from an analog optical signal (continuous-time signal or discrete pulse signal) to a binary representation totally in the optical domain. In particular, this all-optical analog comparator possesses a low threshold power (several mW), high extinction ratio (up to 40 dB), fast operation rate (of the order of tens of Gb/s) and a step-like transfer function. PMID:27550874

  15. All-optical reservoir computing.

    PubMed

    Duport, François; Schneider, Bendix; Smerieri, Anteo; Haelterman, Marc; Massar, Serge

    2012-09-24

    Reservoir Computing is a novel computing paradigm that uses a nonlinear recurrent dynamical system to carry out information processing. Recent electronic and optoelectronic Reservoir Computers based on an architecture with a single nonlinear node and a delay loop have shown performance on standardized tasks comparable to state-of-the-art digital implementations. Here we report an all-optical implementation of a Reservoir Computer, made of off-the-shelf components for optical telecommunications. It uses the saturation of a semiconductor optical amplifier as nonlinearity. The present work shows that, within the Reservoir Computing paradigm, all-optical computing with state-of-the-art performance is possible.

  16. All-optical reservoir computing

    NASA Astrophysics Data System (ADS)

    Duport, François; Schneider, Bendix; Smerieri, Anteo; Haelterman, Marc; Massar, Serge

    2012-09-01

    Reservoir Computing is a novel computing paradigm which uses a nonlinear recurrent dynamical system to carry out information processing. Recent electronic and optoelectronic Reservoir Computers based on an architecture with a single nonlinear node and a delay loop have shown performance on standardized tasks comparable to state-of-the-art digital implementations. Here we report an all-optical implementation of a Reservoir Computer, made of off-the-shelf components for optical telecommunications. It uses the saturation of a semiconductor optical amplifier as nonlinearity. The present work shows that, within the Reservoir Computing paradigm, all-optical computing with state-of-the-art performance is possible.

  17. All-optical repeater.

    PubMed

    Silberberg, Y

    1986-06-01

    An all-optical device containing saturable gain, saturable loss, and unsaturable loss is shown to transform weak, distorted optical pulses into uniform standard-shape pulses. The proposed device performs thresholding, amplification, and pulse shaping as required from an optical repeater. It is shown that such a device could be realized by existing semiconductor technology.

  18. All-optical scheme for detecting the possible Majorana signature based on QD and nanomechanical resonator systems

    NASA Astrophysics Data System (ADS)

    Chen, HuaJun; Zhu, KaDi

    2015-05-01

    Majorana fermions (MFs) are exotic particles that are their own anti-particles. Currently, the search for MFs occurring as quasiparticle excitations in condensed matter systems has attracted widespread interest, because of their importance in fundamental physics and potential applications in topological quantum computation based on solid-state devices. Motivated by recent experimental progress towards the detection and manipulation of MFs in hybrid semiconductor/superconductor heterostructures, in this review, we present a novel proposal to probe MFs in all-optical domain. We introduce a single quantum dot (QD), a hybrid quantum dot-nanomechanical resonators (QD-NR) system, and a carbon nanotube (CNT) resonator implanted in a single electron spin system with optical pump-probe technology to detect MFs, respectively. With this scheme, a possible Majorana signature is investigated via the probe absorption spectrum and nonlinear optical Kerr effect, and the coupling strength between MFs and the QD or the single electron spin is also determined. In the hybrid QD-NR system, vibration of the NR will enhance the nonlinear optical effect, which makes the MFs more sensitive for detection. In the CNT resonator with a single electron, the single electron spin can be considered as a sensitive probe, and the CNT resonator behaved as a phonon cavity is robust for detecting of MFs. This optical scheme will provide another method for the detection MFs and will open the door for new applications ranging from robust manipulation of MFs to quantum information processing based on MFs.

  19. All-optical XOR and OR logic gates based on line and point defects in 2-D photonic crystal

    NASA Astrophysics Data System (ADS)

    Goudarzi, Kiyanoosh; Mir, Ali; Chaharmahali, Iman; Goudarzi, Dariush

    2016-04-01

    In this paper, we have proposed an all-optical logic gate structure based on line and point defects created in the two dimensional square lattice of silicon rods in air photonic crystals (PhCs). Line defects are embedded in the DX and DZ directions of the momentum space. The device has two input and two output ports. It has been shown analytically whether the initial phase difference between the two input beams is π/2, they interfere together constructively or destructively to realize the logical functions. The simulation results show that the device can acts as a XOR and an OR logic gate. It is applicable in the frequency range of 0-0.45 (a/λ), however we set it at (a/λ=) 0.419 for low dispersion condition, correspondingly the lambda is equal to 1.55 μm. The maximum delay time to response to the input signals is about 0.4 ps, hence the speed of the device is about 2.5 THz. Also 6.767 dB is the maximum contrast ratio of the device.

  20. High contrast all-optical diode based on direction-dependent optical bistability within asymmetric ring cavity

    NASA Astrophysics Data System (ADS)

    Xia, Xiu-Wen; Zhang, Xin-Qin; Xu, Jing-Ping; Yang, Ya-Ping

    2016-08-01

    We propose a simple all-optical diode which is comprised of an asymmetric ring cavity containing a two-level atomic ensemble. Attributed to spatial symmetry breaking of the ring cavity, direction-dependent optical bistability is obtained in a classical bistable system. Therefore, a giant optical non-reciprocity is generated, which guarantees an all-optical diode with a high contrast up to 22 dB. Furthermore, its application as an all-optical logic AND gate is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274242, 11474221, and 11574229), the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. U1330203), and the National Key Basic Research Special Foundation of China (Grant Nos. 2011CB922203 and 2013CB632701).

  1. High contrast all-optical diode based on direction-dependent optical bistability within asymmetric ring cavity

    NASA Astrophysics Data System (ADS)

    Xia, Xiu-Wen; Zhang, Xin-Qin; Xu, Jing-Ping; Yang, Ya-Ping

    2016-08-01

    We propose a simple all-optical diode which is comprised of an asymmetric ring cavity containing a two-level atomic ensemble. Attributed to spatial symmetry breaking of the ring cavity, direction-dependent optical bistability is obtained in a classical bistable system. Therefore, a giant optical non-reciprocity is generated, which guarantees an all-optical diode with a high contrast up to 22 dB. Furthermore, its application as an all-optical logic AND gate is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274242, 11474221, and 11574229), the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. U1330203), and the National Key Basic Research Special Foundation of China (Grant Nos. 2011CB922203 and 2013CB632701).

  2. All-optical virtual private network system in OFDM based long-reach PON using RSOA re-modulation technique

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Hun; Jung, Sang-Min; Kang, Su-Min; Han, Sang-Kook

    2015-01-01

    We propose an all-optical virtual private network (VPN) system in an orthogonal frequency division multiplexing (OFDM) based long reach PON (LR-PON). In the optical access network field, technologies based on fundamental upstream (U/S) and downstream (D/S) have been actively researched to accommodate explosion of data capacity. However, data transmission among the end users which is arisen from cloud computing, file-sharing and interactive game takes a large weight inside of internet traffic. Moreover, this traffic is predicted to increase more if Internet of Things (IoT) services are activated. In a conventional PON, VPN data is transmitted through ONU-OLT-ONU via U/S and D/S carriers. It leads to waste of bandwidth and energy due to O-E-O conversion in the OLT and round-trip propagation between OLT and remote node (RN). Also, it causes inevitable load to the OLT for electrical buffer, scheduling and routing. The network inefficiency becomes more critical in a LR-PON which has been researched as an effort to reduce CAPEX and OPEX through metro-access consolidation. In the proposed system, the VPN data is separated from conventional U/S and re-modulated on the D/S carrier by using RSOA in the ONUs to avoid bandwidth consumption of U/S and D/S unlike in previously reported system. Moreover, the transmitted VPN data is re-directed to the ONUs by wavelength selective reflector device in the RN without passing through the OLT. Experimental demonstration for the VPN communication system in an OFDM based LR-PON has been verified.

  3. All-optical Mach-Zehnder interferometer switching based on the phase-shift multiplication effect of an analog on the electromagnetically induced transparency effect

    NASA Astrophysics Data System (ADS)

    Wang, Boyun; Xiong, Liangbin; Zeng, Qingdong; Chen, Zhihong; Lv, Hao; Ding, Yaoming; Du, Jun; Yu, Huaqing

    2016-06-01

    We theoretically and numerically investigate all-optical Mach-Zehnder interferometer switching based on the phase-shift multiplication effect of an all-optical analog on the electromagnetically induced transparency effect. The free-carrier plasma dispersion effect modulation method is applied to improve the tuning rate with a response time of picoseconds. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and coupled-mode formalism. Compared with no phase-shift multiplication effect, the average pump power of all-optical switching required to yield the π-phase shift difference decreases by 55.1%, and the size of the modulation region is reduced by 50.1% when the average pump power reaches 60.8 mW. This work provides a new direction for low-power consumption and miniaturization of microstructure integration light-controlled switching devices in optical communication and quantum information processing.

  4. All-optical Mach-Zehnder interferometer switching based on the phase-shift multiplication effect of an analog on the electromagnetically induced transparency effect

    NASA Astrophysics Data System (ADS)

    Wang, Boyun; Xiong, Liangbin; Zeng, Qingdong; Chen, Zhihong; Lv, Hao; Ding, Yaoming; Du, Jun; Yu, Huaqing

    2016-06-01

    We theoretically and numerically investigate all-optical Mach-Zehnder interferometer switching based on the phase-shift multiplication effect of an all-optical analog on the electromagnetically induced transparency effect. The free-carrier plasma dispersion effect modulation method is applied to improve the tuning rate with a response time of picoseconds. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and coupled-mode formalism. Compared with no phase-shift multiplication effect, the average pump power of all-optical switching required to yield the π-phase shift difference decreases by 55.1%, and the size of the modulation region is reduced by 50.1% when the average pump power reaches 60.8 mW. This work provides a new direction for low-power consumption and miniaturization of microstructure integration light-controlled switching devices in optical communication and quantum information processing.

  5. All-optical diode based on dipole modes of Kerr microcavity in asymmetric L-shaped photonic crystal waveguide.

    PubMed

    Bulgakov, E N; Sadreev, A F

    2014-04-01

    A design of all-optical diode in L-shaped photonic crystal waveguide is proposed that uses the multistability of single nonlinear Kerr microcavity with two dipole modes. Asymmetry of the waveguide is achieved through different couplings of the dipole modes with the left and right legs of the waveguide. Using coupled mode theory we demonstrate an extremely high transmission contrast. The direction of optical diode transmission can be controlled by power or frequency of injected light. The theory agrees with the numerical solution of the Maxwell equations.

  6. All-optical packet header and payload separation based on two TOADs for optical packet switched networks

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Zhang, Min; Ye, Peida

    2006-09-01

    We present a novel all-optical header and payload separation technique that can be utilized in Un-Slotted optical packet switched networks. The technique uses two modified TOADs, one is for packet header extraction with differential modulation scheme and the other performs a simple XOR operation between the packet and its self-derived header to get the separated payload. The main virtue of this system is simple structure and low power consumption. Through numerical simulations, the operating characteristics of the scheme are illustrated. In addition, the system parameters are discussed and designed to optimize the performance of the proposed scheme.

  7. Controllable all-optical stochastic logic gates and their delay storages based on the cascaded VCSELs with optical-injection

    NASA Astrophysics Data System (ADS)

    Zhong, Dongzhou; Luo, Wei; Xu, Geliang

    2016-09-01

    Using the dynamical properties of the polarization bistability that depends on the detuning of the injected light, we propose a novel approach to implement reliable all-optical stochastic logic gates in the cascaded vertical cavity surface emitting lasers (VCSELs) with optical-injection. Here, two logic inputs are encoded in the detuning of the injected light from a tunable CW laser. The logic outputs are decoded from the two orthogonal polarization lights emitted from the optically injected VCSELs. For the same logic inputs, under electro-optic modulation, we perform various digital signal processing (NOT, AND, NAND, XOR, XNOR, OR, NOR) in the all-optical domain by controlling the logic operation of the applied electric field. Also we explore their delay storages by using the mechanism of the generalized chaotic synchronization. To quantify the reliabilities of these logic gates, we further demonstrate their success probabilities. Project supported by the National Natural Science Foundation of China (Grant No. 61475120) and the Innovative Projects in Guangdong Colleges and Universities, China (Grant Nos. 2014KTSCX134 and 2015KTSCX146).

  8. Controllable all-optical stochastic logic gates and their delay storages based on the cascaded VCSELs with optical-injection

    NASA Astrophysics Data System (ADS)

    Zhong, Dongzhou; Luo, Wei; Xu, Geliang

    2016-09-01

    Using the dynamical properties of the polarization bistability that depends on the detuning of the injected light, we propose a novel approach to implement reliable all-optical stochastic logic gates in the cascaded vertical cavity surface emitting lasers (VCSELs) with optical-injection. Here, two logic inputs are encoded in the detuning of the injected light from a tunable CW laser. The logic outputs are decoded from the two orthogonal polarization lights emitted from the optically injected VCSELs. For the same logic inputs, under electro-optic modulation, we perform various digital signal processing (NOT, AND, NAND, XOR, XNOR, OR, NOR) in the all-optical domain by controlling the logic operation of the applied electric field. Also we explore their delay storages by using the mechanism of the generalized chaotic synchronization. To quantify the reliabilities of these logic gates, we further demonstrate their success probabilities. Project supported by the National Natural Science Foundation of China (Grant No. 61475120) and the Innovative Projects in Guangdong Colleges and Universities, China (Grant Nos. 2014KTSCX134 and 2015KTSCX146).

  9. A compact microchip atomic clock based on all-optical interrogation of ultra-cold trapped Rb atoms

    NASA Astrophysics Data System (ADS)

    Farkas, D. M.; Zozulya, A.; Anderson, D. Z.

    2010-12-01

    We propose a compact atomic clock that uses all-optical interrogation of ultra-cold Rb atoms that are magnetically trapped near the surface of an atom microchip. The interrogation scheme, which combines electromagnetically induced transparency with Ramsey's method of separated oscillatory fields, can achieve an atomic shot-noise-level performance better than 10^{-13}/sqrt{tau} for 106 atoms. A two-color Mach-Zehnder interferometer can detect a 100-pW probe beam at the optical shot-noise level using conventional photodetectors. This measurement scheme is nondestructive and therefore can be used to increase the operational duty cycle by reusing the trapped atoms for multiple clock cycles. Numerical calculations of the density matrix equations are used to identify realistic operating parameters at which AC Stark shifts are eliminated. By considering fluctuations in these parameters, we estimate that AC Stark shifts can be canceled to a level better than 2×10-14. An overview of the apparatus is presented with estimates of cycle time and power consumption.

  10. General Strategy for Broadband Coherent Perfect Absorption and Multi-wavelength All-optical Switching Based on Epsilon-Near-Zero Multilayer Films

    PubMed Central

    Kim, Tae Young; Badsha, Md. Alamgir; Yoon, Junho; Lee, Seon Young; Jun, Young Chul; Hwangbo, Chang Kwon

    2016-01-01

    We propose a general, easy-to-implement scheme for broadband coherent perfect absorption (CPA) using epsilon-near-zero (ENZ) multilayer films. Specifically, we employ indium tin oxide (ITO) as a tunable ENZ material, and theoretically investigate CPA in the near-infrared region. We first derive general CPA conditions using the scattering matrix and the admittance matching methods. Then, by combining these two methods, we extract analytic expressions for all relevant parameters for CPA. Based on this theoretical framework, we proceed to study ENZ CPA in a single layer ITO film and apply it to all-optical switching. Finally, using an ITO multilayer of different ENZ wavelengths, we implement broadband ENZ CPA structures and investigate multi-wavelength all-optical switching in the technologically important telecommunication window. In our design, the admittance matching diagram was employed to graphically extract not only the structural parameters (the film thicknesses and incident angles), but also the input beam parameters (the irradiance ratio and phase difference between two input beams). We find that the multi-wavelength all-optical switching in our broadband ENZ CPA system can be fully controlled by the phase difference between two input beams. The simple but general design principles and analyses in this work can be widely used in various thin-film devices. PMID:26965195

  11. General Strategy for Broadband Coherent Perfect Absorption and Multi-wavelength All-optical Switching Based on Epsilon-Near-Zero Multilayer Films.

    PubMed

    Kim, Tae Young; Badsha, Md Alamgir; Yoon, Junho; Lee, Seon Young; Jun, Young Chul; Hwangbo, Chang Kwon

    2016-01-01

    We propose a general, easy-to-implement scheme for broadband coherent perfect absorption (CPA) using epsilon-near-zero (ENZ) multilayer films. Specifically, we employ indium tin oxide (ITO) as a tunable ENZ material, and theoretically investigate CPA in the near-infrared region. We first derive general CPA conditions using the scattering matrix and the admittance matching methods. Then, by combining these two methods, we extract analytic expressions for all relevant parameters for CPA. Based on this theoretical framework, we proceed to study ENZ CPA in a single layer ITO film and apply it to all-optical switching. Finally, using an ITO multilayer of different ENZ wavelengths, we implement broadband ENZ CPA structures and investigate multi-wavelength all-optical switching in the technologically important telecommunication window. In our design, the admittance matching diagram was employed to graphically extract not only the structural parameters (the film thicknesses and incident angles), but also the input beam parameters (the irradiance ratio and phase difference between two input beams). We find that the multi-wavelength all-optical switching in our broadband ENZ CPA system can be fully controlled by the phase difference between two input beams. The simple but general design principles and analyses in this work can be widely used in various thin-film devices. PMID:26965195

  12. General Strategy for Broadband Coherent Perfect Absorption and Multi-wavelength All-optical Switching Based on Epsilon-Near-Zero Multilayer Films

    NASA Astrophysics Data System (ADS)

    Kim, Tae Young; Badsha, Md. Alamgir; Yoon, Junho; Lee, Seon Young; Jun, Young Chul; Hwangbo, Chang Kwon

    2016-03-01

    We propose a general, easy-to-implement scheme for broadband coherent perfect absorption (CPA) using epsilon-near-zero (ENZ) multilayer films. Specifically, we employ indium tin oxide (ITO) as a tunable ENZ material, and theoretically investigate CPA in the near-infrared region. We first derive general CPA conditions using the scattering matrix and the admittance matching methods. Then, by combining these two methods, we extract analytic expressions for all relevant parameters for CPA. Based on this theoretical framework, we proceed to study ENZ CPA in a single layer ITO film and apply it to all-optical switching. Finally, using an ITO multilayer of different ENZ wavelengths, we implement broadband ENZ CPA structures and investigate multi-wavelength all-optical switching in the technologically important telecommunication window. In our design, the admittance matching diagram was employed to graphically extract not only the structural parameters (the film thicknesses and incident angles), but also the input beam parameters (the irradiance ratio and phase difference between two input beams). We find that the multi-wavelength all-optical switching in our broadband ENZ CPA system can be fully controlled by the phase difference between two input beams. The simple but general design principles and analyses in this work can be widely used in various thin-film devices.

  13. Novel Nanoelectronic Device Applications Based on the Nonlinearity of Three-Terminal Ballistic Junctions

    NASA Astrophysics Data System (ADS)

    Sun, Jie; Wallin, D.; Brusheim, P.; Maximov, I.; Wang, Z. G.; Xu, H. Q.

    2007-04-01

    Nanometer-scale electron devices containing three-terminal ballistic junctions are fabricated by electron-beam lithography on InP/InGaAs two-dimensional electron gas materials. Based on the intrinsic nonlinearity of the devices, frequency mixer, phase detector and RS flip-flop memory functioning at room temperature are successfully achieved. The devices have simple structure layout and small size, and are expected to function at high speed.

  14. PPLN-based all-optical 40 Gbit/s ODB/AMI/FSK wavelength conversion and FSK logic NOT gate

    NASA Astrophysics Data System (ADS)

    Wang, J.; Sun, Q.; Sun, J.; Hu, Z.

    2009-07-01

    We propose and demonstrate all-optical wavelength conversion for optical duobinary (ODB), alternate-mark inversion (AMI), and frequency-shift keying (FSK) signals and a logic NOT gate for a FSK signal based on cascaded second-harmonic generation and difference-frequency generation (cSHG/DFG) in a periodically poled lithium niobate (PPLN) waveguide. ODB/AMI/FSK are generated from the demodulation of differential phase-shift keying (DPSK) using one-bit-delay fiber delay interferometer (FDI). PPLN-based 40 Gbit/s ODB/AMI/FSK wavelength conversion and FSK logic NOT gate are simultaneously implemented in the experiment.

  15. High efficiency 160 Gb/s all-optical wavelength converter based on terahertz optical asymmetric demultiplexer with quantum dot semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Han, Huining; Zhang, Fangdi; Yang, Wei; Cai, Libo; Zhang, Min; Ye, Peida

    2007-11-01

    Proposed in this paper is a high efficient 160Gb/s all-optical wavelength converter based on terahertz optical asymmetric demultiplexer with quantum dot Semiconductor optical amplifier (QDSOA -TOAD). The performance of the wavelength converter under various operating conditions, such as different injected current densities, input pulse widths and input control pulse energies, is analyzed in terms of contrast ratio (CR) through numerical simulations. With the properly chosen parameters, a wavelength-converted signal with CR over 19.48 can be obtained.

  16. A compact, all-optical, THz wave generator based on self-modulation in a slab photonic crystal waveguide with a single sub-nanometer graphene layer.

    PubMed

    Asadi, R; Ouyang, Z; Mohammd, M M

    2015-07-14

    We design a compact, all-optical THz wave generator based on self-modulation in a 1-D slab photonic crystal (PhC) waveguide with a single sub-nanometer graphene layer by using enhanced nonlinearity of graphene. It has been shown that at the bandgap edge of higher bands of a 1-D slab PhC, through only one sub-nanometer graphene layer we can obtain a compact, high modulation factor (about 0.98 percent), self-intensity modulator at a high frequency (about 0.6 THz) and low threshold intensity (about 15 MW per square centimeter), and further a compact, all-optical THz wave generator by integrating the self-modulator with a THz photodiode or photonic mixer. Such a THz source is expected to have a relatively high efficiency compared with conventional sources based on optical methods. The proposed THz source can find wide applications in THz science and technology, e.g., in THz imaging, THz sensors and detectors, THz communication systems, and THz optical integrated logic circuits.

  17. Numerical and experimental study of a cascaded microelectromechanical system-based all-optical data center interconnect

    NASA Astrophysics Data System (ADS)

    Kong, Qian; Huang, Shanguo; Guo, Bingli; Li, Xin; Zhang, Min; Zhao, Yongli; Zhang, Jie; Gu, Wanyi

    2016-07-01

    As the scale of the intra-data center network (DCN) grows even larger, the traditional electrical switching has reached a bottle neck in terms of energy consumption, bandwidth provision, and end-to-end latency. Different approaches have been made by employing the optical switch instead of the electrical ones to solve the bandwidth as well as the energy efficiency and the latency problem. We propose a DCN architecture based on cascaded microelectromechanical systems switches for dynamic DCN connectivity provisioning. This architecture provides high port count, which attributes to the demands of the intradata center traffic. Multiple points to one point switching scenario is experimentally demonstrated through this data center interconnect. Numerical simulation is employed to investigate the performance of the proposed architecture. The results show that the blocking probability and latency decrease as the scale of the architecture is upgraded.

  18. All-optical differential equation solver with constant-coefficient tunable based on a single microring resonator

    NASA Astrophysics Data System (ADS)

    Yang, Ting; Dong, Jianji; Lu, Liangjun; Zhou, Linjie; Zheng, Aoling; Zhang, Xinliang; Chen, Jianping

    2014-07-01

    Photonic integrated circuits for photonic computing open up the possibility for the realization of ultrahigh-speed and ultra wide-band signal processing with compact size and low power consumption. Differential equations model and govern fundamental physical phenomena and engineering systems in virtually any field of science and engineering, such as temperature diffusion processes, physical problems of motion subject to acceleration inputs and frictional forces, and the response of different resistor-capacitor circuits, etc. In this study, we experimentally demonstrate a feasible integrated scheme to solve first-order linear ordinary differential equation with constant-coefficient tunable based on a single silicon microring resonator. Besides, we analyze the impact of the chirp and pulse-width of input signals on the computing deviation. This device can be compatible with the electronic technology (typically complementary metal-oxide semiconductor technology), which may motivate the development of integrated photonic circuits for optical computing.

  19. All-optical differential equation solver with constant-coefficient tunable based on a single microring resonator

    PubMed Central

    Yang, Ting; Dong, Jianji; Lu, Liangjun; Zhou, Linjie; Zheng, Aoling; Zhang, Xinliang; Chen, Jianping

    2014-01-01

    Photonic integrated circuits for photonic computing open up the possibility for the realization of ultrahigh-speed and ultra wide-band signal processing with compact size and low power consumption. Differential equations model and govern fundamental physical phenomena and engineering systems in virtually any field of science and engineering, such as temperature diffusion processes, physical problems of motion subject to acceleration inputs and frictional forces, and the response of different resistor-capacitor circuits, etc. In this study, we experimentally demonstrate a feasible integrated scheme to solve first-order linear ordinary differential equation with constant-coefficient tunable based on a single silicon microring resonator. Besides, we analyze the impact of the chirp and pulse-width of input signals on the computing deviation. This device can be compatible with the electronic technology (typically complementary metal-oxide semiconductor technology), which may motivate the development of integrated photonic circuits for optical computing. PMID:24993440

  20. All-optical sensitive phase shifting based on nonlinear out-of-plane coupling through 1-D slab photonic crystal with a layer of graphene.

    PubMed

    Asadi, Reza; Ouyang, Zhengbiao; Yu, Quanqiang; Ruan, Shuangchen

    2014-06-16

    We realize all-optical sensitive phase shifting based on nonlinear out-of-plane coupling to a slab waveguide through Fano resonance of a slab 1-D photonic crystal (PhC). We use a graphene layer as the nonlinear material and change its refractive index by the input light intensity through Kerr nonlinear effect to obtain a shift in the Fano resonance frequency. The Fano resonance and self-focusing effect lead to light-intensity enhancement on the graphene in the PhC, reinforcing the nonlinear effect of refractive index in the graphene. Through finite-difference time-domain simulation, we demonstrate that the phase changing sensitivity obtained can be 4 orders higher than that by a single graphene under the same input light intensity. Moreover the threshold pump intensity for all-optical sensitive phase shifting in the coupled light to the waveguide is as low as ~4 MW per square centimeter. The results are applicable in micro optical integrated circuits for phase shifters, phase modulators, power limiters, and phase logic elements for optical computation, digital phase shift keying in communication systems, and non-contact sensitive signal detectors.

  1. All-optical clock recovery based on simultaneous external injection-locking and self-seeding of a Fabry-Perot laser diode

    NASA Astrophysics Data System (ADS)

    Fang, Xiaohui; Wai, Ping Kong A.; Lu, Chao; Tam, Hwa Yaw; Qureshi, Khurram K.

    2011-02-01

    We proposed and demonstrated a novel, simple, and low cost method for all-optical clock recovery based on the switching between two injection-locked longitudinal modes in a dc-biased multi-quantum-well Fabry-Perot laser diode (FP-LD). The dc biased FP-LD is simultaneously injection-locked by a return-to-zero data signal at one of the longitudinal modes of the FP-LD and self-seeded at another longitudinal mode by using a uniform fiber Bragg grating as a feedback component. The powers and detunes of the data signal and self-seeding signal are chosen such that self-seeding is realized in the FP-LD only when data signal power is low. Clock signals of data streams at different data rates can be obtained by tuning the optical delay line in the external self-seeding loop. We have demonstrated all-optical clock recovery at 10 GHz. The pulse width, time-bandwidth product, side mode suppression ration, root mean square timing jitter, and average power of the recovered clock signals are 50 ps, 0.5, 50 dB, 248 fs, and 3.6 dBm, respectively. Clock recovery is possible at wavelength within the gain band of the FP-LD. We also find and explore in the experiment the influence of detune between the external data signal and the nearest FP-LD longitudinal mode to the recovered clock.

  2. Design of all-optical, hot-electron current-direction-switching device based on geometrical asymmetry.

    PubMed

    Kumarasinghe, Chathurangi S; Premaratne, Malin; Gunapala, Sarath D; Agrawal, Govind P

    2016-01-01

    We propose a nano-scale current-direction-switching device(CDSD) that operates based on the novel phenomenon of geometrical asymmetry between two hot-electron generating plasmonic nanostructures. The proposed device is easy to fabricate and economical to develop compared to most other existing designs. It also has the ability to function without external wiring in nano or molecular circuitry since it is powered and controlled optically. We consider a such CDSD made of two dissimilar nanorods separated by a thin but finite potential barrier and theoretically derive the frequency-dependent electron/current flow rate. Our analysis takes in to account the quantum dynamics of electrons inside the nanorods under a periodic optical perturbation that are confined by nanorod boundaries, modelled as finite cylindrical potential wells. The influence of design parameters, such as geometric difference between the two nanorods, their volumes and the barrier width on quality parameters such as frequency-sensitivity of the current flow direction, magnitude of the current flow, positive to negative current ratio, and the energy conversion efficiency is discussed by considering a device made of Ag/TiO2/Ag. Theoretical insight and design guidelines presented here are useful for customizing our proposed CDSD for applications such as self-powered logic gates, power supplies, and sensors. PMID:26887286

  3. Design of all-optical, hot-electron current-direction-switching device based on geometrical asymmetry

    PubMed Central

    Kumarasinghe, Chathurangi S.; Premaratne, Malin; Gunapala, Sarath D.; Agrawal, Govind P.

    2016-01-01

    We propose a nano-scale current-direction-switching device(CDSD) that operates based on the novel phenomenon of geometrical asymmetry between two hot-electron generating plasmonic nanostructures. The proposed device is easy to fabricate and economical to develop compared to most other existing designs. It also has the ability to function without external wiring in nano or molecular circuitry since it is powered and controlled optically. We consider a such CDSD made of two dissimilar nanorods separated by a thin but finite potential barrier and theoretically derive the frequency-dependent electron/current flow rate. Our analysis takes in to account the quantum dynamics of electrons inside the nanorods under a periodic optical perturbation that are confined by nanorod boundaries, modelled as finite cylindrical potential wells. The influence of design parameters, such as geometric difference between the two nanorods, their volumes and the barrier width on quality parameters such as frequency-sensitivity of the current flow direction, magnitude of the current flow, positive to negative current ratio, and the energy conversion efficiency is discussed by considering a device made of Ag/TiO2/Ag. Theoretical insight and design guidelines presented here are useful for customizing our proposed CDSD for applications such as self-powered logic gates, power supplies, and sensors. PMID:26887286

  4. Design of all-optical, hot-electron current-direction-switching device based on geometrical asymmetry

    NASA Astrophysics Data System (ADS)

    Kumarasinghe, Chathurangi S.; Premaratne, Malin; Gunapala, Sarath D.; Agrawal, Govind P.

    2016-02-01

    We propose a nano-scale current-direction-switching device(CDSD) that operates based on the novel phenomenon of geometrical asymmetry between two hot-electron generating plasmonic nanostructures. The proposed device is easy to fabricate and economical to develop compared to most other existing designs. It also has the ability to function without external wiring in nano or molecular circuitry since it is powered and controlled optically. We consider a such CDSD made of two dissimilar nanorods separated by a thin but finite potential barrier and theoretically derive the frequency-dependent electron/current flow rate. Our analysis takes in to account the quantum dynamics of electrons inside the nanorods under a periodic optical perturbation that are confined by nanorod boundaries, modelled as finite cylindrical potential wells. The influence of design parameters, such as geometric difference between the two nanorods, their volumes and the barrier width on quality parameters such as frequency-sensitivity of the current flow direction, magnitude of the current flow, positive to negative current ratio, and the energy conversion efficiency is discussed by considering a device made of Ag/TiO2/Ag. Theoretical insight and design guidelines presented here are useful for customizing our proposed CDSD for applications such as self-powered logic gates, power supplies, and sensors.

  5. All-optical generation of binary phase-coded microwave signal based on cross-polarization modulation in a highly nonlinear fiber.

    PubMed

    Li, Wei; Wang, Wen Ting; Sun, Wen Hui; Zhu, Ning Hua

    2014-03-15

    We report a novel all-optical approach to generate a binary phase-coded microwave signal based on a cross-polarization modulation effect in a highly nonlinear fiber. The carrier frequency of the binary phase-coded microwave signal is widely tunable. Moreover, the precise π phase shift of the microwave signal is independent of the optical power of the control beam. The proposed approach is theoretically analyzed and experimentally verified. For a proof-of-concept demonstration, the binary phase-coded microwave signals with a carrier frequency of 20 GHz at a coding rate of 5  Gb/s and with a carrier frequency of 30 GHz at a coding rate of 7.5  Gb/s are experimentally generated. The pulse compression capability of the system is also evaluated. The measured and simulated results fit well with each other.

  6. All-optical reservoir computing system based on InGaAsP ring resonators for high-speed identification and optical routing in optical networks

    NASA Astrophysics Data System (ADS)

    Mesaritakis, Charis; Kapsalis, Alexandros; Syvridis, Dimitris

    2015-01-01

    In this paper an all-optical reservoir computing scheme is modeled, that paves an alternative route to photonic high bit rate header identification in optical networks and allow direct processing in the analog domain. The system consists of randomly interconnected InGaAsP micro-ring-resonators, whereas the computation efficiency of the scheme is based on the ultra-fast Kerr effect and two-photon absorption. Validation of the system's efficiency is confirmed through detailed numerical modeling and two application orientated benchmark tests that consists in the classification of 32bit digital headers, encoded an NRZ optical pulses, with a bitrate of 240Gbps,and the identification of pseudo-analog patters for real time sensing applications in the analog domain.

  7. On-site monitoring of atomic density number for an all-optical atomic magnetometer based on atomic spin exchange relaxation.

    PubMed

    Zhang, Hong; Zou, Sheng; Chen, Xiyuan; Ding, Ming; Shan, Guangcun; Hu, Zhaohui; Quan, Wei

    2016-07-25

    We present a method for monitoring the atomic density number on site based on atomic spin exchange relaxation. When the spin polarization P ≪ 1, the atomic density numbers could be estimated by measuring magnetic resonance linewidth in an applied DC magnetic field by using an all-optical atomic magnetometer. The density measurement results showed that the experimental results the theoretical predictions had a good consistency in the investigated temperature range from 413 K to 463 K, while, the experimental results were approximately 1.5 ∼ 2 times less than the theoretical predictions estimated from the saturated vapor pressure curve. These deviations were mainly induced by the radiative heat transfer efficiency, which inevitably leaded to a lower temperature in cell than the setting temperature. PMID:27464172

  8. On-site monitoring of atomic density number for an all-optical atomic magnetometer based on atomic spin exchange relaxation.

    PubMed

    Zhang, Hong; Zou, Sheng; Chen, Xiyuan; Ding, Ming; Shan, Guangcun; Hu, Zhaohui; Quan, Wei

    2016-07-25

    We present a method for monitoring the atomic density number on site based on atomic spin exchange relaxation. When the spin polarization P ≪ 1, the atomic density numbers could be estimated by measuring magnetic resonance linewidth in an applied DC magnetic field by using an all-optical atomic magnetometer. The density measurement results showed that the experimental results the theoretical predictions had a good consistency in the investigated temperature range from 413 K to 463 K, while, the experimental results were approximately 1.5 ∼ 2 times less than the theoretical predictions estimated from the saturated vapor pressure curve. These deviations were mainly induced by the radiative heat transfer efficiency, which inevitably leaded to a lower temperature in cell than the setting temperature.

  9. Ultrafast all-optical logic OR gate based on two-photon absorption with a semiconductor optical amplifier-assisted delayed interferometer

    NASA Astrophysics Data System (ADS)

    Kotb, Amer

    2016-01-01

    The performance of an all-optical logic OR gate is numerically studied and simulated. This Boolean operation is realized by using a semiconductor optical amplifier (SOA) and a delayed interferometer (DI) based on two-photon absorption (TPA). The input pulse intensities are high enough so that the two-photon-induced phase change is larger than the regular gain-induced phase change. The study is carried out with the effect of the amplified spontaneous emission (ASE) taken into account in the simulation analysis. The dependence of the output quality factor ( Q-factor) on the data signals and SOA's parameters is also investigated and discussed. The achieved results show that the OR gate is capable of operating at a data speed of 250 Gb/s with logical correctness and proper Q-factor.

  10. Fast all-optical switch

    NASA Technical Reports Server (NTRS)

    Shay, Thomas M. (Inventor); Poliakov, Evgeni Y. (Inventor); Hazzard, David A. (Inventor)

    2001-01-01

    An apparatus and method wherein polarization rotation in alkali vapors or other mediums is used for all-optical switching and digital logic and where the rate of operation is proportional to the amplitude of the pump field. High rates of speed are accomplished by Rabi flopping of the atomic states using a continuously operating monochromatic atomic beam as the pump.

  11. Towards all-optical quantification of force- and power-based performance metrics in cilia-driven fluid flow physiology (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Huang, Brendan K.; Khokha, Mustafa K.; Loewenberg, Michael; Choma, Michael A.

    2016-03-01

    In pulmonary ciliary physiology, most tissue-level measures of performance focus on flow velocity. However, as with the heart, fluid transport performance requires an understanding of force and power generation under various loading conditions. Here, we present our initial work in quantifying shearing force and net power dissipation from OCT-based cilia-driven fluid flow velocimetry. Typical measurements of force require invasive contact with the ciliated surface, while measurements of power rely on metabolic consumption that reflect energy consumption not just from cilia, but from the entirety of cellular processes. We will present two different approaches to non-contact, all-optical shear force and power dissipation physiology. First, we developed a lumped-parameter model of flow driven by a ciliated surface. The lumped-parameter model yields semi-quantitative, Ohm's law-type relationships (F=U*R and P=U*F) between flow velocity (U), shear force (F), viscous resistance (R), and power dissipation (P). This model allows a lumped (spatially averaged) approach to evaluate force and power performance under viscous loading, an approach we demonstrated using ciliated Xenopus embryos. Second, we numerically estimate shear force and power dissipation using flow velocity fields acquired using OCT. Specifically, the velocity gradient tensor estimated from the flow velocity field contains the required information to estimate both shear force and net power dissipation. We have preliminary data using this numerical approach in Xenopus. Our results support the feasibility of an all-optical approach to estimating mesoscopic measures of force and power in ciliary physiology.

  12. Strip silicon waveguide for code synchronization in all-optical analog-to-digital conversion based on a lumped time-delay compensation scheme

    NASA Astrophysics Data System (ADS)

    Sha, Li; Zhi-Guo, Shi; Zhe, Kang; Chong-Xiu, Yu; Jian-Ping, Wang

    2016-04-01

    An all-optical analog-to-digital converter (ADC) based on the nonlinear effect in a silicon waveguide is a promising candidate for overcoming the limitation of electronic devices and is suitable for photonic integration. In this paper, a lumped time-delay compensation scheme with 2-bit quantization resolution is proposed. A strip silicon waveguide is designed and used to compensate for the entire time-delays of the optical pulses after a soliton self-frequency shift (SSFS) module within a wavelength range of 1550 nm–1580 nm. A dispersion coefficient as high as –19800 ps/(km·nm) with ±0.5 ps/(km·nm) variation is predicted for the strip waveguide. The simulation results show that the maximum supportable sampling rate (MSSR) is 50.45 GSa/s with full width at half maximum (FWHM) variation less than 2.52 ps, along with the 2-bit effective-number-of-bit and Gray code output. Project supported by the Fundamental Research Funds for the Central Universities, China (Grant No. FRF-TP-15-030A1) and China Postdoctoral Science Foundation (Grant No. 2015M580978).

  13. All-optical logic gate based on transient grating from disperse red 1 doped organic-inorganic hybrid films with an improved figure of merit

    SciTech Connect

    Gao, Tianxi; Que, Wenxiu Shao, Jinyou; Wang, Yushu

    2015-10-21

    Azobenzene dyes have large refractive index near their main resonance, but the poor figure of merit (FOM) limits their potential for all-optical applications. To improve this situation, disperse red 1 (DR1) molecules were dispersed in a sol-gel germanium/Ormosil organic-inorganic hybrid matrix. Z-scan measurement results showed a good compatibility between the dopant and the matrix, and also, an improved FOM was obtained as compared to the DR1/polymer films reported previously. To demonstrate the all-optical signal processing effect, a cw Nd:YAG laser emitting at 532 nm and a He-Ne laser emitting at 632.8 nm were used as pump and probe beams, respectively. DR1 acts as an initiator of the photo-induced transient holographic grating, which is attributed to the trans-cis-trans photoisomerization. Thus, a three inputs AND all-optical logic gate was achieved by using choppers with different frequencies. The detailed mechanism of operation is discussed. These results indicate that the DR1 doped germanium/Ormosil organic-inorganic hybrid film with an improved FOM has a great potential in all-optical devices around its main resonance.

  14. Design challenges of EO polymer based leaky waveguide deflector for 40 Gs/s all-optical analog-to-digital converters

    NASA Astrophysics Data System (ADS)

    Hadjloum, Massinissa; El Gibari, Mohammed; Li, Hongwu; Daryoush, Afshin S.

    2016-08-01

    Design challenges and performance optimization of an all-optical analog-to-digital converter (AOADC) is presented here. The paper addresses both microwave and optical design of a leaky waveguide optical deflector using electro-optic (E-O) polymer. The optical deflector converts magnitude variation of the applied RF voltage into variation of deflection angle out of a leaky waveguide optical beam using the linear E-O effect (Pockels effect) as part of the E-O polymer based optical waveguide. This variation of deflection angle as result of the applied RF signal is then quantized using optical windows followed by an array of high-speed photodetectors. We optimized the leakage coefficient of the leaky waveguide and its physical length to achieve the best trade-off between bandwidth and the deflected optical beam resolution, by improving the phase velocity matching between lightwave and microwave on one hand and using pre-emphasis technique to compensate for the RF signal attenuation on the other hand. In addition, for ease of access from both optical and RF perspective, a via-hole less broad bandwidth transition is designed between coplanar pads and coupled microstrip (CPW-CMS) driving electrodes. With the best reported E-O coefficient of 350 pm/V, the designed E-O deflector should allow an AOADC operating over 44 giga-samples-per-seconds with an estimated effective resolution of 6.5 bits on RF signals with Nyquist bandwidth of 22 GHz. The overall DC power consumption of all components used in this AOADC is of order of 4 W and is dominated by power consumption in the power amplifier to generate a 20 V RF voltage in 50 Ohm system. A higher sampling rate can be achieved at similar bits of resolution by interleaving a number of this elementary AOADC at the expense of a higher power consumption.

  15. All-optical mapping of barrel cortex circuits based on simultaneous voltage-sensitive dye imaging and channelrhodopsin-mediated photostimulation

    PubMed Central

    Lo, Shun Qiang; Koh, Dawn X. P.; Sng, Judy C. G.; Augustine, George J.

    2015-01-01

    Abstract. We describe an experimental approach that uses light to both control and detect neuronal activity in mouse barrel cortex slices: blue light patterned by a digital micromirror array system allowed us to photostimulate specific layers and columns, while a red-shifted voltage-sensitive dye was used to map out large-scale circuit activity. We demonstrate that such all-optical mapping can interrogate various circuits in somatosensory cortex by sequentially activating different layers and columns. Further, mapping in slices from whisker-deprived mice demonstrated that chronic sensory deprivation did not significantly alter feedforward inhibition driven by layer 5 pyramidal neurons. Further development of voltage-sensitive optical probes should allow this all-optical mapping approach to become an important and high-throughput tool for mapping circuit interactions in the brain. PMID:26158003

  16. All-optical fast random number generator.

    PubMed

    Li, Pu; Wang, Yun-Cai; Zhang, Jian-Zhong

    2010-09-13

    We propose a scheme of all-optical random number generator (RNG), which consists of an ultra-wide bandwidth (UWB) chaotic laser, an all-optical sampler and an all-optical comparator. Free from the electric-device bandwidth, it can generate 10Gbit/s random numbers in our simulation. The high-speed bit sequences can pass standard statistical tests for randomness after all-optical exclusive-or (XOR) operation.

  17. Femtosecond all-optical parallel logic gates based on tunable saturable to reverse saturable absorption in graphene-oxide thin films

    SciTech Connect

    Roy, Sukhdev Yadav, Chandresh

    2013-12-09

    A detailed theoretical analysis of ultrafast transition from saturable absorption (SA) to reverse saturable absorption (RSA) has been presented in graphene-oxide thin films with femtosecond laser pulses at 800 nm. Increase in pulse intensity leads to switching from SA to RSA with increased contrast due to two-photon absorption induced excited-state absorption. Theoretical results are in good agreement with reported experimental results. Interestingly, it is also shown that increase in concentration results in RSA to SA transition. The switching has been optimized to design parallel all-optical femtosecond NOT, AND, OR, XOR, and the universal NAND and NOR logic gates.

  18. All-optical symmetric ternary logic gate

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay

    2010-09-01

    Symmetric ternary number (radix=3) has three logical states (1¯, 0, 1). It is very much useful in carry free arithmetical operation. Beside this, the logical operation using this type of number system is also effective in high speed computation and communication in multi-valued logic. In this literature all-optical circuits for three basic symmetrical ternary logical operations (inversion, MIN and MAX) are proposed and described. Numerical simulation verifies the theoretical model. In this present scheme the different ternary logical states are represented by different polarized state of light. Terahertz optical asymmetric demultiplexer (TOAD) based interferometric switch has been used categorically in this manuscript.

  19. All-optical buffering for DPSK packets

    NASA Astrophysics Data System (ADS)

    Liu, Guodong; Wu, Chongqing; Liu, Lanlan; Wang, Fu; Mao, Yaya; Sun, Zhenchao

    2013-12-01

    Advanced modulation formats, such as DPSK, DQPSK, QAM, have become the mainstream technologies in the optical network over 40Gb/s, the DPSK format is the fundamental of all advanced modulation formats. Optical buffers, as a key element for temporarily storing packets in order to synchronization or contention resolution in optical nodes, must be adapted to this new requirement. Different from other current buffers to store the NRZ or RZ format, an all-optical buffer of storing DPSK packets based on nonlinear polarization rotation in SOA is proposed and demonstrated. In this buffer, a section of PMF is used as fiber delay line to maintain the polarization states unchanged, the driver current of SOA is optimized, and no amplifier is required in the fiber loop. A packet delay resolution of 400ns is obtained and storage for tens rounds is demonstrated without significant signal degradation. Using proposed the new tunable DPSK demodulator, bit error rate has been measured after buffering for tens rounds for 10Gb/s data payload. Configurations for First-in First-out (FIFO) buffer or First-in Last-out (FILO) buffer are proposed based on this buffer. The buffer is easy control and suitable for integration. The terminal contention caused by different clients can be mitigated by managing packets delays in future all-optical network, such as optical packet switching network and WDM switching network.

  20. Design of DPSS based fiber bragg gratings and their application in all-optical encryption, OCDMA, optical steganography, and orthogonal-division multiplexing.

    PubMed

    Djordjevic, Ivan B; Saleh, Alaa H; Küppers, Franko

    2014-05-01

    The future information infrastructure will be affected by limited bandwidth of optical networks, high energy consumption, heterogeneity of network segments, and security issues. As a solution to all problems, we advocate the use of both electrical basis functions (orthogonal prolate spheroidal basis functions) and optical basis functions, implemented as FBGs with orthogonal impulse response in addition to spatial modes. We design the Bragg gratings with orthogonal impulse responses by means of discrete layer peeling algorithm. The target impulse responses belong to the class of discrete prolate spheroidal sequences, which are mutually orthogonal regardless of the sequence order, while occupying the fixed bandwidth. We then design the corresponding encoders and decoders suitable for all-optical encryption, optical CDMA, optical steganography, and orthogonal-division multiplexing (ODM). Finally, we propose the spectral multiplexing-ODM-spatial multiplexing scheme enabling beyond 10 Pb/s serial optical transport networks.

  1. CROWNs: all-optical WDM multiring topologies

    NASA Astrophysics Data System (ADS)

    Chlamtac, Imrich; Fumagalli, Andrea F.

    1993-10-01

    Ring networks present an attractive solution for optical, high speed local and metropolitan area networks due to the simplicity of network interfaces and access control. Two problems need to be overcome to obtain an all optical network. One, the limitation on power budget resulting from optical losses that occur when data passes through intermediate nodes. The other, a reduced network throughput related to the linearity of the ring topology. Recent progress in WDM techniques has opened the possibility of overcoming this problem by an optical multi- channel solution. WDM taps the large fiber bandwidth by using different portions of the optical spectrum to realize (omega) different channels on the same fiber. However, in extant electronic node based architectures, even though high bandwidth optical transmission can be used to propagate packets between the nodes, the electronic elaboration of data at each node creates a performance bottleneck for the whole communication system. This leads to network throughput that is a mere fraction of the optical bandwidth potential. This work presents an approach to obtaining a concurrently accessed multi-ring all-optical WDM network (CROWN) with a node architecture in which packets pass through the node without being converted into the electronic domain. Using a single high speed transmitter and receiver, CROWN allows the data to be maintained in optical format while resolving receiver contentions.

  2. Ultrahigh brilliance quasi-monochromatic MeV γ-rays based on self-synchronized all-optical Compton scattering

    PubMed Central

    Yu, Changhai; Qi, Rong; Wang, Wentao; Liu, Jiansheng; Li, Wentao; Wang, Cheng; Zhang, Zhijun; Liu, Jiaqi; Qin, Zhiyong; Fang, Ming; Feng, Ke; Wu, Ying; Tian, Ye; Xu, Yi; Wu, Fenxiang; Leng, Yuxin; Weng, Xiufeng; Wang, Jihu; Wei, Fuli; Yi, Yicheng; Song, Zhaohui; Li, Ruxin; Xu, Zhizhan

    2016-01-01

    Inverse Compton scattering between ultra-relativistic electrons and an intense laser field has been proposed as a major route to generate compact high-brightness and high-energy γ-rays. Attributed to the inherent synchronization mechanism, an all-optical Compton scattering γ-ray source, using one laser to both accelerate electrons and scatter via the reflection of a plasma mirror, has been demonstrated in proof-of-principle experiments to produce a x-ray source near 100 keV. Here, by designing a cascaded laser wakefield accelerator to generate high-quality monoenergetic e-beams, which are bound to head-on collide with the intense driving laser pulse via the reflection of a 20-um-thick Ti foil, we produce tunable quasi-monochromatic MeV γ-rays (33% full-width at half-maximum) with a peak brilliance of ~3 × 1022 photons s−1 mm−2 mrad−2 0.1% BW at 1 MeV. To the best of our knowledge, it is one order of magnitude higher than ever reported value of its kinds in MeV regime. This compact ultrahigh brilliance γ-ray source may provide applications in nuclear resonance fluorescence, x-ray radiology and ultrafast pump-probe nondestructive inspection. PMID:27405540

  3. Ultrahigh brilliance quasi-monochromatic MeV γ-rays based on self-synchronized all-optical Compton scattering.

    PubMed

    Yu, Changhai; Qi, Rong; Wang, Wentao; Liu, Jiansheng; Li, Wentao; Wang, Cheng; Zhang, Zhijun; Liu, Jiaqi; Qin, Zhiyong; Fang, Ming; Feng, Ke; Wu, Ying; Tian, Ye; Xu, Yi; Wu, Fenxiang; Leng, Yuxin; Weng, Xiufeng; Wang, Jihu; Wei, Fuli; Yi, Yicheng; Song, Zhaohui; Li, Ruxin; Xu, Zhizhan

    2016-07-13

    Inverse Compton scattering between ultra-relativistic electrons and an intense laser field has been proposed as a major route to generate compact high-brightness and high-energy γ-rays. Attributed to the inherent synchronization mechanism, an all-optical Compton scattering γ-ray source, using one laser to both accelerate electrons and scatter via the reflection of a plasma mirror, has been demonstrated in proof-of-principle experiments to produce a x-ray source near 100 keV. Here, by designing a cascaded laser wakefield accelerator to generate high-quality monoenergetic e-beams, which are bound to head-on collide with the intense driving laser pulse via the reflection of a 20-um-thick Ti foil, we produce tunable quasi-monochromatic MeV γ-rays (33% full-width at half-maximum) with a peak brilliance of ~3 × 10(22) photons s(-1) mm(-2) mrad(-2) 0.1% BW at 1 MeV. To the best of our knowledge, it is one order of magnitude higher than ever reported value of its kinds in MeV regime. This compact ultrahigh brilliance γ-ray source may provide applications in nuclear resonance fluorescence, x-ray radiology and ultrafast pump-probe nondestructive inspection.

  4. Ultrahigh brilliance quasi-monochromatic MeV γ-rays based on self-synchronized all-optical Compton scattering.

    PubMed

    Yu, Changhai; Qi, Rong; Wang, Wentao; Liu, Jiansheng; Li, Wentao; Wang, Cheng; Zhang, Zhijun; Liu, Jiaqi; Qin, Zhiyong; Fang, Ming; Feng, Ke; Wu, Ying; Tian, Ye; Xu, Yi; Wu, Fenxiang; Leng, Yuxin; Weng, Xiufeng; Wang, Jihu; Wei, Fuli; Yi, Yicheng; Song, Zhaohui; Li, Ruxin; Xu, Zhizhan

    2016-01-01

    Inverse Compton scattering between ultra-relativistic electrons and an intense laser field has been proposed as a major route to generate compact high-brightness and high-energy γ-rays. Attributed to the inherent synchronization mechanism, an all-optical Compton scattering γ-ray source, using one laser to both accelerate electrons and scatter via the reflection of a plasma mirror, has been demonstrated in proof-of-principle experiments to produce a x-ray source near 100 keV. Here, by designing a cascaded laser wakefield accelerator to generate high-quality monoenergetic e-beams, which are bound to head-on collide with the intense driving laser pulse via the reflection of a 20-um-thick Ti foil, we produce tunable quasi-monochromatic MeV γ-rays (33% full-width at half-maximum) with a peak brilliance of ~3 × 10(22) photons s(-1) mm(-2) mrad(-2) 0.1% BW at 1 MeV. To the best of our knowledge, it is one order of magnitude higher than ever reported value of its kinds in MeV regime. This compact ultrahigh brilliance γ-ray source may provide applications in nuclear resonance fluorescence, x-ray radiology and ultrafast pump-probe nondestructive inspection. PMID:27405540

  5. Simultaneous all-optical half-adder, half-subtracter, comparator, and decoder based on nonlinear effects harnessing in highly nonlinear fibers

    NASA Astrophysics Data System (ADS)

    Singh, Karamdeep; Kaur, Gurmeet; Singh, Maninder Lal

    2016-07-01

    A multifunctional combinational logic module capable of performing several signal manipulation tasks all-optically, such as half-addition/subtraction, single-bit comparison, and 2-to-4 decoding simultaneously is proposed. Several logic functions (A+B¯, A.B, A¯.B, A.B¯, A⊕B, and A⊙B) between two input signals A and B are implemented by harnessing a number of nonlinear effects, such as cross-phase modulation (XPM), cross-gain modulation (XGM), and four-wave mixing (FWM) inside only two highly nonlinear fibers (HNLF) arranged in a parallel structure. The NOR gate (A+B¯) is realized by the means of XPM effect in the first HNLF, whereas, A‾.B, A.B¯, and A.B logics have relied on utilization of XGM and FWM processes, respectively, in parametric medium made up of the second HNLF of parallel arrangement. The remaining A⊕B and A⊙B logics required for successful implementation of the proposed simultaneous scheme are attained by temporally combining previously achieved (A‾.B and A.B‾) and (A.B and A+B‾) logics. Quality-factor ≥7.4 and extinction ratio ≥12.30 dB have been achieved at repetition rates of 100 Gbps for all logic functions (A+B‾, A.B, A¯.B, A.B¯, A⊕B, and A⊙B), suggesting successful simultaneous implementation.

  6. Ultrahigh brilliance quasi-monochromatic MeV γ-rays based on self-synchronized all-optical Compton scattering

    NASA Astrophysics Data System (ADS)

    Yu, Changhai; Qi, Rong; Wang, Wentao; Liu, Jiansheng; Li, Wentao; Wang, Cheng; Zhang, Zhijun; Liu, Jiaqi; Qin, Zhiyong; Fang, Ming; Feng, Ke; Wu, Ying; Tian, Ye; Xu, Yi; Wu, Fenxiang; Leng, Yuxin; Weng, Xiufeng; Wang, Jihu; Wei, Fuli; Yi, Yicheng; Song, Zhaohui; Li, Ruxin; Xu, Zhizhan

    2016-07-01

    Inverse Compton scattering between ultra-relativistic electrons and an intense laser field has been proposed as a major route to generate compact high-brightness and high-energy γ-rays. Attributed to the inherent synchronization mechanism, an all-optical Compton scattering γ-ray source, using one laser to both accelerate electrons and scatter via the reflection of a plasma mirror, has been demonstrated in proof-of-principle experiments to produce a x-ray source near 100 keV. Here, by designing a cascaded laser wakefield accelerator to generate high-quality monoenergetic e-beams, which are bound to head-on collide with the intense driving laser pulse via the reflection of a 20-um-thick Ti foil, we produce tunable quasi-monochromatic MeV γ-rays (33% full-width at half-maximum) with a peak brilliance of ~3 × 1022 photons s‑1 mm‑2 mrad‑2 0.1% BW at 1 MeV. To the best of our knowledge, it is one order of magnitude higher than ever reported value of its kinds in MeV regime. This compact ultrahigh brilliance γ-ray source may provide applications in nuclear resonance fluorescence, x-ray radiology and ultrafast pump-probe nondestructive inspection.

  7. Ultrahigh brilliance quasi-monochromatic MeV γ-rays based on self-synchronized all-optical Compton scattering

    NASA Astrophysics Data System (ADS)

    Yu, Changhai; Qi, Rong; Wang, Wentao; Liu, Jiansheng; Li, Wentao; Wang, Cheng; Zhang, Zhijun; Liu, Jiaqi; Qin, Zhiyong; Fang, Ming; Feng, Ke; Wu, Ying; Tian, Ye; Xu, Yi; Wu, Fenxiang; Leng, Yuxin; Weng, Xiufeng; Wang, Jihu; Wei, Fuli; Yi, Yicheng; Song, Zhaohui; Li, Ruxin; Xu, Zhizhan

    2016-07-01

    Inverse Compton scattering between ultra-relativistic electrons and an intense laser field has been proposed as a major route to generate compact high-brightness and high-energy γ-rays. Attributed to the inherent synchronization mechanism, an all-optical Compton scattering γ-ray source, using one laser to both accelerate electrons and scatter via the reflection of a plasma mirror, has been demonstrated in proof-of-principle experiments to produce a x-ray source near 100 keV. Here, by designing a cascaded laser wakefield accelerator to generate high-quality monoenergetic e-beams, which are bound to head-on collide with the intense driving laser pulse via the reflection of a 20-um-thick Ti foil, we produce tunable quasi-monochromatic MeV γ-rays (33% full-width at half-maximum) with a peak brilliance of ~3 × 1022 photons s-1 mm-2 mrad-2 0.1% BW at 1 MeV. To the best of our knowledge, it is one order of magnitude higher than ever reported value of its kinds in MeV regime. This compact ultrahigh brilliance γ-ray source may provide applications in nuclear resonance fluorescence, x-ray radiology and ultrafast pump-probe nondestructive inspection.

  8. Flip-Flopping, Presidential Politics, and Abraham Lincoln

    ERIC Educational Resources Information Center

    Neumann, Dave

    2012-01-01

    The American public can count on a few things during the presidential election season. First, candidates will take a moral high ground and forswear mudslinging. Before long however, they will proceed to engage in nasty accusations against their opponents. A vibrant democracy ought to welcome carefully thought-out views that, when intentionally…

  9. Back to School Foot Pain (Flip-Flops)

    MedlinePlus

    ... painful feet. The sounds of back to school season include the ringing of school bells and cash ... over-the-counter shoe inserts. Back to school season will always be painful for some students, but ...

  10. Design of all-optical read-only memory.

    PubMed

    Jung, Young Jin; Park, Namkyoo; Jhon, Young Min; Lee, Seok

    2009-11-01

    A semiconductor optical amplifier-based all-optical read-only memory (ROM) is successfully demonstrated through simulations using a one-level simplification method optimized for optical logic circuits. Design details are presented, and advantages are discussed in comparison with an all-optical ROM-employing decoder. We demonstrate that eight characters can be stored at each address in the American Standard Code for Information Interchange. PMID:19881640

  11. Dynamics of an all-optical atomic spin gyroscope.

    PubMed

    Fang, Jiancheng; Wan, Shuangai; Yuan, Heng

    2013-10-20

    We present the transfer function of an all-optical atomic spin gyroscope through a series of differential equations and validate the transfer function by experimental test. A transfer function is the basis for further control system design. We build the differential equations based on a complete set of Bloch equations describing the all-optical atomic spin gyroscope, and obtain the transfer function through application of the Laplace transformation to these differential equations. Moreover, we experimentally validate the transfer function in an all-optical Cs-Xe129 atomic spin gyroscope through a series of step responses. This transfer function is convenient for analysis of the form of control system required. Furthermore, it is available for the design of the control system specifically to improve the performance of all-optical atomic spin gyroscopes.

  12. All optical switching in henna thin film

    NASA Astrophysics Data System (ADS)

    Henari, Fryad Z.; Jasim, Khalil E.

    2013-08-01

    The optical nonlinearity in henna (Lawson (2- hydroxyl-1,4 naphthoquinone) film was utilized to demonstrate all optical switching. The nonlinear absorption of the henna film was calculated by measuring the transmission of the laser beam ( λ = 488 nm) as a function of incident light intensities. The observed nonlinear absorption is attributed to a two-photon absorption process. The pump and probe technique was used to demonstrate all optical switching. The switching characteristics can be utilized to generate all-optical logic gates such as simple inverter switches (NOT) NOR, AND NAND logic functions.

  13. Evaluation of laser diode based optical switches for optical processors

    NASA Astrophysics Data System (ADS)

    Swanson, Paul D.; Parker, Michael A.; Libby, Stuart I.

    1993-07-01

    Three optical switching elements have been designed, fabricated, and tested for use in an integrated, optical signal processor. The first, an optical NOR logic gate, uses gain quenching as a means of allowing one (or more) light beam(s) to control the output light. This technique, along with the use of a two pad bistable output laser, is used in demonstrating the feasibility of the second device, an all optical RS flip flop. The third device consists of a broad area orthogonal model switching laser, whose corollary outputs correspond to the sign of the voltage difference between its two high impedance electrical inputs. This device also has possible memory applications if bistable mode switching within the broad area laser can be achieved.

  14. The GALAXIE all-optical FEL project

    SciTech Connect

    Rosenzweig, J. B.; Arab, E.; Andonian, G.; Cahill, A.; Fitzmorris, K.; Fukusawa, A.; Hoang, P.; Jovanovic, I.; Marcus, G.; Marinelli, A.; Murokh, A.; Musumeci, P.; Naranjo, B.; O'Shea, B.; O'Shea, F.; Ovodenko, A.; Pogorelsky, I.; Putterman, S.; Roberts, K.; Shumail, M.; and others

    2012-12-21

    We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 {mu}m laser development, ultra-high brightness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.

  15. Degenerate four-wave mixing based all-optical wavelength conversion in a semiconductor optical amplifier and highly-nonlinear photonic crystal fiber parametric loop mirror

    NASA Astrophysics Data System (ADS)

    Liu, Jianguo; Cheng, Tee Hiang; Yeo, Yong kee; Wang, Yixin; Xue, Lifang; Wang, Dawei; Yu, Xiaojun

    2008-11-01

    The idler is separated from the co-propagating pump in a degenerate four-wave mixing (DFWM) with a symmetrical parametric loop mirror (PALM), which is composed of two identical SOAs and a 70 m highly-nonlinear photonic crystal fiber (HN-PCF). The signal and pump are coupled into the symmetrical PALM from different ports, respectively. After the DFWM based wavelength conversion (WC) in the clockwise and anticlockwise, the idler exits from the signal port, while the pump outputs from its input port. Therefore, the pump is effectively suppressed in the idler channel without a high-speed tunable filter. Contrast to a traditional PALM, the DFWM based conversion efficiency is increased greatly, and the functions of the amplification and the WC are integrated in the smart SOA and HN-PCF PALM.

  16. All-optical evaluation of spin-orbit interaction based on diffusive spin motion in a two-dimensional electron gas

    SciTech Connect

    Kohda, M.; Altmann, P.; Salis, G.; Schuh, D.; Ganichev, S. D.; Wegscheider, W.

    2015-10-26

    A method is presented that enables the measurement of spin-orbit coefficients in a diffusive two-dimensional electron gas without the need for processing the sample structure, applying electrical currents or resolving the spatial pattern of the spin mode. It is based on the dependence of the average electron velocity on the spatial distance between local excitation and detection of spin polarization, resulting in a variation of spin precession frequency that in an external magnetic field is linear in the spatial separation. By scanning the relative positions of the exciting and probing spots in a time-resolved Kerr rotation microscope, frequency gradients along the [100] and [010] crystal axes of GaAs/AlGaAs QWs are measured to obtain the Rashba and Dresselhaus spin-orbit coefficients, α and β. This simple method can be applied in a variety of materials with electron diffusion for evaluating spin-orbit coefficients.

  17. Evaluation of the current biased integrated optical processors based on bistable dode elements

    NASA Astrophysics Data System (ADS)

    Tang, C. L.; Swanson, P. D.; Parker, M. A.; Libby, S. I.

    1994-07-01

    Three optical switching elements have been designed, fabricated and tested for use in an integrated, optical signal processor. The first, and optical NOR logic gate, uses gain quenching as a means of allowing one (or more) light beam (s) to control the output light. This technique, along with the use of a two-pad bistable output laser, is used in the demonstration of the feasibility of the second device, an all optical RS flip-flop. The third device consists of a broad area orthogonal mode switch laser, whose corollary outputs correspond to the sign of the voltage difference between its two high impedance electrical inputs. This device also has possible memory applications if bistable mode switching within the broad area laser can be achieved.

  18. Pencil beam all-optical ultrasound imaging

    PubMed Central

    Alles, Erwin J.; Noimark, Sacha; Zhang, Edward; Beard, Paul C.; Desjardins, Adrien E.

    2016-01-01

    A miniature, directional fibre-optic acoustic source is presented that employs geometrical focussing to generate a nearly-collimated acoustic pencil beam. When paired with a fibre-optic acoustic detector, an all-optical ultrasound probe with an outer diameter of 2.5 mm is obtained that acquires a pulse-echo image line at each probe position without the need for image reconstruction. B-mode images can be acquired by translating the probe and concatenating the image lines, and artefacts resulting from probe positioning uncertainty are shown to be significantly lower than those observed for conventional synthetic aperture scanning of a non-directional acoustic source. The high image quality obtained for excised vascular tissue suggests that the all-optical ultrasound probe is ideally suited for in vivo, interventional applications. PMID:27699130

  19. All-optical vector atomic magnetometer.

    PubMed

    Patton, B; Zhivun, E; Hovde, D C; Budker, D

    2014-07-01

    We demonstrate an all-optical magnetometer capable of measuring the magnitude and direction of a magnetic field using nonlinear magneto-optical rotation in cesium vapor. Vector capability is added by effective modulation of the field along orthogonal axes and subsequent demodulation of the magnetic-resonance frequency. This modulation is provided by the ac Stark shift induced by circularly polarized laser beams. The sensor exhibits a demonstrated rms noise floor of ∼65  fT/√[Hz] in measurement of the field magnitude and 0.5  mrad/√[Hz] in the field direction; elimination of technical noise would improve these sensitivities to 12  fT/√[Hz] and 10  μrad/√[Hz], respectively. Applications for this all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron. PMID:25032923

  20. All-Optical Vector Atomic Magnetometer

    NASA Astrophysics Data System (ADS)

    Patton, B.; Zhivun, E.; Hovde, D. C.; Budker, D.

    2014-07-01

    We demonstrate an all-optical magnetometer capable of measuring the magnitude and direction of a magnetic field using nonlinear magneto-optical rotation in cesium vapor. Vector capability is added by effective modulation of the field along orthogonal axes and subsequent demodulation of the magnetic-resonance frequency. This modulation is provided by the ac Stark shift induced by circularly polarized laser beams. The sensor exhibits a demonstrated rms noise floor of ˜65 fT/√Hz in measurement of the field magnitude and 0.5 mrad /√Hz in the field direction; elimination of technical noise would improve these sensitivities to 12 fT /√Hz and 10 μrad /√Hz , respectively. Applications for this all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron.

  1. Pencil beam all-optical ultrasound imaging

    PubMed Central

    Alles, Erwin J.; Noimark, Sacha; Zhang, Edward; Beard, Paul C.; Desjardins, Adrien E.

    2016-01-01

    A miniature, directional fibre-optic acoustic source is presented that employs geometrical focussing to generate a nearly-collimated acoustic pencil beam. When paired with a fibre-optic acoustic detector, an all-optical ultrasound probe with an outer diameter of 2.5 mm is obtained that acquires a pulse-echo image line at each probe position without the need for image reconstruction. B-mode images can be acquired by translating the probe and concatenating the image lines, and artefacts resulting from probe positioning uncertainty are shown to be significantly lower than those observed for conventional synthetic aperture scanning of a non-directional acoustic source. The high image quality obtained for excised vascular tissue suggests that the all-optical ultrasound probe is ideally suited for in vivo, interventional applications.

  2. All-optical vector atomic magnetometer.

    PubMed

    Patton, B; Zhivun, E; Hovde, D C; Budker, D

    2014-07-01

    We demonstrate an all-optical magnetometer capable of measuring the magnitude and direction of a magnetic field using nonlinear magneto-optical rotation in cesium vapor. Vector capability is added by effective modulation of the field along orthogonal axes and subsequent demodulation of the magnetic-resonance frequency. This modulation is provided by the ac Stark shift induced by circularly polarized laser beams. The sensor exhibits a demonstrated rms noise floor of ∼65  fT/√[Hz] in measurement of the field magnitude and 0.5  mrad/√[Hz] in the field direction; elimination of technical noise would improve these sensitivities to 12  fT/√[Hz] and 10  μrad/√[Hz], respectively. Applications for this all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron.

  3. All-optical control of molecular fluorescence

    SciTech Connect

    Bradshaw, David S.; Andrews, David L.

    2010-01-15

    We present a quantum electrodynamical procedure to demonstrate the all-optical control of molecular fluorescence. The effect is achieved on passage of an off-resonant laser beam through an optically activated system; the presence of a surface is not required. Following the derivation and analysis of the all-optical control mechanism, calculations are given to quantify the significant modification of spontaneous fluorescent emission with input laser irradiance. Specific results are given for molecules whose electronic spectra are dominated by transitions between three electronic levels, and suitable laser experimental methods are proposed. It is also shown that the phenomenon is sensitive to the handedness of circularly polarized throughput, producing a conferred form of optical activity.

  4. Plasmonic All-Optical Tunable Wavelength Shifter

    SciTech Connect

    Flugel, B.; Macararenhas, A.; Snoke, D. W.; Pfeiffer, L. N.; West, K.

    2007-12-01

    At present, wavelength-division-multiplexed fibre lines routinely operate at 10 Gbit s{sup -1} per channel. The transition from static-path networks to true all-optical networks encompassing many nodes, in which channels are added/dropped and efficiently reassigned, will require improved tools for all-optical wavelength shifting. Specifically, one must be able to shift the carrier wavelength (frequency) of an optical data signal over tens of nanometres (a THz range) without the bottleneck of electrical conversion. Popular approaches to this problem make use of the nonlinear interaction between two wavelengths within a semiconductor optical amplifier whereas more novel methods invoke terahertz-frequency electro-optic modulation and polaritons. Here we outline the principles and demonstrate the use of optically excited plasmons as a tunable frequency source that can be mixed with a laser frequency through Raman scattering. The scheme is all-optical and enables dynamical control of the output carrier wavelength simply by varying the power of a control laser.

  5. Photonic encryption using all optical logic.

    SciTech Connect

    Blansett, Ethan L.; Schroeppel, Richard Crabtree; Tang, Jason D.; Robertson, Perry J.; Vawter, Gregory Allen; Tarman, Thomas David; Pierson, Lyndon George

    2003-12-01

    With the build-out of large transport networks utilizing optical technologies, more and more capacity is being made available. Innovations in Dense Wave Division Multiplexing (DWDM) and the elimination of optical-electrical-optical conversions have brought on advances in communication speeds as we move into 10 Gigabit Ethernet and above. Of course, there is a need to encrypt data on these optical links as the data traverses public and private network backbones. Unfortunately, as the communications infrastructure becomes increasingly optical, advances in encryption (done electronically) have failed to keep up. This project examines the use of optical logic for implementing encryption in the photonic domain to achieve the requisite encryption rates. In order to realize photonic encryption designs, technology developed for electrical logic circuits must be translated to the photonic regime. This paper examines two classes of all optical logic (SEED, gain competition) and how each discrete logic element can be interconnected and cascaded to form an optical circuit. Because there is no known software that can model these devices at a circuit level, the functionality of the SEED and gain competition devices in an optical circuit were modeled in PSpice. PSpice allows modeling of the macro characteristics of the devices in context of a logic element as opposed to device level computational modeling. By representing light intensity as voltage, 'black box' models are generated that accurately represent the intensity response and logic levels in both technologies. By modeling the behavior at the systems level, one can incorporate systems design tools and a simulation environment to aid in the overall functional design. Each black box model of the SEED or gain competition device takes certain parameters (reflectance, intensity, input response), and models the optical ripple and time delay characteristics. These 'black box' models are interconnected and cascaded in an

  6. Voltage divider based on submicron slits in a high Tc superconducting film and two bicrystal grain boundaries

    NASA Astrophysics Data System (ADS)

    Kaplunenko, V. K.; Ivanov, Z. G.; Stepantsov, E. A.; Claeson, T.; Wikborg, E.

    1995-07-01

    Experiments on a model of rapid single flux quantum (RSFQ) flip-flop cell, based on high-Tc (HTS) Josephson junctions show that it can operate as a voltage divider at frequency up to 400 GHz. The junctions were formed in YBaCuO film, deposited on novel Y-ZrO2 bicrystals with two asymmetric 32° grain boundaries, about 10 μm apart, and allow a new design of RSFQ logic based on a single HTS layer. Small inductances (≂10 pH) were made as narrow, submicron size slits. The junction widths were between 4 and 10 μm and for ten junctions located close to the tested circuits, the linear critical current densities at T=4.4 K were 10.7 μA/μm±50% for one grain boundary and 8.3 μA/μm±50% for the other one. IcRn was about 1 mV±50%. A current density of half the expected value meant that the test circuit did not act as an ideal flip-flop down to the lowest frequency. As a voltage divider it gave a half value division up to 0.82 mV at T=4.4 K and to 0.4 mV at 30 K.

  7. All optical binary delta-sigma modulator

    NASA Astrophysics Data System (ADS)

    Sayeh, Mohammad R.; Siahmakoun, Azad

    2005-09-01

    This paper describes a novel A/D converter called "Binary Delta-Sigma Modulator" (BDSM) which operates only with nonnegative signal with positive feedback and binary threshold. This important modification to the conventional delta-sigma modulator makes the high-speed (>100GHz) all-optical implementation possible. It has also the capability to modify its own sampling frequency as well as its input dynamic range. This adaptive feature helps designers to optimize the system performance under highly noisy environment and also manage the power consumption of the A/D converters.

  8. All-optical nanomechanical heat engine.

    PubMed

    Dechant, Andreas; Kiesel, Nikolai; Lutz, Eric

    2015-05-01

    We propose and theoretically investigate a nanomechanical heat engine. We show how a levitated nanoparticle in an optical trap inside a cavity can be used to realize a Stirling cycle in the underdamped regime. The all-optical approach enables fast and flexible control of all thermodynamical parameters and the efficient optimization of the performance of the engine. We develop a systematic optimization procedure to determine optimal driving protocols. Further, we perform numerical simulations with realistic parameters and evaluate the maximum power and the corresponding efficiency. PMID:26001001

  9. All-optical nanomechanical heat engine.

    PubMed

    Dechant, Andreas; Kiesel, Nikolai; Lutz, Eric

    2015-05-01

    We propose and theoretically investigate a nanomechanical heat engine. We show how a levitated nanoparticle in an optical trap inside a cavity can be used to realize a Stirling cycle in the underdamped regime. The all-optical approach enables fast and flexible control of all thermodynamical parameters and the efficient optimization of the performance of the engine. We develop a systematic optimization procedure to determine optimal driving protocols. Further, we perform numerical simulations with realistic parameters and evaluate the maximum power and the corresponding efficiency.

  10. All-Optical Nanomechanical Heat Engine

    NASA Astrophysics Data System (ADS)

    Dechant, Andreas; Kiesel, Nikolai; Lutz, Eric

    2015-05-01

    We propose and theoretically investigate a nanomechanical heat engine. We show how a levitated nanoparticle in an optical trap inside a cavity can be used to realize a Stirling cycle in the underdamped regime. The all-optical approach enables fast and flexible control of all thermodynamical parameters and the efficient optimization of the performance of the engine. We develop a systematic optimization procedure to determine optimal driving protocols. Further, we perform numerical simulations with realistic parameters and evaluate the maximum power and the corresponding efficiency.

  11. All-optical OFDM network coding scheme for all-optical virtual private communication in PON

    NASA Astrophysics Data System (ADS)

    Li, Lijun; Gu, Rentao; Ji, Yuefeng; Bai, Lin; Huang, Zhitong

    2014-03-01

    A novel optical orthogonal frequency division multiplexing (OFDM) network coding scheme is proposed over passive optical network (PON) system. The proposed scheme for all-optical virtual private network (VPN) does not only improve transmission efficiency, but also realize full-duplex communication mode in a single fiber. Compared with the traditional all-optical VPN architectures, the all-optical OFDM network coding scheme can support higher speed, more flexible bandwidth allocation, and higher spectrum efficiency. In order to reduce the difficulty of alignment for encoding operation between inter-communication traffic, the width of OFDM subcarrier pulse is stretched in our proposed scheme. The feasibility of all-optical OFDM network coding scheme for VPN is verified, and the relevant simulation results show that the full-duplex inter-communication traffic stream can be transmitted successfully. Furthermore, the tolerance of misalignment existing in inter-ONUs traffic is investigated and analyzed for all-optical encoding operation, and the difficulty of pulse alignment is proved to be lower.

  12. All-optically simultaneous slow and fast light

    NASA Astrophysics Data System (ADS)

    Chen, Zhongjie; Luo, Bin; Liu, Yu; Guo, Hong

    2013-11-01

    Simultaneous slow and fast light can be realized all-optically by connecting a four-level closed-loop atom-light interaction scheme to Λ-type electromagnetically induced transparency system. Through manipulation of the relative phase of one of the coupling lights, probe light can be switched among dual-slow light, dual-fast light and simultaneous slow and fast light. A theoretical analysis based on dressed state picture is given.

  13. All-optical switching in optically induced nonlinear waveguide couplers

    SciTech Connect

    Diebel, Falko Boguslawski, Martin; Rose, Patrick; Denz, Cornelia; Leykam, Daniel; Desyatnikov, Anton S.

    2014-06-30

    We experimentally demonstrate all-optical vortex switching in nonlinear coupled waveguide arrays optically induced in photorefractive media. Our technique is based on multiplexing of nondiffracting Bessel beams to induce various types of waveguide configurations. Using double- and quadruple-well potentials, we demonstrate precise control over the coupling strength between waveguides, the linear and nonlinear dynamics and symmetry-breaking bifurcations of guided light, and a power-controlled optical vortex switch.

  14. All-optical vector atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Zhivun, Elena; Patton, Brian; Hovde, Chris; Budker, Dmitry

    2014-05-01

    Alkali-vapor magnetometers are among the most precise magnetic sensors today, reaching sensitivities on the scale of fT/√{Hz}. In general, alkali-vapor magnetometers operating in finite fields can only measure the scalar magnitude of the field (not its direction or projection). In this work we demonstrate an all-optical vector cesium magnetometer with 0 . 2pT /√{Hz} sensitivity to the field magnitude and 4mrad /√{Hz} angular precision in the field direction. Although this can be accomplished by applying orthogonal magnetic fields to the sensor and measuring the change in Larmor frequency, in our sensor we employ the vector light shift induced by orthogonal laser beams to achieve the same effect. We will present results from such a sensor operating in a 10 mG magnetic field and discuss its applications to fundamental physics experiments and remote magnetometry.

  15. Nonlinear fiber applications for ultrafast all-optical signal processing

    NASA Astrophysics Data System (ADS)

    Kravtsov, Konstantin

    In the present dissertation different aspects of all-optical signal processing, enabled by the use of nonlinear fibers, are studied. In particular, we focus on applications of a novel heavily GeO2-doped (HD) nonlinear fiber, that appears to be superior to many other types of nonlinear fibers because of its high nonlinearity and suitability for the use in nonlinear optical loop mirrors (NOLMs). Different functions, such as all-optical switching, thresholding, and wavelength conversion, are demonstrated with the HD fibers in the NOLM configuration. These basic functions are later used for realization of ultrafast time-domain demultiplexers, clock recovery, detectors of short pulses in stealth communications, and primitive elements for analog computations. Another important technology that benefits from the use of nonlinear fiber-based signal processing is optical code-division multiple access (CDMA). It is shown in both theory and experiment that all-optical thresholding is a unique way of improving existing detection methods for optical CDMA. Also, it is the way of implementation of true asynchronous optical spread-spectrum networks, which allows full realization of optical CDMA potential. Some aspects of quantum signal processing and manipulation of quantum states are also studied in this work. It is shown that propagation and collisions of Thirring solitons lead to a substantial squeezing of quantum states, which may find applications for generation of squeezed light.

  16. All-Optical Interrogation of Neural Circuits

    PubMed Central

    2015-01-01

    There have been two recent revolutionary advances in neuroscience: First, genetically encoded activity sensors have brought the goal of optical detection of single action potentials in vivo within reach. Second, optogenetic actuators now allow the activity of neurons to be controlled with millisecond precision. These revolutions have now been combined, together with advanced microscopies, to allow “all-optical” readout and manipulation of activity in neural circuits with single-spike and single-neuron precision. This is a transformational advance that will open new frontiers in neuroscience research. Harnessing the power of light in the all-optical approach requires coexpression of genetically encoded activity sensors and optogenetic probes in the same neurons, as well as the ability to simultaneously target and record the light from the selected neurons. It has recently become possible to combine sensors and optical strategies that are sufficiently sensitive and cross talk free to enable single-action-potential sensitivity and precision for both readout and manipulation in the intact brain. The combination of simultaneous readout and manipulation from the same genetically defined cells will enable a wide range of new experiments as well as inspire new technologies for interacting with the brain. The advances described in this review herald a future where the traditional tools used for generations by physiologists to study and interact with the brain—stimulation and recording electrodes—can largely be replaced by light. We outline potential future developments in this field and discuss how the all-optical strategy can be applied to solve fundamental problems in neuroscience. SIGNIFICANCE STATEMENT This review describes the nexus of dramatic recent developments in optogenetic probes, genetically encoded activity sensors, and novel microscopies, which together allow the activity of neural circuits to be recorded and manipulated entirely using light. The

  17. All-optical signal processing at 10 GHz using a photonic crystal molecule

    SciTech Connect

    Combrié, Sylvain; Lehoucq, Gaëlle; Junay, Alexandra; De Rossi, Alfredo; Malaguti, Stefania; Bellanca, Gaetano; Trillo, Stefano; Ménager, Loic; Peter Reithmaier, Johann

    2013-11-04

    We report on 10 GHz operation of an all-optical gate based on an Indium Phosphide Photonic Crystal Molecule. Wavelength conversion and all-optical mixing of microwave signals are demonstrated using the 2 mW output of a mode locked diode laser. The spectral separation of the optical pump and signal is crucial in suppressing optical cross-talk.

  18. All-optical nonlinear switching cell made of photonic crystal.

    PubMed

    Wirth Lima, A; da Silva, Marcio G; Ferreira, A C; Sombra, A S B

    2009-07-01

    We analyze and propose a directional optical coupler embedded in photonic crystal, which is driven by an external command signal. Therefore, this switching cell can work in an all-optical switch. The switching method uses a low-power external command signal, inserted in the central coupling region, which acts as another waveguide. The switching process is based on the change from the bar state to the cross state due to the external command signal. In our simulations we used the plane wave expansion method, finite-difference time-domain method, and our own binary propagation method.

  19. Realization of an all optical exciton-polariton router

    SciTech Connect

    Marsault, Félix; Nguyen, Hai Son; Tanese, Dimitrii; Lemaître, Aristide; Galopin, Elisabeth; Sagnes, Isabelle; Amo, Alberto

    2015-11-16

    We report on the experimental realization of an all optical router for exciton-polaritons. This device is based on the design proposed by Flayac and Savenko [Appl. Phys. Lett. 103, 201105 (2013)], in which a zero-dimensional island is connected through tunnel barriers to two periodically modulated wires of different periods. Selective transmission of polaritons injected in the island, into either of the two wires, is achieved by tuning the energy of the island state across the band structure of the modulated wires. We demonstrate routing of ps polariton pulses using an optical control beam which controls the energy of the island quantum states, thanks to polariton-exciton interactions.

  20. All-Optical Photochromic Spatial Light Modulators

    NASA Technical Reports Server (NTRS)

    Beratan, David N.; Perry, Joseph W.

    1989-01-01

    Photochemical transfer of electrons enables fast reading and writing. New concept based on transfer of electrons between donor and acceptor molecules randomly distributed or covalently linked and dispersed in glassy-polymer host material. Transfer causes significant changes in optical-transmission characteristics of material and used to modulate transmission of reading beam of light impinging on material.

  1. Bandwidth analysis of all-optical turbo-switch

    NASA Astrophysics Data System (ADS)

    Zhou, Peng; Yang, Xuelin; Hu, Xiaonan; Hu, Weisheng

    2015-01-01

    We propose and develop a frequency-domain model to analyze the bandwidth of all-optical turbo-switch. The model has taken the spatial inhomogeneity of semiconductor optical amplifier (SOA) into consideration for the first time. The simulations based on the model show that the 3-dB bandwidth of turbo-switch could reach up to ~270 GHz when the second SOA is oversaturated. However, the overshoot will be higher, which may result in the distortion of the output signal. There is a trade-off between the bandwidth and the flatness of frequency response characteristics for turbo-switch operation. In addition, the optimum position of the delay-interferometer (DI) is investigated, showing that the level of the overshoot is relatively lower if the DI is placed between the two SOAs.

  2. All-Optical Graphene Oxide Humidity Sensors

    PubMed Central

    Lim, Weng Hong; Yap, Yuen Kiat; Chong, Wu Yi; Ahmad, Harith

    2014-01-01

    The optical characteristics of graphene oxide (GO) were explored to design and fabricate a GO-based optical humidity sensor. GO film was coated onto a SU8 polymer channel waveguide using the drop-casting technique. The proposed sensor shows a high TE-mode absorption at 1550 nm. Due to the dependence of the dielectric properties of the GO film on water content, this high TE-mode absorption decreases when the ambient relative humidity increases. The proposed sensor shows a rapid response (<1 s) to periodically interrupted humid air flow. The transmission of the proposed sensor shows a linear response of 0.553 dB/% RH in the range of 60% to 100% RH. PMID:25526358

  3. All-optical modulation in gallium arsenide integrated optical waveguides

    SciTech Connect

    McWright, G.; Ross, B.; Guthreau, W.; Lafaw, D.; Lowry, M.; Tindall, W.

    1988-01-27

    We have investigated all-optical modulators in gallium arsenide integrated optical waveguides; these modulators use electron-hole pair generation to alter the propagation characteristics of a guided light beam. 6 refs., 6 figs.

  4. All-optical signal processing using dynamic Brillouin gratings

    PubMed Central

    Santagiustina, Marco; Chin, Sanghoon; Primerov, Nicolay; Ursini, Leonora; Thévenaz, Luc

    2013-01-01

    The manipulation of dynamic Brillouin gratings in optical fibers is demonstrated to be an extremely flexible technique to achieve, with a single experimental setup, several all-optical signal processing functions. In particular, all-optical time differentiation, time integration and true time reversal are theoretically predicted, and then numerically and experimentally demonstrated. The technique can be exploited to process both photonic and ultra-wide band microwave signals, so enabling many applications in photonics and in radio science. PMID:23549159

  5. Characterization of the bistable wideband optical filter on the basis of nonlinear 2D photonic crystal

    SciTech Connect

    Guryev, I. V. Sukhoivanov, I. A. Andrade Lucio, J. A. Manzano, O. Ibarra Rodriguez, E. Vargaz Gonzales, D. Claudio Chavez, R. I. Mata Gurieva, N. S.

    2014-05-15

    In our work, we investigated the wideband optical filter on the basis of nonlinear photonic crystal. The all-optical flip-flop using ultra-short pulses with duration lower than 200 fs is obtained in such filters. Here we pay special attention to the stability problem of the nonlinear element. To investigate this problem, the temporal response demonstrating the flip-flop have been computed within the certain range of the wavelengths as well as at different input power.

  6. Resource allocation in circuit-switched all-optical networks

    NASA Astrophysics Data System (ADS)

    Marquis, Douglas; Barry, Richard A.; Finn, Steven G.; Parikh, Salil A.; Swanson, Eric A.; Thomas, Robert E.

    1996-03-01

    We describe an all-optical network testbed deployed in the Boston area, and research surrounding the allocation of optical resources -- frequencies and time slots -- within the network. The network was developed by a consortium of AT&T Bell Laboratories, Digital Equipment Corporation, and Massachusetts Institute of Technology under a grant from ARPA. The network is organized as a hierarchy consisting of local, metropolitan, and wide area nodes tea support optical broadcast and routing modes. Frequencies are shared and reused to enhance network scalability. Electronic access is provided through optical terminals that support multiple services having data rates between 10 Mbps/user and 10 Gbps/user. Of particular interest for this work is the 'B-service,' which simultaneously hops frequency and time slots on each optical terminal to allow frequency sharing within the AON. B-service provides 1.244 Gbps per optical terminal, with bandwidth for individual connections divided in increments as small as 10 Mbps. We have created interfaces between the AON and commercially available electronic circuit-switched and packet-switched networks. The packet switches provide FDDI (datacomm), T3 (telecomm), and ATM/SONET switching at backplane rates of over 3 Gbps. We show results on network applications that dynamically allocate optical bandwidth between electronic packet-switches based on the offered load presented by users. Bandwidth allocation granularity is proportional to B-Service slots (10-1244 Mbps), and switching times are on the order of one second. We have also studied the effects of wavelength changers upon the network capacity and blocking probabilities in wide area all-optical networks. Wavelength changers allow a change in the carrier frequency (within the network) without disturbing the data modulation. The study includes both a theoretical model of blocking probabilities based on network design parameters, and a computer simulation of blocking in networks with and

  7. All-optical wavelength conversion for mode division multiplexed superchannels.

    PubMed

    Gong, Jiaxin; Xu, Jing; Luo, Ming; Li, Xiang; Qiu, Ying; Yang, Qi; Zhang, Xinliang; Yu, Shaohua

    2016-04-18

    We report in this work the first all-optical wavelength conversion (AOWC) of a mode division multiplexed (MDM) superchannel consisting of 2N modes by dividing the superchannel into N single-mode (SM) tributaries, wavelength converting N SM signals using well developed SM-AOWC techniques, and finally combining the N SM tributaries back to an MDM superchannel at the converted wavelength, inspired by the idea of using SM filtering techniques to filter multimode signals in astronomy. The conversions between multimode and SM are realized by 3D laser-writing photonic lanterns and SM-AOWCs are realized based on polarization insensitive four wave mixing (FWM) configuration in N semiconductor optical amplifiers (SOAs). As a proof of concept demonstration, the conversion of a 6-mode MDM superchannel with each mode modulated with orthogonal frequency division multiplexed (OFDM) quadrature phase-shift keying (QPSK)/16 quadrature amplitude modulation (QAM) signals is demonstrated in this work, indicating that the scheme is transparent to data format, polarization and compatible with multi-carrier signals. Data integrity of the converted superchannel has been verified by using coherent detection and digital signal processing (DSP). Bit error rates (BERs) below the forward error correction (FEC) hard limit (3.8 × 10-3) have been obtained for QPSK modulation at a net bitrate of 104.2 Gbit/s and BERs below the soft decision FEC threshold (1.98 × 10-2) have been achieved for 16-QAM format, giving a total aggregate bit rate of 185.8 Gbit/s when taking 20% coding overhead into account. Add and drop functionalities that usually come along with wavelength conversion in flexible network nodes have also been demonstrated. The working conditions of the SOAs, especially the pump and signal power levels, are critical for the quality of the converted signal and have been thoroughly discussed. The impact of imbalanced FWM conversion efficiency among different SM

  8. Dissipative Particle Dynamics Simulations for Phospholipid Membranes Based on a Four-To-One Coarse-Grained Mapping Scheme.

    PubMed

    Li, Xiaoxu; Gao, Lianghui; Fang, Weihai

    2016-01-01

    In this article, a new set of parameters compatible with the dissipative particle dynamics (DPD) force field is developed for phospholipids. The coarse-grained (CG) models of these molecules are constructed by mapping four heavy atoms and their attached hydrogen atoms to one bead. The beads are divided into types distinguished by charge type, polarizability, and hydrogen-bonding capacity. First, we derive the relationship between the DPD repulsive force and Flory-Huggins χ-parameters based on this four-to-one CG mapping scheme. Then, we optimize the DPD force parameters for phospholipids. The feasibility of this model is demonstrated by simulating the structural and thermodynamic properties of lipid bilayer membranes, including the membrane thickness, the area per lipid, the lipid tail orientation, the bending rigidity, the rupture behavior, and the potential of mean force for lipid flip-flop. PMID:27137463

  9. Dissipative Particle Dynamics Simulations for Phospholipid Membranes Based on a Four-To-One Coarse-Grained Mapping Scheme

    PubMed Central

    Li, Xiaoxu; Gao, Lianghui; Fang, Weihai

    2016-01-01

    In this article, a new set of parameters compatible with the dissipative particle dynamics (DPD) force field is developed for phospholipids. The coarse-grained (CG) models of these molecules are constructed by mapping four heavy atoms and their attached hydrogen atoms to one bead. The beads are divided into types distinguished by charge type, polarizability, and hydrogen-bonding capacity. First, we derive the relationship between the DPD repulsive force and Flory-Huggins χ-parameters based on this four-to-one CG mapping scheme. Then, we optimize the DPD force parameters for phospholipids. The feasibility of this model is demonstrated by simulating the structural and thermodynamic properties of lipid bilayer membranes, including the membrane thickness, the area per lipid, the lipid tail orientation, the bending rigidity, the rupture behavior, and the potential of mean force for lipid flip-flop. PMID:27137463

  10. All-optical regulation of gene expression in targeted cells

    NASA Astrophysics Data System (ADS)

    Wang, Yisen; He, Hao; Li, Shiyang; Liu, Dayong; Lan, Bei; Hu, Minglie; Cao, Youjia; Wang, Chingyue

    2014-06-01

    Controllable gene expression is always a challenge and of great significance to biomedical research and clinical applications. Recently, various approaches based on extra-engineered light-sensitive proteins have been developed to provide optogenetic actuators for gene expression. Complicated biomedical techniques including exogenous genes engineering, transfection, and material delivery are needed. Here we present an all-optical method to regulate gene expression in targeted cells. Intrinsic or exogenous genes can be activated by a Ca2+-sensitive transcription factor nuclear factor of activated T cells (NFAT) driven by a short flash of femtosecond-laser irradiation. When applied to mesenchymal stem cells, expression of a differentiation regulator Osterix can be activated by this method to potentially induce differentiation of them. A laser-induced ``Ca2+-comb'' (LiCCo) by multi-time laser exposure is further developed to enhance gene expression efficiency. This noninvasive method hence provides an encouraging advance of gene expression regulation, with promising potential of applying in cell biology and stem-cell science.

  11. Enhanced all-optical switching with double slow light pulses

    NASA Astrophysics Data System (ADS)

    Lin, Chi-Ching; Wu, Meng-Chang; Shiau, Bor-Wen; Chen, Yi-Hsin; Yu, Ite A.; Chen, Yong-Fan; Chen, Ying-Cheng

    2012-12-01

    We experimentally demonstrate an all-optical switching (AOS) scheme based on double slow light (DSL) pulses, in which one pulse is switched by another due to the cross-Kerr nonlinearity. The interaction time is prolonged by optically dense atomic media and matched group velocities. The interaction strength is maintained at a high level by keeping both fields at their electromagnetically-induced-transparency resonances to minimize the linear loss. In the AOS without the DSL scheme, the group velocity mismatch sets an upper limit on the switching efficiency of two photons per atomic cross section as discussed by Harris and Hau [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.82.4611 82, 4611 (1999)]. Compared to that limit, we have obtained an enhanced switching efficiency by a factor of 3 with our DSL scheme. The nonlinear efficiency can be further improved by increasing the optical depth of the medium. Our work advances low-light-level nonlinear optics and provides essential ingredients for quantum many-body physics using strongly interacting photons.

  12. All-optical broadband ultrasonography of single cells

    PubMed Central

    Dehoux, T.; Ghanem, M. Abi; Zouani, O. F.; Rampnoux, J.-M.; Guillet, Y.; Dilhaire, S.; Durrieu, M.-C.; Audoin, B.

    2015-01-01

    Cell mechanics play a key role in several fundamental biological processes, such as migration, proliferation, differentiation and tissue morphogenesis. In addition, many diseased conditions of the cell are correlated with altered cell mechanics, as in the case of cancer progression. For this there is much interest in methods that can map mechanical properties with a sub-cell resolution. Here, we demonstrate an inverted pulsed opto-acoustic microscope (iPOM) that operates in the 10 to 100 GHz range. These frequencies allow mapping quantitatively cell structures as thin as 10 nm and resolving the fibrillar details of cells. Using this non-invasive all-optical system, we produce high-resolution images based on mechanical properties as the contrast mechanisms, and we can observe the stiffness and adhesion of single migrating stem cells. The technique should allow transferring the diagnostic and imaging abilities of ultrasonic imaging to the single-cell scale, thus opening new avenues for cell biology and biomaterial sciences. PMID:25731090

  13. All-optical information processing in photonic crystals

    NASA Astrophysics Data System (ADS)

    Yanik, Mehmet Fatih

    This thesis covers coherent and incoherent all-optical information processing using photonic bandgap nanostructures and microcavities. The first 3 chapters introduce all-optical bistable switching, transistor and memory elements with sub-micron scale dimensions. A strategy for large scale integration without optical isolators is also described. In chapters 4 and 5, dynamically modulated photonic crystal structures are introduced. It is shown that light pulses can be stopped and stored all-optically without requiring any coherent or resonant light-matter interaction. In chapter 6, it is shown that light pulses can be coherently time-reversed by using only index modulations and linear optics. In chapter 7, a supercomputer implementation of an object oriented finite difference time domain simulation is described to simulate photonic nanostructures with arbitrary material & geometric features.

  14. Simple novel all-optical half-adder

    NASA Astrophysics Data System (ADS)

    Chen, Zhixin

    2010-04-01

    On the basis of Sagnac interferometric structure, a simple novel ultrafast scheme of all-optical half-adder is proposed. The structure comprises two of the same balanced terahertz optical asymmetric demultiplexers (TOADs). One TOAD is utilized to achieve an all-optical XOR gate, which is logic SUM. The other is utilized to obtain an all-optical AND gate, which is logic CARRY. Logical SUM and CARRY are simultaneously realized at 80 Gbit/s. Through numerical analysis, the operating characteristics of the scheme are illustrated at 80 Gbit/s. Furthermore, the carrier recovery time of the semiconductor optical amplifier is no longer a crucial parameter to restrict the operation speed of this scheme.

  15. Tunable all-optical plasmonic rectifier in nanoscale metal-insulator-metal waveguides.

    PubMed

    Xu, Yi; Wang, Xiaomeng; Deng, Haidong; Guo, Kangxian

    2014-10-15

    We propose a tunable all-optical plasmonic rectifier based on the nonlinear Fano resonance in a metal-insulator-metal plasmonic waveguide and cavities coupling system. We develop a theoretical model based on the temporal coupled-mode theory to study the device physics of the nanoscale rectifier. We further demonstrate via the finite difference time domain numerical experiment that our idea can be realized in a plasmonic system with an ultracompact size of ~120×800  nm². The tunable plasmonic rectifier could facilitate the all-optical signal processing in nanoscale.

  16. Frequency-time coherence for all-optical sampling without optical pulse source

    PubMed Central

    Preußler, Stefan; Raoof Mehrpoor, Gilda; Schneider, Thomas

    2016-01-01

    Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift. PMID:27687495

  17. Numerical investigation of an all-optical switch in a graded nonlinear plasmonic grating.

    PubMed

    Wang, Guoxi; Lu, Hua; Liu, Xueming; Gong, Yongkang

    2012-11-01

    We have proposed and numerically investigated an all-optical switch based on a metal-insulator-metal waveguide with graded nonlinear plasmonic gratings. The influences of grating depth and refractive index of a Kerr nonlinear medium on the transmission of the switch are exactly analyzed by utilizing transmission line theory. The finite-difference time-domain simulation results show that the highly compact structure possesses excellent switch function by tuning the incident electric field intensity. In addition, the simulation results show that this all-optical switch has an ultrawide operating frequency regime and femtosecond-scale response time (~130 fs). Such a switch can find potential applications for all-optical signal processing and optical communication.

  18. Frequency-time coherence for all-optical sampling without optical pulse source

    NASA Astrophysics Data System (ADS)

    Preußler, Stefan; Raoof Mehrpoor, Gilda; Schneider, Thomas

    2016-09-01

    Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift.

  19. Cascaded all-optical operations in a hybrid integrated 80-Gb/s logic circuit.

    PubMed

    LeGrange, J D; Dinu, M; Sochor, T; Bollond, P; Kasper, A; Cabot, S; Johnson, G S; Kang, I; Grant, A; Kay, J; Jaques, J

    2014-06-01

    We demonstrate logic functionalities in a high-speed all-optical logic circuit based on differential Mach-Zehnder interferometers with semiconductor optical amplifiers as the nonlinear optical elements. The circuit, implemented by hybrid integration of the semiconductor optical amplifiers on a planar lightwave circuit platform fabricated in silica glass, can be flexibly configured to realize a variety of Boolean logic gates. We present both simulations and experimental demonstrations of cascaded all-optical operations for 80-Gb/s on-off keyed data.

  20. Plasmonic enhancement of ultrafast all-optical magnetization reversal

    NASA Astrophysics Data System (ADS)

    Kochergin, Vladimir; Neely, Lauren N.; Allin, Leigh J.; Kochergin, Eugene V.; Wang, Kang L.

    2011-10-01

    Ultrafast all optical magnetization switching in GdFeCo layers on the basis of Inverse Faraday Effect (IFE) was demonstrated recently and suggested as a possible path toward next generation magnetic data storage medium with much faster writing time. However, to date, the demonstrations of ultrafast all-optical magnetization switching were performed with powerful femtosecond lasers, hardly useful for practical applications in data storage and data processing. Here we show that utilization of IFE enhancement in plasmonic nanostructures enables fast all-optical magnetization switching with smaller/cheaper laser sources with longer pulse durations. Our modeling results predict significant enhancement of IFE around all major types of plasmonic nanostructures for a circularly polarized incident light. Unlike the IFE in uniform bulk materials, nonzero value of IFE is predicted in plasmonic nanostructures even with a linearly polarized excitation. Experimentally, all-optical magnetization switching at 20 times lower laser fluence and roughly 100 times lower value of laser fluence/pulse duration ratio is demonstrated in plasmonic samples to verify the model predictions. The path to achieve higher levels of enhancement experimentally is discussed.

  1. Description of all-optical network test bed and applications

    NASA Astrophysics Data System (ADS)

    Marquis, Douglas; Castagnozzi, Daniel M.; Hemenway, B. R.; Parikh, Salil A.; Stevens, Mark L.; Swanson, Eric A.; Thomas, Robert E.; Ozveren, C.; Kaminow, Ivan P.

    1995-12-01

    We describe an all-optical network testbed deployed in the Boston metropolitan area, and some of the experimental applications running over the network. The network was developed by a consortium of AT&T Bell Laboratories, Digital Equipment Corporation, and Massachusetts Institute of Technology under a grant from ARPA. The network is an optical WDM system organized as a hierarchy consisting of local, metropolitan, and wide area nodes that support optical broadcast and routing modes. Frequencies are shared and reused to enhance network scalability. Electronic access is provided through optical terminals that support multiple services having data rates between 10 Mbps/user and 10 Gbps/user. Novel components used to implement the network include fast-tuning 1.5 micrometers distributed Bragg reflector lasers, passive wavelength routers, and broadband optical frequency converters. An overlay control network implemented at 1.3 micrometers allows reliable out-of-band control and standardized network management of all network nodes. We have created interfaces between the AON and commercially available electronic circuit-switched and packet-switched networks. We will report on network applications that can dynamically allocate optical bandwidth between electronic packet-switches based on the offered load presented by users, without requiring interfaces between users and the AON control system. We will also describe video and telemedicine applications running over the network. We have demonstrated an audio/video codec that is directly interfaced to the optical network, and is capable of transmitting high-rate digitized video signals for broadcast or videoconferencing applications. We have also demonstrated a state-of-the-art radiological workstation that uses the AON to transport 2000 X 2000 X 16 bit images from a remote image server.

  2. Phase-coherent all-optical frequency division by three

    SciTech Connect

    Lee, Dong-Hoon; Klein, Marvin E.; Meyn, Jan-Peter; Wallenstein, Richard; Gross, Petra; Boller, Klaus-Jochen

    2003-01-01

    The properties of all-optical phase-coherent frequency division by 3, based on a self-phase-locked continuous-wave (cw) optical parametric oscillator (OPO), are investigated theoretically and experimentally. The frequency to be divided is provided by a diode laser master-oscillator power-amplifier system operated at a wavelength of 812 nm and used as the pump source of the OPO. Optical self-phase-locking of the OPO signal and idler waves is achieved by mutual injection locking of the signal wave and the intracavity frequency-doubled idler wave. The OPO process and the second-harmonic generation of the idler wave are simultaneously phase matched through quasi-phase-matching using two periodically poled sections of different period manufactured within the same LiNbO{sub 3} crystal. An optical self-phase-locking range of up to 1 MHz is experimentally observed. The phase coherence of frequency division by three is measured via the phase stability of an interference pattern formed by the input and output waves of the OPO. The fractional frequency instability of the divider is measured to be smaller than 7.6x10{sup -14} for a measurement time of 10 s (resolution limited). The self-phase-locking characteristics of the cw OPO are theoretically investigated by analytically solving the coupled field equations in the steady-state regime. For the experimental parameters of the OPO, the calculations predict a locking range of 1.3 MHz and a fractional frequency instability of 1.6x10{sup -15}, in good agreement with the experimental results.

  3. Bufferless Ultra-High Speed All-Optical Packet Routing

    NASA Astrophysics Data System (ADS)

    Muttagi, Shrihari; Prince, Shanthi

    2011-10-01

    All-Optical network is still in adolescence to cope up with steep rise in data traffic at the backbone network. Routing of packets in optical network depends on the processing speed of the All-Optical routers, thus there is a need to enhance optical processing to curb the delay in packet forwarding unit. In the proposed scheme, the header processing takes place on fly, therefore processing delay is at its lower limit. The objective is to propose a framework which establishes high data rate transmission with least latency in data routing from source to destination. The Routing table and optical header pulses are converted into Pulse Position (PP) format, thus reducing the complexity and in turn the processing delay. Optical pulse matching is exercised which results in multi-output transmission. This results in ultra-high speed packet forwarding unit. In addition, this proposed scheme includes dispersion compensation unit, which makes the data reliable.

  4. Monolithically integrated nonlinear interferometers for all-optical switching

    SciTech Connect

    Jahn, E.; Agrawal, N.; Ehrke, H.J.; Pieper, W.; Franke, D.; Fuerst, W.; Weinert, C.M.

    1996-12-31

    All-optical switching devices are expected to play an important role in future optical communication networks. For example, nonlinear interferometer (NLI) arrangements consisting of one or two semiconductor laser amplifiers (SLA) are very attractive. Here, the cross-phase modulation due to the gain-saturation nonlinearity of SLAs could be used for switching in time, space, and wavelength domains. The first of such devices was configured as a nonlinear Sagnac interferometer (NSI) by using an SLA in a fiber loop mirror (SLALOM) for time domain switching. So far, these devices have been assembled using discrete SLA components. Other arrangements like Mach-Zehnder interferometer (MZI) with SLAs provide additional flexibility but require their realization as integrated devices for stable operation. In this paper the authors report on the development of monolithically integrated NLIs for all-optical signal processing in high bit-rate optical time division multiplexing systems. Both NSI and MZI configurations are considered.

  5. Analysis of all-optically tunable functionalities in subwavelength periodic structures by the Fourier modal method

    NASA Astrophysics Data System (ADS)

    Bej, Subhajit; Tervo, Jani; Francés, Jorge; Svirko, Yuri P.; Turunen, Jari

    2016-05-01

    We propose the nonlinear Fourier Modal Method (FMM) [J. Opt. Soc. Am. B 31, 2371 (2014)] as a convenient and versatile numerical tool for the design and analysis of grating based next generation all-optical devices. Here, we include several numerical examples where the FMM is used to simulate all-optically tunable functionalities in sub-wavelength periodic structures. At first, we numerically investigate a 1-D periodic nonlinear binary grating with amorphous TiO2. We plot the diffraction efficiency in the transmitted orders against the structure depth for normally incident plane wave. Change in diffraction efficiencies for different incident field amplitudes are evident from the plots. We verify the accuracy of our implementation by comparing our results with the results obtained with the nonlinear Split Field-Finite Difference Time Domain (SF-FDTD) method. Next we repeat the same experiment with vertically standing amorphous Titanium dioxide (TiO2) nanowire arrays grown on top of quartz which are periodic in two mutually perpendicular directions and examine the efficiencies in the direct transmitted light for different incident field amplitudes. Our third example includes analysis of a form birefringent linear grating with Kerr medium. With FMM we demonstrate that the birefringence of such a structure can be tuned by all-optical means. As a final example, we design a narrow band Guided Mode Resonance Filter (GMRF). Numerical experiments based on the nonlinear FMM reveal that the spectral tunability of such a filter can be obtained by all-optical means.

  6. Memory for flip-flopping: Detection and recollection of political contradictions

    PubMed Central

    Putnam, Adam L.; Wahlheim, Christopher N.; Jacoby, Larry L.

    2015-01-01

    During political campaigns, candidates often change their positions on controversial issues. Does changing positions create confusion and impair memory for a politician's current position? In 3 experiments, two political candidates held positions on controversial issues in two debates. Across the debates, their positions were repeated, changed, or held only in the second debate (control). Relative to the control condition, recall of the most recent position on issues was enhanced when change was detected and recollected, whereas recall was impaired when change was not recollected. Furthermore, examining the errors revealed that subjects were more likely to intrude a Debate 1 response than to recall a blend of the two positions, and that recollecting change decreased Debate 1 intrusions. We argue that detecting change produces a recursive representation that embeds the original position in memory along with the more recent position. Recollecting change then enhances memory for the politician's positions and their order of occurrence by accessing the recursive trace. PMID:24858525

  7. On the 'flip-flop' instability of Bondi-Hoyle accretion flows

    NASA Technical Reports Server (NTRS)

    Livio, Mario; Soker, Noam; Matsuda, Takuya; Anzer, Ulrich

    1991-01-01

    A simple physical interpretation is advanced by means of an analysis of the shock cone in the accretion flows past a compact object and with an examination of the accretion-line stability analyses. The stability of the conical shock is examined against small angular deflections with attention given to several simplifying assumptions. A line instability is identified in the Bondi-Hoyle accretion flows that leads to the formation of a large opening-angle shock. When the opening angle becomes large the instability becomes irregular oscillation. The analytical methodology is compared to previous numerical configurations that demonstrate different shock morphologies. The Bondi-Hoyle accretion onto a compact object is concluded to generate a range of nonlinear instabilities in both homogeneous and inhomogeneous cases with a quasiperiodic oscillation in the linear regime.

  8. Application of a Flip-Flop Nozzle on Plume Mixing Enhancement

    NASA Technical Reports Server (NTRS)

    Schreck, Stefan; Michaelian, Mark; Ho, Chih-Ming

    1999-01-01

    Mach wave radiation is a major source of noise in high speed jets. It is created by turbulent eddies which travel at supersonic speed within the shear layer of the jet. Downstream of the potential core, the convection speed of the eddies decays and noise production is reduced. Once the convection speeds drops below the speed of sound, eddy Mach wave radiation ceases. Mach wave radiation may be reduced by shortening the core length of the jet. This requires a faster growth of the shear layer, i.e. enhanced mixing in the jet. We investigated the possibility of mixing enhancement by the excitation of the instability waves in a supersonic rectangular jet.

  9. Coordinated phenotype switching with large-scale chromosome flip-flop inversion observed in bacteria.

    PubMed

    Cui, Longzhu; Neoh, Hui-min; Iwamoto, Akira; Hiramatsu, Keiichi

    2012-06-19

    Genome inversions are ubiquitous in organisms ranging from prokaryotes to eukaryotes. Typical examples can be identified by comparing the genomes of two or more closely related organisms, where genome inversion footprints are clearly visible. Although the evolutionary implications of this phenomenon are huge, little is known about the function and biological meaning of this process. Here, we report our findings on a bacterium that generates a reversible, large-scale inversion of its chromosome (about half of its total genome) at high frequencies of up to once every four generations. This inversion switches on or off bacterial phenotypes, including colony morphology, antibiotic susceptibility, hemolytic activity, and expression of dozens of genes. Quantitative measurements and mathematical analyses indicate that this reversible switching is stochastic but self-organized so as to maintain two forms of stable cell populations (i.e., small colony variant, normal colony variant) as a bet-hedging strategy. Thus, this heritable and reversible genome fluctuation seems to govern the bacterial life cycle; it has a profound impact on the course and outcomes of bacterial infections.

  10. All-optical implementation of ASCII by use of nonlinear material for optical encoding of necessary symbols

    NASA Astrophysics Data System (ADS)

    Dhar, Shantanu K.; Mukhopadhyay, Sourangshu

    2005-06-01

    We propose a simple all-optical technique for digital encoding of ASCII. The method accommodates a digital encoding system by using the optical tree architecture and a nonlinear-material-based optical switching operation.

  11. Photonic encryption : modeling and functional analysis of all optical logic.

    SciTech Connect

    Tang, Jason D.; Schroeppel, Richard Crabtree; Robertson, Perry J.

    2004-10-01

    With the build-out of large transport networks utilizing optical technologies, more and more capacity is being made available. Innovations in Dense Wave Division Multiplexing (DWDM) and the elimination of optical-electrical-optical conversions have brought on advances in communication speeds as we move into 10 Gigabit Ethernet and above. Of course, there is a need to encrypt data on these optical links as the data traverses public and private network backbones. Unfortunately, as the communications infrastructure becomes increasingly optical, advances in encryption (done electronically) have failed to keep up. This project examines the use of optical logic for implementing encryption in the photonic domain to achieve the requisite encryption rates. This paper documents the innovations and advances of work first detailed in 'Photonic Encryption using All Optical Logic,' [1]. A discussion of underlying concepts can be found in SAND2003-4474. In order to realize photonic encryption designs, technology developed for electrical logic circuits must be translated to the photonic regime. This paper examines S-SEED devices and how discrete logic elements can be interconnected and cascaded to form an optical circuit. Because there is no known software that can model these devices at a circuit level, the functionality of S-SEED devices in an optical circuit was modeled in PSpice. PSpice allows modeling of the macro characteristics of the devices in context of a logic element as opposed to device level computational modeling. By representing light intensity as voltage, 'black box' models are generated that accurately represent the intensity response and logic levels in both technologies. By modeling the behavior at the systems level, one can incorporate systems design tools and a simulation environment to aid in the overall functional design. Each black box model takes certain parameters (reflectance, intensity, input response), and models the optical ripple and time delay

  12. All-optical processes in double quantum dot structure.

    PubMed

    Rehman, Ektefaa; Al-Khursan, Amin H

    2016-09-10

    The ladder-plus-Y double quantum dot structure was modeled for all-optical processing by combining the density matrix theory with the pulse width description of the applied pulse. The momentum matrix elements are calculated including the wetting layer. The ladder-plus-Y structure exhibits pattern-free output with high bit rate (50 Tbps), which is critical in optical communication applications. It is shown that very high ground-state occupation with periodic shape for state occupations is critical in obtaining a pattern-free eye diagram.

  13. Protection method of all-optical mesh networks

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Zhang, Min; Liu, Junwei; Gu, Wanyi

    2001-10-01

    A protection scheme that chooses protection routes in advance in All-Optical Mesh network is proposed in this paper. Two rules, minimum relativity among routes and minimum the number of hops, are given and analyzed in detail. In order to perform protection quickly and correctly, the compromise between two principles must be considered when choosing protection routes. The protection method that appointing ring networks in mesh networks is proposed too. In addition, some key technologies such as avoiding oscillation, line protection and misconnect squelched are also proposed in this paper.

  14. Ultrafast all-optical technologies for bidirectional optical wireless communications.

    PubMed

    Jin, Xian; Hristovski, Blago A; Collier, Christopher M; Geoffroy-Gagnon, Simon; Born, Brandon; Holzman, Jonathan F

    2015-04-01

    In this Letter, a spherical retro-modulator architecture is introduced for operation as a bidirectional transceiver in passive optical wireless communication links. The architecture uses spherical retroreflection to enable retroreflection with broad directionality (2π steradians), and it uses all-optical beam interaction to enable modulation on ultrafast timescales (120 fs duration). The spherical retro-modulator is investigated from a theoretical standpoint and is fabricated for testing with three glasses, N-BK7, N-LASF9, and S-LAH79. It is found that the S-LAH79 structure provides the optimal refraction and nonlinearity for the desired retroreflection and modulation capabilities.

  15. All-optical processes in double quantum dot structure.

    PubMed

    Rehman, Ektefaa; Al-Khursan, Amin H

    2016-09-10

    The ladder-plus-Y double quantum dot structure was modeled for all-optical processing by combining the density matrix theory with the pulse width description of the applied pulse. The momentum matrix elements are calculated including the wetting layer. The ladder-plus-Y structure exhibits pattern-free output with high bit rate (50 Tbps), which is critical in optical communication applications. It is shown that very high ground-state occupation with periodic shape for state occupations is critical in obtaining a pattern-free eye diagram. PMID:27661371

  16. In-fiber all-optical fractional differentiator.

    PubMed

    Cuadrado-Laborde, C; Andrés, M V

    2009-03-15

    We demonstrate that an asymmetrical pi phase-shifted fiber Bragg grating operated in reflection can provide the required spectral response for implementing an all-optical fractional differentiator. There are different (but equivalent) ways to design it, e.g., by using different gratings lengths and keeping the same index modulation depth at both sides of the pi phase shift, or vice versa. Analytical expressions were found relating the fractional differentiator order with the grating parameters. The device shows a good accuracy calculating the fractional time derivatives of the complex field of an arbitrary input optical waveform. The introduced concept is supported by numerical simulations.

  17. All-optical processing in coherent nonlinear spectroscopy

    SciTech Connect

    Oron, Dan; Dudovich, Nirit; Silberberg, Yaron

    2004-08-01

    In spectroscopy, the fingerprint of a substance is usually comprised of a sequence of spectral lines with characteristic frequencies and strengths. Identification of substances often involves postprocessing, where the measured spectrum is compared with tabulated fingerprint spectra. Here we suggest a scheme for nonlinear spectroscopy, where, through coherent control of the nonlinear process, the information from the entire spectrum can be practically collected into a single coherent entity. We apply this for all-optical analysis of coherent Raman spectra and demonstrate enhanced detection and effective background suppression using coherent processing.

  18. All-optical cryptography of M-QAM formats by using two-dimensional spectrally sliced keys.

    PubMed

    Abbade, Marcelo L F; Cvijetic, Milorad; Messani, Carlos A; Alves, Cleiton J; Tenenbaum, Stefan

    2015-05-10

    There has been an increased interest in enhancing the security of optical communications systems and networks. All-optical cryptography methods have been considered as an alternative to electronic data encryption. In this paper we propose and verify the use of a novel all-optical scheme based on cryptographic keys applied on the spectral signal for encryption of the M-QAM modulated data with bit rates of up to 200 gigabits per second.

  19. All-optical cryptography of M-QAM formats by using two-dimensional spectrally sliced keys.

    PubMed

    Abbade, Marcelo L F; Cvijetic, Milorad; Messani, Carlos A; Alves, Cleiton J; Tenenbaum, Stefan

    2015-05-10

    There has been an increased interest in enhancing the security of optical communications systems and networks. All-optical cryptography methods have been considered as an alternative to electronic data encryption. In this paper we propose and verify the use of a novel all-optical scheme based on cryptographic keys applied on the spectral signal for encryption of the M-QAM modulated data with bit rates of up to 200 gigabits per second. PMID:25967489

  20. Rapidly reconfigurable all-optical universal logic gate

    DOEpatents

    Goddard, Lynford L.; Bond, Tiziana C.; Kallman, Jeffrey S.

    2010-09-07

    A new reconfigurable cascadable all-optical on-chip device is presented. The gate operates by combining the Vernier effect with a novel effect, the gain-index lever, to help shift the dominant lasing mode from a mode where the laser light is output at one facet to a mode where it is output at the other facet. Since the laser remains above threshold, the speed of the gate for logic operations as well as for reprogramming the function of the gate is primarily limited to the small signal optical modulation speed of the laser, which can be on the order of up to about tens of GHz. The gate can be rapidly and repeatedly reprogrammed to perform any of the basic digital logic operations by using an appropriate analog optical or electrical signal at the gate selection port. Other all-optical functionality includes wavelength conversion, signal duplication, threshold switching, analog to digital conversion, digital to analog conversion, signal routing, and environment sensing. Since each gate can perform different operations, the functionality of such a cascaded circuit grows exponentially.

  1. All-optical generation of surface plasmons in graphene

    NASA Astrophysics Data System (ADS)

    Constant, T. J.; Hornett, S. M.; Chang, D. E.; Hendry, E.

    2016-02-01

    Surface plasmons in graphene offer a compelling route to many useful photonic technologies. As a plasmonic material, graphene offers several intriguing properties, such as excellent electro-optic tunability, crystalline stability, large optical nonlinearities and extremely high electromagnetic field concentration. As such, recent demonstrations of surface plasmon excitation in graphene using near-field scattering of infrared light have received intense interest. Here we present an all-optical plasmon coupling scheme which takes advantage of the intrinsic nonlinear optical response of graphene. Free-space, visible light pulses are used to generate surface plasmons in a planar graphene sheet using difference frequency wave mixing to match both the wavevector and energy of the surface wave. By carefully controlling the phase matching conditions, we show that one can excite surface plasmons with a defined wavevector and direction across a large frequency range, with an estimated photon efficiency in our experiments approaching 10-5.

  2. Integrated all-optical infrared switchable plasmonic quantum cascade laser.

    PubMed

    Kohoutek, John; Bonakdar, Alireza; Gelfand, Ryan; Dey, Dibyendu; Nia, Iman Hassani; Fathipour, Vala; Memis, Omer Gokalp; Mohseni, Hooman

    2012-05-01

    We report a type of infrared switchable plasmonic quantum cascade laser, in which far field light in the midwave infrared (MWIR, 6.1 μm) is modulated by a near field interaction of light in the telecommunications wavelength (1.55 μm). To achieve this all-optical switch, we used cross-polarized bowtie antennas and a centrally located germanium nanoslab. The bowtie antenna squeezes the short wavelength light into the gap region, where the germanium is placed. The perturbation of refractive index of the germanium due to the free carrier absorption produced by short wavelength light changes the optical response of the antenna and the entire laser intensity at 6.1 μm significantly. This device shows a viable method to modulate the far field of a laser through a near field interaction.

  3. All-Optical Implementation of the Ant Colony Optimization Algorithm.

    PubMed

    Hu, Wenchao; Wu, Kan; Shum, Perry Ping; Zheludev, Nikolay I; Soci, Cesare

    2016-01-01

    We report all-optical implementation of the optimization algorithm for the famous "ant colony" problem. Ant colonies progressively optimize pathway to food discovered by one of the ants through identifying the discovered route with volatile chemicals (pheromones) secreted on the way back from the food deposit. Mathematically this is an important example of graph optimization problem with dynamically changing parameters. Using an optical network with nonlinear waveguides to represent the graph and a feedback loop, we experimentally show that photons traveling through the network behave like ants that dynamically modify the environment to find the shortest pathway to any chosen point in the graph. This proof-of-principle demonstration illustrates how transient nonlinearity in the optical system can be exploited to tackle complex optimization problems directly, on the hardware level, which may be used for self-routing of optical signals in transparent communication networks and energy flow in photonic systems. PMID:27222098

  4. All-Optical Implementation of the Ant Colony Optimization Algorithm

    PubMed Central

    Hu, Wenchao; Wu, Kan; Shum, Perry Ping; Zheludev, Nikolay I.; Soci, Cesare

    2016-01-01

    We report all-optical implementation of the optimization algorithm for the famous “ant colony” problem. Ant colonies progressively optimize pathway to food discovered by one of the ants through identifying the discovered route with volatile chemicals (pheromones) secreted on the way back from the food deposit. Mathematically this is an important example of graph optimization problem with dynamically changing parameters. Using an optical network with nonlinear waveguides to represent the graph and a feedback loop, we experimentally show that photons traveling through the network behave like ants that dynamically modify the environment to find the shortest pathway to any chosen point in the graph. This proof-of-principle demonstration illustrates how transient nonlinearity in the optical system can be exploited to tackle complex optimization problems directly, on the hardware level, which may be used for self-routing of optical signals in transparent communication networks and energy flow in photonic systems. PMID:27222098

  5. All-Optical Implementation of the Ant Colony Optimization Algorithm

    NASA Astrophysics Data System (ADS)

    Hu, Wenchao; Wu, Kan; Shum, Perry Ping; Zheludev, Nikolay I.; Soci, Cesare

    2016-05-01

    We report all-optical implementation of the optimization algorithm for the famous “ant colony” problem. Ant colonies progressively optimize pathway to food discovered by one of the ants through identifying the discovered route with volatile chemicals (pheromones) secreted on the way back from the food deposit. Mathematically this is an important example of graph optimization problem with dynamically changing parameters. Using an optical network with nonlinear waveguides to represent the graph and a feedback loop, we experimentally show that photons traveling through the network behave like ants that dynamically modify the environment to find the shortest pathway to any chosen point in the graph. This proof-of-principle demonstration illustrates how transient nonlinearity in the optical system can be exploited to tackle complex optimization problems directly, on the hardware level, which may be used for self-routing of optical signals in transparent communication networks and energy flow in photonic systems.

  6. An all-optical vector atomic magnetometer for fundamental physics applications

    NASA Astrophysics Data System (ADS)

    Wurm, David; Mateos, Ignacio; Zhivun, Elena; Patton, Brian; Fierlinger, Peter; Beck, Douglas; Budker, Dmitry

    2014-05-01

    We have developed a laboratory prototype of a compact all-optical vector magnetometer. Due to their high precision and absolute accuracy, atomic magnetometers are crucial sensors in fundamental physics experiments which require extremely stable magnetic fields (e.g., neutron EDM searches). This all-optical sensor will allow high-resolution measurements of the magnitude and direction of a magnetic field without perturbing the magnetic environment. Moreover, its absolute accuracy makes it calibration-free, an advantage in space applications (e.g., space-based gravitational-wave detection). Magnetometry in precision experiments or space applications also demands long-term stability and well-understood noise characteristics at frequencies below 10-4 Hz. We have characterized the low-frequency noise floor of this sensor and will discuss methods to improve its long-time performance.

  7. 20Gbit/s all-optical logic OR in terahertz optical asymmetric demultiplexer (TOAD)

    NASA Astrophysics Data System (ADS)

    Yan, Yumei; Wu, Jian; Lin, Jintong

    2005-01-01

    A scheme for all-optical logic OR based on transparent teraherz optical asymmetric demultiplexer (transparent-TOAD) is proposed in this paper. In the transparent-TOAD, the SOA is biased at transparency and the gain recovery time determined by the intraband effect has the value of only a few picoseconds. Numerical analysis shows that the switching window of the transparent-TOAD is only about 0.54ps and the potential for ultrahigh speed all-optical logic processing is shown. Numerical demonstration is performed for 4-bit and 16-bit logic OR at 20Gbit/s. The results coincide with the OR truth table, showing high extinction ratio and no pattern dependency. Detailed analysis is carried out on the performance of the logic OR scheme.

  8. Study of all-optical sampling using a semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Wu, Chen; Wang, Yongjun; Wang, Lina; Wang, Fu

    2016-08-01

    All-optical sampling is an important research content of all-optical signal processing. In recent years, the application of the semiconductor optical amplifier (SOA) in optical sampling has attracted lots of attention because of its small volume and large nonlinear coefficient. We propose an optical sampling model based on nonlinear polarization rotation effect of the SOA. The proposed scheme has the advantages of high sampling speed and small input pump power, and a transfer curve with good linearity was obtained through simulation. To evaluate the performance of sampling, we analyze the linearity and efficiency of sampling pulse considering the impact of pulse width and analog signal frequency. We achieve the sampling of analog signal to high frequency pulse and exchange the positions of probe light and pump light to study another sampling.

  9. Model for multishot all-thermal all-optical switching in ferromagnets

    NASA Astrophysics Data System (ADS)

    Gorchon, J.; Yang, Y.; Bokor, J.

    2016-07-01

    All-optical magnetic switching (AOS) is a recently observed rich and puzzling phenomenon that offers promising technological applications. However, a fundamental understanding of the underlying mechanisms remains elusive. Here we present a model for multishot helicity-dependent AOS in ferromagnetic materials based on a purely heat-driven mechanism in the presence of magnetic circular dichroism (MCD). We predict that AOS should be possible with as little as 0.5% of MCD, after a minimum number of laser shots heat the sample close to the Curie temperature. Finally, we qualitatively reproduce the all-optically switched domain patterns observed experimentally by numerically simulating the result of multiple laser shots on an FePtC granular ferromagnetic film.

  10. Software Defined Networking (SDN) controlled all optical switching networks with multi-dimensional switching architecture

    NASA Astrophysics Data System (ADS)

    Zhao, Yongli; Ji, Yuefeng; Zhang, Jie; Li, Hui; Xiong, Qianjin; Qiu, Shaofeng

    2014-08-01

    Ultrahigh throughout capacity requirement is challenging the current optical switching nodes with the fast development of data center networks. Pbit/s level all optical switching networks need to be deployed soon, which will cause the high complexity of node architecture. How to control the future network and node equipment together will become a new problem. An enhanced Software Defined Networking (eSDN) control architecture is proposed in the paper, which consists of Provider NOX (P-NOX) and Node NOX (N-NOX). With the cooperation of P-NOX and N-NOX, the flexible control of the entire network can be achieved. All optical switching network testbed has been experimentally demonstrated with efficient control of enhanced Software Defined Networking (eSDN). Pbit/s level all optical switching nodes in the testbed are implemented based on multi-dimensional switching architecture, i.e. multi-level and multi-planar. Due to the space and cost limitation, each optical switching node is only equipped with four input line boxes and four output line boxes respectively. Experimental results are given to verify the performance of our proposed control and switching architecture.

  11. All-optical tuning of a magnetic-fluid-filled optofluidic ring resonator.

    PubMed

    Liu, Yang; Shi, Lei; Xu, Xinbiao; Zhao, Ping; Wang, Zheqi; Pu, Shengli; Zhang, Xinliang

    2014-08-21

    An all-optical tunable optofluidic ring resonator (OFRR) is proposed and experimentally demonstrated. The all-optical control of a silica microresonator is highly attractive, but it is difficult to realize because of the relatively weak Kerr effect and the absence of a plasma dispersion effect of silica. Here, we infuse a silica microcapillary-based optofluidic ring resonator with a magnetic fluid, into which pump light is injected by a fiber taper. Iron oxide nanoparticles dispersed in the magnetic fluid produce a strong pump light absorption, and this leads to a resonance shift of the silica microresonator due to the photothermal effect. To the best of our knowledge, this is the first scheme for all-optical tuning of an OFRR. A tuning sensitivity of up to 0.15 nm mW(-1) and a tuning range of 3.3 nm are achieved. With such excellent performance, the magnetic-fluid-filled OFRR has great potential in filtering, sensing, and signal processing applications. PMID:24941312

  12. Flexible all-optical frequency allocation of OFDM subcarriers.

    PubMed

    Lowery, Arthur James; Schröder, Jochen; Du, Liang B

    2014-01-13

    We investigate the underlying mechanism that allows OFDM subcarriers in an all-optical OFDM system to be assigned to any optical frequency using an optical filter, even if that frequency is not generated by the comb-line source feeding the filters. We confirm our analysis using simulations, and present experimental results from a 252-subcarrier system that uses a mode-locked laser (MLL) as the comb source and a wavelength selective switch. The experimental results show that there is no correlation between the programmed frequency offset between a subcarrier and nearest comb line, and the received signal quality. Thus, subcarriers could be inserted into unused portions of an optical transmission system's spectrum without restriction on their particular center frequencies. Any percentage of cyclic prefix can be added to the OFDM symbol simply by reprogramming the optical filter to give wider subcarrier frequency spacing than the comb line spacing, which is useful for tailoring the CP to the dispersion of various optical transmission paths, to maximize the spectral efficiency. Finally, the MLL's center frequency need not be locked to a system reference. PMID:24515064

  13. Spectral amplitude and phase measurement of ultrafast pulses using all-optical differential tomography.

    PubMed

    Londero, Pablo; Kuzucu, Onur; Gaeta, Alexander L

    2011-05-01

    We demonstrate a simple, all-optical, fiber-based method for characterizing the spectral amplitude and phase of ultrafast pulses using a differential tomographic measurement realized via four-wave mixing. The technique is applied to subpicosecond pulses in the C-band of the telecommunication spectrum. Characterization of amplified pulses and propagation through dispersive media is demonstrated and compared with autocorrelation measurements and calculated predictions. We show how our approach can be extended to larger bandwidths in similar systems, extending tomographic reconstruction of coherent fields to nearly an octave of bandwidth while maintaining a robust, waveguide-based geometry.

  14. Spectral amplitude and phase measurement of ultrafast pulses using all-optical differential tomography.

    PubMed

    Londero, Pablo; Kuzucu, Onur; Gaeta, Alexander L

    2011-05-01

    We demonstrate a simple, all-optical, fiber-based method for characterizing the spectral amplitude and phase of ultrafast pulses using a differential tomographic measurement realized via four-wave mixing. The technique is applied to subpicosecond pulses in the C-band of the telecommunication spectrum. Characterization of amplified pulses and propagation through dispersive media is demonstrated and compared with autocorrelation measurements and calculated predictions. We show how our approach can be extended to larger bandwidths in similar systems, extending tomographic reconstruction of coherent fields to nearly an octave of bandwidth while maintaining a robust, waveguide-based geometry. PMID:21540969

  15. Tangled nonlinear driven chain reactions of all optical singularities

    NASA Astrophysics Data System (ADS)

    Vasil'ev, V. I.; Soskin, M. S.

    2012-03-01

    Dynamics of polarization optical singularities chain reactions in generic elliptically polarized speckle fields created in photorefractive crystal LiNbO3 was investigated in details Induced speckle field develops in the tens of minutes scale due to photorefractive 'optical damage effect' induced by incident beam of He-Ne laser. It was shown that polarization singularities develop through topological chain reactions of developing speckle fields driven by photorefractive nonlinearities induced by incident laser beam. All optical singularities (C points, optical vortices, optical diabolos,) are defined by instantaneous topological structure of the output wavefront and are tangled by singular optics lows. Therefore, they have develop in tangled way by six topological chain reactions driven by nonlinear processes in used nonlinear medium (photorefractive LiNbO3:Fe in our case): C-points and optical diabolos for right (left) polarized components domains with orthogonally left (right) polarized optical vortices underlying them. All elements of chain reactions consist from loop and chain links when nucleated singularities annihilated directly or with alien singularities in 1:9 ratio. The topological reason of statistics was established by low probability of far enough separation of born singularities pair from existing neighbor singularities during loop trajectories. Topology of developing speckle field was measured and analyzed by dynamic stokes polarimetry with few seconds' resolution. The hierarchy of singularities govern scenario of tangled chain reactions was defined. The useful space-time data about peculiarities of optical damage evolution were obtained from existence and parameters of 'islands of stability' in developing speckle fields.

  16. All-Optical Ultrasound Transducers for High Resolution Imaging

    NASA Astrophysics Data System (ADS)

    Sheaff, Clay Smith

    High frequency ultrasound (HFUS) has increasingly been used within the past few decades to provide high resolution (< 200 mum) imaging in medical applications such as endoluminal imaging, intravascular imaging, ophthalmology, and dermatology. The optical detection and generation of HFUS using thin films offers numerous advantages over traditional piezoelectric technology. Circumvention of an electronic interface with the device head is one of the most significant given the RF noise, crosstalk, and reduced capacitance that encumbers small-scale electronic transducers. Thin film Fabry-Perot interferometers - also known as etalons - are well suited for HFUS receivers on account of their high sensitivity, wide bandwidth, and ease of fabrication. In addition, thin films can be used to generate HFUS when irradiated with optical pulses - a method referred to as Thermoelastic Ultrasound Generation (TUG). By integrating a polyimide (PI) film for TUG into an etalon receiver, we have created for the first time an all-optical ultrasound transducer that is both thermally stable and capable of forming fully sampled 2-D imaging arrays of arbitrary configuration. Here we report (1) the design and fabrication of PI-etalon transducers; (2) an evaluation of their optical and acoustic performance parameters; (3) the ability to conduct high-resolution imaging with synthetic 2-D arrays of PI-etalon elements; and (4) work towards a fiber optic PI-etalon for in vivo use. Successful development of a fiber optic imager would provide a unique field-of-view thereby exposing an abundance of prospects for minimally-invasive analysis, diagnosis, and treatment of disease.

  17. Nonlinear silicon-on-insulator waveguides for all-optical signal processing

    NASA Astrophysics Data System (ADS)

    Koos, C.; Jacome, L.; Poulton, C.; Leuthold, J.; Freude, W.

    2007-05-01

    Values up to γ=7×106/(Wkm) for the nonlinear parameter are feasible if silicon-on-insulator based strip and slot waveguides are properly designed. This is more than three orders of magnitude larger than for state-of-the-art highly nonlinear fibers, and it enables ultrafast all-optical signal processing with nonresonant compact devices. At λ=1.55μm we provide universal design curves for strip and slot waveguides which are covered with different linear and nonlinear materials, and we calculate the resulting maximum γ.

  18. Three-photon-absorption resonance for all-optical atomic clocks

    SciTech Connect

    Zibrov, Sergei; Novikova, Irina; Phillips, David F.; Taichenachev, Aleksei V.; Yudin, Valeriy I.; Walsworth, Ronald L.; Zibrov, Alexander S.

    2005-07-15

    We report an experimental study of an all-optical three-photon-absorption resonance (known as an 'N resonance') and discuss its potential application as an alternative to atomic clocks based on coherent population trapping. We present measurements of the N-resonance contrast, width and light shift for the D{sub 1} line of {sup 87}Rb with varying buffer gases, and find good agreement with an analytical model of this resonance. The results suggest that N resonances are promising for atomic clock applications.

  19. Design of polarization encoded all-optical 4-valued MAX logic gate and its applications

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay; Nath Roy, Jitendra

    2013-07-01

    Quaternary maximum (QMAX) gate is one type of multi-valued logic gate. An all-optical scheme of polarization encoded quaternary (4-valued) MAX logic gate with the help of Terahertz Optical Asymmetric Demultiplexer (TOAD) based fiber interferometric switch is proposed and described. For the quaternary information processing in optics, the quaternary number (0, 1, 2, 3) can be represented by four discrete polarized states of light. Numerical simulation result confirming the described methods is given in this paper. Some applications of MAX gate in logical operation and memory device are also given.

  20. All-optical repetition rate multiplication of pseudorandom bit sequences by employing power coupler and equalizer

    NASA Astrophysics Data System (ADS)

    Sun, Zhenchao; Wang, Zhi; Wu, Chongqing; Wang, Fu; Li, Qiang

    2015-10-01

    A scheme for all-optical repetition rate multiplication of pseudorandom bit sequences (PRBS) is demonstrated with a precision delay feedback loop cascaded with a terahertz optical asymmetric demultiplexer (TOAD)-based power equalizer. Its feasibility has been verified by experiments, which show a multiplication for PRBS at cycle 2^7-1 from 2.5 to 10 Gb/s. This scheme can be employed for the rate multiplication of a much longer cycle PRBS at a much higher bit rate over 40 Gb/s if the time-delay, the loss, and the dispersion of an optical delay line are all precisely managed.

  1. Burst switching without guard interval in all-optical software-define star intra-data center network

    NASA Astrophysics Data System (ADS)

    Ji, Philip N.; Wang, Ting

    2014-02-01

    Optical switching has been introduced in intra-data center networks (DCNs) to increase capacity and to reduce power consumption. Recently we proposed a star MIMO OFDM-based all-optical DCN with burst switching and software-defined networking. Here, we introduce the control procedure for the star DCN in detail for the first time. The timing, signaling, and operation are described for each step to achieve efficient bandwidth resource utilization. Furthermore, the guidelines for the burst assembling period selection that allows burst switching without guard interval are discussed. The star all-optical DCN offers flexible and efficient control for next-generation data center application.

  2. All-optical AND gate with improved extinction ratio using signal induced nonlinearities in a bulk semiconductor optical amplifier.

    PubMed

    Guo, L Q; Connelly, M J

    2006-04-01

    An all-optical AND gate based on optically induced nonlinear polarization rotation of a probe light in a bulk semiconductor optical amplifier is realized at a bit rate of 2.5Gbit/s. By operating the AND gate in an up and inverted wavelength conversion scheme, the extinction ratio is improved by 8dB compared with previously published work.

  3. High Speed All Optical Nyquist Signal Generation and Full-band Coherent Detection

    PubMed Central

    Zhang, Junwen; Yu, Jianjun; Fang, Yuan; Chi, Nan

    2014-01-01

    Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation formats is challenging. Electrical Nyquist pulse generation is restricted by the limited sampling rate and processor capacities of digital-to-analog convertor devices, while the optical Nyquist signals can provide a much higher symbol rate using time domain multiplexing method. However, most optical Nyquist signals are based on direct detection with simple modulation formats. Here we report the first experimental demonstration of high speed all optical Nyquist signal generation based on Sinc-shaped pulse generation and time-division multiplexing with high level modulation format and full-band coherent detection. Our experiments demonstrate a highly flexible and compatible all optical high speed Nyquist signal generation and detection scheme for future fiber communication systems. PMID:25142269

  4. Engineered materials for all-optical helicity-dependent magnetic switching.

    PubMed

    Mangin, S; Gottwald, M; Lambert, C-H; Steil, D; Uhlíř, V; Pang, L; Hehn, M; Alebrand, S; Cinchetti, M; Malinowski, G; Fainman, Y; Aeschlimann, M; Fullerton, E E

    2014-03-01

    The possibility of manipulating magnetic systems without applied magnetic fields have attracted growing attention over the past fifteen years. The low-power manipulation of the magnetization, preferably at ultrashort timescales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. Here we explore the optical manipulation of the magnetization in engineered magnetic materials. We demonstrate that all-optical helicity-dependent switching (AO-HDS) can be observed not only in selected rare earth-transition metal (RE-TM) alloy films but also in a much broader variety of materials, including RE-TM alloys, multilayers and heterostructures. We further show that RE-free Co-Ir-based synthetic ferrimagnetic heterostructures designed to mimic the magnetic properties of RE-TM alloys also exhibit AO-HDS. These results challenge present theories of AO-HDS and provide a pathway to engineering materials for future applications based on all-optical control of magnetic order.

  5. High speed all optical Nyquist signal generation and full-band coherent detection.

    PubMed

    Zhang, Junwen; Yu, Jianjun; Fang, Yuan; Chi, Nan

    2014-08-21

    Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation formats is challenging. Electrical Nyquist pulse generation is restricted by the limited sampling rate and processor capacities of digital-to-analog convertor devices, while the optical Nyquist signals can provide a much higher symbol rate using time domain multiplexing method. However, most optical Nyquist signals are based on direct detection with simple modulation formats. Here we report the first experimental demonstration of high speed all optical Nyquist signal generation based on Sinc-shaped pulse generation and time-division multiplexing with high level modulation format and full-band coherent detection. Our experiments demonstrate a highly flexible and compatible all optical high speed Nyquist signal generation and detection scheme for future fiber communication systems.

  6. All-optical electrophysiology in mammalian neurons using engineered microbial rhodopsins.

    PubMed

    Hochbaum, Daniel R; Zhao, Yongxin; Farhi, Samouil L; Klapoetke, Nathan; Werley, Christopher A; Kapoor, Vikrant; Zou, Peng; Kralj, Joel M; Maclaurin, Dougal; Smedemark-Margulies, Niklas; Saulnier, Jessica L; Boulting, Gabriella L; Straub, Christoph; Cho, Yong Ku; Melkonian, Michael; Wong, Gane Ka-Shu; Harrison, D Jed; Murthy, Venkatesh N; Sabatini, Bernardo L; Boyden, Edward S; Campbell, Robert E; Cohen, Adam E

    2014-08-01

    All-optical electrophysiology-spatially resolved simultaneous optical perturbation and measurement of membrane voltage-would open new vistas in neuroscience research. We evolved two archaerhodopsin-based voltage indicators, QuasAr1 and QuasAr2, which show improved brightness and voltage sensitivity, have microsecond response times and produce no photocurrent. We engineered a channelrhodopsin actuator, CheRiff, which shows high light sensitivity and rapid kinetics and is spectrally orthogonal to the QuasArs. A coexpression vector, Optopatch, enabled cross-talk-free genetically targeted all-optical electrophysiology. In cultured rat neurons, we combined Optopatch with patterned optical excitation to probe back-propagating action potentials (APs) in dendritic spines, synaptic transmission, subcellular microsecond-timescale details of AP propagation, and simultaneous firing of many neurons in a network. Optopatch measurements revealed homeostatic tuning of intrinsic excitability in human stem cell-derived neurons. In rat brain slices, Optopatch induced and reported APs and subthreshold events with high signal-to-noise ratios. The Optopatch platform enables high-throughput, spatially resolved electrophysiology without the use of conventional electrodes.

  7. Ultrasmall all-optical plasmonic switch and its application to superresolution imaging

    NASA Astrophysics Data System (ADS)

    Wu, Hsueh-Yu; Huang, Yen-Ta; Shen, Po-Ting; Lee, Hsuan; Oketani, Ryosuke; Yonemaru, Yasuo; Yamanaka, Masahito; Shoji, Satoru; Lin, Kung-Hsuan; Chang, Chih-Wei; Kawata, Satoshi; Fujita, Katsumasa; Chu, Shi-Wei

    2016-04-01

    Because of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.001 μm3, can be optically switched off with less than 100 μW power. Over 80% modulation depth is observed, and shows no degradation after repetitive switching. The spectral bandwidth approaches 100 nm. The underlying mechanism is suggested to be photothermal effects, and the effective single-particle nonlinearity reaches nearly 10‑9 m2/W, which is to our knowledge the largest record of metallic materials to date. As a novel application, the non-bleaching and unlimitedly switchable scattering is used to enhance optical resolution to λ/5 (λ/9 after deconvolution), with 100-fold less intensity requirement compared to similar superresolution techniques. Our work not only opens up a new field of ultrasmall all-optical control based on scattering from a single nanoparticle, but also facilitates superresolution imaging for long-term observation.

  8. All-optical electrophysiology in mammalian neurons using engineered microbial rhodopsins

    PubMed Central

    Hochbaum, Daniel R.; Zhao, Yongxin; Farhi, Samouil L.; Klapoetke, Nathan; Werley, Christopher A.; Kapoor, Vikrant; Zou, Peng; Kralj, Joel M.; Maclaurin, Dougal; Smedemark-Margulies, Niklas; Saulnier, Jessica L.; Boulting, Gabriella L.; Straub, Christoph; Cho, Yong Ku; Melkonian, Michael; Wong, Gane Ka-Shu; Harrison, D. Jed; Murthy, Venkatesh N.; Sabatini, Bernardo; Boyden, Edward S.; Campbell, Robert E.; Cohen, Adam E.

    2014-01-01

    All-optical electrophysiology—spatially resolved simultaneous optical perturbation and measurement of membrane voltage—would open new vistas in neuroscience research. We evolved two archaerhodopsin-based voltage indicators, QuasAr1 and 2, which show improved brightness and voltage sensitivity, microsecond response times, and produce no photocurrent. We engineered a novel channelrhodopsin actuator, CheRiff, which shows improved light sensitivity and kinetics, and spectral orthogonality to the QuasArs. A co-expression vector, Optopatch, enabled crosstalk-free genetically targeted all-optical electrophysiology. In cultured neurons, we combined Optopatch with patterned optical excitation to probe back-propagating action potentials in dendritic spines, synaptic transmission, sub-cellular microsecond-timescale details of action potential propagation, and simultaneous firing of many neurons in a network. Optopatch measurements revealed homeostatic tuning of intrinsic excitability in human stem cell-derived neurons. In brain slice, Optopatch induced and reported action potentials and subthreshold events, with high signal-to-noise ratios. The Optopatch platform enables high-throughput, spatially resolved electrophysiology without use of conventional electrodes. PMID:24952910

  9. Ultrasmall all-optical plasmonic switch and its application to superresolution imaging

    PubMed Central

    Wu, Hsueh-Yu; Huang, Yen-Ta; Shen, Po-Ting; Lee, Hsuan; Oketani, Ryosuke; Yonemaru, Yasuo; Yamanaka, Masahito; Shoji, Satoru; Lin, Kung-Hsuan; Chang, Chih-Wei; Kawata, Satoshi; Fujita, Katsumasa; Chu, Shi-Wei

    2016-01-01

    Because of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.001 μm3, can be optically switched off with less than 100 μW power. Over 80% modulation depth is observed, and shows no degradation after repetitive switching. The spectral bandwidth approaches 100 nm. The underlying mechanism is suggested to be photothermal effects, and the effective single-particle nonlinearity reaches nearly 10−9 m2/W, which is to our knowledge the largest record of metallic materials to date. As a novel application, the non-bleaching and unlimitedly switchable scattering is used to enhance optical resolution to λ/5 (λ/9 after deconvolution), with 100-fold less intensity requirement compared to similar superresolution techniques. Our work not only opens up a new field of ultrasmall all-optical control based on scattering from a single nanoparticle, but also facilitates superresolution imaging for long-term observation. PMID:27063920

  10. All-Optical Formation of Coherent Dark States of Silicon-Vacancy Spins in Diamond

    NASA Astrophysics Data System (ADS)

    Pingault, Benjamin; Becker, Jonas N.; Schulte, Carsten H. H.; Arend, Carsten; Hepp, Christian; Godde, Tillmann; Tartakovskii, Alexander I.; Markham, Matthew; Becher, Christoph; Atatüre, Mete

    2014-12-01

    Spin impurities in diamond can be versatile tools for a wide range of solid-state-based quantum technologies, but finding spin impurities that offer sufficient quality in both photonic and spin properties remains a challenge for this pursuit. The silicon-vacancy center has recently attracted much interest because of its spin-accessible optical transitions and the quality of its optical spectrum. Complementing these properties, spin coherence is essential for the suitability of this center as a spin-photon quantum interface. Here, we report all-optical generation of coherent superpositions of spin states in the ground state of a negatively charged silicon-vacancy center using coherent population trapping. Our measurements reveal a characteristic spin coherence time, T2* , exceeding 45 nanoseconds at 4 K. We further investigate the role of phonon-mediated coupling between orbital states as a source of irreversible decoherence. Our results indicate the feasibility of all-optical coherent control of silicon-vacancy spins using ultrafast laser pulses.

  11. All-optical swapping of spectral amplitude code labels for packet-switched networks

    NASA Astrophysics Data System (ADS)

    Chen, Lawrence R.

    2008-08-01

    Packet-switched networks have attracted considerable attention as a basis for next-generation optical networks due to their advantages in terms of flexibility and network efficiency over traditional circuit-switched networks. Optical code multi-protocol label switching (OC-MPLS) promises fast, flexible, power-efficient switching by keeping signals in the optical domain and avoiding costly conversions to the electrical domain. In this paper, we review the use of spectral amplitude codes (SACs) for implementing OC-MPLS labels. We discuss the principles and features, as well as key enabling technologies required for their processing. In particular, we compare three different approaches for low cost all-optical swapping of SAC labels. All approaches are based on semiconductor fiber lasers and exploit nonlinearity in a semiconductor device: the first uses cross-absorption modulation in an electroabsorption modulator, the second uses cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA), and the third makes use of XGM in an SOA as well as injection locking in a Fabry-Pérot laser. We present the static and dynamic responses of each for swapping a multi-wavelength input label to a multi-wavelength output label. The benefits and limitations of each approach as well as future improvements are discussed. We also present the results of systems experiments which demonstrate error-free all-optical label swapping, recognition, and switching of multi-rate packets in packet-switched networks using multi-wavelength labels.

  12. All-optical switching of magnetoresistive devices using telecom-band femtosecond laser

    SciTech Connect

    He, Li; Chen, Jun-Yang; Wang, Jian-Ping E-mail: moli@umn.edu; Li, Mo E-mail: moli@umn.edu

    2015-09-07

    Ultrafast all-optical switching of the magnetization of various magnetic systems is an intriguing phenomenon that can have tremendous impact on information storage and processing. Here, we demonstrate all-optical switching of GdFeCo alloy films using a telecom-band femtosecond fiber laser. We further fabricate Hall cross devices and electrically readout all-optical switching by measuring anomalous Hall voltage changes. The use of a telecom laser and the demonstrated all-optical switching of magnetoresistive devices represent the first step toward integration of opto-magnetic devices with mainstream photonic devices to enable novel optical and spintronic functionalities.

  13. Coherent all-optical control of ultracold atoms arrays in permanent magnetic traps.

    PubMed

    Abdelrahman, Ahmed; Mukai, Tetsuya; Häffner, Hartmut; Byrnes, Tim

    2014-02-10

    We propose a hybrid architecture for quantum information processing based on magnetically trapped ultracold atoms coupled via optical fields. The ultracold atoms, which can be either Bose-Einstein condensates or ensembles, are trapped in permanent magnetic traps and are placed in microcavities, connected by silica based waveguides on an atom chip structure. At each trapping center, the ultracold atoms form spin coherent states, serving as a quantum memory. An all-optical scheme is used to initialize, measure and perform a universal set of quantum gates on the single and two spin-coherent states where entanglement can be generated addressably between spatially separated trapped ultracold atoms. This allows for universal quantum operations on the spin coherent state quantum memories. We give detailed derivations of the composite cavity system mediated by a silica waveguide as well as the control scheme. Estimates for the necessary experimental conditions for a working hybrid device are given. PMID:24663640

  14. Multiport InP monolithically integrated all-optical wavelength router.

    PubMed

    Zheng, Xiu; Raz, Oded; Calabretta, Nicola; Zhao, Dan; Lu, Rongguo; Liu, Yong

    2016-08-15

    An indium phosphide-based monolithically integrated wavelength router is demonstrated in this Letter. The wavelength router has four input ports and four output ports, which integrate four wavelength converters and a 4×4 arrayed-waveguide grating router. Each wavelength converter is achieved based on cross-gain modulation and cross-phase modulation effects in a semiconductor optical amplifier. Error-free wavelength switching for a non-return-to-zero 231-1 ps eudorandom binary sequence at 40 Gb/s data rate is performed. Both 1×4 and 3×1 all-optical routing functions of this chip are demonstrated for the first time with power penalties as low as 3.2 dB. PMID:27519116

  15. All-optical measurement of elastic constants in nematic liquid crystals.

    PubMed

    Klus, Bartłomiej; Laudyn, Urszula A; Karpierz, Mirosław A; Sahraoui, Bouchta

    2014-12-01

    In this article we present a new all-optical method to measure elastic constants connected with twist and bend deformations. The method is based on the optical Freedericksz threshold effect induced by the linearly polarized electro-magnetic wave. In the experiment elastic constants are measured of commonly used liquid crystals 6CHBT and E7 and two new nematic mixtures with low birefringence. The proposed method is neither very sensitive on the variation of cell thickness, beam waist or the power of a light beam nor does it need any special design of a liquid crystal cell. The experimental results are in good agreement with the values obtain by other methods based on an electro-optical effect. PMID:25606956

  16. Performance analysis of an all-optical OFDM system in presence of non-linear phase noise.

    PubMed

    Hmood, Jassim K; Harun, Sulaiman W; Emami, Siamak D; Khodaei, Amin; Noordin, Kamarul A; Ahmad, Harith; Shalaby, Hossam M H

    2015-02-23

    The potential for higher spectral efficiency has increased the interest in all-optical orthogonal frequency division multiplexing (OFDM) systems. However, the sensitivity of all-optical OFDM to fiber non-linearity, which causes nonlinear phase noise, is still a major concern. In this paper, an analytical model for estimating the phase noise due to self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM) in an all-optical OFDM system is presented. The phase noise versus power, distance, and number of subcarriers is evaluated by implementing the mathematical model using Matlab. In order to verify the results, an all-optical OFDM system, that uses coupler-based inverse fast Fourier transform/fast Fourier transform without any nonlinear compensation, is demonstrated by numerical simulation. The system employs 29 subcarriers; each subcarrier is modulated by a 4-QAM or 16-QAM format with a symbol rate of 25 Gsymbol/s. The results indicate that the phase variance due to FWM is dominant over those induced by either SPM or XPM. It is also shown that the minimum phase noise occurs at -3 dBm and -1 dBm for 4-QAM and 16-QAM, respectively. Finally, the error vector magnitude (EVM) versus subcarrier power and symbol rate is quantified using both simulation and the analytical model. It turns out that both EVM results are in good agreement with each other.

  17. A streptavidin-SOG chimera for all-optical immunoassays.

    PubMed

    Wurtzler, Elizabeth M; Wendell, David

    2014-01-13

    Immunological detection has been developed into a sensitive and versatile technique and is based on two requisite elements: targeting antibodies and an indicator, usually in the form of horseradish peroxidase or alkaline phosphatase. The specificity and turnover rate of these enzymes provide an efficient means of signal amplification, but both require a stopping agent to prevent overdevelopment, which limits scalability to mechanized fluidic systems. As an alternative, we present a fully optical detection system based on a streptavidin-singlet oxygen generating chimeric protein that produces singlet oxygen from blue light. When used with trans-1-(2'-methoxyvinyl)pyrene, the photosynthetic streptavidin combines indicator development and reporting in sufficiently distinct visible wavelengths while retaining the sensitivity and scale of enzymatic systems that use horseradish peroxidase. By combining photosensitive development and detection into one system, we can enable future, highly parallel immunological testing to be controlled with the spatial and temporal precision of light.

  18. Demonstration and characterisation of a non-inverting all-optical read/write regenerative memory

    NASA Astrophysics Data System (ADS)

    Johnson, N. C.; Harrison, J. A.; Blow, K. J.

    2008-09-01

    An all-optical regenerative memory device using a single loop mirror and a semiconductor optical amplifier is experimentally demonstrated. This configuration has potential for a low power all-optical stable memory device with non-inverting characteristics where packets are stored by continuously injecting the regenerated data back into the loop.

  19. All-optical reconstruction of atomic ground-state population

    NASA Astrophysics Data System (ADS)

    London, P.; Firstenberg, O.; Shuker, M.; Ron, A.

    2010-04-01

    The population distribution within the ground state of an atomic ensemble is of great significance in a variety of quantum-optics processes. We present a method to reconstruct the detailed population distribution from a set of absorption measurements with various frequencies and polarizations, by utilizing the differences between the dipole matrix elements of the probed transitions. The technique is experimentally implemented on a thermal rubidium vapor, demonstrating a population-based analysis in two optical-pumping examples. The results are used to verify and calibrate an elaborated numerical model, and the limitations of the reconstruction scheme, which result from the symmetry properties of the dipole matrix elements, are discussed.

  20. All-optical slow-light on a photonic chip.

    PubMed

    Okawachi, Yoshitomo; Foster, Mark; Sharping, Jay; Gaeta, Alexander; Xu, Qianfan; Lipson, Michal

    2006-03-20

    We demonstrate optically tunable delays in a silicon-on-insulator planar waveguide based on slow light induced by stimulated Raman scattering (SRS). Inside an 8-mm-long nanoscale waveguide, we produce a group-index change of 0.15 and generate controllable delays as large as 4 ps for signal pulses as short as 3 ps. The scheme can be implemented at bandwidths exceeding 100 GHz for wavelengths spanning the entire low-loss fiber-optics communications window and thus represents an important step in the development of chip-scale photonics devices that process light with light.

  1. All-optical phase modulation in a cavity-polariton Mach–Zehnder interferometer

    PubMed Central

    Sturm, C.; Tanese, D.; Nguyen, H.S.; Flayac, H.; Galopin, E.; Lemaître, A.; Sagnes, I.; Solnyshkov, D.; Amo, A.; Malpuech, G.; Bloch, J.

    2014-01-01

    Quantum fluids based on light is a highly developing research field, since they provide a nonlinear platform for developing optical functionalities and quantum simulators. An important issue in this context is the ability to coherently control the properties of the fluid. Here we propose an all-optical approach for controlling the phase of a flow of cavity-polaritons, making use of their strong interactions with localized excitons. Here we illustrate the potential of this method by implementing a compact exciton–polariton interferometer, which output intensity and polarization can be optically controlled. This interferometer is cascadable with already reported polariton devices and is promising for future polaritonic quantum optic experiments. Complex phase patterns could be also engineered using this optical method, providing a key tool to build photonic artificial gauge fields. PMID:24513781

  2. A novel noninvasive all optical technique to monitor physiology of an exercising muscle

    NASA Astrophysics Data System (ADS)

    Saxena, Vishal; Marcu, Laura; Karunasiri, Gamani

    2008-11-01

    An all optical technique based on near-infrared spectroscopy and mid-infrared imaging (MIRI) is applied as a noninvasive, in vivo tool to monitor the vascular status of skeletal muscle and the physiological changes that occur during exercise. A near-infrared spectroscopy (NIRS) technique, namely, steady state diffuse optical spectroscopy (SSDOS) along with MIRI is applied for monitoring the changes in the values of tissue oxygenation and thermometry of an exercising muscle. The NIRS measurements are performed at five discrete wavelengths in a spectral window of 650-850 nm and MIRI is performed in a spectral window of 8-12 µm. The understanding of tissue oxygenation status and the behavior of the physiological parameters derived from thermometry may provide a useful insight into muscle physiology, therapeutic response and treatment.

  3. All optical active high decoder using integrated 2D square lattice photonic crystals

    NASA Astrophysics Data System (ADS)

    Moniem, Tamer A.

    2015-11-01

    The paper introduces a novel all optical active high 2 × 4 decoder based on 2D photonic crystals (PhC) of silicon rods with permittivity of ε = 10.1 × 10-11 farad/m. The main structure of optical decoder is designed using a combination of five nonlinear photonic crystal ring resonator, set of T-type waveguide, and line defect of Y and T branch splitters. The proposed structure has two logic input ports, four output ports, and one bias input port. The total size of the proposed 2 × 4 decoder is equal to 40 μm × 38 μm. The PhC structure has a square lattice of silicon rod with refractive index of 3.39 in air. The overall design and the results are discussed through the realization and the numerically simulation to confirm its operation and feasibility.

  4. All-optical hash code generation and verification for low latency communications.

    PubMed

    Paquot, Yvan; Schröder, Jochen; Pelusi, Mark D; Eggleton, Benjamin J

    2013-10-01

    We introduce an all-optical, format transparent hash code generator and a hash comparator for data packets verification with low latency at high baudrate. The device is reconfigurable and able to generate hash codes based on arbitrary functions and perform the comparison directly in the optical domain. Hash codes are calculated with custom interferometric circuits implemented with a Fourier domain optical processor. A novel nonlinear scheme featuring multiple four-wave mixing processes in a single waveguide is implemented for simultaneous phase and amplitude comparison of the hash codes before and after transmission. We demonstrate the technique with single polarisation BPSK and QPSK signals up to a data rate of 80 Gb/s.

  5. Banded all-optical OFDM super-channels with low-bandwidth receivers.

    PubMed

    Song, Binhuang; Zhu, Chen; Corcoran, Bill; Zhuang, Leimeng; Lowery, Arthur James

    2016-08-01

    We propose a banded all-optical orthogonal frequency division multiplexing (AO-OFDM) transmission system based on synthesising a number of truncated sinc-shaped subcarriers for each sub-band. This approach enables sub-band by sub-band reception and therefore each receiver's electrical bandwidth can be significantly reduced compared with a conventional AO-OFDM system. As a proof-of-concept experiment, we synthesise 6 × 10-Gbaud subcarriers in both conventional and banded AO-OFDM systems. With a limited receiver electrical bandwidth, the experimental banded AO-OFDM system shows 2-dB optical signal to noise ratio (OSNR) benefit over conventional AO-OFDM at the 7%-overhead forward error correction (FEC) threshold. After transmission over 800-km of single-mode fiber, ≈3-dB improvement in Q-factor can be achieved at the optimal launch power at a cost of increasing the spectral width by 14%. PMID:27505764

  6. Numerical simulation for all-optical Thomson scattering X-ray source

    NASA Astrophysics Data System (ADS)

    Tan, Fang; Zhu, Bin; Han, Dan; Xin, Jian-Ting; Zhao, Zong-Qing; Cao, Lei-Feng; Gu, Yu-Qiu; Zhang, Bao-Han

    2014-03-01

    Energy spectra, angular distributions, and temporal profiles of the photons produced by an all-optical Thomson scattering X-ray source are explored through numerical simulations based on the parameters of the SILEX-I laser system (800 nm, 30 fs, 300 TW) and the previous wakefield acceleration experimental results. The simulation results show that X-ray pulses with a duration of 30 fs and an emission angle of 50 mrad can be produced from such a source. Using the optimized electron parameters, X-ray pulses with better directivity and narrower energy spectra can be obtained. Besides the electron parameters, the laser parameters such as the wavelength, pulse duration, and spot size also affect the X-ray yield, the angular distribution, and the maximum photon energy, except the X-ray pulse duration which is slightly changed for the case of ultrafast laser—electron interaction.

  7. All-optical non-conjugated wavelength multicasting of QPSK signal with capability of phase regeneration.

    PubMed

    Lian, Junzi; Fu, Songnian; Meng, Yan; Tang, Ming; Shum, Perry; Liu, Deming

    2014-09-22

    We propose all-optical one-to-three non-conjugated wavelength multicasting of QPSK signal with capability of phase regeneration, using dual-conjugated-pump phase sensitive amplification (PSA). Based on the seven-wave model, we can obtain phase transfer functions of individual multicasting channel. Different from two multicasting copies, the phase regeneration performance of input signal is determined by the nonlinear phase shift. Moreover, the optimal squeezing points of three multicasting channels have a deviation. Thus, there exists a regeneration performance trade-off among three multicasting channels. Our numerical simulation shows that the error vector magnitude (EVM) of 50 Gb/s QPSK signal can be successfully improved when both nonlinear phase shift and four-state position in its constellation are optimized. The calculated BER curves verify that the OSNR penalties of three multicasting channels are improved by around 1dB at BER = 10(-3).

  8. An all-optical software defined radio prototype platform

    NASA Astrophysics Data System (ADS)

    Paquet, Stephane; Qi, Guohua; Seregelyi, Joe; Yao, Jianping; Bélisle, J. Claude; Oldham, John

    2005-09-01

    Software Defined Radio (SDR), a radio that provides software control of a variety of modulation techniques over a broad frequency range, is an emerging technology that offers numerous advantages over conventional radio designs. With SDR, one would implement a common hardware platform and accommodate the different communications standards and technologies via software modules and firmware. This platform must be compatible with the high degree of versatility of SDR-based communication systems. SDR technology is being promoted by the US Department of Defence to replace tens of thousands of single protocol, single use radios with a common platform that could be reprogrammed to ensure interoperability. Military and public safety organisations from around the world are also considering this technology to solve their interoperability problems. Although SDR can be easily implemented below 6 GHz using conventional electronics, it is increasingly difficult to do so at the higher operating frequencies proposed by many new wireless and SATCOM standards. To take full advantage of the SDR concept, a hardware platform is required that is capable of continuous operation from frequencies where electrical sources have difficulty providing continuously tunable operation, up to 60 GHz. In addition, various signal modulation schemes will need to be supported. We present here a prototype for such a transmitter based on optical technology. It can generate a RF carrier tunable from about 18 to more than 40 GHz, which can be modulated using both intensity and phase modulation techniques. Simulations and experimental results are presented.

  9. All-optical automatic pollen identification: Towards an operational system

    NASA Astrophysics Data System (ADS)

    Crouzy, Benoît; Stella, Michelle; Konzelmann, Thomas; Calpini, Bertrand; Clot, Bernard

    2016-09-01

    We present results from the development and validation campaign of an optical pollen monitoring method based on time-resolved scattering and fluorescence. Focus is first set on supervised learning algorithms for pollen-taxa identification and on the determination of aerosol properties (particle size and shape). The identification capability provides a basis for a pre-operational automatic pollen season monitoring performed in parallel to manual reference measurements (Hirst-type volumetric samplers). Airborne concentrations obtained from the automatic system are compatible with those from the manual method regarding total pollen and the automatic device provides real-time data reliably (one week interruption over five months). In addition, although the calibration dataset still needs to be completed, we are able to follow the grass pollen season. The high sampling from the automatic device allows to go beyond the commonly-presented daily values and we obtain statistically significant hourly concentrations. Finally, we discuss remaining challenges for obtaining an operational automatic monitoring system and how the generic validation environment developed for the present campaign could be used for further tests of automatic pollen monitoring devices.

  10. Transmission and full-band coherent detection of polarization-multiplexed all-optical Nyquist signals generated by Sinc-shaped Nyquist pulses.

    PubMed

    Zhang, Junwen; Yu, Jianjun; Chi, Nan

    2015-09-01

    All optical method is considered as a promising technique for high symbol rate Nyquist signal generation, which has attracted a lot of research interests for high spectral-efficiency and high-capacity optical communication system. In this paper, we extend our previous work and report the fully experimental demonstration of polarization-division multiplexed (PDM) all-optical Nyquist signal generation based on Sinc-shaped Nyquist pulse with advanced modulation formats, fiber-transmission and single-receiver full-band coherent detection. Using this scheme, we have successfully demonstrated the generation, fiber transmission and single-receiver full-band coherent detection of all-optical Nyquist PDM-QPSK and PDM-16QAM signals up to 125-GBaud. 1-Tb/s single-carrier PDM-16QAM signal generation and full-band coherent detection is realized, which shows the advantage and feasibility of the single-carrier all-optical Nyquist signals.

  11. Transmission and full-band coherent detection of polarization-multiplexed all-optical Nyquist signals generated by Sinc-shaped Nyquist pulses

    PubMed Central

    Zhang, Junwen; Yu, Jianjun; Chi, Nan

    2015-01-01

    All optical method is considered as a promising technique for high symbol rate Nyquist signal generation, which has attracted a lot of research interests for high spectral-efficiency and high-capacity optical communication system. In this paper, we extend our previous work and report the fully experimental demonstration of polarization-division multiplexed (PDM) all-optical Nyquist signal generation based on Sinc-shaped Nyquist pulse with advanced modulation formats, fiber-transmission and single-receiver full-band coherent detection. Using this scheme, we have successfully demonstrated the generation, fiber transmission and single-receiver full-band coherent detection of all-optical Nyquist PDM-QPSK and PDM-16QAM signals up to 125-GBaud. 1-Tb/s single-carrier PDM-16QAM signal generation and full-band coherent detection is realized, which shows the advantage and feasibility of the single-carrier all-optical Nyquist signals. PMID:26323238

  12. All-optical ultrafast XOR/XNOR logic gates, binary counter, and double-bit comparator with silicon microring resonators.

    PubMed

    Sethi, Purnima; Roy, Sukhdev

    2014-10-01

    We present designs of all-optical ultrafast YES/NOT, XOR/XNOR logic gates, binary counter, and double-bit comparator based on all-optical switching by two-photon absorption induced free-carrier injection in silicon 2 × 2 add-drop microring resonators. The proposed circuits have been theoretically analyzed using time-domain coupled-mode theory based on reported experimental values to realize low power (∼ 28 mW) ultrafast (∼ 22 ps) operation with high modulation (80%) and bit rate (45 Gb/s). The designs are complementary metal-oxide semiconductor compatible and provide advantages of high Q-factor, tunability, compactness, cascadibility, scalability, reconfigurability, simplicity, and minimal number of switches and inputs for realization of the desired logic. Although a two-bit counter has been shown, the scheme can easily be extended to N-bit counter through cascading.

  13. All-optical investigation of tunable picosecond magnetization dynamics in ferromagnetic nanostripes with a width down to 50 nm

    NASA Astrophysics Data System (ADS)

    Saha, Susmita; Barman, Saswati; Otani, Yoshichika; Barman, Anjan

    2015-10-01

    Ferromagnetic nanostripes are important elements for a number of interesting technologies including magnetic racetrack memory, spin logic and magnonics. Understanding and controlling magnetization dynamics in such nanostripes are hence important problems in nanoscience and technology. Here we present an all-optical excitation and detection of ultrafast magnetization dynamics, including spin waves, in 5 μm long Ni80Fe20 nanostripes with varying stripe widths from 200 nm down to 50 nm. We observed a strong width dependent variation in the frequency, anisotropy and the spatial nature of spin waves in these systems. The effect of inter-stripe interaction is also studied and the 50 nm wide stripe is found to be nearly magnetostatically isolated, allowing us to detect the dynamics of a 50 nm wide individual stripe using an all-optical measurement technique. The tunability in magnetization dynamics with stripe widths is important for their applications in various spin based technologies.

  14. A metro-access integrated network with all-optical virtual private network function using DPSK/ASK modulation format

    NASA Astrophysics Data System (ADS)

    Tian, Yue; Leng, Lufeng; Su, Yikai

    2008-11-01

    All-optical virtual private network (VPN), which offers dedicated optical channels to connect users within a VPN group, is considered a promising approach to efficient internetworking with low latency and enhanced security implemented in the physical layer. On the other hand, time-division multiplexed (TDM) / wavelength-division multiplexed (WDM) network architecture based on a feeder-ring with access-tree topology, is considered a pragmatic migration scenario from current TDM-PONs to future WDM-PONs and a potential convergence scheme for access and metropolitan networks, due to its efficiently shared hardware and bandwidth resources. All-optical VPN internetworking in such a metro-access integrated structure is expected to cover a wider service area and therefore is highly desirable. In this paper, we present a TDM/WDM metro-access integrated network supporting all-optical VPN internetworking among ONUs in different sub- PONs based on orthogonal differential-phase-shift keying (DPSK) / amplitude-shift keying (ASK) modulation format. In each ONU, no laser but a single Mach-Zehnder modulator (MZM) is needed for the upstream and VPN signal generation, which is cost-effective. Experiments and simulations are performed to verify its feasibility as a potential solution to the future access service.

  15. Magnetic induction tomography using an all-optical ⁸⁷Rb atomic magnetometer.

    PubMed

    Wickenbrock, Arne; Jurgilas, Sarunas; Dow, Albert; Marmugi, Luca; Renzoni, Ferruccio

    2014-11-15

    We demonstrate magnetic induction tomography (MIT) with an all-optical atomic magnetometer. Our instrument creates a conductivity map of conductive objects. Both the shape and size of the imaged samples compare very well with the actual shape and size. Given the potential of all-optical atomic magnetometers for miniaturization and extreme sensitivity, the proof-of-principle presented in this Letter opens up promising avenues in the development of instrumentation for MIT.

  16. Ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials at optical communication range.

    PubMed

    Zhu, Yu; Hu, Xiaoyong; Fu, Yulan; Yang, Hong; Gong, Qihuang

    2013-01-01

    Actively all-optical tunable plasmon-induced transparency in metamaterials paves the way for achieving ultrahigh-speed quantum information processing chips. Unfortunately, up to now, very small experimental progress has been made for all-optical tunable plasmon-induced transparency in metamaterials in the visible and near-infrared range because of small third-order optical nonlinearity of conventional materials. The achieved operating pump intensity was as high as several GW/cm(2) order. Here, we report an ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials coated on polycrystalline indium-tin oxide layer at the optical communication range. Compared with previous reports, the threshold pump intensity is reduced by four orders of magnitude, while an ultrafast response time of picoseconds order is maintained. This work not only offers a way to constructing photonic materials with large nonlinearity and ultrafast response, but also opens up the possibility for realizing quantum solid chips and ultrafast integrated photonic devices based on metamaterials.

  17. All-optical 4x10 Gbps NAND gate using single mode Fabry-Pérot laser diode.

    PubMed

    Nakarmi, B; Zhang, X; Won, Y H

    2015-10-19

    We demonstrate all-optical 4x10 Gbps NAND gate with an individual input data rate of 10 Gbps using single mode Fabry-Pérot laser diode. The proposed scheme is based on the principle of multi-input injection locking. All-optical NAND gate is one of the universal logic gates which can be used for realizing all other logic gates for optical communication and networks. The output performance of the proposed all-optical multi-input NAND gate is verified with output spectrum domain results, waveforms, rising-falling time, and eye diagram measurement at 10 Gbps input. The ON/OFF contrast ratio of 41 dB is measured at the spectrum domain output when all four input beams are logic high. In all other combinations of four inputs, maximum ON/OFF contrast ratio of 1.5 dB ON/OFF is measured. Clear output waveform, output eye diagram with an extinction ratio of about 11 dB, and rising-falling time of about 35 ps are obtained. The BER measurement is carried out and we found the power penalty of about 1.7 dB at BER of 10(-9).

  18. Ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials at optical communication range

    PubMed Central

    Zhu, Yu; Hu, Xiaoyong; Fu, Yulan; Yang, Hong; Gong, Qihuang

    2013-01-01

    Actively all-optical tunable plasmon-induced transparency in metamaterials paves the way for achieving ultrahigh-speed quantum information processing chips. Unfortunately, up to now, very small experimental progress has been made for all-optical tunable plasmon-induced transparency in metamaterials in the visible and near-infrared range because of small third-order optical nonlinearity of conventional materials. The achieved operating pump intensity was as high as several GW/cm2 order. Here, we report an ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials coated on polycrystalline indium-tin oxide layer at the optical communication range. Compared with previous reports, the threshold pump intensity is reduced by four orders of magnitude, while an ultrafast response time of picoseconds order is maintained. This work not only offers a way to constructing photonic materials with large nonlinearity and ultrafast response, but also opens up the possibility for realizing quantum solid chips and ultrafast integrated photonic devices based on metamaterials. PMID:23903825

  19. Ultralow bias power all-optical photonic crystal memory realized with systematically tuned L3 nanocavity

    SciTech Connect

    Kuramochi, Eiichi Nozaki, Kengo; Shinya, Akihiko; Taniyama, Hideaki; Notomi, Masaya; Takeda, Koji; Matsuo, Shinji; Sato, Tomonari

    2015-11-30

    An InP photonic crystal nanocavity with an embedded InGaAsP active region is a unique technology that has realized an all-optical memory with a sub-micro-watt operating power and limitless storage time. In this study, we employed an L3 design with systematic multi-hole tuning, which realized a higher loaded Q factor (>40 000) and a lower mode volume (0.9 μm{sup 3}) than a line-defect-based buried-heterostructure nanocavity (16 000 and 2.2 μm{sup 3}). Excluding the active region realized a record loaded Q factor (210 000) in all for InP-based nanocavities. The minimum bias power for bistable memory operation was reduced to 2.3 ± 0.3 nW, which is about 1/10 of the previous record of 30 nW. This work further established the capability of a bistable nanocavity memory for use in future ultralow-power-consumption on-chip integrated photonics.

  20. Current Developments on Optical Feedback Interferometry as an All-Optical Sensor for Biomedical Applications.

    PubMed

    Perchoux, Julien; Quotb, Adam; Atashkhooei, Reza; Azcona, Francisco J; Ramírez-Miquet, Evelio E; Bernal, Olivier; Jha, Ajit; Luna-Arriaga, Antonio; Yanez, Carlos; Caum, Jesus; Bosch, Thierry; Royo, Santiago

    2016-01-01

    Optical feedback interferometry (OFI) sensors are experiencing a consistent increase in their applications to biosensing due to their contactless nature, low cost and compactness, features that fit very well with current biophotonics research and market trends. The present paper is a review of the work in progress at UPC-CD6 and LAAS-CNRS related to the application of OFI to different aspects of biosensing, both in vivo and ex vivo. This work is intended to present the variety of opportunities and potential applications related to OFI that are available in the field. The activities presented are divided into two main sensing strategies: The measurement of optical path changes and the monitoring of flows, which correspond to sensing strategies linked to the reconstruction of changes of amplitude from the interferometric signal, and to classical Doppler frequency measurements, respectively. For optical path change measurements, measurements of transient pulses, usual in biosensing, together with the measurement of large displacements applied to designing palliative care instrumentation for Parkinson disease are discussed. Regarding the Doppler-based approach, progress in flow-related signal processing and applications in real-time monitoring of non-steady flows, human blood flow monitoring and OFI pressure myograph sensing will be presented. In all cases, experimental setups are discussed and results presented, showing the versatility of the technique. The described applications show the wide capabilities in biosensing of the OFI sensor, showing it as an enabler of low-cost, all-optical, high accuracy biomedical applications. PMID:27187406

  1. All-optical central-frequency-programmable and bandwidth-tailorable radar.

    PubMed

    Zou, Weiwen; Zhang, Hao; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2016-01-22

    Radar has been widely used for military, security, and rescue purposes, and modern radar should be reconfigurable at multi-bands and have programmable central frequencies and considerable bandwidth agility. Microwave photonics or photonics-assisted radio-frequency technology is a unique solution to providing such capabilities. Here, we demonstrate an all-optical central-frequency-programmable and bandwidth-tailorable radar architecture that provides a coherent system and utilizes one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates a wideband linearly chirped radar signal. The working bands can be flexibly tailored with the desired bandwidth at a user-preferred carrier frequency. Radar echoes are first modulated onto the pre-chirped optical pulse, which is also used for signal generation, and then stretched in time or compressed in frequency several fold based on the time-stretch principle. Thus, digitization is facilitated without loss of detection ability. We believe that our results demonstrate an innovative radar architecture with an ultra-high-range resolution.

  2. Rapid, all-optical crystal orientation imaging of two-dimensional transition metal dichalcogenide monolayers

    SciTech Connect

    David, Sabrina N.; Zhai, Yao; Zande, Arend M. van der; O'Brien, Kevin; Huang, Pinshane Y.; Chenet, Daniel A.; Hone, James C.; Zhang, Xiang; Yin, Xiaobo

    2015-09-14

    Two-dimensional (2D) atomic materials such as graphene and transition metal dichalcogenides (TMDCs) have attracted significant research and industrial interest for their electronic, optical, mechanical, and thermal properties. While large-area crystal growth techniques such as chemical vapor deposition have been demonstrated, the presence of grain boundaries and orientation of grains arising in such growths substantially affect the physical properties of the materials. There is currently no scalable characterization method for determining these boundaries and orientations over a large sample area. We here present a second-harmonic generation based microscopy technique for rapidly mapping grain orientations and boundaries of 2D TMDCs. We experimentally demonstrate the capability to map large samples to an angular resolution of ±1° with minimal sample preparation and without involved analysis. A direct comparison of the all-optical grain orientation maps against results obtained by diffraction-filtered dark-field transmission electron microscopy plus selected-area electron diffraction on identical TMDC samples is provided. This rapid and accurate tool should enable large-area characterization of TMDC samples for expedited studies of grain boundary effects and the efficient characterization of industrial-scale production techniques.

  3. Dense all-optical WDM-SCM technology for high-speed computer interconnects

    NASA Astrophysics Data System (ADS)

    Ih, Charles S.; Tian, Rongsheng; Zhou, H. X.; Xia, Xiang-Gen

    1993-07-01

    We describe a dense and flexible all optical multi-channel communication system for high speed computer interconnects. The system can provide 10 Gb/s for each individual node with a total system capacity to 250 Gb/s using currently available technologies. The system capacity can be scaled to 1 Tb/s using optical amplifiers with a broader bandwidth and higher modulations. The system is based on the multi-beam (heterodyne) modulator (MBM) recently demonstrated in our laboratory and other current technologies in tunable laser arrays and acousto-optical tunable filter (AOTF). Each MBM automatically forms a high frequency microwave sub-carrier multiplexing (SCM) with sub-carrier frequency to tens of GHz. A MBM with sub-carriers at 17 and 21 GHz has already been demonstrated and can be scaled to higher frequencies by using a higher frequency detector. Each SCM group may consist of up to 10 one-Gb/s channels and occupies only 1 nm spectral width. Therefore we can form a conventional WDM with 25 divisions within the bandwidth of commercially available optical amplifiers.

  4. Simultaneous all-optical manipulation and recording of neural circuit activity with cellular resolution in vivo

    PubMed Central

    Packer, Adam M.; Russell, Lloyd E.; Dalgleish, Henry W.P.; Häusser, Michael

    2016-01-01

    We describe an all-optical strategy for simultaneously manipulating and recording the activity of multiple neurons with cellular resolution in vivo. Concurrent two-photon optogenetic activation and calcium imaging is enabled by coexpression of a red-shifted opsin and a genetically encoded calcium indicator. A spatial light modulator allows tens of user-selected neurons to be targeted for spatiotemporally precise optogenetic activation, while simultaneous fast calcium imaging provides high-resolution network-wide readout of the manipulation with negligible optical crosstalk. Proof-of-principle experiments in mouse barrel cortex demonstrate interrogation of the same neuronal population during different behavioral states, and targeting of neuronal ensembles based on their functional signature. This approach extends the optogenetic toolkit beyond the specificity obtained with genetic or viral approaches, enabling high-throughput, flexible and long-term optical interrogation of functionally defined neural circuits with single-cell and single-spike resolution in the mammalian brain in vivo. PMID:25532138

  5. Analysis of all-optical light modulation in proteorhodopsin protein molecules

    NASA Astrophysics Data System (ADS)

    Roy, Sukhdev; Sharma, Parag

    2008-03-01

    We present a detailed steady-state and time-dependent theoretical analysis of all-optical light modulation in the recently discovered, wild-type proteorhodopsin (WTpR) protein molecules based on excited-state absorption. Amplitude modulation of cw probe laser beam transmissions at 520, 405, 555 and 560 nm, corresponding to the peak absorption of pR, pRM, pRK and pRN intermediate states of pR photocycle, respectively, by cw and pulsed modulating pump laser beam at 520 nm have been analyzed. The effect of various spectral and kinetic parameters on modulation characteristics has been studied. There is an optimum value of concentration for a given pump intensity value for which maximum modulation of the probe beam can be achieved. The switching characteristics of probe beam at 405 and 520 nm exhibit dip and peak, respectively, which can be removed by decreasing the absorption of pRM state at 520 nm. The modulation in WTpR is at lower pump powers with smaller contrast in comparison to WT bacteriorhodopsin (bR) and WT pharaonis phoborhodopsin (ppR). The modulation characteristics exhibit unique features compared to bR and ppR.

  6. Ultra fast all-optical fiber pressure sensor for blast event evaluation

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Wang, Wenhui; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

    2011-05-01

    Traumatic brain injury (TBI) is a great potential threat to soldiers who are exposed to explosions or athletes who receive cranial impacts. Protecting people from TBI has recently attracted a significant amount of attention due to recent military operations in the Middle East. Recording pressure transient data in a blast event is very critical to the understanding of the effects of blast events on TBI. However, due to the fast change of the pressure during blast events, very few sensors have the capability to effectively track the dynamic pressure transients. This paper reports an ultra fast, miniature and all-optical fiber pressure sensor which could be mounted at different locations of a helmet to measure the fast changing pressure simultaneously. The sensor is based on Fabry-Perot (FP) principle. The end face of the fiber is wet etched. A well controlled thickness silicon dioxide diaphragm is thermal bonded on the end face to form an FP cavity. A shock tube test was conducted at Natick Soldier Research Development and Engineering Center, where the sensors were mounted in a shock tube side by side with a reference sensor to measure the rapidly changing pressure. The results of the test demonstrated that the sensor developed had an improved rise time (shorter than 0.4 μs) when compared to a commercially available reference sensor.

  7. Current Developments on Optical Feedback Interferometry as an All-Optical Sensor for Biomedical Applications.

    PubMed

    Perchoux, Julien; Quotb, Adam; Atashkhooei, Reza; Azcona, Francisco J; Ramírez-Miquet, Evelio E; Bernal, Olivier; Jha, Ajit; Luna-Arriaga, Antonio; Yanez, Carlos; Caum, Jesus; Bosch, Thierry; Royo, Santiago

    2016-05-13

    Optical feedback interferometry (OFI) sensors are experiencing a consistent increase in their applications to biosensing due to their contactless nature, low cost and compactness, features that fit very well with current biophotonics research and market trends. The present paper is a review of the work in progress at UPC-CD6 and LAAS-CNRS related to the application of OFI to different aspects of biosensing, both in vivo and ex vivo. This work is intended to present the variety of opportunities and potential applications related to OFI that are available in the field. The activities presented are divided into two main sensing strategies: The measurement of optical path changes and the monitoring of flows, which correspond to sensing strategies linked to the reconstruction of changes of amplitude from the interferometric signal, and to classical Doppler frequency measurements, respectively. For optical path change measurements, measurements of transient pulses, usual in biosensing, together with the measurement of large displacements applied to designing palliative care instrumentation for Parkinson disease are discussed. Regarding the Doppler-based approach, progress in flow-related signal processing and applications in real-time monitoring of non-steady flows, human blood flow monitoring and OFI pressure myograph sensing will be presented. In all cases, experimental setups are discussed and results presented, showing the versatility of the technique. The described applications show the wide capabilities in biosensing of the OFI sensor, showing it as an enabler of low-cost, all-optical, high accuracy biomedical applications.

  8. All-optical central-frequency-programmable and bandwidth-tailorable radar

    PubMed Central

    Zou, Weiwen; Zhang, Hao; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2016-01-01

    Radar has been widely used for military, security, and rescue purposes, and modern radar should be reconfigurable at multi-bands and have programmable central frequencies and considerable bandwidth agility. Microwave photonics or photonics-assisted radio-frequency technology is a unique solution to providing such capabilities. Here, we demonstrate an all-optical central-frequency-programmable and bandwidth-tailorable radar architecture that provides a coherent system and utilizes one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates a wideband linearly chirped radar signal. The working bands can be flexibly tailored with the desired bandwidth at a user-preferred carrier frequency. Radar echoes are first modulated onto the pre-chirped optical pulse, which is also used for signal generation, and then stretched in time or compressed in frequency several fold based on the time-stretch principle. Thus, digitization is facilitated without loss of detection ability. We believe that our results demonstrate an innovative radar architecture with an ultra-high-range resolution. PMID:26795596

  9. Current Developments on Optical Feedback Interferometry as an All-Optical Sensor for Biomedical Applications

    PubMed Central

    Perchoux, Julien; Quotb, Adam; Atashkhooei, Reza; Azcona, Francisco J.; Ramírez-Miquet, Evelio E.; Bernal, Olivier; Jha, Ajit; Luna-Arriaga, Antonio; Yanez, Carlos; Caum, Jesus; Bosch, Thierry; Royo, Santiago

    2016-01-01

    Optical feedback interferometry (OFI) sensors are experiencing a consistent increase in their applications to biosensing due to their contactless nature, low cost and compactness, features that fit very well with current biophotonics research and market trends. The present paper is a review of the work in progress at UPC-CD6 and LAAS-CNRS related to the application of OFI to different aspects of biosensing, both in vivo and ex vivo. This work is intended to present the variety of opportunities and potential applications related to OFI that are available in the field. The activities presented are divided into two main sensing strategies: The measurement of optical path changes and the monitoring of flows, which correspond to sensing strategies linked to the reconstruction of changes of amplitude from the interferometric signal, and to classical Doppler frequency measurements, respectively. For optical path change measurements, measurements of transient pulses, usual in biosensing, together with the measurement of large displacements applied to designing palliative care instrumentation for Parkinson disease are discussed. Regarding the Doppler-based approach, progress in flow-related signal processing and applications in real-time monitoring of non-steady flows, human blood flow monitoring and OFI pressure myograph sensing will be presented. In all cases, experimental setups are discussed and results presented, showing the versatility of the technique. The described applications show the wide capabilities in biosensing of the OFI sensor, showing it as an enabler of low-cost, all-optical, high accuracy biomedical applications. PMID:27187406

  10. Superstructures of chiral nematic microspheres as all-optical switchable distributors of light

    PubMed Central

    Aβhoff, Sarah J.; Sukas, Sertan; Yamaguchi, Tadatsugu; Hommersom, Catharina A.; Le Gac, Séverine; Katsonis, Nathalie

    2015-01-01

    Light technology is based on generating, detecting and controlling the wavelength, polarization and direction of light. Emerging applications range from electronics and telecommunication to health, defence and security. In particular, data transmission and communication technologies are currently asking for increasingly complex and fast devices, and therefore there is a growing interest in materials that can be used to transmit light and also to control the distribution of light in space and time. Here, we design chiral nematic microspheres whose shape enables them to reflect light of different wavelengths and handedness in all directions. Assembled in organized hexagonal superstructures, these microspheres of well-defined sizes communicate optically with high selectivity for the colour and chirality of light. Importantly, when the microspheres are doped with photo-responsive molecular switches, their chiroptical communication can be tuned, both gradually in wavelength and reversibly in polarization. Since the kinetics of the “on” and “off” switching can be adjusted by molecular engineering of the dopants and because the photonic cross-communication is selective with respect to the chirality of the incoming light, these photo-responsive microspheres show potential for chiroptical all-optical distributors and switches, in which wavelength, chirality and direction of the reflected light can be controlled independently and reversibly. PMID:26400584

  11. All-optical central-frequency-programmable and bandwidth-tailorable radar.

    PubMed

    Zou, Weiwen; Zhang, Hao; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2016-01-01

    Radar has been widely used for military, security, and rescue purposes, and modern radar should be reconfigurable at multi-bands and have programmable central frequencies and considerable bandwidth agility. Microwave photonics or photonics-assisted radio-frequency technology is a unique solution to providing such capabilities. Here, we demonstrate an all-optical central-frequency-programmable and bandwidth-tailorable radar architecture that provides a coherent system and utilizes one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates a wideband linearly chirped radar signal. The working bands can be flexibly tailored with the desired bandwidth at a user-preferred carrier frequency. Radar echoes are first modulated onto the pre-chirped optical pulse, which is also used for signal generation, and then stretched in time or compressed in frequency several fold based on the time-stretch principle. Thus, digitization is facilitated without loss of detection ability. We believe that our results demonstrate an innovative radar architecture with an ultra-high-range resolution. PMID:26795596

  12. Superstructures of chiral nematic microspheres as all-optical switchable distributors of light

    NASA Astrophysics Data System (ADS)

    Aβhoff, Sarah J.; Sukas, Sertan; Yamaguchi, Tadatsugu; Hommersom, Catharina A.; Le Gac, Séverine; Katsonis, Nathalie

    2015-09-01

    Light technology is based on generating, detecting and controlling the wavelength, polarization and direction of light. Emerging applications range from electronics and telecommunication to health, defence and security. In particular, data transmission and communication technologies are currently asking for increasingly complex and fast devices, and therefore there is a growing interest in materials that can be used to transmit light and also to control the distribution of light in space and time. Here, we design chiral nematic microspheres whose shape enables them to reflect light of different wavelengths and handedness in all directions. Assembled in organized hexagonal superstructures, these microspheres of well-defined sizes communicate optically with high selectivity for the colour and chirality of light. Importantly, when the microspheres are doped with photo-responsive molecular switches, their chiroptical communication can be tuned, both gradually in wavelength and reversibly in polarization. Since the kinetics of the “on” and “off” switching can be adjusted by molecular engineering of the dopants and because the photonic cross-communication is selective with respect to the chirality of the incoming light, these photo-responsive microspheres show potential for chiroptical all-optical distributors and switches, in which wavelength, chirality and direction of the reflected light can be controlled independently and reversibly.

  13. Green Distributed Quality of Transmission Aware Routing and Wavelength Assignment in All-Optical Networks

    NASA Astrophysics Data System (ADS)

    Kakekhani, Amir; Rahbar, Akbar Ghaffarpour

    2013-06-01

    The Routing and Wavelength Assignment (RWA) algorithms that consider quality of transmission (QoT) in light-path setup spend more time than their conventional counterparts due to exhaustive search and QoT estimation. This paper proposes distributed Quality of Transmission Aware Routing and Wavelength Assignment (QARWA) algorithm to handle dynamic light-path provisioning in wavelength routed all-optical networks taking energy consumption of optical switch nodes into account. Specifically, the QARWA considers bit-error rate (BER), setup delay, and energy consumption constraints at the same time, and establishes light-paths with small BER, low setup latency, and reduced energy consumption. We present and evaluate an enhanced wavelength-assignment solution in the QARWA to handle the wavelength continuity constraint. In QARWA, a source node determines the connection path by means of the shortest path algorithm and a destination node selects a wavelength based on the BER limitation and decreasing order of setup latency. Relating energy consumption to processing time, we show that QARWA can decrease the total energy consumption by reducing the processing time at each node. Under QARWA, when a node finishes the processing of the last control packet, it makes transition to either sleep state or idle state. Hence, QARWA can provide the best performance since it can reduce processing time in control units, light-path setup latency, and energy consumption of nodes.

  14. Energy-bandwidth trade-off in all-optical photonic crystal microcavity switches.

    PubMed

    Heuck, Mikkel; Kristensen, Philip Trøst; Mørk, Jesper

    2011-09-12

    The performance of all-optical switches is a compromise between the achievable bandwidth of the switched signal and the energy requirement of the switching operation. In this work we consider a system consisting of a photonic crystal cavity coupled to two input and two output waveguides. As a specific example of a switching application, we investigate the demultiplexing of an optical time division multiplexed signal. To quantify the energy-bandwidth trade-off, we introduce a figure of merit for the detection of the demultiplexed signal. In such investigations it is crucial to consider patterning effects, which occur on time scales that are longer than the bit period. Our analysis is based on a coupled mode theory, which allows for an extensive investigation of the influence of the system parameters on the switching dynamics. The analysis is shown to provide new insights into the ultrafast dynamics of the switching operation, and the results show optimum parameter ranges that may serve as design guidelines in device fabrication.

  15. Study on all-optical switching characteristics of ethyl orange-doped polymer film

    NASA Astrophysics Data System (ADS)

    Xu, Tang; Zhang, Chunping; Lin, Yu; Qi, Shengwen

    2008-10-01

    The all-optical switching polymer thin films with azobenzene dye ethyl orange as the guest material and polyvinyl alcohol (PVA) as the host material were prepared by adulteration and spin-coating methods. The all-optical switching characteristics of the samples were measured at different intensities and modulation frequencies of the pump beam (532 nm, CW); the influence of doping concentration on the all-optical switching effect of the films was studied. It is shown that, under room temperature conditions and with a low pump power of 6 mW, the all-optical switch has a response time of about 2 ms and a modulation depth of 45%, and the maximal modulation depth reaches 90%. In addition, it is found that samples with higher doping concentration show a stronger all-optical switching effect but a larger background signal, and good switching performance is obtained by choosing the doping concentrations from 0.8% to 2% of the sample.

  16. All-optical switching in a symmetric three-waveguide coupler with phase-mismatched absorptive central waveguide.

    PubMed

    Chen, Yijing; Ho, Seng-Tiong; Krishnamurthy, Vivek

    2013-12-20

    All-optical switching operation based on manipulation of absorption in a three-waveguide directional coupler is theoretically investigated. The proposed structure consists of one absorptive central waveguide and two identical passive side waveguides. Optically induced absorption change in the central waveguide effectively controls the coupling of light between the two side waveguides, leading to optical switching action. The proposed architecture alleviates the fabrication challenges and waveguide index matching conditions that limit previous demonstrations of similar switching schemes based on a two-waveguide directional coupler. The proposed device accommodates large modal index difference between absorptive and passive waveguides without compromising the switching extinction ratio.

  17. All-optical controllable channel-drop filters in two-dimensional square-lattice photonic crystals

    NASA Astrophysics Data System (ADS)

    Fasihi, K.

    2016-05-01

    A novel all-optical controllable channel-drop filter in photonic crystals (PC) of square lattice is presented. We show that using a resonant-cavity-based add-drop filter with a wavelength-selective reflection feedback and a single-control switching module which is based on nonlinear PC microcavities, the dropped channel can be routed to the drop port or returned to the bus waveguide. Using the temporal coupled-mode theory and two-dimensional nonlinear finite-difference time-domain method, the performance of the proposed device is investigated and the simulation results show the validity of the proposed design.

  18. Two types of all-optical magnetization switching mechanisms using femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    El Hadri, M. S.; Pirro, P.; Lambert, C.-H.; Petit-Watelot, S.; Quessab, Y.; Hehn, M.; Montaigne, F.; Malinowski, G.; Mangin, S.

    2016-08-01

    Using a time-dependent electrical investigation of the all-optical switching in ferrimagnetic and ferromagnetic Hall crosses via the anomalous Hall effect, intriguing insights into the rich physics underlying the all-optical switching are provided. We demonstrate that two different all-optical magnetization switching mechanisms can be distinguished; a "single pulse" switching for ferrimagnetic GdFeCo alloys, and a "two regimes" switching process for both ferrimagnetic TbCo alloys and ferromagnetic Pt/Co multilayers. We show that the latter takes place at two different time scales, and consists of a steplike helicity-independent multiple-domain formation within the first 1 ms followed by a helicity-dependent remagnetization on several tens of milliseconds.

  19. A study of high repetition rate pulse generation and all-optical add/drop multiplexing

    NASA Astrophysics Data System (ADS)

    Chen, Hongmin

    Ultra high-speed optical time-division-multiplexed (OTDM) transmission technologies are essential for the construction of ultra high-speed all-optical networks needed in the information era. In this Ph. D thesis dissertation, essential mechanisms associated with ultra high speed OTDM transmission systems, such as, high speed ultra short pulse generation, all optical demultiplexing and all optical add/drop multiplexing, have been studied. Both experimental demonstrations and numerical simulations have been performed. In order to realize high-speed optical TDM systems, high repetition rate, ultra short pulses are needed. A rational harmonic mode-locked ring fiber laser has been used to produce ultrashort pulses, the pulse jitter will be eliminated using a Phase-Locked-Loop (PLL), and the self-pulsation has been suppressed using a semiconductor optical amplifier (SOA). Sub pico-second pulses are very important for all optical sampling in the ultrahigh-speed OTDM transmission system. In this thesis, a two stage compression scheme utilizing the nonlinearity and dispersion of the optical fibers has been constructed and used to compress the gain switched DFB laser pulses. Also a nonlinear optical loop mirror has been constructed to suppress the wings associated with nonlinear compression. Pedestal free, transform-limited pulses with pulse widths in range of 0.2 to 0.4 ps have been generated. LiNbO3 modulators play a very important role in fiber optical communication systems. In this thesis, LiNbO3 modulators have been used to perform high repetition rate pulse generation, all optical demultiplexing and all optical add/drop for the TDM transmission system.

  20. All-optical steering of the interactions between multiple spatial solitons in isotropic polymers

    NASA Astrophysics Data System (ADS)

    Yan, Li-fen; Zhang, Dong; Jin, Qing-li; Wang, Hong-cheng; Zhang, Yao-ju

    2010-11-01

    All-optical steering of the nonlinear interactions between multiple spatial solitons can be performed in an isotropic photoisomerization polymer, by propagating an external control beam in perpendicular direction. Fusing, giving birth to another new soliton, and transferring energy can take place in the interactions of signal beams, which can be achieved by changing the incident position of the control beam, the initial relative phase and the power ratio between the signal beams and the control beam. These phenomena are physically explained, and they have significantly potential applications in optical signal readdressing, logic gating, and all-optical switching, etc.

  1. Optical latches using optical amplifiers

    NASA Astrophysics Data System (ADS)

    Li, Wenbo; Hu, Hongyu; Dutta, Niloy K.

    2013-05-01

    Optical latches are important for a wide range of applications including communication systems, optical logic systems, optical random access memory (RAM) and encryption. All optical logic operations using quantum dot (QD) based semiconductor optical amplifier (SOA) and Mach-Zehnder interferometer (MZI) have been studied. The building block of an optical latch such as NAND gate has been fabricated and their operation experimentally demonstrated at ~ 80 GHz. A rate equation model has been developed for the QD-SOA-MZI and it has been used to analyze the Boolean logic operation. The model has been used to analyze the Set-Reset (S-R) latch and the D-Flip-Flop (DFF) devices. The DFF is the basic device for building larger logic circuits. The results show that the latches would work to speeds of ~ 250 Gb/s.

  2. Controllable mode multistability in microring lasers.

    PubMed

    Yuan, Guohui; Wang, Zhuoran

    2013-04-22

    We investigate mode multistability, i.e. coexistence of direction bistability and wavelength bi/multistability in microring lasers (MRLs) theoretically and numerically. We derive the expressions for conditions required for mode multistable operation in microring lasers based on a nonlinear multimode model with nonlinear effects stemming from carrier density pulsation, carrier heating and spectral hole burning included. We find theoretically that lasing mode can be selected from the multistable modes by external optical injection through gain saturation, and removal of the external optical injection will not affect the stability of the established lasing mode. Numerical results on all-optical multistate flip-flop function demonstrate that switching between multistable modes can be induced by trigger signals with each states self-sustained after the removal of the trigger signals in a 50µm-radius microring laser.

  3. All-optical multi-channel wavelength conversion of Nyquist 16 QAM signal using a silicon waveguide.

    PubMed

    Long, Yun; Liu, Jun; Hu, Xiao; Wang, Andong; Zhou, Linjie; Zou, Kaiheng; Zhu, Yixiao; Zhang, Fan; Wang, Jian

    2015-12-01

    We experimentally demonstrate on-chip all-optical multi-channel wavelength conversion of Nyquist 16 ary quadrature amplitude modulation (16 QAM) signal in a silicon waveguide. The measured optical signal-to-noise ratio (OSNR) penalties of wavelength conversion are ∼2  dB. The observed constellations of converted idlers indicate favorable performance of silicon-waveguide-based multi-channel wavelength conversion. We also experimentally study and compare the phase-conjugated wavelength conversion by degenerate four-wave mixing (FWM) and transparent wavelength conversion by non-degenerate FWM in the silicon waveguide.

  4. Design and analysis of polarization independent all-optical logic gates in silicon-on-insulator photonic crystal

    NASA Astrophysics Data System (ADS)

    Rani, Preeti; Kalra, Yogita; Sinha, R. K.

    2016-09-01

    In this paper, we have reported design and analysis of polarization independent all optical logic gates in silicon-on-insulator photonic crystal consisting of two dimensional honeycomb lattices with two different air holes exhibiting photonic band gap for both TE and TM mode in the optical communication window. The proposed structures perform as an AND optical logic gate and all the optical logic gates based on the phenomenon of interference. The response period and bit rate for TE and TM polarizations at a wavelength of 1.55 μm show improved results as reported earlier.

  5. A Power Conditioning Stage Based on Analog-Circuit MPPT Control and a Superbuck Converter for Thermoelectric Generators in Spacecraft Power Systems

    NASA Astrophysics Data System (ADS)

    Sun, Kai; Wu, Hongfei; Cai, Yan; Xing, Yan

    2014-06-01

    A thermoelectric generator (TEG) is a very important kind of power supply for spacecraft, especially for deep-space missions, due to its long lifetime and high reliability. To develop a practical TEG power supply for spacecraft, a power conditioning stage is indispensable, being employed to convert the varying output voltage of the TEG modules to a definite voltage for feeding batteries or loads. To enhance the system reliability, a power conditioning stage based on analog-circuit maximum-power-point tracking (MPPT) control and a superbuck converter is proposed in this paper. The input of this power conditioning stage is connected to the output of the TEG modules, and the output of this stage is connected to the battery and loads. The superbuck converter is employed as the main circuit, featuring low input current ripples and high conversion efficiency. Since for spacecraft power systems reliable operation is the key target for control circuits, a reset-set flip-flop-based analog circuit is used as the basic control circuit to implement MPPT, being much simpler than digital control circuits and offering higher reliability. Experiments have verified the feasibility and effectiveness of the proposed power conditioning stage. The results show the advantages of the proposed stage, such as maximum utilization of TEG power, small input ripples, and good stability.

  6. Integration of photonic nanojets and semiconductor nanoparticles for enhanced all-optical switching

    PubMed Central

    Born, Brandon; Krupa, Jeffrey D. A.; Geoffroy-Gagnon, Simon; Holzman, Jonathan F.

    2015-01-01

    All-optical switching is the foundation of emerging all-optical (terabit-per-second) networks and processors. All-optical switching has attracted considerable attention, but it must ultimately support operation with femtojoule switching energies and femtosecond switching times to be effective. Here we introduce an all-optical switch architecture in the form of a dielectric sphere that focuses a high-intensity photonic nanojet into a peripheral coating of semiconductor nanoparticles. Milli-scale spheres coated with Si and SiC nanoparticles yield switching energies of 200 and 100 fJ with switching times of 10 ps and 350 fs, respectively. Micro-scale spheres coated with Si and SiC nanoparticles yield switching energies of 1 pJ and 20 fJ with switching times of 2 ps and 270 fs, respectively. We show that femtojoule switching energies are enabled by localized photoinjection from the photonic nanojets and that femtosecond switching times are enabled by localized recombination within the semiconductor nanoparticles. PMID:26314911

  7. Magnetic induction measurements using an all-optical {sup 87}Rb atomic magnetometer

    SciTech Connect

    Wickenbrock, Arne; Tricot, François; Renzoni, Ferruccio

    2013-12-09

    In this work we propose, and experimentally demonstrate, the use of a self-oscillating all-optical atomic magnetometer for magnetic induction measurements. Given the potential for miniaturization of atomic magnetometers, and their extreme sensitivity, the present work shows that atomic magnetometers may play a key role in the development of instrumentation for magnetic induction tomography.

  8. All-optical magnetization reversal by circularly polarized laser pulses: Experiment and multiscale modeling

    NASA Astrophysics Data System (ADS)

    Vahaplar, K.; Kalashnikova, A. M.; Kimel, A. V.; Gerlach, S.; Hinzke, D.; Nowak, U.; Chantrell, R.; Tsukamoto, A.; Itoh, A.; Kirilyuk, A.; Rasing, Th.

    2012-03-01

    We present results of detailed experimental and theoretical studies of all-optical magnetization reversal by single circularly-polarized laser pulses in ferrimagnetic rare earth—transition metal (RE-TM) alloys GdxFe90-xCo10 (20%all-optically driven linear reversal can be modeled as a result of a two-fold impact of the laser pulse on the medium. First, due to absorption of the light and ultrafast laser-induced heating, the medium is brought to a highly nonequilibrium state. Simultaneously, due to the ultrafast inverse Faraday effect the circularly polarized laser pulse acts as an effective magnetic field of the amplitude up to ˜20 T. We show that the polarization-dependent reversal triggered by the circularly polarized light is feasible only in a narrow range (below 10%) of laser fluences. The duration of the laser pulse required for the reversal can be varied from ˜40 fs up to at least ˜1700 fs. We also investigate experimentally the role of the ferrimagnetic properties of GdFeCo in the all-optical reversal. In particular, the optimal conditions for the all-optical reversal are achieved just below the ferrimagnetic compensation temperature, where the magnetic information can be all-optically written by a laser pulse of minimal fluence and read out within just 30 ps. We argue that this is the fastest write-read event demonstrated for magnetic recording so far.

  9. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range.

    PubMed

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-01-01

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications.

  10. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range.

    PubMed

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-01-01

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications. PMID:27073154

  11. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range

    PubMed Central

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-01-01

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications. PMID:27073154

  12. Phase engineering techniques in superconducting quantum electronics

    NASA Astrophysics Data System (ADS)

    Mielke, O.; Ortlepp, Th; Dimov, B.; Uhlmann, F. H.

    2008-02-01

    Due to the pulse driven nature of the Rapid Single Flux Quantum electronics nearly every basic cell requires the capability of temporary data storing. Implementing phase shifting elements in this essential device leads to several advantages concerning the device characteristics. There are different concepts enabling phase shifting elements. We give a comparative overview about these approaches. The effect of this novel element on a basic cell is analyzed exampling a toggle-flip-flop. Based on the effective noise temperature determined from the experimental results of a standard flip-flop, the bit error rate for several toggle-flip-flop realizations containing different phase shifting elements was calculated. A significantly improved area of function could be shown by simulated error rates lower than 10-12 with a DC bias margin better than ±63.5%.

  13. Engineered materials for all-optical helicity-dependent magnetic switching

    NASA Astrophysics Data System (ADS)

    Fullerton, Eric

    2014-03-01

    The possibilities of manipulating magnetization without applied magnetic fields have attracted growing attention over the last fifteen years. The low-power manipulation of magnetization, preferably at ultra-short time scales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. Here we explore the optical manipulation of the magnetization of engineered materials and devices using 100 fs optical pulses. We demonstrate that all optical - helicity dependent switching (AO-HDS) can be observed not only in selected rare-earth transition-metal (RE-TM) alloy films but also in a much broader variety of materials, including alloys, multilayers, heterostructures and RE-free Co-Ir-based synthetic ferrimagnets. The discovery of AO-HDS in RE-free TM-based synthetic ferrimagnets can enable breakthroughs for numerous applications since it exploits materials that are currently used in magnetic data storage, memories and logic technologies. In addition, this materials study of AO-HDS offers valuable insight into the underlying mechanisms involved. Indeed the common denominator of the diverse structures showing AO-HDS in this study is that two ferromagnetic sub-lattices exhibit magnetization compensation (and therefore angular momentum compensation) at temperatures near or above room temperature. We are highlighting that compensation plays a major role and that this compensation can be established at the atomic level as in alloys but also over a larger nanometers scale as in the multilayers or in heterostructures. We will also discuss the potential to extend AO-HDS to new classes of magnetic materials. This work was done in collaboration with S. Mangin, M. Gottwald, C-H. Lambert, D. Steil, V. Uhlíř, L. Pang, M. Hehn, S. Alebrand, M. Cinchetti, G. Malinowski, Y. Fainman, and M. Aeschlimann. Supported by the ANR-10-BLANC-1005 ``Friends,'' a grant from the Advanced Storage Technology Consortium, Partner University Fund

  14. Ultrafast, low-power, all-optical switching via birefringent phase-matched transverse mode conversion in integrated waveguides.

    PubMed

    Hellwig, Tim; Epping, Jörn P; Schnack, Martin; Boller, Klaus-J; Fallnich, Carsten

    2015-07-27

    We demonstrate the potential of birefringence-based, all-optical, ultrafast conversion between the transverse modes in integrated optical waveguides by modelling the conversion process by numerically solving the multi-mode coupled nonlinear Schroedinger equations. The observed conversion is induced by a control beam and due to the Kerr effect, resulting in a transient index grating which coherently scatters probe light from one transverse waveguide mode into another. We introduce birefringent phase matching to enable efficient all-optically induced mode conversion at different wavelengths of the control and probe beam. It is shown that tailoring the waveguide geometry can be exploited to explicitly minimize intermodal group delay as well as to maximize the nonlinear coefficient, under the constraint of a phase matching condition. The waveguide geometries investigated here, allow for mode conversion with over two orders of magnitude reduced control pulse energy compared to previous schemes and thereby promise nonlinear mode switching exceeding efficiencies of 90% at switching energies below 1 nJ. PMID:26367581

  15. Ultralow-light-level all-optical transistor in rubidium vapor

    SciTech Connect

    Jing, Jietai Zhou, Zhifan; Liu, Cunjin; Qin, Zhongzhong; Fang, Yami; Zhou, Jun; Zhang, Weiping

    2014-04-14

    An all-optical transistor (AOT) is a device in which one light beam can efficiently manipulate another. It is the foundational component of an all-optical communication network. An AOT that can operate at ultralow light levels is especially attractive for its potential application in the quantum information field. Here, we demonstrate an AOT driven by a weak light beam with an energy density of 2.5 × 10{sup −5} photons/(λ{sup 2}/2π) (corresponding to 6  yJ/(λ{sup 2}/2π) and about 800 total photons) using the double-Λ four-wave mixing process in hot rubidium vapor. This makes it a promising candidate for ultralow-light-level optical communication and quantum information science.

  16. All-optical transistor action with bistable switching in a photonic crystal cross-waveguide geometry.

    PubMed

    Yanik, Mehmet Fatih; Fan, Shanhui; Soljacić, Marin; Joannopoulos, J D

    2003-12-15

    We demonstrate all-optical switching action in a nonlinear photonic crystal cross-waveguide geometry with instantaneous Kerr nonlinearity, in which the transmission of a signal can be reversibly switched on and off by a control input. Our geometry accomplishes both spatial and spectral separation between the signal and the control in the nonlinear regime. The device occupies a small footprint of a few micrometers squared and requires only a few milliwatts of power at a 10-Gbit/s switching rate by use of Kerr nonlinearity in AlGaAs below half the electronic bandgap. We also show that the switching dynamics, as revealed by both coupled-mode theory and finite-difference time domain simulations, exhibits collective behavior that can be exploited to generate high-contrast logic levels and all-optical memory.

  17. Photonic integrated circuit for all-optical millimeter-wave signal generation

    SciTech Connect

    Vawter, G.A.; Mar, A.; Zolper, J.; Hietala, V.

    1997-03-01

    Generation of millimeter-wave electronic signals and power is required for high-frequency communication links, RADAR, remote sensing and other applications. However, in the 30 to 300 GHz mm-wave regime, signal sources are bulky and inefficient. All-optical generation of mm-wave signals promises to improve efficiency to as much as 30 to 50 percent with output power as high as 100 mW. All of this may be achieved while taking advantage of the benefits of monolithic integration to reduce the overall size to that of a single semiconductor chip only a fraction of a square centimeter in size. This report summarizes the development of the first monolithically integrated all-optical mm-wave signal generator ever built. The design integrates a mode-locked semiconductor ring diode laser with an optical amplifier and high-speed photodetector into a single optical integrated circuit. Frequency generation is demonstrated at 30, 60 and 90 Ghz.

  18. All-optical code routing in interconnected optical CDMA and WDM ring networks.

    PubMed

    Deng, Yanhua; Fok, Mable P; Prucnal, Paul R; Wang, Ting

    2010-11-01

    We propose an all-optical hybrid network composed of optical code division multiple access (CDMA) rings interconnecting through a reconfigurable wavelength division multiplexing (WDM) metro area ring. This network retains the advantages of both the optical CDMA and WDM techniques, including asynchronous access and differentiated quality of service, while removing the hard limit on the number of subscribers and increasing network flexibility. The all-optical network is enabled by using nonlinear optical loop mirrors in an add/drop router (ADR) that performs code conversion, dropping, and switching asynchronously. We experimentally demonstrate the functionalities of the ADR in the proposed scheme asynchronously and obtain error-free performance. The bit-error rate measurements show acceptable power penalties for different code routes.

  19. Passive all-optical polarization switch, binary logic gates, and digital processor.

    PubMed

    Zaghloul, Y A; Zaghloul, A R M; Adibi, A

    2011-10-10

    We introduce the passive all-optical polarization switch, which modulates light with light. That switch is used to construct all the binary logic gates of two or more inputs. We discuss the design concepts and the operation of the AND, OR, NAND, and NOR gates as examples. The rest of the 16 logic gates are similarly designed. Cascading of such gates is straightforward as we show and discuss. Cascading in itself does not require a power source, but feedback at this stage of development does. The design and operation of an SR Latch is presented as one of the popular basic sequential devices used for memory cells. That completes the essential components of an all-optical polarization digital processor. The speed of such devices is well above 10 GHz for bulk implementations and is much higher for chip-size implementations. In addition, the presented devices do have the four essential characteristics previously thought unique to the microelectronic ones.

  20. All-optical control of microfiber resonator by graphene's photothermal effect

    NASA Astrophysics Data System (ADS)

    Wang, Yadong; Gan, Xuetao; Zhao, Chenyang; Fang, Liang; Mao, Dong; Xu, Yiping; Zhang, Fanlu; Xi, Teli; Ren, Liyong; Zhao, Jianlin

    2016-04-01

    We demonstrate an efficient all-optical control of microfiber resonator assisted by graphene's photothermal effect. Wrapping graphene onto a microfiber resonator, the light-graphene interaction can be strongly enhanced via the resonantly circulating light, which enables a significant modulation of the resonance with a resonant wavelength shift rate of 71 pm/mW when pumped by a 1540 nm laser. The optically controlled resonator enables the implementation of low threshold optical bistability and switching with an extinction ratio exceeding 13 dB. The thin and compact structure promises a fast response speed of the control, with a rise (fall) time of 294.7 μs (212.2 μs) following the 10%-90% rule. The proposed device, with the advantages of compact structure, all-optical control, and low power acquirement, offers great potential in the miniaturization of active in-fiber photonic devices.

  1. Optical packet header identification utilizing an all-optical feedback chaotic reservoir computing

    NASA Astrophysics Data System (ADS)

    Qin, Jie; Zhao, Qingchun; Xu, Dongjiao; Yin, Hongxi; Chang, Ying; Huang, Degen

    2016-06-01

    In this paper, an all-optical reservoir computing (RC) setup is proposed for identifying the types of optical packet headers in optical packet switching (OPS) network. The numerical simulation identification results of 3 bits and 32 bits optical headers with the bit rate of 10 Gbps are as low as 0.625% and 2.25%, respectively. The identification errors with the variation of the feedback strength and feedback delay are presented separately. Hence, the optimal feedback parameters are obtained. The all-optical feedback RC setup is robust to the white Gaussian noise. The recognition error is acceptable when the signal-to-noise ratio (SNR) is greater than 15 dB.

  2. An all-optical modulation method in sub-micron scale

    PubMed Central

    Yang, Longzhi; Pei, Chongyang; Shen, Ao; Zhao, Changyun; Li, Yan; Li, Xia; Yu, Hui; Li, Yubo; Jiang, Xiaoqing; Yang, Jianyi

    2015-01-01

    We report a theoretical study showing that by utilizing the illumination of an external laser, the Surface Plasmon Polaritons (SPP) signals on the graphene sheet can be modulated in the sub-micron scale. The SPP wave can propagate along the graphene in the middle infrared range when the graphene is properly doped. Graphene's carrier density can be modified by a visible laser when the graphene sheet is exfoliated on the hydrophilic SiO2/Si substrate, which yields an all-optical way to control the graphene's doping level. Consequently, the external laser beam can control the propagation of the graphene SPP between the ON and OFF status. This all-optical modulation effect is still obvious when the spot size of the external laser is reduced to 400 nm while the modulation depth is as high as 114.7 dB/μm. PMID:25777581

  3. Ultrafast, broadband, and configurable midinfrared all-optical switching in nonlinear graphene plasmonic waveguides

    NASA Astrophysics Data System (ADS)

    Ooi, Kelvin J. A.; Cheng, J. L.; Sipe, J. E.; Ang, L. K.; Tan, Dawn T. H.

    2016-07-01

    Graphene plasmonics provides a unique and excellent platform for nonlinear all-optical switching, owing to its high nonlinear conductivity and tight optical confinement. In this paper, we show that impressive switching performance on graphene plasmonic waveguides could be obtained for both phase and extinction modulations at sub-MW/cm2 optical pump intensities. Additionally, we find that the large surface-induced nonlinearity enhancement that comes from the tight confinement effect can potentially drive the propagating plasmon pump power down to the pW range. The graphene plasmonic waveguides have highly configurable Fermi-levels through electrostatic-gating, allowing for versatility in device design and a broadband optical response. The high capabilities of nonlinear graphene plasmonics would eventually pave the way for the adoption of the graphene plasmonics platform in future all-optical nanocircuitry.

  4. All-optical signal amplifier and distributor using cavity-atom coupling systems

    NASA Astrophysics Data System (ADS)

    Duan, Yafan; Lin, Gongwei; Niu, Yueping; Gong, Shangqing

    2016-05-01

    We report an all-optical signal amplifier and a signal distributor using cavity-atom coupling systems. In this system we couple atoms with an optical cavity and realize the great enhancement of a control laser by the cavity with the help of two high coupling lasers. By this effect, we can use one weak control field to control another strong target field and the intensity changes are linear with our experimental conditions. This can be used as an all-optical signal amplifier, also known as a ‘transphasor’. In our experiment, the gain of the weak field to strong field can be as high as 60. Furthermore, we can realize the distribution of optical signals, if we coordinate multiple cavity-atom coupling systems.

  5. An all-optical modulation method in sub-micron scale.

    PubMed

    Yang, Longzhi; Pei, Chongyang; Shen, Ao; Zhao, Changyun; Li, Yan; Li, Xia; Yu, Hui; Li, Yubo; Jiang, Xiaoqing; Yang, Jianyi

    2015-01-01

    We report a theoretical study showing that by utilizing the illumination of an external laser, the Surface Plasmon Polaritons (SPP) signals on the graphene sheet can be modulated in the sub-micron scale. The SPP wave can propagate along the graphene in the middle infrared range when the graphene is properly doped. Graphene's carrier density can be modified by a visible laser when the graphene sheet is exfoliated on the hydrophilic SiO2/Si substrate, which yields an all-optical way to control the graphene's doping level. Consequently, the external laser beam can control the propagation of the graphene SPP between the ON and OFF status. This all-optical modulation effect is still obvious when the spot size of the external laser is reduced to 400 nm while the modulation depth is as high as 114.7 dB/μm. PMID:25777581

  6. Femtojoule-Scale All-Optical Latching and Modulation via Cavity Nonlinear Optics

    NASA Astrophysics Data System (ADS)

    Kwon, Yeong-Dae; Armen, Michael A.; Mabuchi, Hideo

    2013-11-01

    We experimentally characterize Hopf bifurcation phenomena at femtojoule energy scales in a multiatom cavity quantum electrodynamical (cavity QED) system and demonstrate how such behaviors can be exploited in the design of all-optical memory and modulation devices. The data are analyzed by using a semiclassical model that explicitly treats heterogeneous coupling of atoms to the cavity mode. Our results highlight the interest of cavity QED systems for ultralow power photonic signal processing as well as for fundamental studies of mesoscopic nonlinear dynamics.

  7. Improved parameters metropolitan area network supported with all-optical network's technology

    NASA Astrophysics Data System (ADS)

    Gradkowska, Magdalena; Kalita, Mariusz

    2006-03-01

    The advantages of all-optical network's technics make them one of main elements of the metropolitan area networks. They enable different applications in high quality mulitimedia services and guarantee a constant and reliable access to the Internet. As the growing expansion of the Internet continues in an unpredictable direction, many new solutions are expected. The major challenge is the increasing demand for flexible, transparent and customised bandwidth services for both private and business customers.

  8. Realization of all-optical switch and diode via Raman gain process using a Kerr field

    NASA Astrophysics Data System (ADS)

    Abbas, Muqaddar; Qamar, Sajid; Qamar, Shahid

    2016-08-01

    The idea of optical photonic crystal, which is generated using two counter-propagating fields, is revisited to study gain-assisted all-optical switch and diode using Kerr field. Two counter-propagating fields with relative detuning Δ ν generate standing-wave field pattern which interacts with a four-level atomic system. The standing-wave field pattern acts like a static photonic crystal for Δ ν =0 , however, it behaves as a moving photonic crystal for Δ ν \

  9. An All-Optical Microwave Mixer with 8db RF Gain

    NASA Technical Reports Server (NTRS)

    Shieh, W.; Yao, S. X.; Lutes, G.; Maleki, L.

    1997-01-01

    An all-optical microwave mixer with an 8dB RF gain is demonstrated by using a semiconductor optical amplifier (SOA). 6GHz RF signal on a 1312 nm optical carrier is up-converted and down-converted to 1GHZ and 11 GHz by a 5GHz local oscillation (LO) signal on a 1320 nm optical carrier. Such a carrier could readily extend to millimeter wave range.

  10. On-chip integratable all-optical quantizer using strong cross-phase modulation in a silicon-organic hybrid slot waveguide

    PubMed Central

    Kang, Zhe; Yuan, Jinhui; Zhang, Xianting; Sang, Xinzhu; Wang, Kuiru; Wu, Qiang; Yan, Binbin; Li, Feng; Zhou, Xian; Zhong, Kangping; Zhou, Guiyao; Yu, Chongxiu; Farrell, Gerald; Lu, Chao; Yaw Tam, Hwa; Wai, P. K. A.

    2016-01-01

    High performance all-optical quantizer based on silicon waveguide is believed to have significant applications in photonic integratable optical communication links, optical interconnection networks, and real-time signal processing systems. In this paper, we propose an integratable all-optical quantizer for on-chip and low power consumption all-optical analog-to-digital converters. The quantization is realized by the strong cross-phase modulation and interference in a silicon-organic hybrid (SOH) slot waveguide based Mach-Zehnder interferometer. By carefully designing the dimension of the SOH waveguide, large nonlinear coefficients up to 16,000 and 18,069 W−1/m for the pump and probe signals can be obtained respectively, along with a low pulse walk-off parameter of 66.7 fs/mm, and all-normal dispersion in the wavelength regime considered. Simulation results show that the phase shift of the probe signal can reach 8π at a low pump pulse peak power of 206 mW and propagation length of 5 mm such that a 4-bit all-optical quantizer can be realized. The corresponding signal-to-noise ratio is 23.42 dB and effective number of bit is 3.89-bit. PMID:26777054

  11. All-optical photonic crystal AND, XOR, and OR logic gates using nonlinear Kerr effect and ring resonators

    NASA Astrophysics Data System (ADS)

    Salmanpour, Aryan; Mohammadnejad, Shahram; Bahrami, Ali

    2015-05-01

    In this article, two structures are proposed for all-optical AND, XOR, and OR logic gates based on nonlinear photonic crystals. The proposed structures include a Y-junction and ring resonator-based limiters. Two different structures are designed as the limiter in order to produce AND-XOR and AND-OR logic gates. Nonlinear rods of proposed structure have been used in order to create the frequency shift for different values of input power. Finite difference time domain method has been utilized to simulate the performance of proposed logic gates. Simulation results show that the smallest ON-OFF logic-level contrast ratio for the structures proposed for AND-XOR and AND-OR logic gates are 20.29 dB and 16.7 dB, respectively.

  12. Quantum optics. All-optical routing of single photons by a one-atom switch controlled by a single photon.

    PubMed

    Shomroni, Itay; Rosenblum, Serge; Lovsky, Yulia; Bechler, Orel; Guendelman, Gabriel; Dayan, Barak

    2014-08-22

    The prospect of quantum networks, in which quantum information is carried by single photons in photonic circuits, has long been the driving force behind the effort to achieve all-optical routing of single photons. We realized a single-photon-activated switch capable of routing a photon from any of its two inputs to any of its two outputs. Our device is based on a single atom coupled to a fiber-coupled, chip-based microresonator. A single reflected control photon toggles the switch from high reflection (R ~ 65%) to high transmission (T ~ 90%), with an average of ~1.5 control photons per switching event (~3, including linear losses). No additional control fields are required. The control and target photons are both in-fiber and practically identical, making this scheme compatible with scalable architectures for quantum information processing.

  13. Fast, high-fidelity, all-optical and dynamically-controlled polarization gate using room-temperature atomic vapor

    SciTech Connect

    Li, Runbing; Zhu, Chengjie; Deng, L.; Hagley, E. W.

    2014-10-20

    We demonstrate a fast, all-optical polarization gate in a room-temperature atomic medium. Using a Polarization-Selective-Kerr-Phase-Shift (PSKPS) technique, we selectively write a π phase shift to one circularly-polarized component of a linearly-polarized input signal field. The output signal field maintains its original strength but acquires a 90° linear polarization rotation, demonstrating fast, high-fidelity, dynamically-controlled polarization gate operation. The intensity of the polarization-switching field used in this PKSPK-based polarization gate operation is only 2 mW/cm{sup 2}, which would be equivalent to 0.5 nW of light power (λ = 800 nm) confined in a typical commercial photonic hollow-core fiber. This development opens a realm of possibilities for potential future extremely low light level telecommunication and information processing systems.

  14. All-optical pump-and-probe detection of two-time correlations in a Fermi gas

    SciTech Connect

    Dao, T.-L.; Kollath, C.; Carusotto, I.; Koehl, M.

    2010-04-15

    We propose an all-optical scheme to probe the dynamical correlations of a strongly interacting gas of ultracold atoms in an optical lattice potential. The proposed technique is based on a pump-and-probe scheme: a coherent light pulse is initially converted into an atomic coherence and later retrieved after a variable storage time. The efficiency of the proposed method to measure the two-time one-particle Green function of the gas is validated by numerical and analytical calculations of the expected signal for the two cases of a normal Fermi gas and a BCS superfluid state. Protocols to extract the superfluid gap and the full quasiparticle dispersions are discussed.

  15. All-optical pulse data generation in a semiconductor optical amplifier gain controlled by a reshaped optical clock injection

    NASA Astrophysics Data System (ADS)

    Lin, Gong-Ru; Chang, Yung-Cheng; Yu, Kun-Chieh

    2006-05-01

    Wavelength-maintained all-optical pulse data pattern transformation based on a modified cross-gain-modulation architecture in a strongly gain-depleted semiconductor optical amplifier (SOA) is investigated. Under a backward dark-optical-comb injection with 70% duty-cycle reshaping from the received data clock at 10GHz, the incoming optical data stream is transformed into a pulse data stream with duty cycle, rms timing jitter, and conversion gain of 15%, 4ps, and 3dB, respectively. The high-pass filtering effect of the gain-saturated SOA greatly improves the extinction ratio of data stream by 8dB and reduces its bit error rate to 10-12 at -18dBm.

  16. Probing nonlinear magnetization dynamics in Fe/MgO(001) film by all optical pump-probe technique

    SciTech Connect

    He, Wei; Hu, Bo; Zhang, Xiang-Qun; Cheng, Zhao-Hua; Zhan, Qing-Feng

    2014-04-07

    An all-optical pump-probe technique has been employed to investigate the nonlinear magnetization dynamics of a 10 nm Fe/MgO(001) thin film in time domain. The magnetization precession was excited by pump-laser pulses and modulated by laser fluence variations. With increasing the laser fluence up to 7.1 mJ/cm{sup 2}, in addition to the uniform precession mode, a second harmonic signal was detected. The time evolution of the second harmonic signal was obtained in time-frequency domain. Based on the Landau-Lifshitz-Gilbert equation, the numerical simulation was performed to reproduce the observed the frequency doubling behaviors in Fe/MgO(001) film.

  17. All-optical trion generation in single-walled carbon nanotubes.

    PubMed

    Santos, Silvia M; Yuma, Bertrand; Berciaud, Stéphane; Shaver, Jonah; Gallart, Mathieu; Gilliot, Pierre; Cognet, Laurent; Lounis, Brahim

    2011-10-28

    We present evidence of all-optical trion generation and emission in pristine single-walled carbon nanotubes (SWCNTs). Luminescence spectra, recorded on individual SWCNTs over a large cw excitation intensity range, show trion emission peaks redshifted with respect to the bright exciton peak. Clear chirality dependence is observed for 22 separate SWCNT species, allowing for determination of electron-hole exchange interaction and trion binding energy contributions. Luminescence data together with ultrafast pump-probe experiments on chirality-sorted bulk samples suggest that exciton-exciton annihilation processes generate dissociated carriers that allow for trion creation upon a subsequent photon absorption event.

  18. Resolution-enhanced all-optical analog-to-digital converter employing cascade optical quantization operation.

    PubMed

    Kang, Zhe; Zhang, Xianting; Yuan, Jinhui; Sang, Xinzhu; Wu, Qiang; Farrell, Gerald; Yu, Chongxiu

    2014-09-01

    In this paper, a cascade optical quantization scheme is proposed to realize all-optical analog-to-digital converter with efficiently enhanced quantization resolution and achievable high analog bandwidth of larger than 20 GHz. Employing the cascade structure of an unbalanced Mach-zehnder modulator and a specially designed optical directional coupler, we predict the enhancement of number-of-bits can be up to 1.59-bit. Simulation results show that a 25 GHz RF signal is efficiently digitalized with the signal-to-noise ratio of 33.58 dB and effective-number-of-bits of 5.28-bit.

  19. Anomalous nonlinear absorption in epsilon-near-zero materials: optical limiting and all-optical control.

    PubMed

    Vincenti, M A; de Ceglia, D; Scalora, Michael

    2016-08-01

    We investigate nonlinear absorption in films of epsilon-near-zero materials. The combination of large local electric fields at the fundamental frequency and material losses at the harmonic frequencies induce unusual intensity-dependent phenomena. We predict that the second-order nonlinearity of a low-damping, epsilon-near-zero slab produces an optical limiting effect that mimics a two-photon absorption process. Anomalous absorption profiles that depend on low permittivity values at the pump frequency are also predicted for third-order nonlinearities. These findings suggest new opportunities for all-optical light control and novel ways to design reconfigurable and tunable nonlinear devices.

  20. Nanopattern enabled terahertz all-optical switching on vanadium dioxide thin film

    NASA Astrophysics Data System (ADS)

    Choi, S. B.; Kyoung, J. S.; Kim, H. S.; Park, H. R.; Park, D. J.; Kim, Bong-Jun; Ahn, Y. H.; Rotermund, F.; Kim, Hyun-Tak; Ahn, K. J.; Kim, D. S.

    2011-02-01

    We demonstrate ultrafast all-optical control of terahertz (THz) radiation through nanoresonators, slot antennas with a hundred micron length but submicron width in thin gold layers, fabricated on vanadium dioxide (VO2) thin films. Our THz nanoresonators show almost perfect transmission at resonance. By virtue of phase transition of VO2 from insulating to metallic state, induced in subpicosecond time scale by moderate optical pump, ultrafast control of THz transmission is enabled. This is compared to bare VO2 films where no switching dynamics are observed under similar conditions.

  1. Coherent-population-trapping resonances with linearly polarized light for all-optical miniature atomic clocks

    SciTech Connect

    Zibrov, Sergei A.; Velichansky, Vladimir L.; Novikova, Irina; Phillips, David F.; Walsworth, Ronald L.; Zibrov, Alexander S.; Taichenachev, Alexey V.; Yudin, Valery I.

    2010-01-15

    We present a joint theoretical and experimental characterization of the coherent population trapping (CPT) resonance excited on the D{sub 1} line of {sup 87}Rb atoms by bichromatic linearly polarized laser light. We observe high-contrast transmission resonances (up to approx =25%), which makes this excitation scheme promising for miniature all-optical atomic clock applications. We also demonstrate cancellation of the first-order light shift by proper choice of the frequencies and relative intensities of the two laser-field components. Our theoretical predictions are in good agreement with the experimental results.

  2. Polarization insensitive all-optical wavelength conversion of polarization multiplexed signals using co-polarized pumps.

    PubMed

    Anthur, Aravind P; Zhou, Rui; O'Duill, Sean; Walsh, Anthony J; Martin, Eamonn; Venkitesh, Deepa; Barry, Liam P

    2016-05-30

    We study and experimentally validate the vector theory of four-wave mixing (FWM) in semiconductor optical amplifiers (SOA). We use the vector theory of FWM to design a polarization insensitive all-optical wavelength converter, suitable for advanced modulation formats, using non-degenerate FWM in SOAs and parallelly polarized pumps. We demonstrate the wavelength conversion of polarization-multiplexed (PM)-QPSK, PM-16QAM and a Nyquist WDM super-channel modulated with PM-QPSK signals at a baud rate of 12.5 GBaud, with total data rates of 50 Gbps, 100 Gbps and 200 Gbps respectively. PMID:27410100

  3. All-optical mitigation of amplitude and phase-shift drift noise in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Rocha, Peterson; Gallep, Cristiano M.; Conforti, Evandro

    2015-10-01

    An all-optical scheme aimed at minimizing distortions induced by semiconductor optical amplifiers (SOAs) over modulated optical carriers is presented. The scheme employs an additional SOA properly biased to act as a saturated absorber, and thus counteract the distortions induced by the first amplifying device. The scheme here is demonstrated in silico, for 40 and 100 Gb/s (10 and 25 Gbaud, 16 QAM), with reasonable total gain (>20 dB) for symbol error rate below the forward error correction limit.

  4. Spectrally-efficient all-optical OFDM by WSS and AWG.

    PubMed

    Hoxha, J; Morosi, J; Shimizu, S; Martelli, P; Boffi, P; Wada, N; Cincotti, G

    2015-05-01

    We report on the transmission experiment of seven 12.5-GHz spaced all optical-orthogonal frequency division multiplexed (AO-OFDM) subcarriers over a 35-km fiber link, using differential quadrature phase shift keying (DQPSK) modulation and direct detection. The system does not require chromatic dispersion compensation, optical time gating at the receiver (RX) or cyclic prefix (CP), achieving the maximum spectral efficiency. We use a wavelength selective switch (WSS) at the transmitter (TX) to allow subcarrier assignment flexibility and optimal filter shaping; an arrayed waveguide grating (AWG) AO-OFDM demultiplexer is used at the RX, to reduce the system cost and complexity. PMID:25969193

  5. Fiber Lasers and all Optical Logic Gates for Header Processing in High-Bit Optical Networks

    NASA Astrophysics Data System (ADS)

    Barnett, Brandon Craig

    As information technologies push network capacities toward higher bit rates, fiber-optic communication networks will eventually be capable of transmitting data at a rate at which electronic switches cannot respond. A solution to this problem is to replace the electronics at the front and back ends of the transmission system where data enters and exists in optical format with all-optical header processors. In this thesis, I will describe how the header processor has been divided into all-optical switching modules, which will act as the basic building block for the header processing unit. Each module arises from the integration of an erbium -doped fiber laser and an all-optical logic gate. The erbium-doped fiber laser (EDFL) acts as a local power supply for the module. It restores the pulse shape, pulse amplitude, and timing of an incoming optical bit stream. The development of a short-pulse EDFL and a high-power EDFL for this application is described. The high-power EDFL employs a unique cavity design that eliminates multiple pulses when pumped with high powers. Data processing is performed within the module by all-optical logic gates, which switch due to the nonlinear interaction of one pulse of light with another in optical fiber. Therefore, these gates can work at the bit rate of the transmission system and avoid the bottlenecks inherent in electronic processors. The design and demonstration of a low-latency soliton-dragging gate and a low-birefringent nonlinear optical loop mirror (low-bi NOLM) logic gate are described. The two logic gates are optimized for energy contrast, switching energy, timing sensitivity, and cascadability. Logic functionality is also demonstrated. The thesis culminates in an experiment that integrates the laser and logic gate work by driving two cascaded low -bi NOLM's with an EDFL. It is shown that this experiment utilizes all the components necessary to read the header of a high-bit-rate data packet, bringing closure to the switching

  6. All-optical packet header and payload separation for un-slotted optical packet switched networks

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Zhang, Min; Ye, Peida

    2005-11-01

    A novel all-optical header and payload separation technique that can be utilized in un-slotted optical packet switched networks is presented. The technique uses a modified TOAD for packet header extraction with differential modulation scheme and two SOAs that perform a simple XOR operation between the packet and its self-derived header to get the separated payload. The main virtue of this system is simple structure and need not any additional continuous pulses. Through numerical simulations, the operating characteristics of the scheme are illustrated. In addition, the parameters of the system are discussed and designed to optimize the operation performance.

  7. All-optical tomography of electron spins in (In,Ga)As quantum dots

    NASA Astrophysics Data System (ADS)

    Varwig, S.; René, A.; Economou, Sophia E.; Greilich, A.; Yakovlev, D. R.; Reuter, D.; Wieck, A. D.; Reinecke, T. L.; Bayer, M.

    2014-02-01

    We demonstrate the basic features of an all-optical spin tomography on picosecond time scale. The magnetization vector associated with a mode-locked electron spin ensemble in singly charged quantum dots is traced by ellipticity measurements using picosecond laser pulses. After optical orientation the spins precess about a perpendicular magnetic field. By comparing the dynamics of two interacting ensembles with the dynamics of a single ensemble we find buildup of a spin component along the magnetic field in the two-ensemble case. This component arises from a Heisenberg-like spin-spin interaction.

  8. Ultrafast defect dynamics: A new approach to all optical broadband switching employing amorphous selenium thin films

    SciTech Connect

    Sharma, Rituraj; Adarsh, K. V. E-mail: adarsh@iiserb.ac.in; Prasai, Kiran; Drabold, D. A. E-mail: adarsh@iiserb.ac.in

    2015-07-15

    Optical switches offer higher switching speeds than electronics, however, in most cases utilizing the interband transitions of the active medium for switching. As a result, the signal suffers heavy losses. In this article, we demonstrate a simple and yet efficient ultrafast broadband all-optical switching on ps timescale in the sub-bandgap region of the a-Se thin film, where the intrinsic absorption is very weak. The optical switching is attributed to short-lived transient defects that form localized states in the bandgap and possess a large electron-phonon coupling. We model these processes through first principles simulation that are in agreement with the experiments.

  9. Low-power all-optical tunable plasmonic-mode coupling in nonlinear metamaterials

    SciTech Connect

    Zhang, Fan; Yang, Hong; Hu, Xiaoyong E-mail: qhgong@pku.edu.cn; Gong, Qihuang E-mail: qhgong@pku.edu.cn

    2014-03-31

    All-optical tunable plasmonic-mode coupling is realized in a nonlinear photonic metamaterial consisting of periodic arrays of gold asymmetrically split ring resonators, covered with a poly[(methyl methacrylate)-co-(disperse red 13 acrylate)] azobenzene polymer layer. The third-order optical nonlinearity of the azobenzene polymer is enormously enhanced by using resonant excitation. Under excitation with a 17-kW/cm{sup 2}, 532-nm pump light, plasmonic modes shift by 51 nm and the mode interval is enlarged by 30 nm. Compared with previous reports, the threshold pump intensity is reduced by five orders of magnitude, while extremely large tunability is maintained.

  10. 40Gb/s all-optical binary-coded-decimal decoder

    NASA Astrophysics Data System (ADS)

    Lei, Lei; Zhang, Yin; Dong, Jianji; Yu, Yu; Zhang, Xinliang

    2011-12-01

    We have experimentally demonstrated a 40Gb/s all-optical binary-coded-decimal (BCD) decoder for the first time, utilizing delay interferometers (DIs) and cascading semiconductor optical amplifiers (SOAs) without any assisting light. Extinction ratios (ERs) of the intermediate results after the first SOA are all over 11dB which ensures the capability to cascade to the second one. The final results are in the form of return-to-zero (RZ) format with correct and clear temporal waveforms. The proposed scheme could be extended to 1-of-16 decoder, logic minterms and read only memory (ROM).

  11. Propagation of all-optical crosstalk attack in transparent optical networks

    NASA Astrophysics Data System (ADS)

    Peng, Yunfeng; Sun, Zeyu; Du, Shu; Long, Keping

    2011-08-01

    Transparent optical network (TON) is now rapidly booming to be popular, and a threat of an all-optical crosstalk attack with high power will emerge. In this paper, the penalty of crosstalk attack propagation, including intrachannel crosstalk inside the optical cross-connects, as well as direct and indirect interchannel crosstalk within fibers, is evaluated. Our work has proved that these crosstalk attacks do propagate in the TON but with limited propagation stages, which will be useful for the planning, management, and design of TON.

  12. Angular and polarization dependence of all optical diode in one-dimensional photonic crystal

    NASA Astrophysics Data System (ADS)

    Jamshidi-Ghaleh, Kazem; Safari, Zeinab; Moslemi, Fatemeh

    2015-05-01

    The effect of the incident angle on all-optical diode (AOD) efficiency in a one-dimensional photonic crystal structure (1DPC) for TE and TM polarizations was studied. An asymmetric hybrid Fabry Perot resonator type 1DPC structure composed of linear and nonlinear materials was considered in this communication. The nonlinear transmission curves around the defect mode resonant frequency inside the photonic band gap for both TE and TM polarizations at different incident angles, from left to right (L-R) and right to left (R-L) incidences, are illustrated. Results showed that with increasing the incident angle, AOD performance efficiency increases only for TM polarization. The AOD efficiency increased to 80% for an incident angle of 60 degrees because of the dynamical shifting of the defect mode peak frequency caused by the intensity-dependency of the nonlinear layer refractive index along the z-axes. For TE polarization, the z-component of the electric field remained constant for all incident angles. The results of this study can be important in optical data communications and information analysis in all-optical integrated circuits.

  13. Design for sequentially timed all-optical mapping photography with optimum temporal performance.

    PubMed

    Tamamitsu, Miu; Nakagawa, Keiichi; Horisaki, Ryoichi; Iwasaki, Atsushi; Oishi, Yu; Tsukamoto, Akira; Kannari, Fumihiko; Sakuma, Ichiro; Goda, Keisuke

    2015-02-15

    A recently developed ultrafast burst imaging method known as sequentially timed all-optical mapping photography (STAMP) [Nat. Photonics8, 695 (2014)10.1038/nphoton.2014.163] has been shown effective for studying a diverse range of complex ultrafast phenomena. Its all-optical image separation circumvents mechanical and electronic restrictions that traditional burst imaging methods have long struggled with, hence realizing ultrafast, continuous, burst-type image recording at a fame rate far beyond what is achievable with conventional methods. In this Letter, considering various design parameters and limiting factors, we present an optimum design for STAMP in terms of temporal properties including exposure time and frame rate. Specifically, we first derive master equations that can be used to predict the temporal performance of a STAMP system and then analyze them to realize optimum conditions. This Letter serves as a general guideline for the camera parameters of a STAMP system with optimum temporal performance that is expected to be of use for tackling problems in science that are previously unsolvable with conventional imagers.

  14. Electrical characterization of all-optical helicity-dependent switching in ferromagnetic Hall crosses

    NASA Astrophysics Data System (ADS)

    El Hadri, M. S.; Pirro, P.; Lambert, C.-H.; Bergeard, N.; Petit-Watelot, S.; Hehn, M.; Malinowski, G.; Montaigne, F.; Quessab, Y.; Medapalli, R.; Fullerton, E. E.; Mangin, S.

    2016-02-01

    We present an experimental study of all-optical helicity-dependent switching (AO-HDS) of ferromagnetic Pt/Co/Pt heterostructures with perpendicular magnetic anisotropy. The sample is patterned into a Hall cross and the AO-HDS is measured via the anomalous Hall effect. This all-electrical probing of the magnetization during AO-HDS enables a statistical quantification of the switching ratio for different laser parameters, such as the threshold power to achieve AO-HDS and the exposure time needed to reach complete switching at a given laser power. We find that the AO-HDS is a cumulative process, a certain number of optical pulses is needed to obtain a full and reproducible helicity-dependent switching. The deterministic switching of the ferromagnetic Pt/Co/Pt Hall cross provides a full "opto-spintronic device," where the remanent magnetization can be all-optically and reproducibly written and erased without the need of an external magnetic field.

  15. Formation and all-optical control of optical patterns in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Binder, R.; Tsang, C. Y.; Tse, Y. C.; Luk, M. H.; Kwong, N. H.; Chan, Chris K. P.; Leung, P. T.; Lewandowski, P.; Schumacher, Stefan; Lafont, O.; Baudin, E.; Tignon, J.

    2016-05-01

    Semiconductor microcavities offer a unique way to combine transient all-optical manipulation of GaAs quantum wells with the benefits of structural advantages of microcavities. In these systems, exciton-polaritons have dispersion relations with very small effective masses. This has enabled prominent effects, for example polaritonic Bose condensation, but it can also be exploited for the design of all-optical communication devices. The latter involves non-equilibrium phase transitions in the spatial arrangement of exciton-polaritons. We consider the case of optical pumping with normal incidence, yielding a spatially homogeneous distribution of exciton-polaritons in optical cavities containing the quantum wells. Exciton-exciton interactions can trigger instabilities if certain threshold behavior requirements are met. Such instabilities can lead, for example, to the spontaneous formation of hexagonal polariton lattices (corresponding to six-spot patterns in the far field), or to rolls (corresponding to two-spot far field patterns). The competition among these patterns can be controlled to a certain degree by applying control beams. In this paper, we summarize the theory of pattern formation and election in microcavities and illustrate the switching between patterns via simulation results.

  16. High-resolution all-optical photoacoustic imaging system for remote interrogation of biological specimens

    NASA Astrophysics Data System (ADS)

    Sampathkumar, Ashwin

    2014-05-01

    Conventional photoacoustic imaging (PAI) employs light pulses to produce a photoacoustic (PA) effect and detects the resulting acoustic waves using an ultrasound transducer acoustically coupled to the target tissue. The resolution of conventional PAI is limited by the sensitivity and bandwidth of the ultrasound transducer. We have developed an all-optical versatile PAI system for characterizing ex vivo and in vivo biological specimens. The system employs noncontact interferometric detection of the acoustic signals that overcomes limitations of conventional PAI. A 532-nm pump laser with a pulse duration of 5 ns excited the PA effect in tissue. Resulting acoustic waves produced surface displacements that were sensed using a 532-nm continuous-wave (CW) probe laser in a Michelson interferometer with a GHz bandwidth. The pump and probe beams were coaxially focused using a 50X objective giving a diffraction-limited spot size of 0.48 μm. The phase-encoded probe beam was demodulated using a homodyne interferometer. The detected time-domain signal was time reversed using k-space wave-propagation methods to produce a spatial distribution of PA sources in the target tissue. Performance was assessed using PA images of ex vivo rabbit lymph node specimens and human tooth samples. A minimum peak surface displacement sensitivity of 0.19 pm was measured. The all-optical PAI (AOPAI) system is well suited for assessment of retinal diseases, caries lesion detection, skin burns, section less histology and pressure or friction ulcers.

  17. All-optical coherent population trapping with defect spin ensembles in silicon carbide.

    PubMed

    Zwier, Olger V; O'Shea, Danny; Onur, Alexander R; van der Wal, Caspar H

    2015-01-01

    Divacancy defects in silicon carbide have long-lived electronic spin states and sharp optical transitions. Because of the various polytypes of SiC, hundreds of unique divacancies exist, many with spin properties comparable to the nitrogen-vacancy center in diamond. If ensembles of such spins can be all-optically manipulated, they make compelling candidate systems for quantum-enhanced memory, communication, and sensing applications. We report here direct all-optical addressing of basal plane-oriented divacancy spins in 4H-SiC. By means of magneto-spectroscopy, we fully identify the spin triplet structure of both the ground and the excited state, and use this for tuning of transition dipole moments between particular spin levels. We also identify a role for relaxation via intersystem crossing. Building on these results, we demonstrate coherent population trapping -a key effect for quantum state transfer between spins and photons- for divacancy sub-ensembles along particular crystal axes. These results, combined with the flexibility of SiC polytypes and device processing, put SiC at the forefront of quantum information science in the solid state.

  18. Experimental validation of optical layer performance monitoring using an all-optical network testbed

    NASA Astrophysics Data System (ADS)

    Vukovic, Alex; Savoie, Michel J.; Hua, Heng

    2004-11-01

    Communication transmission systems continue to evolve towards higher data rates, increased wavelength densities, longer transmission distances and more intelligence. Further development of dense wavelength division multiplexing (DWDM) and all-optical networks (AONs) will demand ever-tighter monitoring to assure a specified quality of service (QoS). Traditional monitoring methods have been proven to be insufficient. Higher degree of self-control, intelligence and optimization for functions within next generation networks require new monitoring schemes to be developed and deployed. Both perspective and challenges of performance monitoring, its techniques, requirements and drivers are discussed. It is pointed out that optical layer monitoring is a key enabler for self-control of next generation optical networks. Aside from its real-time feedback and the safeguarding of neighbouring channels, optical performance monitoring ensures the ability to build and control complex network topologies while maintaining an efficiently high QoS. Within an all-optical network testbed environment, key performance monitoring parameters are identified, assessed through real-time proof-of-concept, and proposed for network applications for the safeguarding of neighbouring channels in WDM systems.

  19. All-optical dynamical Casimir effect in a three-dimensional terahertz photonic band gap

    NASA Astrophysics Data System (ADS)

    Hagenmüller, David

    2016-06-01

    We identify an architecture for the observation of all-optical dynamical Casimir effect in realistic experimental conditions. We suggest that by integrating quantum wells in a three-dimensional (3D) photonic band-gap material made out of large-scale (˜200 -μ m ) germanium logs, it is possible to achieve ultrastrong light-matter coupling at terahertz frequencies for the cyclotron transition of a two-dimensional electron gas interacting with long-lived optical modes, in which vacuum Rabi splitting is comparable to the Landau level spacing. When a short, intense electromagnetic transient of duration ˜250 fs and carrying a peak magnetic field ˜5 T is applied to the structure, the cyclotron transition can be suddenly tuned on resonance with a desired photon mode, switching on the light-matter interaction and leading to a Casimir radiation emitted parallel to the quantum well plane. The radiation spectrum consists of sharp peaks with frequencies coinciding with engineered optical modes within the 3D photonic band gap, and its characteristics are extremely robust to the nonradiative damping which can be large in our system. Furthermore, the absence of continuum with associated low-energy excitations for both electromagnetic and electronic quantum states can prevent the rapid absorption of the photon flux which is likely to occur in other proposals for all-optical dynamical Casimir effect.

  20. All-optical NRZ-to-RZ data format conversion with optically injected laser diode or semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Lin, Gong-Ru; Chang, Yung-Cheng; Yu, Kun-Chieh

    2006-09-01

    By injecting the optical NRZ data into a Fabry-Perot laser diode (FPLD) synchronously modulated at below threshold condition or a semiconductor optical amplifier (SOA) gain-depleted with a backward injected clock stream, the all-optical non-return to zero (NRZ) to return-to-zero (RZ) format conversion of a STM-64 date-stream for synchronous digital hierarchy (SDH) or an OC-192 data stream for synchronous optical network (SONET) in high-speed fiber-optic communication link can be performed. Without the assistance of any complicated RF electronic circuitry, the output RZ data-stream at bit rate of up to 10 Gbit/s is successfully transformed in the optically NRZ injection-locked FPLD, in which the incoming NRZ data induces gain-switching of the FPLD without DC driving current or at below threshold condition. A power penalty of 1.2 dB is measured after NRZ-to-RZ transformation in the FPLD. Alternatively, the all-optical 10Gbits/s NRZ-to-RZ format conversion can also be demonstrated in a semiconductor optical amplifier under a backward dark-optical-comb injection with its duty-cycle 70%, which is obtained by reshaping from the received data clock at 10 GHz. The incoming optical NRZ data-stream is transformed into a pulsed RZ data-stream with its duty-cycle, rms timing jitter, and conversion gain of 15%, 4ps, and 3dB, respectively. In contrast to the FPLD, the SOA based NRZ-to-RZ converter exhibits an enhanced extinction ratio from 7 to 13 dB, and BER of 10 -13 at -18.5 dBm. In particular, the power penalty of the received RZ data-stream has greatly improved by 5 dB as compared to that obtained from FPLD.

  1. 25th anniversary article: Design of polymethine dyes for all-optical switching applications: guidance from theoretical and computational studies.

    PubMed

    Gieseking, Rebecca L; Mukhopadhyay, Sukrit; Risko, Chad; Marder, Seth R; Brédas, Jean-Luc

    2014-01-01

    All-optical switching--controlling light with light--has the potential to meet the ever-increasing demand for data transmission bandwidth. The development of organic π-conjugated molecular materials with the requisite properties for all-optical switching applications has long proven to be a significant challenge. However, recent advances demonstrate that polymethine dyes have the potential to meet the necessary requirements. In this review, we explore the theoretical underpinnings that guide the design of π-conjugated materials for all-optical switching applications. We underline, from a computational chemistry standpoint, the relationships among chemical structure, electronic structure, and optical properties that make polymethines such promising materials.

  2. All optical mode controllable Er-doped random fiber laser with distributed Bragg gratings.

    PubMed

    Zhang, W L; Ma, R; Tang, C H; Rao, Y J; Zeng, X P; Yang, Z J; Wang, Z N; Gong, Y; Wang, Y S

    2015-07-01

    An all-optical method to control the lasing modes of Er-doped random fiber lasers (RFLs) is proposed and demonstrated. In the RFL, an Er-doped fiber (EDF) recoded with randomly separated fiber Bragg gratings (FBG) is used as the gain medium and randomly distributed reflectors, as well as the controllable element. By combining random feedback of the FBG array and Fresnel feedback of a cleaved fiber end, multi-mode coherent random lasing is obtained with a threshold of 14 mW and power efficiency of 14.4%. Moreover, a laterally-injected control light is used to induce local gain perturbation, providing additional gain for certain random resonance modes. As a result, active mode selection of the RFL is realized by changing locations of the laser cavity that is exposed to the control light. PMID:26125397

  3. Sequentially timed all-optical mapping photography (STAMP) utilizing spectral filtering.

    PubMed

    Suzuki, Takakazu; Isa, Fumihiro; Fujii, Leo; Hirosawa, Kenichi; Nakagawa, Keiichi; Goda, Keisuke; Sakuma, Ichiro; Kannari, Fumihiko

    2015-11-16

    We propose and experimentally demonstrate a new method called SF-STAMP for sequentially timed all-optical mapping photography (STAMP) that utilizes spectral filtering. SF-STAMP is composed of a diffractive optical element (DOE), a band-pass filter, and two Fourier transform lenses. Using a linearly frequency-chirped pulse and converting the wavelength to the time axis, we realize single-shot ultrafast burst imaging. As an experimental demonstration of SF-STAMP, we monitor the dynamics of a laser ablation using a linearly frequency-chirped broadband pulse (>100 nm) that is temporally stretched up to ~40 ps. This imaging method is expected to be effective for investigating ultrafast dynamics in a diverse range of fields, such as photochemistry, plasma physics, and fluidics. PMID:26698529

  4. Microscale Marangoni actuation: all-optical and all-electrical methods.

    PubMed

    Farahi, R H; Passian, A; Zahrai, S; Lereu, A L; Ferrell, T L; Thundat, T

    2006-01-01

    We present experimental results from an all-optical microfluidic platform that may be complimented by a thin film all-electrical network. Using these configurations we have studied the microfluidic convective flow systems of silicone oil, glycerol, and 1,3,5-trinitrotoluene on open surfaces through the production of surface tension gradients derived from thermal gradients. We show that sufficient localized thermal variation can be created utilizing surface plasmons and/or engaging individually addressable resistive thermal elements. Both studies manipulate fluids via Marangoni forces, each having their unique exploitable advantages. Surface plasmon excitation in metal foils are the driving engine of many physical-, chemical-, and bio-sensing applications. Incorporating, for the first time, the plasmon concept in microfluidics, our results thus demonstrate great potential for simultaneous fluid actuation and sensing.

  5. Practical concept of an all-optical hot carrier solar cell

    NASA Astrophysics Data System (ADS)

    König, Dirk; Yao, Yao

    2015-08-01

    The all-optical hot carrier solar cell (aoHCSC) is an intriguing device concept which circumvents HC thermalization by feeding HCs into local radiative recombination centers. These have transition energies above the HC absorber (HCA) bandgap and are located within the HCA to match the HC ballistic mean free path, suppressing HC cooling as major loss mechanism. HC energy extraction proceeds by photon emission. We propose a technologically feasible concept of the aoHC energy converter (aoHCEC) which feeds into a conventional solar cell with its bandgap matching the emitted photons. Using real materials, the concept builds upon waveguides within a HCA which consist of highly polar direct bandgap material to promote radiative carrier recombination.

  6. Artificial eye for scotopic vision with bioinspired all-optical photosensitivity enhancer

    PubMed Central

    Liu, Hewei; Huang, Yinggang; Jiang, Hongrui

    2016-01-01

    The ability to acquire images under low-light conditions is critical for many applications. However, to date, strategies toward improving low-light imaging primarily focus on developing electronic image sensors. Inspired by natural scotopic visual systems, we adopt an all-optical method to significantly improve the overall photosensitivity of imaging systems. Such optical approach is independent of, and can effectively circumvent the physical and material limitations of, the electronics imagers used. We demonstrate an artificial eye inspired by superposition compound eyes and the retinal structure of elephantnose fish. The bioinspired photosensitivity enhancer (BPE) that we have developed enhances the image intensity without consuming power, which is achieved by three-dimensional, omnidirectionally aligned microphotocollectors with parabolic reflective sidewalls. Our work opens up a previously unidentified direction toward achieving high photosensitivity in imaging systems. PMID:26976565

  7. Studies in optical parallel processing. [All optical and electro-optic approaches

    NASA Technical Reports Server (NTRS)

    Lee, S. H.

    1978-01-01

    Threshold and A/D devices for converting a gray scale image into a binary one were investigated for all-optical and opto-electronic approaches to parallel processing. Integrated optical logic circuits (IOC) and optical parallel logic devices (OPA) were studied as an approach to processing optical binary signals. In the IOC logic scheme, a single row of an optical image is coupled into the IOC substrate at a time through an array of optical fibers. Parallel processing is carried out out, on each image element of these rows, in the IOC substrate and the resulting output exits via a second array of optical fibers. The OPAL system for parallel processing which uses a Fabry-Perot interferometer for image thresholding and analog-to-digital conversion, achieves a higher degree of parallel processing than is possible with IOC.

  8. Nanoscale sub-100 picosecond all-optical magnetization switching in GdFeCo microstructures.

    PubMed

    Le Guyader, L; Savoini, M; El Moussaoui, S; Buzzi, M; Tsukamoto, A; Itoh, A; Kirilyuk, A; Rasing, T; Kimel, A V; Nolting, F

    2015-01-01

    Ultrafast magnetization reversal driven by femtosecond laser pulses has been shown to be a promising way to write information. Seeking to improve the recording density has raised intriguing fundamental questions about the feasibility of combining ultrafast temporal resolution with sub-wavelength spatial resolution for magnetic recording. Here we report on the experimental demonstration of nanoscale sub-100 ps all-optical magnetization switching, providing a path to sub-wavelength magnetic recording. Using computational methods, we reveal the feasibility of nanoscale magnetic switching even for an unfocused laser pulse. This effect is achieved by structuring the sample such that the laser pulse, via both refraction and interference, focuses onto a localized region of the structure, the position of which can be controlled by the structural design. Time-resolved photo-emission electron microscopy studies reveal that nanoscale magnetic switching employing such focusing can be pushed to the sub-100 ps regime. PMID:25581133

  9. All-Optical Generation and Switching of Few-Cycle Millimeter-Wave Pulses

    NASA Astrophysics Data System (ADS)

    Lin, Jim-Wein; Wun, Jhih-Min; Shi, Jin-Wei; Pan, Ci-Ling

    2014-10-01

    We conducted a comparative study of two schemes of photonic generation and switching of few-cycle sub-THz or millimeter wave (MMW) pulses by use of a photonic-transmitter-mixer (PTM) module with a broadband and high-power near-ballistic uni-traveling carrier photodiode (NBUTC-PD). In the first scheme, we performed all-optical ultra-fast switching (bias modulation) of the PTM injected with a 93 GHz optical local-oscillator signal. Sub-2-cycle short MMW pulses with central frequency at 93 GHz were generated. To compare, in scheme 2, we employed femtosecond optical short pulses to directly excite the PTM under a DC bias (optical modulation). The former approach is shown to be capable of providing much less signal distortion and much shorter pulse duration than the latter.

  10. Ultrafast Nyquist OTDM demultiplexing using optical Nyquist pulse sampling in an all-optical nonlinear switch.

    PubMed

    Hirooka, Toshihiko; Seya, Daiki; Harako, Koudai; Suzuki, Daiki; Nakazawa, Masataka

    2015-08-10

    We propose the ultrahigh-speed demultiplexing of Nyquist OTDM signals using an optical Nyquist pulse as both a signal and a sampling pulse in an all-optical nonlinear switch. The narrow spectral width of the Nyquist pulses means that the spectral overlap between data and control pulses is greatly reduced, and the control pulse itself can be made more tolerant to dispersion and nonlinear distortions inside the nonlinear switch. We apply the Nyquist control pulse to the 640 to 40 Gbaud demultiplexing of DPSK and DQPSK signals using a nonlinear optical loop mirror (NOLM), and demonstrate a large performance improvement compared with conventional Gaussian control pulses. We also show that the optimum spectral profile of the Nyquist control pulse depends on the walk-off property of the NOLM.

  11. Tuning all-Optical Analog to Electromagnetically Induced Transparency in nanobeam cavities using nanoelectromechanical system

    PubMed Central

    Shi, Peng; Zhou, Guangya; deng, Jie; Tian, Feng; Chau, Fook Siong

    2015-01-01

    We report the observations of all-optical electromagnetically induced transparency in nanostructures using waveguide side-coupled with photonic crystal nanobeam cavities, which has measured linewidths much narrower than individual resonances. The quality factor of transparency resonance can be 30 times larger than those of measured individual resonances. When the gap between cavity and waveguide is reduced to 10 nm, the bandwidth of destructive interference region can reach 10 nm while the width of transparency resonance is 0.3 nm. Subsequently, a comb-drive actuator is introduced to tune the line shape of the transparency resonance. The width of the peak is reduced to 15 pm and the resulting quality factor exceeds 105. PMID:26415907

  12. Femtosecond all-optical synchronization of an X-ray free-electron laser

    DOE PAGES

    Schulz, S.; Grguraš, I.; Behrens, C.; Bromberger, H.; Costello, J. T.; Czwalinna, M. K.; Felber, M.; Hoffmann, M. C.; Ilchen, M.; Liu, H. Y.; et al

    2015-01-20

    Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarilymore » by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses.« less

  13. All-optical code-division multiple-access applications: 2(n) extended-prime codes.

    PubMed

    Zhang, J G; Kwong, W C; Mann, S

    1997-09-10

    A new family of 2(n) codes, called 2(n) extended-prime codes, is proposed for all-optical code-division multiple-access networks. Such 2(n) codes are derived from so-called extended-prime codes so that their cross-correlation functions are not greater than 1, as opposed to 2 for recently proposed 2(n) prime codes. As a result, a larger number of active users can now be supported by the new codes for a given bit-error rate than can be by 2(n) prime codes, while power-efficient, waveguide-integrable all-serial coding and correlating configurations proposed for the 2(n) prime codes can still be employed.

  14. Femtosecond all-optical synchronization of an X-ray free-electron laser

    SciTech Connect

    Schulz, S.; Grguraš, I.; Behrens, C.; Bromberger, H.; Costello, J. T.; Czwalinna, M. K.; Felber, M.; Hoffmann, M. C.; Ilchen, M.; Liu, H. Y.; Mazza, T.; Meyer, M.; Pfeiffer, S.; Prędki, P.; Schefer, S.; Schmidt, C.; Wegner, U.; Schlarb, H.; Cavalieri, A. L.

    2015-01-20

    Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses.

  15. Remoted all optical instantaneous frequency measurement system using nonlinear mixing in highly nonlinear optical fiber.

    PubMed

    Bui, Lam Anh; Mitchell, Arnan

    2013-04-01

    A novel remoted instantaneous frequency measurement system using all optical mixing is demonstrated. This system copies an input intensity modulated optical carrier using four wave mixing, delays this copy and then mixes it with the original signal, to produce an output idler tone. The intensity of this output can be used to determine the RF frequency of the input signal. This system is inherently broadband and can be easily scaled beyond 40 GHz while maintaining a DC output which greatly simplifies receiving electronics. The remoted configuration isolates the sensitive and expensive receiver hardware from the signal sources and importantly allows the system to be added to existing microwave photonic implementations without modification of the transmission module. PMID:23571944

  16. Nanoscale Confinement of All-Optical Magnetic Switching in TbFeCo

    NASA Astrophysics Data System (ADS)

    Liu, Tianmin; Wang, Tianhan; Reid, Alexander; Savoini, Matteo; Wu, Xiaofei; Konene, Benny; Granitzka, Patrick; Graves, Catherine; Higley, Daniel; Chen, Zhao; Razinskas, Gary; Hantschmann, Markus; Scherz, Andreas; Stohr, Joachim; Tsukamoto, Arata; Hecht, Bert; Kimel, Alexey; Kirilyuk, Andrei; Rasing, Theo; Durr, Hermann; Durr/Stohr Team; Theo Rasing Team; Arata Tsukamoto Team; Bert Hecht Team

    Gold two-wire antennas structures are placed upon the surface of the all-optical switching film TbFeCo. They resonate with the optical field and create a field enhancement in its vicinity, which is used to confine the area where optical switching can occur. It is demonstrated that single femtosecond optical laser pulses can reverse magnetization in a controllable fashion by such confinement. The magnetic states are imaged using resonant X-ray holography and magnetic circular dichroism. The results not only show the feasibility of controllable switching with antenna assistance but also demonstrate the highly inhomogeneous nature of the switching process, which is attributed to the material's heterogeneity. Research is supported by U.S. DOE, Office of Basic Energy Sciences, Materials Sciences and Engineering Division.

  17. Artificial eye for scotopic vision with bioinspired all-optical photosensitivity enhancer

    NASA Astrophysics Data System (ADS)

    Liu, Hewei; Huang, Yinggang; Jiang, Hongrui

    2016-04-01

    The ability to acquire images under low-light conditions is critical for many applications. However, to date, strategies toward improving low-light imaging primarily focus on developing electronic image sensors. Inspired by natural scotopic visual systems, we adopt an all-optical method to significantly improve the overall photosensitivity of imaging systems. Such optical approach is independent of, and can effectively circumvent the physical and material limitations of, the electronics imagers used. We demonstrate an artificial eye inspired by superposition compound eyes and the retinal structure of elephantnose fish. The bioinspired photosensitivity enhancer (BPE) that we have developed enhances the image intensity without consuming power, which is achieved by three-dimensional, omnidirectionally aligned microphotocollectors with parabolic reflective sidewalls. Our work opens up a previously unidentified direction toward achieving high photosensitivity in imaging systems.

  18. Artificial eye for scotopic vision with bioinspired all-optical photosensitivity enhancer.

    PubMed

    Liu, Hewei; Huang, Yinggang; Jiang, Hongrui

    2016-04-12

    The ability to acquire images under low-light conditions is critical for many applications. However, to date, strategies toward improving low-light imaging primarily focus on developing electronic image sensors. Inspired by natural scotopic visual systems, we adopt an all-optical method to significantly improve the overall photosensitivity of imaging systems. Such optical approach is independent of, and can effectively circumvent the physical and material limitations of, the electronics imagers used. We demonstrate an artificial eye inspired by superposition compound eyes and the retinal structure of elephantnose fish. The bioinspired photosensitivity enhancer (BPE) that we have developed enhances the image intensity without consuming power, which is achieved by three-dimensional, omnidirectionally aligned microphotocollectors with parabolic reflective sidewalls. Our work opens up a previously unidentified direction toward achieving high photosensitivity in imaging systems. PMID:26976565

  19. Femtosecond all-optical synchronization of an X-ray free-electron laser

    PubMed Central

    Schulz, S.; Grguraš, I.; Behrens, C.; Bromberger, H.; Costello, J. T.; Czwalinna, M. K.; Felber, M.; Hoffmann, M. C.; Ilchen, M.; Liu, H. Y.; Mazza, T.; Meyer, M.; Pfeiffer, S.; Prędki, P.; Schefer, S.; Schmidt, C.; Wegner, U.; Schlarb, H.; Cavalieri, A. L.

    2015-01-01

    Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses. PMID:25600823

  20. Spin centres in SiC for all-optical nanoscale quantum sensing under ambient conditions

    NASA Astrophysics Data System (ADS)

    Anisimov, A. N.; Babunts, R. A.; Kidalov, S. V.; Mokhov, E. N.; Soltamov, V. A.; Baranov, P. G.

    2016-07-01

    Level anticrossing (LAC) spectroscopy was demonstrated on a family of uniaxially oriented spin colour centres with S = 3/2 in the ground and excited states in hexagonal 4H-, 6H- and rhombic 15R- SiC polytypes. It was shown that these centres exhibit unique characteristics such as optical spin alignment up to the temperatures of 250 ◦C. A sharp variation of the IR photoluminescence intensity in the vicinity of LAC with the record contrast was observed, which can be used for a purely all-optical sensing of the magnetic field and temperature without applying radiofrequency field. A distinctive feature of the LAC signal is weak dependence on the direction of the magnetic field that allows one to monitor the LAC signals in the nonoriented systems, such as powder of SiC nanocrystals.

  1. All-optical pulse-echo ultrasound probe for intravascular imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Colchester, Richard J.; Noimark, Sacha; Mosse, Charles A.; Zhang, Edward Z.; Beard, Paul C.; Parkin, Ivan P.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2016-02-01

    High frequency ultrasound probes such as intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) catheters can be invaluable for guiding minimally invasive medical procedures in cardiology such as coronary stent placement and ablation. With current-generation ultrasound probes, ultrasound is generated and received electrically. The complexities involved with fabricating these electrical probes can result in high costs that limit their clinical applicability. Additionally, it can be challenging to achieve wide transmission bandwidths and adequate wideband reception sensitivity with small piezoelectric elements. Optical methods for transmitting and receiving ultrasound are emerging as alternatives to their electrical counterparts. They offer several distinguishing advantages, including the potential to generate and detect the broadband ultrasound fields (tens of MHz) required for high resolution imaging. In this study, we developed a miniature, side-looking, pulse-echo ultrasound probe for intravascular imaging, with fibre-optic transmission and reception. The axial resolution was better than 70 microns, and the imaging depth in tissue was greater than 1 cm. Ultrasound transmission was performed by photoacoustic excitation of a carbon nanotube/polydimethylsiloxane composite material; ultrasound reception, with a fibre-optic Fabry-Perot cavity. Ex vivo tissue studies, which included healthy swine tissue and diseased human tissue, demonstrated the strong potential of this technique. To our knowledge, this is the first study to achieve an all-optical pulse-echo ultrasound probe for intravascular imaging. The potential for performing all-optical B-mode imaging (2D and 3D) with virtual arrays of transmit/receive elements, and hybrid imaging with pulse-echo ultrasound and photoacoustic sensing are discussed.

  2. All-optical photoacoustic microscopy (AOPAM) system for remote characterization of biological tissues

    NASA Astrophysics Data System (ADS)

    Sampathkumar, Ashwin; Chitnis, Parag V.; Silverman, Ronald H.

    2014-03-01

    Conventional photoacoustic microscopy (PAM) employs light pulses to produce a photoacoustic (PA) effect and detects the resulting acoustic waves using an ultrasound transducer acoustically coupled to the target. The resolution of conventional PAM is limited by the sensitivity and bandwidth of the ultrasound transducer. We investigated a versatile, all-optical PAM (AOPAM) system for characterizing in vivo as well as ex vivo biological specimens. The system employs non-contact interferometric detection of PA signals that overcomes limitations of conventional PAM. A 532-nm pump laser with a pulse duration of 5 ns excites the PA effect in tissue. Resulting acoustic waves produce surface displacements that are sensed using a 532-nm continuous-wave (CW) probe laser in a Michelson interferometer with a 1- GHz bandwidth. The pump and probe beams are coaxially focused using a 50X objective giving a diffraction-limited spot size of 0.48 μm. The phase-encoded probe beam is demodulated using homodyne methods. The detected timedomain signal is time reversed using k-space wave-propagation methods to produce a spatial distribution of PA sources in the target tissue. A minimum surface-displacement sensitivity of 0.19 pm was measured. PA-induced surface displacements are very small; therefore, they impose stringent detection requirements and determine the feasibility of implementing an all-optical PAM in biomedical applications. 3D PA images of ex vivo porcine retina specimens were generated successfully. We believe the AOPAM system potentially is well suited for assessing retinal diseases and other near-surface biomedical applications such as sectionless histology and evaluation of skin burns and pressure or friction ulcers.

  3. OptoDyCE: Automated system for high-throughput all-optical dynamic cardiac electrophysiology

    NASA Astrophysics Data System (ADS)

    Klimas, Aleksandra; Yu, Jinzhu; Ambrosi, Christina M.; Williams, John C.; Bien, Harold; Entcheva, Emilia

    2016-02-01

    In the last two decades, <30% of drugs withdrawals from the market were due to cardiac toxicity, where unintended interactions with ion channels disrupt the heart's normal electrical function. Consequently, all new drugs must undergo preclinical testing for cardiac liability, adding to an already expensive and lengthy process. Recognition that proarrhythmic effects often result from drug action on multiple ion channels demonstrates a need for integrative and comprehensive measurements. Additionally, patient-specific therapies relying on emerging technologies employing stem-cell derived cardiomyocytes (e.g. induced pluripotent stem-cell-derived cardiomyocytes, iPSC-CMs) require better screening methods to become practical. However, a high-throughput, cost-effective approach for cellular cardiac electrophysiology has not been feasible. Optical techniques for manipulation and recording provide a contactless means of dynamic, high-throughput testing of cells and tissues. Here, we consider the requirements for all-optical electrophysiology for drug testing, and we implement and validate OptoDyCE, a fully automated system for all-optical cardiac electrophysiology. We demonstrate the high-throughput capabilities using multicellular samples in 96-well format by combining optogenetic actuation with simultaneous fast high-resolution optical sensing of voltage or intracellular calcium. The system can also be implemented using iPSC-CMs and other cell-types by delivery of optogenetic drivers, or through the modular use of dedicated light-sensitive somatic cells in conjunction with non-modified cells. OptoDyCE provides a truly modular and dynamic screening system, capable of fully-automated acquisition of high-content information integral for improved discovery and development of new drugs and biologics, as well as providing a means of better understanding of electrical disturbances in the heart.

  4. Experimental demonstration of all optical XOR and XNOR gates for differential phase modulated data

    NASA Astrophysics Data System (ADS)

    Kakarla, Ravikiran; Venkitesh, Deepa

    2014-05-01

    All optical logic gates play a key role in implementing an optically transparent network where the node functionalities are performed in the optical domain to reduce latency and power consumption. In this paper we present the experimental demonstration and details of optimization of all optical XOR/ XNOR gate using four-wave mixing (FWM) in Semiconductor Optical Amplifier (SOA) for 10 Gbps Differential Phase Shift Keyed (DPSK) data. Two DPSK modulated signals at carrier frequencies ω1 and ω2, phases ϕ1and ϕ2and a continuous wave pump at frequency ωCW and phase ϕCW are allowed to undergo FWM in a non-linear SOA to generate additional frequency components. The phase of the generated FWM idler corresponding to the frequency ω1+ ω2-ωCW given by ϕ1+ ϕ2- CW corresponds to the XOR operation in DPSK format. Light from a DFB and tunable laser source (TLS) are combined and phase-modulated using a pseudo-random bit sequence. The bit sequences in the two carrier wavelengths are separated in time by propagating through a sufficient length of SMF; the data is combined with a CW pump from a tunable laser and allowed to undergo non-degenerate FWM in a nonlinear SOA. The relative spacing between the pump and the signal wavelengths and their polarization states are optimized to yield maximum conversion efficiency in the desired idler. The XOR output is further propagated through a delay-line interferometer (DLI) to obtain XOR and XNOR outputs in the two ports of the DLI, in the OOK format. Extinction ratio and Contrast ratio of better than 7.2 dB and 10.6 dB respectively for the XNOR gate and 6.8 dB and 7.5 dB for the XOR gaterespectively.

  5. Numerical investigation of high-contrast ultrafast all-optical switching in low-refractive-index polymeric photonic crystal nanobeam microcavities

    NASA Astrophysics Data System (ADS)

    Meng, Zi-Ming; Zhong, Xiao-Lan; Wang, Chen; Li, Zhi-Yuan

    2012-06-01

    With the development of micro- or nano-fabrication technologies, great interest has been aroused in exploiting photonic crystal nanobeam structures. In this article the design of high-quality-factor (Q) polymeric photonic crystal nanobeam microcavities suitable for realizing ultrafast all-optical switching is presented based on the three-dimensional finite-difference time-domain method. Adopting the pump-probe technique, the ultrafast dynamic response of the all-optical switching in a nanobeam microcavity with a quality factor of 1000 and modal volume of 1.22 (λ/n)3 is numerically studied and a switching time as fast as 3.6 picoseconds is obtained. Our results indicate the great promise of applying photonic crystal nanobeam microcavities to construct integrated ultrafast tunable photonic devices or circuits incorporating polymer materials with large Kerr nonlinearity and ultrafast response speed.

  6. All-Optical 1-to-8 Wavelength Multicasting at 20 Gbit/s Exploiting Self-Phase Modulation in Dispersion Flattened Highly Nonlinear Photonic Crystal Fiber

    PubMed Central

    Hui, Zhan-Qiang

    2014-01-01

    All-optical multicasting of performing data routing from single node to multiple destinations in the optical domain is promising for next generation ultrahigh-peed photonic networks. Based on the self-phase modulation in dispersion flattened highly nonlinear photonic crystal fiber and followed spectral filtering, simultaneous 1-to-8 all-optical wavelength multicasting return-to-zero (RZ) signal at 20 Gbit/s with 100 GHz channel spaced is achieved. Wavelength tunable range and dynamic characteristic of proposed wavelength multicasting scheme is further investigated. The results show our designed scheme achieve operation wavelength range of 25 nm, OSNR of 32.01 dB and Q factor of 12.8. Moreover, the scheme has simple structure as well as high tolerance to signal power fluctuation. PMID:24711738

  7. All-optical clock recovery, photonic balancing, and saturated asymmetric filtering for fiber optic communication systems

    NASA Astrophysics Data System (ADS)

    Parsons, Earl Ryan

    In this dissertation I investigated a multi-channel and multi-bit rate all-optical clock recovery device. This device, a birefringent Fabry-Perot resonator, had previously been demonstrated to simultaneously recover the clock signal from 10 wavelength channels operating at 10 Gb/s and one channel at 40 Gb/s. Similar to clock signals recovered from a conventional Fabry-Perot resonator, the clock signal from the birefringent resonator suffers from a bit pattern effect. I investigated this bit pattern effect for birefringent resonators numerically and experimentally and found that the bit pattern effect is less prominent than for clock signals from a conventional Fabry-Perot resonator. I also demonstrated photonic balancing which is an all-optical alternative to electrical balanced detection for phase shift keyed signals. An RZ-DPSK data signal was demodulated using a delay interferometer. The two logically opposite outputs from the delay interferometer then counter-propagated in a saturated SOA. This process created a differential signal which used all the signal power present in two consecutive symbols. I showed that this scheme could provide an optical alternative to electrical balanced detection by reducing the required OSNR by 3 dB. I also show how this method can provide amplitude regeneration to a signal after modulation format conversion. In this case an RZ-DPSK signal was converted to an amplitude modulation signal by the delay interferometer. The resulting amplitude modulated signal is degraded by both the amplitude noise and the phase noise of the original signal. The two logically opposite outputs from the delay interferometer again counter-propagated in a saturated SOA. Through limiting amplification and noise modulation this scheme provided amplitude regeneration and improved the Q-factor of the demodulated signal by 3.5 dB. Finally I investigated how SPM provided by the SOA can provide a method to reduce the in-band noise of a communication signal. The

  8. Exchange scattering as the driving force for ultrafast all-optical and bias-controlled reversal in ferrimagnetic metallic structures

    NASA Astrophysics Data System (ADS)

    Kalashnikova, A. M.; Kozub, V. I.

    2016-02-01

    Experimentally observed ultrafast all-optical magnetization reversal in ferrimagnetic metals and heterostructures based on antiferromagnetically coupled ferromagnetic d - and f -metallic layers relies on intricate energy and angular momentum flow between electrons, phonons, and spins. Here we treat the problem of angular momentum transfer in the course of ultrafast laser-induced dynamics in a ferrimagnetic metallic system using microscopical approach based on the system of rate equations. We show that the magnetization reversal is supported by a coupling of d and f subsystems to delocalized s or p electrons. The latter can transfer spin between the two subsystems in an incoherent way owing to the (s ;p )-(d ;f ) exchange scattering. Since the effect of the external excitation in this process is reduced to the transient heating of the mobile electron subsystem, we also discuss the possibility to trigger the magnetization reversal by applying a voltage bias pulse to antiferromagnetically coupled metallic ferromagnetic layers embedded in point contact or tunneling structures. We argue that such devices allow controlling reversal with high accuracy. We also suggest using the anomalous Hall effect to register the reversal, thus playing a role of reading probes.

  9. All-optical switching, bistability, and slow-light transmission in photonic crystal waveguide-resonator structures.

    PubMed

    Mingaleev, Sergei F; Miroshnichenko, Andrey E; Kivshar, Yuri S; Busch, Kurt

    2006-10-01

    We analyze the resonant linear and nonlinear transmission through a photonic crystal waveguide side-coupled to a Kerr-nonlinear photonic crystal resonator. First, we extend the standard coupled-mode theory analysis to photonic crystal structures and obtain explicit analytical expressions for the bistability thresholds and transmission coefficients which provide the basis for a detailed understanding of the possibilities associated with these structures. Next, we discuss limitations of standard coupled-mode theory and present an alternative analytical approach based on the effective discrete equations derived using a Green's function method. We find that the discrete nature of the photonic crystal waveguides allows a geometry-driven enhancement of nonlinear effects by shifting the resonator location relative to the waveguide, thus providing an additional control of resonant waveguide transmission and Fano resonances. We further demonstrate that this enhancement may result in the lowering of the bistability threshold and switching power of nonlinear devices by several orders of magnitude. Finally, we show that employing such enhancements is of paramount importance for the design of all-optical devices based on slow-light photonic crystal waveguides.

  10. Gold nanoparticle-assisted all optical localized stimulation and monitoring of Ca2+ signaling in neurons

    PubMed Central

    Lavoie-Cardinal, Flavie; Salesse, Charleen; Bergeron, Éric; Meunier, Michel; De Koninck, Paul

    2016-01-01

    Light-assisted manipulation of cells to control membrane activity or intracellular signaling has become a major avenue in life sciences. However, the ability to perform subcellular light stimulation to investigate localized signaling has been limited. Here, we introduce an all optical method for the stimulation and the monitoring of localized Ca2+ signaling in neurons that takes advantage of plasmonic excitation of gold nanoparticles (AuNPs). We show with confocal microscopy that 800 nm laser pulse application onto a neuron decorated with a few AuNPs triggers a transient increase in free Ca2+, measured optically with GCaMP6s. We show that action potentials, measured electrophysiologically, can be induced with this approach. We demonstrate activation of local Ca2+ transients and Ca2+ signaling via CaMKII in dendritic domains, by illuminating a single or few functionalized AuNPs specifically targeting genetically-modified neurons. This NP-Assisted Localized Optical Stimulation (NALOS) provides a new complement to light-dependent methods for controlling neuronal activity and cell signaling. PMID:26857748

  11. Network connectivity enhancement by exploiting all optical multicast in semiconductor ring laser

    NASA Astrophysics Data System (ADS)

    Siraj, M.; Memon, M. I.; Shoaib, M.; Alshebeili, S.

    2015-03-01

    The use of smart phone and tablet applications will provide the troops for executing, controlling and analyzing sophisticated operations with the commanders providing crucial documents directly to troops wherever and whenever needed. Wireless mesh networks (WMNs) is a cutting edge networking technology which is capable of supporting Joint Tactical radio System (JTRS).WMNs are capable of providing the much needed bandwidth for applications like hand held radios and communication for airborne and ground vehicles. Routing management tasks can be efficiently handled through WMNs through a central command control center. As the spectrum space is congested, cognitive radios are a much welcome technology that will provide much needed bandwidth. They can self-configure themselves, can adapt themselves to the user requirement, provide dynamic spectrum access for minimizing interference and also deliver optimal power output. Sometimes in the indoor environment, there are poor signal issues and reduced coverage. In this paper, a solution utilizing (CR WMNs) over optical network is presented by creating nanocells (PCs) inside the indoor environment. The phenomenon of four-wave mixing (FWM) is exploited to generate all-optical multicast using semiconductor ring laser (SRL). As a result same signal is transmitted at different wavelengths. Every PC is assigned a unique wavelength. By using CR technology in conjunction with PC will not only solve network coverage issue but will provide a good bandwidth to the secondary users.

  12. All-optical modulation in Mid-Wavelength Infrared using porous Si membranes.

    PubMed

    Park, Sung Jin; Zakar, Ammar; Zerova, Vera L; Chekulaev, Dimitri; Canham, Leigh T; Kaplan, Andre

    2016-01-01

    We demonstrate for the first time the possibility of all-optical modulation of self-standing porous Silicon (pSi) membrane in the Mid-Wavelength Infrared (MWIR) range using femtosecond pump-probe techniques. To study optical modulation, we used pulses of an 800 nm, 60 femtosecond for pump and a MWIR tunable probe in the spectral range between 3.5 and 4.4 μm. We show that pSi possesses a natural transparency window centred around 4 μm. Yet, about 55% of modulation contrast can be achieved by means of optical excitation at the pump power of 60 mW (4.8 mJ/cm(2)). Our analysis shows that the main mechanism of the modulation is interaction of the MWIR signal with the free charge carrier excited by the pump. The time-resolved measurements showed a sub-picosecond rise time and a recovery time of about 66 ps, which suggests a modulation speed performance of ~15 GHz. This optical modulation of pSi membrane in MWIR can be applied to a variety of applications such as thermal imaging and free space communications. PMID:27440224

  13. All-Optical Quasi-Phase Matching of Frequency Doubling Using Counterpropagating Light

    NASA Astrophysics Data System (ADS)

    Camuccio, Richard; Myer, Rachel; Penfield, Allison; Gagnon, Etienne; Lytle, Amy

    Nonlinear optical frequency conversion is a useful method for creating coherent light sources with unique capabilities. The main challenge for conversion efficiency of processes like frequency doubling is the chromatic dispersion of the nonlinear medium. Successful techniques for correcting the phase mismatch between the different frequencies are often limited by the type of nonlinear medium that may be used. An all-optical method of quasi-phase matching using counterpropagating light has recently been demonstrated for high-order harmonic generation, an extreme nonlinear process. Sequences of counterpropagating pulses are used to interfere with the harmonic generation process periodically, correcting the phase mismatch and boosting efficiency. We report progress on an experimental investigation of the effect of counterpropagating light on the more commonly used low-order nonlinear optical processes. We present data showing the effects of a single counterpropagating pulse on the efficiency of frequency doubling of a Ti:sapphire ultrafast laser oscillator in beta-Barium Borate. Research Corporation for Science Advancement (RCSA), Cottrell College Science Award #21084; Franklin & Marshall Hackman Summer Scholars Program.

  14. All-optical light storage in bound states in the continuum and release by demand.

    PubMed

    Bulgakov, E N; Pichugin, K N; Sadreev, A F

    2015-08-24

    In the framework of the temporal coupled mode theory we consider bound states embedded in the continuum (BSC) of photonic crystal waveguide as a capacity for light storage. A symmetry protected BSC occurs in two off-channel microresonators positioned symmetrically relative to the waveguide. We demonstrate that the symmetry protected BSC captures a fraction of a light pulse due to the Kerr effect as the pulse passes by the microresonators. However the amount of captured light is found to be strongly sensitive to the parameters of the gaussian light pulse such as basic frequency, duration and intensity. In contrast to the above case the BSC resulted from a full destructive interference of two eigenmodes of a single microresonator accumulates a fixed amount of light dependent on the material parameters of the microresonator but independent of the light pulse. The BSCs in the Fabry-Perot resonator show similar effects. We also show that the accumulated light can be released by a secondary pulse. These phenomena pave a way for all-optical storage and release of light.

  15. All-Optical dc Nanotesla Magnetometry Using Silicon Vacancy Fine Structure in Isotopically Purified Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Simin, D.; Soltamov, V. A.; Poshakinskiy, A. V.; Anisimov, A. N.; Babunts, R. A.; Tolmachev, D. O.; Mokhov, E. N.; Trupke, M.; Tarasenko, S. A.; Sperlich, A.; Baranov, P. G.; Dyakonov, V.; Astakhov, G. V.

    2016-07-01

    We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-28SiC) and reveal not yet considered terms in the spin Hamiltonian, originated from the trigonal pyramidal symmetry of this spin-3 /2 color center. These terms give rise to additional spin transitions, which would be otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity better than 100 nT /√{Hz } within a volume of 3 ×10-7m m3 at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radio-frequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3 mm3 , the projection noise limit is below 100 fT /√{Hz } .

  16. Polyimide-etalon all-optical ultrasound transducer for high frequency applications

    NASA Astrophysics Data System (ADS)

    Sheaff, Clay; Ashkenazi, Shai

    2014-03-01

    We have enhanced our design for an all-optical high frequency ultrasound transducer consisting of a UV-absorbing polyimide film integrated into an etalon receiver operating in the NIR range. A dielectric stack having high NIR reflectivity and high UV transmittance was chosen as the first mirror for increased sensitivity and the allowance of polyimide as the etalon medium. A 13 ns, 0.7 μJ optical pulse at 355 nm and a continuous-wave NIR laser were focused onto the structure with a spot diameter of 120 and 35 μm, respectively. In receive mode the etalon had a noise-equivalent pressure of 4.1 kPa over a bandwidth of 5 - 50 MHz (0.61 Pa/√Hz ). The device generated a pressure of 270 kPa at a depth of 200 μm, and the -3 dB bandwidth of the emission extended from 27 to 60 MHz. In transmit/receive mode, the pulse-echo had a center frequency of 35 MHz with a -6 dB bandwidth of 49 MHz (140 %). Lastly, wire targets were imaged by scanning the UV spot to create a synthetic aperture of transmitters centered upon a single receiver.

  17. Carrier transport in an InGaAs(P)/InP all-optical switching structure

    SciTech Connect

    Knorr, C.; Wilhelm, U.; Ottenwaelder, D.; Scholz, F.; Hangleiter, A.

    1996-12-31

    All-optical switches play a central role in optical computing and optical data processing. SEEDs (self electro-optic effect devices) are one class of devices, which work at low optical power, but need an external electrical feedback. The authors presented a specially designed SCMQW structure, where hole transport is controlled by an additional large heterobarrier. This barrier gives access to steady state escape times by measuring the charge carrier induced field change in the MWQ region. The authors get a minimum value for the hole extraction time over the barrier of several {micro}s at 77 K. At a temperature of 200 K the measured time constants lie below the values, which their rate equation model and the semi-classical model predict, and show a stronger field dependence. This could be accounted for thermally assisted tunneling and contribution of light hole transport, which both reduce the effective barrier height and show a stronger field dependence. Further investigations of the transport times are currently in progress by changing the thickness of the InP barrier and the barrier height of the quaternary material.

  18. Imaging and detection of early stage dental caries with an all-optical photoacoustic microscope

    NASA Astrophysics Data System (ADS)

    Hughes, D. A.; Sampathkumar, A.; Longbottom, C.; Kirk, K. J.

    2015-01-01

    Tooth decay, at its earliest stages, manifests itself as small, white, subsurface lesions in the enamel. Current methods for detection in the dental clinic are visual and tactile investigations, and bite-wing X-ray radiographs. These techniques suffer from poor sensitivity and specificity at the earliest (and reversible) stages of the disease due to the small size (<100μm) of the lesion. A fine-resolution (600 nm) ultra-broadband (200 MHz) all-optical photoacoustic microscopy system was is used to image the early signs of tooth decay. Ex-vivo tooth samples exhibiting white spot lesions were scanned and were found to generate a larger (one order of magnitude) photoacoustic (PA) signal in the lesion regions compared to healthy enamel. The high contrast in the PA images potentially allows lesions to be imaged and measured at a much earlier stage than current clinical techniques allow. PA images were cross referenced with histology photographs to validate our experimental results. Our PA system provides a noncontact method for early detection of white-spot lesions with a high detection bandwidth that offers advantages over previously demonstrated ultrasound methods. The technique provides the sensing depth of an ultrasound system, but with the spatial resolution of an optical system.

  19. All optical read-out radiation dosimeter using CVD synthetic diamond

    NASA Astrophysics Data System (ADS)

    Preciado-Flores, S.; Schreck, M.; Meléndrez, R.; Chernov, V.; Pedroza-Montero, M.; Barboza-Flores, M.

    2006-09-01

    In the present work, we evaluate the optically stimulated luminescence (OSL) dosimetric properties of two polycrystalline 10 m thick films, undoped and 750 ppm nitrogen doped, grown on (100) silicon substrates exposed to beta radiation. The samples were optically stimulated to free and to induce radiative recombination of the trapped charges caused by radiation absorption. This all optical technique uses IR laser 830 nm light for stimulation and a PMT coupled to a BG-39 (300-600 nm) filter for light intensity measurements. The OSL of both samples is very similar in output intensity and hyperbolic decay type. The OSL signal of non doped samples involves localized trapping states around the 373-653 K as compared to nitrogen doped sample which involves the charge detrapping of localized states in the 353-550 K range. The OSL signal in the first 0.16 s shows two linearity regions for 0-35 Gy and 35-100 Gy dose ranges. An obvious advantage of OSL over TL/TSC methods is that no heating is required, it may also open the possibility of using CVD diamond coupled to optical fibers for stimulation and read-out light signals allowing in situ and real time dose measurements.

  20. Quantum-dot all-optical logic in a structured vacuum

    SciTech Connect

    Ma Xun; John, Sajeev

    2011-07-15

    We demonstrate multiwavelength channel optical logic operations on the Bloch vector of a quantum two-level system in the structured electromagnetic vacuum of a bimodal photonic crystal waveguide. This arises through a bichromatic strong-coupling effect that enables unprecedented control over single quantum-dot (QD) excitation through two beams of ultrashort femtojoule pulses. The second driving pulse (signal) with slightly different frequency and weaker strength than the first (holding) pulse leads to controllable strong modulation of the QD Bloch vector evolution path. This occurs through resonant coupling of the signal pulse with the Mollow sideband transitions created by the holding pulse. The movement of the Mollow sidebands during the passage of the holding pulse leads to an effective chirping in transition frequency seen by the signal. Bloch vector dynamics in the rotating frame of the signal pulse and within the dressed-state basis created by the holding pulse reveals that this chirped coupling between the signal pulse and the Mollow sidebands leads to either augmentation or negation of the final quantum-dot population (after pulse passage) compared to the outcome of the holding pulse alone and depending on the relative frequencies of the pulses. By making use of this extra degree of freedom for ultrafast control of QD excitations, applications in ultrafast all-optical logic and, or, and not gates are proposed in the presence of significant (0.1) THz nonradiative dephasing and (about 1%) inhomogeneous broadening.

  1. All-optical frequency and intensity noise suppression of single-frequency fiber laser.

    PubMed

    Li, Can; Xu, Shanhui; Huang, Xiang; Xiao, Yu; Feng, Zhouming; Yang, Changsheng; Zhou, Kaijun; Lin, Wei; Gan, Jiulin; Yang, Zhongmin

    2015-05-01

    An all-optical frequency and intensity noise suppression technique of a single-frequency fiber laser is demonstrated. By exploiting the recursive noise reduction effect of a semiconductor optical amplifier (SOA) in a self-injection locked fiber laser, the frequency and intensity noise of the laser are remarkably suppressed in a significantly wide frequency range. In addition to the linewidth suppression from 3.5 kHz to 700 Hz, the frequency noise has been reduced by ∼25  dB. After suppression, the relative intensity noise (RIN) is within 5 dB of the shot noise limit at frequencies from 1.5 to 3 MHz, and the frequency range of the suppression reaches about 30 MHz. The relaxation oscillation peak is observed to shift to lower frequencies and is reduced by about 35 dB from -90  dB/Hz to -125  dB/Hz. It is believed that the achieved low noise makes the fiber laser a promising candidate in applications such as ultra-long haul coherent optical communication and LIDAR.

  2. All-optical modulation in Mid-Wavelength Infrared using porous Si membranes.

    PubMed

    Park, Sung Jin; Zakar, Ammar; Zerova, Vera L; Chekulaev, Dimitri; Canham, Leigh T; Kaplan, Andre

    2016-07-21

    We demonstrate for the first time the possibility of all-optical modulation of self-standing porous Silicon (pSi) membrane in the Mid-Wavelength Infrared (MWIR) range using femtosecond pump-probe techniques. To study optical modulation, we used pulses of an 800 nm, 60 femtosecond for pump and a MWIR tunable probe in the spectral range between 3.5 and 4.4 μm. We show that pSi possesses a natural transparency window centred around 4 μm. Yet, about 55% of modulation contrast can be achieved by means of optical excitation at the pump power of 60 mW (4.8 mJ/cm(2)). Our analysis shows that the main mechanism of the modulation is interaction of the MWIR signal with the free charge carrier excited by the pump. The time-resolved measurements showed a sub-picosecond rise time and a recovery time of about 66 ps, which suggests a modulation speed performance of ~15 GHz. This optical modulation of pSi membrane in MWIR can be applied to a variety of applications such as thermal imaging and free space communications.

  3. All optical experimental design for neuron excitation, inhibition, and action potential detection

    NASA Astrophysics Data System (ADS)

    Walsh, Alex J.; Tolstykh, Gleb; Martens, Stacey; Sedelnikova, Anna; Ibey, Bennett L.; Beier, Hope T.

    2016-03-01

    Recently, infrared light has been shown to both stimulate and inhibit excitatory cells. However, studies of infrared light for excitatory cell inhibition have been constrained by the use of invasive and cumbersome electrodes for cell excitation and action potential recording. Here, we present an all optical experimental design for neuronal excitation, inhibition, and action potential detection. Primary rat neurons were transfected with plasmids containing the light sensitive ion channel CheRiff. CheRiff has a peak excitation around 450 nm, allowing excitation of transfected neurons with pulsed blue light. Additionally, primary neurons were transfected with QuasAr2, a fast and sensitive fluorescent voltage indicator. QuasAr2 is excited with yellow or red light and therefore does not spectrally overlap CheRiff, enabling imaging and action potential activation, simultaneously. Using an optic fiber, neurons were exposed to blue light sequentially to generate controlled action potentials. A second optic fiber delivered a single pulse of 1869nm light to the neuron causing inhibition of the evoked action potentials (by the blue light). When used in concert, these optical techniques enable electrode free neuron excitation, inhibition, and action potential recording, allowing research into neuronal behaviors with high spatial fidelity.

  4. All-optical modulation in Mid-Wavelength Infrared using porous Si membranes

    PubMed Central

    Park, Sung Jin; Zakar, Ammar; Zerova, Vera L.; Chekulaev, Dimitri; Canham, Leigh T.; Kaplan, Andre

    2016-01-01

    We demonstrate for the first time the possibility of all-optical modulation of self-standing porous Silicon (pSi) membrane in the Mid-Wavelength Infrared (MWIR) range using femtosecond pump-probe techniques. To study optical modulation, we used pulses of an 800 nm, 60 femtosecond for pump and a MWIR tunable probe in the spectral range between 3.5 and 4.4 μm. We show that pSi possesses a natural transparency window centred around 4 μm. Yet, about 55% of modulation contrast can be achieved by means of optical excitation at the pump power of 60 mW (4.8 mJ/cm2). Our analysis shows that the main mechanism of the modulation is interaction of the MWIR signal with the free charge carrier excited by the pump. The time-resolved measurements showed a sub-picosecond rise time and a recovery time of about 66 ps, which suggests a modulation speed performance of ~15 GHz. This optical modulation of pSi membrane in MWIR can be applied to a variety of applications such as thermal imaging and free space communications. PMID:27440224

  5. All-optical bidirectional neural interfacing using hybrid multiphoton holographic optogenetic stimulation

    PubMed Central

    Paluch-Siegler, Shir; Mayblum, Tom; Dana, Hod; Brosh, Inbar; Gefen, Inna; Shoham, Shy

    2015-01-01

    Abstract. Our understanding of neural information processing could potentially be advanced by combining flexible three-dimensional (3-D) neuroimaging and stimulation. Recent developments in optogenetics suggest that neurophotonic approaches are in principle highly suited for noncontact stimulation of network activity patterns. In particular, two-photon holographic optical neural stimulation (2P-HONS) has emerged as a leading approach for multisite 3-D excitation, and combining it with temporal focusing (TF) further enables axially confined yet spatially extended light patterns. Here, we study key steps toward bidirectional cell-targeted 3-D interfacing by introducing and testing a hybrid new 2P-TF-HONS stimulation path for accurate parallel optogenetic excitation into a recently developed hybrid multiphoton 3-D imaging system. The system is shown to allow targeted all-optical probing of in vitro cortical networks expressing channelrhodopsin-2 using a regeneratively amplified femtosecond laser source tuned to 905 nm. These developments further advance a prospective new tool for studying and achieving distributed control over 3-D neuronal circuits both in vitro and in vivo. PMID:26217673

  6. An all-optical Compton source for single-exposure x-ray imaging

    NASA Astrophysics Data System (ADS)

    Döpp, A.; Guillaume, E.; Thaury, C.; Gautier, J.; Andriyash, I.; Lifschitz, A.; Malka, V.; Rousse, A.; Phuoc, K. Ta

    2016-03-01

    All-optical Compton sources are innovative, compact devices to produce high energy femtosecond x-rays. Here we present results on a single-pulse scheme that uses a plasma mirror to reflect the drive beam of a laser plasma accelerator and to make it collide with the highly-relativistic electrons in its wake. The accelerator is operated in the self-injection regime, producing quasi-monoenergetic electron beams of around 150 MeV peak energy. Scattering with the intense femtosecond laser pulse leads to the emission of a collimated high energy photon beam. Using continuum-attenuation filters we measure significant signal content beyond 100 keV and with simulations we estimate a peak photon energy of around 500 keV. The source divergence is about 13 mrad and the pointing stability is 7 mrad. We demonstrate that the photon yield from the source is sufficiently high to illuminate a centimeter-size sample placed 90 centimeters behind the source, thus obtaining radiographs in a single shot.

  7. Gold nanoparticle-assisted all optical localized stimulation and monitoring of Ca2+ signaling in neurons

    NASA Astrophysics Data System (ADS)

    Lavoie-Cardinal, Flavie; Salesse, Charleen; Bergeron, Éric; Meunier, Michel; de Koninck, Paul

    2016-02-01

    Light-assisted manipulation of cells to control membrane activity or intracellular signaling has become a major avenue in life sciences. However, the ability to perform subcellular light stimulation to investigate localized signaling has been limited. Here, we introduce an all optical method for the stimulation and the monitoring of localized Ca2+ signaling in neurons that takes advantage of plasmonic excitation of gold nanoparticles (AuNPs). We show with confocal microscopy that 800 nm laser pulse application onto a neuron decorated with a few AuNPs triggers a transient increase in free Ca2+, measured optically with GCaMP6s. We show that action potentials, measured electrophysiologically, can be induced with this approach. We demonstrate activation of local Ca2+ transients and Ca2+ signaling via CaMKII in dendritic domains, by illuminating a single or few functionalized AuNPs specifically targeting genetically-modified neurons. This NP-Assisted Localized Optical Stimulation (NALOS) provides a new complement to light-dependent methods for controlling neuronal activity and cell signaling.

  8. All-optical modulation in Mid-Wavelength Infrared using porous Si membranes

    NASA Astrophysics Data System (ADS)

    Park, Sung Jin; Zakar, Ammar; Zerova, Vera L.; Chekulaev, Dimitri; Canham, Leigh T.; Kaplan, Andre

    2016-07-01

    We demonstrate for the first time the possibility of all-optical modulation of self-standing porous Silicon (pSi) membrane in the Mid-Wavelength Infrared (MWIR) range using femtosecond pump-probe techniques. To study optical modulation, we used pulses of an 800 nm, 60 femtosecond for pump and a MWIR tunable probe in the spectral range between 3.5 and 4.4 μm. We show that pSi possesses a natural transparency window centred around 4 μm. Yet, about 55% of modulation contrast can be achieved by means of optical excitation at the pump power of 60 mW (4.8 mJ/cm2). Our analysis shows that the main mechanism of the modulation is interaction of the MWIR signal with the free charge carrier excited by the pump. The time-resolved measurements showed a sub-picosecond rise time and a recovery time of about 66 ps, which suggests a modulation speed performance of ~15 GHz. This optical modulation of pSi membrane in MWIR can be applied to a variety of applications such as thermal imaging and free space communications.

  9. Continuous all-optical deceleration and single-photon cooling of molecular beams

    NASA Astrophysics Data System (ADS)

    Jayich, A. M.; Vutha, A. C.; Hummon, M. T.; Porto, J. V.; Campbell, W. C.

    2014-02-01

    Ultracold molecular gases are promising as an avenue to rich many-body physics, quantum chemistry, quantum information, and precision measurements. This richness, which flows from the complex internal structure of molecules, makes the creation of ultracold molecular gases using traditional methods (laser plus evaporative cooling) a challenge, in particular due to the spontaneous decay of molecules into dark states. We propose a way to circumvent this key bottleneck using an all-optical method for decelerating molecules using stimulated absorption and emission with a single ultrafast laser. We further describe single-photon cooling of the decelerating molecules that exploits their high dark state pumping rates, turning the principal obstacle to molecular laser cooling into an advantage. Cooling and deceleration may be applied simultaneously and continuously to load molecules into a trap. We discuss implementation details including multilevel numerical simulations of strontium monohydride. These techniques are applicable to a large number of molecular species and atoms with the only requirement being an electric dipole transition that can be accessed with an ultrafast laser.

  10. A Day at the Beach: A Multidisciplinary Business Law Case Study

    ERIC Educational Resources Information Center

    Rymsza, Leonard; Saunders, Kurt; Baum, Paul; Tontz, Richard

    2010-01-01

    This case study, written for use in a multidisciplinary course, exposes students to concepts in business law, economics, and statistics. The case is based upon a hypothetical scenario involving a young woman who, having spent a relaxing day at the beach, heads for home. On the drive home, a flip-flop she is wearing becomes lodged under the gas…

  11. All-optical single-sideband frequency upconversion utilizing the XPM effect in an SOA-MZI.

    PubMed

    Kim, Doo-Ho; Lee, Joo-Young; Choi, Hyung-June; Song, Jong-In

    2016-09-01

    An all-optical single sideband (OSSB) frequency upconverter based on the cross-phase modulation (XPM) effect is proposed and experimentally demonstrated to overcome the power fading problem caused by the chromatic dispersion of fiber in radio-over-fiber systems. The OSSB frequency upconverter consists of an arrayed waveguide grating (AWG) and a semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) and does not require an extra delay line used for phase noise compensation. The generated OSSB radio frequency (RF) signal transmitted over single-mode fibers up to 20 km shows a flat electrical RF power response as a function of the fiber length. The upconverted electrical RF signal at 48 GHz shows negligible degradation of the phase noise even without an extra delay line. The measured phase noise of the upconverted RF signal (48 GHz) is -74.72 dBc/Hz at an offset frequency of 10 kHz. The spurious free dynamic range (SFDR) measured by a two-tone test to estimate the linearity of the OSSB frequency upconverter is 72.5 dB·Hz2/3. PMID:27607637

  12. Effectiveness of phase-conjugated twin waves on fiber nonlinearity in spatially multiplexed all-optical OFDM system

    NASA Astrophysics Data System (ADS)

    Hmood, Jassim K.; Noordin, Kamarul A.; Harun, Sulaiman W.

    2016-07-01

    In this paper, we investigate the effectiveness of using phase-conjugated twin waves (PCTWs) technique to mitigate fiber nonlinear impairments in spatially multiplexed all-optical orthogonal frequency division multiplexing (AO-OFDM) systems. In this technique, AO-OFDM signal and its phase-conjugated copy are directly transmitted through two identical fiber links. At the receiver, the two signals are coherently superimposed to cancel the phase noise and to enhance signal-to-noise ratio (SNR). To show the effectiveness of proposed technique, a spatially multiplexed AO-OFDM system is demonstrated by numerical simulation. AO-OFDM signal and its phase conjugated copy are optically generated by using optical coupler-based inverse fast Fourier transform (OIFFT)/fast Fourier transform (OFFT). The generated signal includes 29 subcarriers where each subcarrier is modulated by 4-quadrature amplitude modulation (4QAM) format at a symbol rate of 25 Gsymbol/s. The results reveal that transmission performance is considerably improved where the transmission distance of the proposed system is increased by ∼45% as compared to that of original system without PCTWs technique.

  13. Applications of all optical signal processing for advanced optical modulation formats

    NASA Astrophysics Data System (ADS)

    Nuccio, Scott R.

    signal processing may play a role in the future development of more efficient optical transmission systems. The hope is that performing signal processing in the optical domain may reduce optical-to-electronic conversion inefficiencies, eliminate bottlenecks and take advantage of the ultrahigh bandwidth inherent in optics. While 40 to 50 Gbit/s electronic components are the peak of commercial technology and 100 Gbit/s capable RF components are still in their infancy, optical signal processing of these high-speed data signals may provide a potential solution. Furthermore, any optical processing system or sub-system must be capable of handling the wide array of data formats and data rates that networks may employ. It is also worth noting that future networks may use a combination of data-rates and formats while it has been estimated that "we may start seeing the first commercial use of Terabit Ethernets by 2015". -Robert Metcalfe. To this end, the work presented in this Ph.D. dissertation is aimed at addressing the issue of optical processing for advanced optical modulation formats. All optical multiplexing and demultiplexing of Pol-MUX and phase and QAM encoded signals at the 100 Gbit/s Ethernet standard is addressed. The creation and development of an extremely large continuously tunable all-optical delay capable of handling a variety of modulation formats and data rates is presented. As optical delays are viewed as a critical element to achieve efficient and reconfigurable signal processing, the presented delay line is also utilized to enable a tunable packet buffer capable of handling data packets of varying rate, varying size, and multiple modulation formats.

  14. A mathematical model of the sleep/wake cycle.

    PubMed

    Rempe, Michael J; Best, Janet; Terman, David

    2010-05-01

    We present a biologically-based mathematical model that accounts for several features of the human sleep/wake cycle. These features include the timing of sleep and wakefulness under normal and sleep-deprived conditions, ultradian rhythms, more frequent switching between sleep and wakefulness due to the loss of orexin and the circadian dependence of several sleep measures. The model demonstrates how these features depend on interactions between a circadian pacemaker and a sleep homeostat and provides a biological basis for the two-process model for sleep regulation. The model is based on previous "flip-flop" conceptual models for sleep/wake and REM/NREM and we explore whether the neuronal components in these flip-flop models, with the inclusion of a sleep-homeostatic process and the circadian pacemaker, are sufficient to account for the features of the sleep/wake cycle listed above. The model is minimal in the sense that, besides the sleep homeostat and constant cortical drives, the model includes only those nuclei described in the flip-flop models. Each of the cell groups is modeled by at most two differential equations for the evolution of the total population activity, and the synaptic connections are consistent with those described in the flip-flop models. A detailed analysis of the model leads to an understanding of the mathematical mechanisms, as well as insights into the biological mechanisms, underlying sleep/wake dynamics.

  15. Effect of pH on all-optical switching with bR films

    NASA Astrophysics Data System (ADS)

    Fimia, A.; Gomariz, M.; Murciano, A.; Acebal, P.; Madrigal, R.; Blaya, S.; Carretero, L.; Alemañ, R.; Meseguer, I.

    2012-06-01

    Protein Bacteriorhodopsin (bR) is one of the most promising and widely studied biomaterials for photonic applications like optical storage, modulation devices and photosynthetic light energy transduction. In this paper, we present the corresponding experimental results when pH-controlled modifications of bR doped polymeric films are realized in order to apply these systems to all-optical switching processes and technologies. In this work, the performance of wild type bR processed in polymeric films with different pH was tested in several series of experiments by varying the pump beam (532 nm) period of ON and OFF and analyzing the amplitude contrast and switching time of the probe beam (633 nm). The influence of pH values on contrast ratio and switching time were also discussed and the optimal value was found by defining a new parameter called "switching speed". As a result, the variation of pH can be used to obtain different time of response and speed of modulation. Concretely, we find that, in function of pH, variations of a magnitude order in contrast ratio and time response can be obtained. So, at the red region of the probe beam, high pH values produce high transmission with flat response in the contrast ratio and a magnitude order variation in switching time. On the other hand, at medium pH values and when high intensities are used, the switching time and contrast ratio are better. Moreover, it is demonstrated that as a function of the wavelength of the probe beam the transmission response curve changes. Absorption response is very important and depends on relaxation time processes of intermediate species which are function of pH values. Therefore, these results bring the possibility for controlling the contrast ratio and the switching time in a specific way which could be useful for different applications.

  16. All-optical photoacoustic imaging and detection of early-stage dental caries

    NASA Astrophysics Data System (ADS)

    Sampathkumar, Ashwin; Hughes, David A.; Longbottom, Chris; Kirk, Katherine J.

    2015-02-01

    Dental caries remain one of the most common oral diseases in the world. Current detection methods, such as dental explorer and X-ray radiography, suffer from poor sensitivity and specificity at the earliest (and reversible) stages of the disease because of the small size (< 100 microns) of early-stage lesions. We have developed a fine-resolution (480 nm), ultra-broadband (1 GHz), all-optical photoacoustic imaging (AOPAI) system to image and detect early stages of tooth decay. This AOPAI system provides a non-contact, non-invasive and non-ionizing means of detecting early-stage dental caries. Ex-vivo teeth exhibiting early-stage, white-spot lesions were imaged using AOPAI. Experimental scans targeted each early-stage lesion and a reference healthy enamel region. Photoacoustic (PA) signals were generated in the tooth using a 532-nm pulsed laser and the light-induced broadband ultrasound signal was detected at the surface of the tooth with an optical path-stabilized Michelson interferometer operating at 532 nm. The measured time-domain signal was spatially resolved and back-projected to form 2D and 3D maps of the lesion using k-wave reconstruction methods. Experimental data collected from areas of healthy and diseased enamel indicate that the lesion generated a larger PA response compared to healthy enamel. The PA-signal amplitude alone was able to detect a lesion on the surface of the tooth. However, time- reversal reconstructions of the PA scans also quantitatively depicted the depth of the lesion. 3D PA reconstruction of the diseased tooth indicated a sub-surface lesion at a depth of 0.6 mm, in addition to the surface lesion. These results suggest that our AOPAI system is well suited for rapid clinical assessment of early-stage dental caries. An overview of the AOPAI system, fine-resolution PA and histology results of diseased and healthy teeth will be presented.

  17. Adaptive Light Modulation for Improved Resolution and Efficiency in All-Optical Pulse-Echo Ultrasound.

    PubMed

    Alles, Erwin J; Colchester, Richard J; Desjardins, Adrien E

    2016-01-01

    In biomedical all-optical pulse-echo ultrasound systems, ultrasound is generated with the photoacoustic effect by illuminating an optically absorbing structure with a temporally modulated light source. Nanosecond range laser pulses are typically used, which can yield bandwidths exceeding 100 MHz. However, acoustical attenuation within tissue or nonuniformities in the detector or source power spectra result in energy loss at the affected frequencies and in a reduced overall system efficiency. In this work, a laser diode is used to generate linear and nonlinear chirp optical modulations that are extended to microsecond time scales, with bandwidths constrained to the system sensitivity. Compared to those obtained using a 2-ns pulsed laser, pulse-echo images of a phantom obtained using linear chirp excitation exhibit similar axial resolution (99 versus 92 μm, respectively) and signal-to-noise ratios (SNRs) (10.3 versus 9.6 dB). In addition, the axial point spread function (PSF) exhibits lower sidelobe levels in the case of chirp modulation. Using nonlinear (time-stretched) chirp excitations, where the nonlinearity is computed from measurements of the spectral sensitivity of the system, the power spectrum of the imaging system was flattened and its bandwidth broadened. Consequently, the PSF has a narrower axial extent and still lower sidelobe levels. Pulse-echo images acquired with time-stretched chirps as optical modulation have higher axial resolution (64 μm) than those obtained with linear chirps, at the expense of a lower SNR (6.8 dB). Using a linear or time-stretched chirp, the conversion efficiency from optical power to acoustical pressure improved by a factor of 70 or 61, respectively, compared to that obtained with pulsed excitation. PMID:26552084

  18. Adaptive Light Modulation for Improved Resolution and Efficiency in All-Optical Pulse-Echo Ultrasound.

    PubMed

    Alles, Erwin J; Colchester, Richard J; Desjardins, Adrien E

    2016-01-01

    In biomedical all-optical pulse-echo ultrasound systems, ultrasound is generated with the photoacoustic effect by illuminating an optically absorbing structure with a temporally modulated light source. Nanosecond range laser pulses are typically used, which can yield bandwidths exceeding 100 MHz. However, acoustical attenuation within tissue or nonuniformities in the detector or source power spectra result in energy loss at the affected frequencies and in a reduced overall system efficiency. In this work, a laser diode is used to generate linear and nonlinear chirp optical modulations that are extended to microsecond time scales, with bandwidths constrained to the system sensitivity. Compared to those obtained using a 2-ns pulsed laser, pulse-echo images of a phantom obtained using linear chirp excitation exhibit similar axial resolution (99 versus 92 μm, respectively) and signal-to-noise ratios (SNRs) (10.3 versus 9.6 dB). In addition, the axial point spread function (PSF) exhibits lower sidelobe levels in the case of chirp modulation. Using nonlinear (time-stretched) chirp excitations, where the nonlinearity is computed from measurements of the spectral sensitivity of the system, the power spectrum of the imaging system was flattened and its bandwidth broadened. Consequently, the PSF has a narrower axial extent and still lower sidelobe levels. Pulse-echo images acquired with time-stretched chirps as optical modulation have higher axial resolution (64 μm) than those obtained with linear chirps, at the expense of a lower SNR (6.8 dB). Using a linear or time-stretched chirp, the conversion efficiency from optical power to acoustical pressure improved by a factor of 70 or 61, respectively, compared to that obtained with pulsed excitation.

  19. Controllable vacuum-induced diffraction of matter-wave superradiance using an all-optical dispersive cavity

    NASA Astrophysics Data System (ADS)

    Su, Shih-Wei; Lu, Zhen-Kai; Gou, Shih-Chuan; Liao, Wen-Te

    2016-10-01

    Cavity quantum electrodynamics (CQED) has played a central role in demonstrating the fundamental principles of the quantum world, and in particular those of atom-light interactions. Developing fast, dynamical and non-mechanical control over a CQED system is particularly desirable for controlling atomic dynamics and building future quantum networks at high speed. However conventional mirrors do not allow for such flexible and fast controls over their coupling to intracavity atoms mediated by photons. Here we theoretically investigate a novel all-optical CQED system composed of a binary Bose-Einstein condensate (BEC) sandwiched by two atomic ensembles. The highly tunable atomic dispersion of the CQED system enables the medium to act as a versatile, all-optically controlled atomic mirror that can be employed to manipulate the vacuum-induced diffraction of matter-wave superradiance. Our study illustrates a innovative all-optical element of atomtroics and sheds new light on controlling light-matter interactions.

  20. All-optical, polarization-insensitive light tuning properties in silver nanorod arrays covered with photoresponsive liquid crystals.

    PubMed

    Si, Guangyuan; Leong, Eunice S P; Jiang, Xiaoxiao; Lv, Jiangtao; Lin, Jiao; Dai, Haitao; Liu, Yan Jun

    2015-05-28

    Active plasmonics has been an interesting and important topic recently. Here we demonstrate the all-optical, polarization-insensitive tunable manipulation of a hybrid system that integrates a silver nanorod array with photoresponsive liquid crystals. The large-area plasmonic nanorod arrays are fabricated by laser interference lithography and ion milling. By covering a layer of photoresponsive liquid crystals, tunable control of plasmon resonance is achieved under an external light pump. The silver nanorod array also enables the homeotropic alignment of the liquid crystals, which makes the all-optical tuning behavior polarization-insensitive. With its advantages of cost-effective fabrication, easy integration, all-optical control, and polarization-insensitivity, the hybrid system could be valuable in many nanophotonic applications. PMID:25758775