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Sample records for half-period optical pulse

  1. Half-period optical pulse generation using a free-electron laser

    SciTech Connect

    Jaroszynski, D.A.; Chaix, P.; Piovella, N.

    1995-12-31

    Recently there has been growth, in interest in non-equilibrium interaction of half-period long optical pulses with matter. To date the optical pulses have been produced by chopping out a half-period long segment from a longer pulse using a semiconductor switch driven by a femtosecond laser. In this paper we present new methods for producing tunable ultra-short optical pulses as short as half an optical period using a free-electron laser driven by electron bunches with a duration a fraction of an optical period. Two different methods relying on the production of coherent spontaneous emission will be described. In the first method we show that when a train of ultra-short optical pulses as short as one half period. We present calculations which show that the small signal gain is unimportant in the early stages of radiation build up in the cavity when the startup process is dominated by coherent spontaneous emission. To support our proposed method we present encouraging experimental results from the FELIX experiment in the Netherlands which show that interference effects between the coherent spontaneous optical pulses at start-up are very important. The second proposed method relies on the fact that coherent spontaneous emission mimics the undulations of electrons as they pass through the undulator. We show that ultra-short optical pulses are produced by coherent spontaneous emission when ultra-short electron bunches pass through an ultra-short undulator. We discuss the interesting case of such undulator radiation in the presence of an optical cavity and show that the optical pulse can be {open_quotes}taylored{close_quotes} by simply adjusting the optical cavity desynchronism. The proposed methods may be realisable using existing rf driven FELs in the far-infrared.

  2. Half-period Aharonov-Bohm oscillations in disordered rotating optical ring cavities

    NASA Astrophysics Data System (ADS)

    Li, Huanan; Kottos, Tsampikos; Shapiro, Boris

    2016-09-01

    There exists an analogy between Maxwell equations in a rotating frame and the Schrödinger equation for a charged particle in the presence of a magnetic field. We exploit this analogy to point out that electromagnetic phenomena in the rotating frame, under appropriate conditions, can exhibit periodicity with respect to the angular velocity of rotation. In particular, in disordered ring cavities one finds the optical analog of the Al'tshuler-Aronov-Spivak effect well known in mesoscopic physics of disordered metals.

  3. Pulsed Optics

    NASA Astrophysics Data System (ADS)

    Hirlimann, C.

    Optics is the field of physics which comprises knowledge on the interaction between light and matter. When the superposition principle can be applied to electromagnetic waves or when the properties of matter do not depend on the intensity of light, one speaks of linear optics. This situation occurs with regular light sources such as light bulbs, low-intensity light-emitting diodes and the sun. With such low-intensity sources the reaction of matter to light can be characterized by a set of parameters such as the index of refraction, the absorption and reflection coefficients and the orientation of the medium with respect to the polarization of the light. These parameters depend only on the nature of the medium. The situation changed dramatically after the development of lasers in the early sixties, which allowed the generation of light intensities larger than a kilowatt per square centimeter. Actual large-scale short-pulse lasers can generate peak powers in the petawatt regime. In that large-intensity regime the optical parameters of a material become functions of the intensity of the impinging light. In 1818 Fresnel wrote a letter to the French Academy of Sciences in which he noted that the proportionality between the vibration of the light and the subsequent vibration of matter was only true because no high intensities were available. The intensity dependence of the material response is what usually defines nonlinear optics.

  4. Femtosecond optical pulse amplification

    NASA Astrophysics Data System (ADS)

    Knox, Wayne H.

    1988-02-01

    A number of techniques have been developed for amplification of optical pulses of approximately 100-fs duration. These amplifiers span a wide range of operating parameters from kilowatt to gigawatt peak powers and from 10 Hz to megahertz repetition rates. Amplification of femtosecond pulses has also been demonstrated at several wavelengths including visible, near-infrared, and ultraviolet regions. Several problems arise when amplifying short optical pulses to very high intensities. The problems are discussed and the state of the art of femtosecond optical pulse amplification is reviewed.

  5. Optically pulsed electron accelerator

    DOEpatents

    Fraser, J.S.; Sheffield, R.L.

    1985-05-20

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radiofrequency-powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  6. Optically pulsed electron accelerator

    DOEpatents

    Fraser, John S.; Sheffield, Richard L.

    1987-01-01

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radio frequency powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  7. Efficient optical pulse stacker system

    DOEpatents

    Seppala, Lynn G.; Haas, Roger A.

    1982-01-01

    Method and apparatus for spreading and angle-encoding each pulse of a multiplicity of small area, short pulses into several temporally staggered pulses by use of appropriate beam splitters, with the optical elements being arranged so that each staggered pulse is contiguous with one or two other such pulses, and the entire sequence of stacked pulses comprising a single, continuous long pulse. The single long pulse is expanded in area, and then doubly passed through a nonstorage laser amplifier such as KrF. After amplification, the physically separated, angle-encoded and temporally staggered pulses are recombined into a single pulse of short duration. This high intensity output beam is well collimated and may be propagated over long distance, or used for irradiating inertial confinement fusion targets.

  8. Nondegenerate optical parametric chirped pulse amplifier

    DOEpatents

    Jovanovic, Igor; Ebbers, Christopher A.

    2005-03-22

    A system provides an input pump pulse and a signal pulse. A first dichroic beamsplitter is highly reflective for the input signal pulse and highly transmissive for the input pump pulse. A first optical parametric amplifier nonlinear crystal transfers part of the energy from the input pump pulse to the input signal pulse resulting in a first amplified signal pulse and a first depleted pump pulse. A second dichroic beamsplitter is highly reflective for the first amplified signal pulse and highly transmissive for the first depleted pump pulse. A second optical parametric amplifier nonlinear crystal transfers part of the energy from the first depleted pump pulse to the first amplified signal pulse resulting in a second amplified signal pulse and a second depleted pump pulse. A third dichroic beamsplitter receives the second amplified signal pulse and the second depleted pump pulse. The second depleted pump pulse is discarded.

  9. Temporal waveguides for optical pulses

    SciTech Connect

    Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

    2016-05-12

    Here we discuss, temporal total internal reflection (TIR), in analogy to the conventional TIR of an optical beam at a dielectric interface, is the total reflection of an optical pulse inside a dispersive medium at a temporal boundary across which the refractive index changes. A pair of such boundaries separated in time acts as the temporal analog of planar dielectric waveguides. We study the propagation of optical pulses inside such temporal waveguides, both analytically and numerically, and show that the waveguide supports a finite number of temporal modes. We also discuss how a single-mode temporal waveguide can be created in practice. In contrast with the spatial case, the confinement can occur even when the central region has a lower refractive index.

  10. Temporal waveguides for optical pulses

    SciTech Connect

    Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

    2016-05-12

    Here we discuss, temporal total internal reflection (TIR), in analogy to the conventional TIR of an optical beam at a dielectric interface, is the total reflection of an optical pulse inside a dispersive medium at a temporal boundary across which the refractive index changes. A pair of such boundaries separated in time acts as the temporal analog of planar dielectric waveguides. We study the propagation of optical pulses inside such temporal waveguides, both analytically and numerically, and show that the waveguide supports a finite number of temporal modes. We also discuss how a single-mode temporal waveguide can be created in practice. In contrast with the spatial case, the confinement can occur even when the central region has a lower refractive index.

  11. Temporal waveguides for optical pulses

    DOE PAGES

    Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

    2016-05-12

    Here we discuss, temporal total internal reflection (TIR), in analogy to the conventional TIR of an optical beam at a dielectric interface, is the total reflection of an optical pulse inside a dispersive medium at a temporal boundary across which the refractive index changes. A pair of such boundaries separated in time acts as the temporal analog of planar dielectric waveguides. We study the propagation of optical pulses inside such temporal waveguides, both analytically and numerically, and show that the waveguide supports a finite number of temporal modes. We also discuss how a single-mode temporal waveguide can be created inmore » practice. In contrast with the spatial case, the confinement can occur even when the central region has a lower refractive index.« less

  12. Pulsed optically pumped frequency standard

    SciTech Connect

    Godone, Aldo; Micalizio, Salvatore; Levi, Filippo

    2004-08-01

    We reconsider the idea of a pulsed optically pumped frequency standard conceived in the early 1960s to eliminate the light-shift effect. The development of semiconductor lasers and of pulsed electronic techniques for atomic fountains and new theoretical findings allow an implementation of this idea which may lead to a frequency standard whose frequency stability is limited only by the thermal noise in the short term and by the temperature drift in the long term. We shall also show both theoretically and experimentally the possibility of doubling the atomic quality factor with respect to the classical Ramsey technique approach.

  13. Pulsed Optically Pumped Rb clock

    NASA Astrophysics Data System (ADS)

    Micalizio, S.; Levi, F.; Godone, A.; Calosso, C. E.; François, B.; Boudot, R.; Affolderbach, C.; Kang, S.; Gharavipour, M.; Gruet, F.; Mileti, G.

    2016-06-01

    INRIM demonstrated a Rb vapour cell clock based on pulsed optical pumping (POP) with unprecedented frequency stability performances, both in the short and in the medium-long term period. In the frame of a EMRP project, we are developing a new clock based on the same POP principle but adopting solutions aimed at reducing the noise sources affecting the INRIM clock. At the same time, concerning possible technological applications, particular care are devoted in the project to reduce the size and the weight of the clock, still keeping the excellent stability of the INRIM clock. The paper resumes the main results of this activity.

  14. Nonlinear Optical Pulsed Control of Composite Metamaterials

    DTIC Science & Technology

    2011-10-07

    Final report for project entitled "Nonlinear optical pulsed control of composite metamaterials", under Grant no. AOARD - 094042 The stated...pump (control) radiation. 2. Study temporal pulse dynamics in order to optimize pump probe delays, intensities, carrier frequencies and the pulse ...nanostructures using simple time and cost effective lithographic technique termed as ‘Laser Interference Lithography’. Figure-1 below shows a

  15. Pulse front adaptive optics in multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The accurate focusing of ultrashort laser pulses is extremely important in multiphoton microscopy. Using adaptive optics to manipulate the incident ultrafast beam in either the spectral or spatial domain can introduce significant benefits when imaging. Here we introduce pulse front adaptive optics: manipulating an ultrashort pulse in both the spatial and temporal domains. A deformable mirror and a spatial light modulator are operated in concert to modify contours of constant intensity in space and time within an ultrashort pulse. Through adaptive control of the pulse front, we demonstrate an enhancement in the measured fluorescence from a two photon microscope.

  16. Apparatus and method for optical pulse measurement

    SciTech Connect

    Trebino, Rick P.; Tsang, Thomas; Fittinghoff, David N.; Sweetser, John N.; Krumbuegel, Marco A.

    1999-12-28

    Practical third-order frequency-resolved optical grating (FROG) techniques for characterization of ultrashort optical pulses are disclosed. The techniques are particularly suited to the measurement of single and/or weak optical pulses having pulse durations in the picosecond and subpicosecond regime. The relative quantum inefficiency of third-order nonlinear optical effects is compensated for through i) use of phase-matched transient grating beam geometry to maximize interaction length, and ii) use of interface-enhanced third-harmonic generation.

  17. Optical physics: Ultrashort light pulses shake atoms

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Taec

    2016-02-01

    The response of electrons in atoms to ultrashort optical light pulses has been probed by measuring the ultraviolet light emitted by the atoms. This reveals that a finite time delay occurs before the response. See Letter p.66

  18. System for generating shaped optical pulses and measuring optical pulses using spectral beam deflection (SBD)

    DOEpatents

    Skupsky, S.; Kessler, T.J.; Letzring, S.A.

    1993-11-16

    A temporally shaped or modified optical output pulse is generated from a bandwidth-encoded optical input pulse in a system in which the input pulse is in the form of a beam which is spectrally spread into components contained within the bandwidth, followed by deflection of the spectrally spread beam (SBD) thereby spatially mapping the components in correspondence with the temporal input pulse profile in the focal plane of a lens, and by spatially selective attenuation of selected components in that focal plane. The shaped or modified optical output pulse is then reconstructed from the attenuated spectral components. The pulse-shaping system is particularly useful for generating optical pulses of selected temporal shape over a wide range of pulse duration, such pulses finding application in the fields of optical communication, optical recording and data storage, atomic and molecular spectroscopy and laser fusion. An optical streak camera is also provided which uses SBD to display the beam intensity in the focal plane as a function of time during the input pulse. 10 figures.

  19. System for generating shaped optical pulses and measuring optical pulses using spectral beam deflection (SBD)

    DOEpatents

    Skupsky, Stanley; Kessler, Terrance J.; Letzring, Samuel A.

    1993-01-01

    A temporally shaped or modified optical output pulse is generated from a bandwidth-encoded optical input pulse in a system in which the input pulse is in the form of a beam which is spectrally spread into components contained within the bandwidth, followed by deflection of the spectrally spread beam (SBD) thereby spatially mapping the components in correspondence with the temporal input pulse profile in the focal plane of a lens, and by spatially selective attenuation of selected components in that focal plane. The shaped or modified optical output pulse is then reconstructed from the attenuated spectral components. The pulse-shaping system is particularly useful for generating optical pulses of selected temporal shape over a wide range of pulse duration, such pulses finding application in the fields of optical communication, optical recording and data storage, atomic and molecular spectroscopy and laser fusion. An optical streak camera is also provided which uses SBD to display the beam intensity in the focal plane as a function of time during the input pulse.

  20. Optical pulse generation using fiber lasers and integrated optics

    SciTech Connect

    Wilcox, R.B.; Browning, D.F.; Burkhart, S.C.; VanWonterghem, B.W.

    1995-03-27

    We have demonstrated an optical pulse forming system using fiber and integrated optics, and have designed a multiple-output system for a proposed fusion laser facility. Our approach is an advancement over previous designs for fusion lasers, and an unusual application of fiber lasers and integrated optics.

  1. Pulse front control with adaptive optics

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The focusing of ultrashort laser pulses is extremely important for processes including microscopy, laser fabrication and fundamental science. Adaptive optic elements, such as liquid crystal spatial light modulators or membrane deformable mirrors, are routinely used for the correction of aberrations in these systems, leading to improved resolution and efficiency. Here, we demonstrate that adaptive elements used with ultrashort pulses should not be considered simply in terms of wavefront modification, but that changes to the incident pulse front can also occur. We experimentally show how adaptive elements may be used to engineer pulse fronts with spatial resolution.

  2. Multifilamentation of powerful optical pulses in silica

    SciTech Connect

    Berge, L.; Mauger, S.; Skupin, S.

    2010-01-15

    The multiple filamentation of powerful light pulses in fused silica is numerically investigated for central wavelengths at 355 nm and 1550 nm. We consider different values for beam waist and pulse duration and compare the numerical results with behaviors expected from the plane-wave modulational instability theory. Before the nonlinear focus, the spatiotemporal intensity patterns can be explained in the framework of this theory. Once the clamping intensity is reached, for long input pulse durations (approx1 ps), the ionization front defocuses all trailing components within a collective dynamic, and a spatial replenishment scenario takes place upon further propagation. Short pulses (approx50 fs) undergo similar ionization fronts, before an optically turbulent regime sets in. We observe moderate changes in the total temporal extent of ultraviolet pulses and in the corresponding spectra. In contrast, infrared pulses may undergo strong temporal compression and important spectral broadening. For short input pulses, anomalous dispersion and self-steepening push all pulse components to the trailing edge, where many small-scaled filaments are nucleated. In the leading part of the pulse, different spatial landscapes, e.g., broad ring patterns, may survive and follow their own propagation dynamics.

  3. Pulse Shepherding in Nonlinear Fiber Optics

    NASA Technical Reports Server (NTRS)

    Yeh, C.; Bergman, L.

    1996-01-01

    In a wavelength division multiplexed fiber system, where pulses on different wavelength beams may co-propagate in a single mode fiber, the cross-phase-modulation (CPM) effects caused by the nonlinearity of the optical fiber are unavoidable. In other words, pulses on different wavelength beams can interact with and affect each other through the intensity dependence of the refractive index of the fiber. Although CPM will not cause energy to be exchanged among the beams, the pulse shapes and locations on these beams can be altered significantly. This phenomenon makes possible the manipulation and control of pulses co-propagating on different wavelength beams through the introduction of a shepherd pulse at a separate wavelength. How this can be accomplished is demonstrated in this paper.

  4. Optical frequency comb generation by pulsed pumping

    NASA Astrophysics Data System (ADS)

    Malinowski, Marcin; Rao, Ashutosh; Delfyett, Peter; Fathpour, Sasan

    2017-06-01

    A synchronously pumped Kerr cavity is proposed and studied for power-efficient frequency comb generation in optical microring resonators. The system is modeled using the Lugiato-Lefever equation. Analytical solutions are provided for an ideal case and extended by numerical methods to account for optical loss and higher orders of dispersion. It is shown that the average power requirement is reduced by the duty cycle of the pulse with respect to the conventional continuous-wave-pumped microrings, and it is significantly lower than the pulsed pumping of straight waveguides.

  5. Time-frequency spectrograms of optical pulses

    SciTech Connect

    Beck, M.

    1995-11-01

    The authors present a discussion of several different types of joint time-frequency distributions of optical pulses. Particular attention is paid to the Wigner distribution W(t,{omega}), as it is the fundamental distribution from which all others can be derived. They elucidate the relationship between the Wigner distribution and other spectrograms of current-interest, such as that obtained from frequency-resolved optical gating (FROG).

  6. Pressure Pulse Measurements Using Optical Hydrophone Principles

    NASA Astrophysics Data System (ADS)

    Ueberle, Friedrich; Jamshidi-Rad, Abtin

    2011-02-01

    Pressure pulses are used in extracorporeal lithotripsy, pain therapy and other medical applications. Typical lithotripter pulses reach positive pressure amplitudes of ca. 20 to more than 100 MPa and negative pressures of -5 to more than -20 MPa, depending on the focusing properties and energy settings of the source. The IEC standard 61846, which defines the acoustic parameters of pressure pulse fields, describes the properties of "Focus-" and "Field-" type hydrophones, which were originally specified as PVDF sensors. During recent years, two types of optical sensors were developed, which are based on the principle of measuring reflection changes of a laser beam at a glass-water surface: The fiber optic sensor using bare optical fibers and the "light spot" sensor using a thick glass block. Measurements with both hydrophone types were made with a low pressure transducer (p+max=3 MPa), and two electromagnetic lithotripter sources with the same total acoustic energy (E5MPa=90mJ), one with a wide focus (FWHM = 11 mm, p+max = 30 MPa) and the other with a small focus (FWHM = 3,5 mm, p+max = 83 MPa). The results show that both optical sensor types provide high pressure-time signal fidelity comparable to PVDF membrane sensors. Both optical hydrophones can serve as "Focus-" and "Field-" hydrophones as defined in the lithotripsy measurement standard IEC 61846.

  7. Nanosecond pulsed laser texturing of optical diffusers

    NASA Astrophysics Data System (ADS)

    Alqurashi, Tawfiq; Sabouri, Aydin; Yetisen, Ali K.; Butt, Haider

    2017-02-01

    High-quality optical glass diffusers have applications in aerospace, displays, imaging systems, medical devices, and optical sensors. The development of rapid and accurate fabrication techniques is highly desirable for their production. Here, a micropatterning method for the fast fabrication of optical diffusers by means of nanosecond pulsed laser ablation is demonstrated (λ=1064 nm, power=7.02, 9.36 and 11.7 W and scanning speed=200 and 800 mm s-1). The experiments were carried out by point-to-point texturing of a glass surface in spiral shape. The laser machining parameters, the number of pulses and their power had significant effect on surface features. The optical characteristics of the diffusers were characterized at different scattering angles. The features of the microscale structures influenced average roughness from 0.8 μm to 1.97 μm. The glass diffusers scattered light at angles up to 20° and their transmission efficiency were measured up to ˜97% across the visible spectrum. The produced optical devices diffuse light less but do so with less scattering and energy losses as compared to opal diffusing glass. The presented fabrication method can be applied to any other transparent material to create optical diffusers. It is anticipated that the optical diffusers presented in this work will have applications in the production of LED spotlights and imaging devices.

  8. Nonlinear and Dispersive Optical Pulse Propagation

    NASA Astrophysics Data System (ADS)

    Dijaili, Sol Peter

    In this dissertation, there are basically four novel contributions to the field of picosecond pulse propagation and measurement. The first contribution is the temporal ABCD matrix which is an analog of the traditional ABCD ray matrices used in Gaussian beam propagation. The temporal ABCD matrix allows for the easy calculation of the effects of linear chirp or group velocity dispersion in the time domain. As with Gaussian beams in space, there also exists a complete Hermite-Gaussian basis in time whose propagation can be tracked with the temporal ABCD matrices. The second contribution is the timing synchronization between a colliding pulse mode-locked dye laser and a gain-switched Fabry-Perot type AlGaAs laser diode that has achieved less than 40 femtoseconds of relative timing jitter by using a pulsed optical phase lock loop (POPLL). The relative timing jitter was measured using the error voltage of the feedback loop. This method of measurement is accurate since the frequencies of all the timing fluctuations fall within the loop bandwidth. The novel element is a broad band optical cross-correlator that can resolve femtosecond time delay errors between two pulse trains. The third contribution is a novel dispersive technique of determining the nonlinear frequency sweep of a picosecond pulse with relatively good accuracy. All the measurements are made in the time domain and hence there is no time-bandwidth limitation to the accuracy. The fourth contribution is the first demonstration of cross -phase modulation in a semiconductor laser amplifier where a variable chirp was observed. A simple expression for the chirp imparted on a weak signal pulse by the action of a strong pump pulse is derived. A maximum frequency excursion of 16 GHz due to the cross-phase modulation was measured. A value of 5 was found for alpha _{xpm} which is a factor for characterizing the cross-phase modulation in a similar manner to the conventional linewidth enhancement factor, alpha.

  9. Temporal laser pulse manipulation using multiple optical ring-cavities

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet (Inventor); Kojima, Jun (Inventor)

    2010-01-01

    An optical pulse stretcher and a mathematical algorithm for the detailed calculation of its design and performance is disclosed. The optical pulse stretcher has a plurality of optical cavities, having multiple optical reflectors such that an optical path length in each of the optical cavities is different. The optical pulse stretcher also has a plurality of beam splitters, each of which intercepts a portion of an input optical beam and diverts the portion into one of the plurality of optical cavities. The input optical beam is stretched and a power of an output beam is reduced after passing through the optical pulse stretcher and the placement of the plurality of optical cavities and beam splitters is optimized through a model that takes into account optical beam divergence and alignment in the pluralities of the optical cavities. The optical pulse stretcher system can also function as a high-repetition-rate (MHz) laser pulse generator, making it suitable for use as a stroboscopic light source for high speed ballistic projectile imaging studies, or it can be used for high speed flow diagnostics using a laser light sheet with digital particle imaging velocimetry. The optical pulse stretcher system can also be implemented using fiber optic components to realize a rugged and compact optical system that is alignment free and easy to use.

  10. Optical reprogramming with ultrashort femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Uchugonova, Aisada; Breunig, Hans G.; Batista, Ana; König, Karsten

    2015-03-01

    The use of sub-15 femtosecond laser pulses in stem cell research is explored with particular emphasis on the optical reprogramming of somatic cells. The reprogramming of somatic cells into induced pluripotent stem (iPS) cells can be evoked through the ectopic expression of defined transcription factors. Conventional approaches utilize retro/lenti-viruses to deliver genes/transcription factors as well as to facilitate the integration of transcription factors into that of the host genome. However, the use of viruses may result in insertional mutations caused by the random integration of genes and as a result, this may limit the use within clinical applications due to the risk of the formation of cancer. In this study, a new approach is demonstrated in realizing non-viral reprogramming through the use of ultrashort laser pulses, to introduce transcription factors into the cell so as to generate iPS cells.

  11. Optical penetration sensor for pulsed laser welding

    DOEpatents

    Essien, Marcelino; Keicher, David M.; Schlienger, M. Eric; Jellison, James L.

    2000-01-01

    An apparatus and method for determining the penetration of the weld pool created from pulsed laser welding and more particularly to an apparatus and method of utilizing an optical technique to monitor the weld vaporization plume velocity to determine the depth of penetration. A light source directs a beam through a vaporization plume above a weld pool, wherein the plume changes the intensity of the beam, allowing determination of the velocity of the plume. From the velocity of the plume, the depth of the weld is determined.

  12. Enhanced Pulse Compression in Nonlinear Fiber by a WDM Optical Pulse

    NASA Technical Reports Server (NTRS)

    Yeh, C.; Bergman, L.

    1997-01-01

    A new way to compress an optical pulse in a single-mode fiber is presented in this paper. By the use of the cross phase modulation (CPM) effect caused by the nonlinearity of the optical fiber, a shepherd pulse propagating on a different wavelength beam in a wavelength division multiplexed (WDM) single-mode fiber system can be used to enhance the pulse compression of a co-propagating primary pulse.

  13. Cavity Optical Pulse Extraction: ultra-short pulse generation as seeded Hawking radiation.

    PubMed

    Eilenberger, Falk; Kabakova, Irina V; de Sterke, C Martijn; Eggleton, Benjamin J; Pertsch, Thomas

    2013-01-01

    We show that light trapped in an optical cavity can be extracted from that cavity in an ultrashort burst by means of a trigger pulse. We find a simple analytic description of this process and show that while the extracted pulse inherits its pulse length from that of the trigger pulse, its wavelength can be completely different. Cavity Optical Pulse Extraction is thus well suited for the development of ultrashort laser sources in new wavelength ranges. We discuss similarities between this process and the generation of Hawking radiation at the optical analogue of an event horizon with extremely high Hawking temperature. Our analytic predictions are confirmed by thorough numerical simulations.

  14. Steerable THz pulses from thin emitters via optical pulse-front tilt.

    PubMed

    Smith, B C; Whitaker, J F; Rand, S C

    2016-09-05

    A new method of steering THz pulses radiated from a thin emitter excited by tilted optical pulse-fronts has been developed theoretically and validated in a proof-of-concept experiment. This steering technique is potentially efficient and rapid, and it should benefit from a THz-pulse energy that can scale with optical-beam size and magnitude. Conversely, the method employed for measuring the steered THz pulses is also capable of characterizing the pulse-front tilt of an optical beam.

  15. Optically generated terahertz pulses with strong quasistatic precursors

    NASA Astrophysics Data System (ADS)

    Bakunov, M. I.; Maslov, A. V.; Tsarev, M. V.

    2017-06-01

    We found theoretically that optical rectification of an ultrashort laser pulse in an electro-optic crystal can produce a terahertz pulse with a quasistatic electromagnetic precursor propagating ahead of the pulse. The strengths of the electric and magnetic fields in the precursor can be comparable to those in the main terahertz pulse. This effect occurs if the pump optical pulse is intense enough to produce two-photon or multiphoton ionization in the crystal. The precursor is generated by the current of the optically created carriers, which are accelerated by the electric field of the terahertz pulse. The optically generated strong quasistatic precursors can be used for particle acceleration, control of magnetic materials, and in streaking techniques.

  16. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOEpatents

    Smirl, Arthur; Trebino, Rick P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques.

  17. CW seeded optical parametric amplifier providing wavelength and pulse duration tunable nearly transform limited pulses.

    PubMed

    Hädrich, S; Gottschall, T; Rothhardt, J; Limpert, J; Tünnermann, A

    2010-02-01

    An optical parametric amplifier that delivers nearly transform limited pulses is presented. The center wavelength of these pulses can be tuned between 993 nm and 1070 nm and, at the same time, the pulse duration is varied between 206 fs and 650 fs. At the shortest pulse duration the pulse energy was increased up to 7.2 microJ at 50 kHz repetition rate. Variation of the wavelength is achieved by applying a tunable cw seed while the pulse duration can be varied via altering the pump pulse duration. This scheme offers superior flexibility and scaling possibilities.

  18. Propagation of Complex Laser Pulses in Optically Dense Media

    NASA Astrophysics Data System (ADS)

    Fetterman, M. R.; Davis, J. C.; Goswami, D.; Yang, W.; Warren, W. S.

    1999-05-01

    Ultrafast laser pulses with complex envelopes (amplitude and frequency modulated) are used to excite an optically dense column of rubidium vapor. Pulse reshaping, stimulated emission dynamics, and residual electronic excitation in the Rb vapor are all shown to depend strongly on the laser pulse shape. Pulses that produce adiabatic passage in the optically thin limit exhibit more complex behavior in optically thick samples, including an unexpected dependence on the sign of the frequency sweep. Numerical solutions of the Maxwell-Bloch equations are shown to account for our results.

  19. Device For Trapping Laser Pulses In An Optical Delay Line

    DOEpatents

    Yu, David U. L.; Bullock, Donald L.

    1997-12-23

    A device for maintaining a high-energy laser pulse within a recirculating optical delay line for a period time to optimize the interaction of the pulse with an electron beam pulse train comprising closely spaced electron micropulses. The delay line allows a single optical pulse to interact with many of the electron micropulses in a single electron beam macropulse in sequence and for the introduction of additional optical pulses to interact with the micropulses of additional electron beam macropulses. The device comprises a polarization-sensitive beam splitter for admitting an optical pulse to and ejecting it from the delay line according to its polarization state, a Pockels cell to control the polarization of the pulse within the delay line for the purpose of maintaining it within the delay line or ejecting it from the delay line, a pair of focusing mirrors positioned so that a collimated incoming optical pulse is focused by one of them to a focal point where the pulse interacts with the electron beam and then afterwards the pulse is recollimated by the second focusing mirror, and a timing device which synchronizes the introduction of the laser pulse into the optical delay line with the arrival of the electron macropulse at the delay line to ensure the interaction of the laser pulse with a prescribed number of electron micropulses in sequence. In a first embodiment of the invention, the principal optical elements are mounted with their axes collinear. In a second embodiment, all principal optical elements are mounted in the configuration of a ring.

  20. Filamentational instability of partially coherent femtosecond optical pulses in air.

    PubMed

    Marklund, M; Shukla, P K

    2006-06-15

    The filamentational instability of spatially broadband femtosecond optical pulses in air is investigated by means of a kinetic wave equation for spatially incoherent photons. An explicit expression for the spatial amplification rate is derived and analyzed. It is found that the spatial spectral broadening of the pulse can lead to stabilization of the filamentation instability. Thus optical smoothing techniques could optimize current applications of ultrashort laser pulses, such as atmospheric remote sensing.

  1. Generation of frequency-chirped optical pulses with felix

    SciTech Connect

    Knippels, G.M.H.; Meer, A.F.G. van der; Mols, R.F.X.A.M.

    1995-12-31

    Frequency-chirped optical pulses have been produced in the picosecond regime by varying the energy of the electron beam on a microsecond time scale. These pulses were then compressed close to their bandwidth limit by an external pulse compressor. The amount of chirp can be controlled by varying the sweep rate on the electron beam energy and by cavity desynchronisation. To examine the generated chirp we used the following diagnostics: a pulse compressor, a crossed beam autocorrelator, a multichannel electron spectrometer and multichannel optical spectrometer. The compressor is build entirely using reflective optics to permit broad band operation. The autocorrelator is currently operating from 6 {mu}m to 30 {mu}m with one single crystal. It has been used to measure pulses as short as 500 fs. All diagnostics are evacuated to prevent pulse shape distortion or pulse lengthening caused by absorption in ambient water vapour. Pulse length measurements and optical spectra will be presented for different electron beam sweep rates, showing the presence of a frequency chirp. Results on the compression of the optical pulses to their bandwidth limit are given for different electron sweep rates. More experimental results showing the dependence of the amount of chirp on cavity desynchronisation will be presented.

  2. Thermally driven continuous-wave and pulsed optical vortex.

    PubMed

    Ding, Yitian; Xu, Miaomiao; Zhao, Yongguang; Yu, Haohai; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang

    2014-04-15

    We demonstrated a continuous-wave (cw) and pulsed optical vortex with topological charges driven by heat generated during the lasing process without introducing the astigmatism effect and reducing lasing efficiency. During the lasing process, the topological charges were changeable by the thermal-induced lens and selected by the mode-matching between the pump and oscillating beams. With a graphene sample as the saturable absorber, a pulsed optical vortex was achieved at a wavelength of 1.36 μm, which identified that graphene could be used as a pulse modulator for the generation of a pulsed optical vortex. Thermally driven cw and pulsed optical vortexes should have various promising applications based on the compact structure, changeable topological charges, and specific wavelength.

  3. Precision short-pulse damage test station utilizing optical parametric chirped-pulse amplification

    SciTech Connect

    Jovanovic, I; Brown, C; Wattellier, B; Nielsen, N; Molander, W; Stuart, B; Pennington, D; Barty, C J

    2004-03-22

    The next generation of high-energy petawatt (HEPW)-class lasers will utilize multilayer dielectric diffraction gratings for pulse compression, due to their high efficiency and high damage threshold for picosecond pulses. The peak power of HEPW lasers will be determined by the aperture and damage threshold of the final dielectric grating in the pulse compressor and final focusing optics. We have developed a short-pulse damage test station for accurate determination of the damage threshold of the optics used on future HEPW lasers. Our damage test station is based on a highly stable, high-beam-quality optical parametric chirped-pulse amplifier (OPCPA) operating at 1053 nm at a repetition rate of 10 Hz. We present the design of our OPCPA system pumped by a commercial Q-switched pump laser and the results of the full system characterization. Initial short-pulse damage experiments in the far field using our system have been performed.

  4. Spatial and temporal pulse propagation for dispersive paraxial optical systems

    SciTech Connect

    Marcus, G.

    2016-04-01

    The formalism for pulse propagation through dispersive paraxial optical systems first presented by Kostenbauder (IEEE J. Quant. Elec. 261148–1157 (1990)) using 4 × 4 ray-pulse matrices is extended to 6 × 6 matrices and includes non-separable spatial-temporal couplings in both transverse dimensions as well as temporal dispersive effects up to a quadratic phase. The eikonal in a modified Huygens integral in the Fresnell approximation is derived and can be used to propagate pulses through complicated dispersive optical systems within the paraxial approximation. Additionally, a simple formula for the propagation of ultrashort pulses having a Gaussian profile both spatially and temporally is presented.

  5. Effect of Orbital Angular Momentum on Nondiffracting Ultrashort Optical Pulses.

    PubMed

    Ornigotti, Marco; Conti, Claudio; Szameit, Alexander

    2015-09-04

    We introduce a new class of nondiffracting optical pulses possessing orbital angular momentum. By generalizing the X-wave solution of the Maxwell equation, we discover the coupling between angular momentum and the temporal degrees of freedom of ultrashort pulses. The spatial twist of propagation invariant light pulse turns out to be directly related to the number of optical cycles. Our results may trigger the development of novel multilevel classical and quantum transmission channels free of dispersion and diffraction. They may also find application in the manipulation of nanostructured objects by ultrashort pulses and for novel approaches to the spatiotemporal measurements in ultrafast photonics.

  6. Electro-Optic Generation and Detection of Femtosecond Electromagnetic Pulses

    DTIC Science & Technology

    1991-11-20

    electromagnetic pulses from an electro - optic crystal following their generation by electro - optic Cherenkov radiation, and their subsequent propagation and detection...in free space; (4) The measurement of subpicosecond electrical response of a new organic electrooptic material (polymer); (5) The observation of terahertz transition radiation from the surfaces of electro - optic crystals.

  7. Pulse front adaptive optics: a new method for control of ultrashort laser pulses.

    PubMed

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2015-07-27

    Ultrafast lasers enable a wide range of physics research and the manipulation of short pulses is a critical part of the ultrafast tool kit. Current methods of laser pulse shaping are usually considered separately in either the spatial or the temporal domain, but laser pulses are complex entities existing in four dimensions, so full freedom of manipulation requires advanced forms of spatiotemporal control. We demonstrate through a combination of adaptable diffractive and reflective optical elements - a liquid crystal spatial light modulator (SLM) and a deformable mirror (DM) - decoupled spatial control over the pulse front (temporal group delay) and phase front of an ultra-short pulse was enabled. Pulse front modulation was confirmed through autocorrelation measurements. This new adaptive optics technique, for the first time enabling in principle arbitrary shaping of the pulse front, promises to offer a further level of control for ultrafast lasers.

  8. Pulse front adaptive optics in two-photon microscopy.

    PubMed

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2015-11-01

    Adaptive optics has been extensively studied for the correction of phase front aberrations in optical systems. In systems using ultrafast lasers, distortions can also exist in the pulse front (contour of constant intensity in space and time), but until now their correction has been mostly unexplored due to technological limitations. In this Letter, we apply newly developed pulse front adaptive optics, for the first time to our knowledge, to practical compensation of a two-photon fluorescence microscope. With adaptive correction of the system-induced pulse front distortion, improvements beyond conventional phase correction are demonstrated.

  9. Fast magneto-optic switch based on nanosecond pulses

    NASA Astrophysics Data System (ADS)

    Weng, Zi-Hua; Ruan, Jian-Jian; Lin, Shao-Han; Chen, Zhi-Min

    2011-09-01

    The paper studies an all fiber high-speed magneto-optic switch which includes an optical route, a nanosecond pulse generator, and a magnetic field module in order to reduce the switching time of the optical switch in the all optical network. A compact nanosecond pulse generator can be designed based on the special character of the avalanche transistor. The output current pulse of the nanosecond pulse generator is less than 5 ns, while the pulse amplitude is more than 100 V and the pulse width is about 10 to 20 ns, which is able to drive a high-speed magnetic field. A solenoid is used as the magnetic field module, and a bismuth-substituted rare-earth iron garnet single crystal is chosen as the Faraday rotator. By changing the direction of current in the solenoid quickly, the magnetization of the magneto-optic material is reversed, and the optical beam can be rapidly switched. The experimental results indicate that the switching time of the device is about 100 to 400 ns, which can partially meet the demand of the rapid development of the all optical network.

  10. Synchronization using pulsed edge tracking in optical PPM communication system

    NASA Technical Reports Server (NTRS)

    Gagliardi, R.

    1972-01-01

    A pulse position modulated (PPM) optical communication system using narrow pulses of light for data transmission requires accurate time synchronization between transmitter and receiver. The presence of signal energy in the form of optical pulses suggests the use of a pulse edge tracking method of maintaining the necessary timing. The edge tracking operation in a binary PPM system is examined, taking into account the quantum nature of the optical transmissions. Consideration is given first to pure synchronization using a periodic pulsed intensity, then extended to the case where position modulation is present and auxiliary bit decisioning is needed to aid the tracking operation. Performance analysis is made in terms of timing error and its associated statistics. Timing error variances are shown as a function of system signal to noise ratio.

  11. Pulse laser assist optical tweezers (PLAT) with long-duration pulse laser

    NASA Astrophysics Data System (ADS)

    Maeda, Saki; Sugiura, Tadao; Minato, Kotaro

    2011-07-01

    Optical tweezers is a technique to trap and to manipulate micron sized objects under a microscope by radiation pressure force exerted by a laser beam. Optical tweezers has been utilized for single-molecular measurements of force exerted by molecular interactions and for cell palpation. To extend applications of optical tweezers we have developed a novel optical tweezers system combined with a pulse laser. We utilize a pulse laser (Q-switched Nd: YAG laser, wavelength of 1064 nm) to assist manipulations by conventional optical tweezers with a continuous wave (CW) laser. The pulse laser beam is introduced into the same optics for conventional optical tweezers. In principle, instantaneous radiation force is proportional to instantaneous power of laser beam. As a result, pulse laser beam generates strong instantaneous force on an object to be manipulated. If the radiation force becomes strong enough to get over an obstacle structure and/or to be released from adhesion, the object will be free from these difficulties. We investigate the effect of pulse laser assistance with changing pulse duration of the laser. We report optimum pulse duration of 100 ns to 200 ns deduced from motion analysis of a particle in a beam spot. Our goal is to realize in-vivo manipulation and operation of a cell. For this purpose we need to reduce light energy of pulse laser beam and to avoid laser induced breakdown caused by strong light field. So we have developed a pulse laser with 160-ns pulse duration and have confirmed that availability on manipulation of living cells.

  12. Laser Pulse-Stretching Using Multiple Optical Ring-Cavities

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Nguyen, Quang-Viet; Lee, Chi-Ming (Technical Monitor)

    2002-01-01

    We describe a simple and passive nanosecond-long (ns-long) laser 'pulse-stretcher' using multiple optical ring-cavities. We present a model of the pulse-stretching process for an arbitrary number of optical ring-cavities. Using the model, we optimize the design of a pulse-stretcher for use in a spontaneous Raman scattering excitation system that avoids laser-induced plasma spark problems. From the optimized design, we then experimentally demonstrate and verify the model with a 3-cavity pulse-stretcher system that converts a 1000 mJ, 8.4 ns-long input laser pulse into an approximately 75 ns-long (FWHM) output laser pulse with a peak power reduction of 0.10X, and an 83% efficiency.

  13. Modeling propagation of coherent optical pulses through molecular vapor

    SciTech Connect

    Shore, B.W.; Eberly, J.H.

    1982-01-01

    Results of modeling the mutual coupling of coherent molecular response and coherent optical pulses during propagation are described. The propagation is treated numerically, with particular emphasis on both continuum and discrete behavior associated with the quasicontinuum model.

  14. Optical pulse synthesis using brillouin selective sideband amplification

    NASA Technical Reports Server (NTRS)

    Yao, X. Steve (Inventor)

    2002-01-01

    Techniques for producing optical pulses based on Brillouin selective sideband amplification by using a common modulation control signal to modulate both a signal beam to produce multiple sideband signals and a single pump beam to produce multiple pump beams.

  15. Pulse laser assisted optical tweezers for biomedical applications.

    PubMed

    Sugiura, Tadao; Maeda, Saki; Honda, Ayae

    2012-01-01

    Optical tweezers which enables to trap micron to nanometer sized objects by radiation pressure force is utilized for manipulation of particles under a microscope and for measurement of forces between biomolecules. Weak force of optical tweezers causes some limitations such as particle adhesion or steric barrier like lipid membrane in a cell prevent further movement of objects. For biomedical applications we need to overcome these difficulties. We have developed a technique to exert strong instantaneous force by use of a pulse laser beam and to assist conventional optical tweezers. A pulse laser beam has huge instantaneous laser power of more than 1000 times as strong as a conventional continuous-wave laser beam so that the instantaneous force is strong enough to break chemical bonding and molecular force between objects and obstacles. We derive suitable pulse duration for pulse assist of optical tweezers and demonstrate particle manipulation in difficult situations through an experiment of particle removal from sticky surface of glass substrate.

  16. Effect of idler absorption in pulsed optical parametric oscillators.

    PubMed

    Rustad, Gunnar; Arisholm, Gunnar; Farsund, Øystein

    2011-01-31

    Absorption at the idler wavelength in an optical parametric oscillator (OPO) is often considered detrimental. We show through simulations that pulsed OPOs with significant idler absorption can perform better than OPOs with low idler absorption both in terms of conversion efficiency and beam quality. The main reason for this is reduced back conversion. We also show how the beam quality depends on the beam width and pump pulse length, and present scaling relations to use the example simulations for other pulsed nanosecond OPOs.

  17. Time-resolved pulsed EPR: microwave and optical detection

    SciTech Connect

    Trifunac, A.D.; Smith, J.P.

    1981-01-01

    Time-resolved pulsed EPR spectrometers are described. EPR spectra, kinetic profiles, and relaxation studies are used to illustrate some capabilities of the pulsed EPR experiment. Optical detection of time-resolved EPR spectra of radical ion pairs is used to study radical-ion recombination kinetics, recombination pathways, and the structure of radical anions and cations. 17 figures.

  18. Spatiotemporal optical pulse transformation by a resonant diffraction grating

    SciTech Connect

    Golovastikov, N. V.; Bykov, D. A. Doskolovich, L. L. Soifer, V. A.

    2015-11-15

    The diffraction of a spatiotemporal optical pulse by a resonant diffraction grating is considered. The pulse diffraction is described in terms of the signal (the spatiotemporal incident pulse envelope) passage through a linear system. An analytic approximation in the form of a rational function of two variables corresponding to the angular and spatial frequencies has been obtained for the transfer function of the system. A hyperbolic partial differential equation describing the general form of the incident pulse envelope transformation upon diffraction by a resonant diffraction grating has been derived from the transfer function. A solution of this equation has been obtained for the case of normal incidence of a pulse with a central frequency lying near the guided-mode resonance of a diffraction structure. The presented results of numerical simulations of pulse diffraction by a resonant grating show profound changes in the pulse envelope shape that closely correspond to the proposed theoretical description. The results of the paper can be applied in creating new devices for optical pulse shape transformation, in optical information processing problems, and analog optical computations.

  19. Differential processing for frequency chirp measurement using optical pulse synthesizer

    NASA Astrophysics Data System (ADS)

    Kashiwagi, Ken; Seki, Satoshi; Tsuda, Hiroyuki; Takenouchi, Hirokazu; Kurokawa, Takashi

    2017-03-01

    In this study, we introduced an optical pulse synthesizer (OPS) to measure frequency chirps of optical pulses by differential processing. The OPS has a single-chip integrated structure of all elements for the differential filtering and enables stable measurement. Because the exact filter causes a large loss, we employed a phase-only filter, whose frequency response was only in phase. We measured chirp rates of pulses which were induced by propagating standard single mode fibers with different lengths. The retrieved chirp rates were comparable to calculated results. We simulated accuracy of the method and concluded that our experiment had phase control accuracy within 0.07π.

  20. Absorbing Boundary Conditions For Optical Pulses In Dispersive, Nonlinear Materials

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M.; Kwak, Dochan (Technical Monitor)

    1995-01-01

    This paper will present results in computational nonlinear optics. An algorithm will be described that provides absorbing boundary conditions for optical pulses in dispersive, nonlinear materials. A new numerical absorber at the boundaries has been developed that is responsive to the spectral content of the pulse. Also, results will be shown of calculations of 2-D electromagnetic nonlinear waves computed by directly integrating in time the nonlinear vector Maxwell's equations. The results will include simulations of "light bullet" like pulses. Here diffraction and dispersion will be counteracted by nonlinear effects. Comparisons will be shown of calculations that use the standard boundary conditions and the new ones.

  1. Optical pulse generation system for the National Ignition Facility (NIF)

    SciTech Connect

    Penko, F; Braucht,; Browning, D; Crane, J K; Dane, B; Deadrick, F; Dreifuerst, G; Henesian, M; Jones, B A; Kot, L; Laumann, C; Martinez, M; Moran, B; Rothenberg, J E; Skulina, K; Wilcox, R B

    1998-06-18

    We describe the Optical Pulse Generation (OPG) system for the National Ignition Facility ( NIF ). The OPG system begins with the Master Oscillator Room ( MOR ) where the initial, seed pulse for the entire laser system is produced and properly formatted to enhance ignition in the target. The formatting consists of temporally shaping the pulse and adding additional bandwidth to increase the coupling of the laser generated x-rays to the high density target plasma. The pulse produced in the MOR fans out to 48 identical preamplifier modules where it is amplified by a factor of ten billion and spatially shaped for injection into the 192 main amplifier chai

  2. Electro-optic time lens model for femtosecond pulses

    NASA Astrophysics Data System (ADS)

    Marinho, Francisco J.; Bernardo, Luís M.

    2008-04-01

    We propose an electro-optic time-lens (EOTL) model based on the coupled-mode theory. The model describes the propagation of a femtosecond pulse in an electro-optical crystal with parabolic refractive index modulation by a microwave. The proposed model integrates the second order dispersion approximation (β II ≠ 0) and takes into consideration the possible mismatch between the microwave phase velocity and the pulse group velocity. The coupled-mode theory uses the Hermite-Gaussian functions which are the modes of an ideal electro-optic time-lens. The model characterizes completely the performances of EOTL, including the aberrations, and it establishes the maximum velocity mismatch for which the pulse profile propagates through the crystal without significant distortion. The theoretical model is numerically implement considering the propagation of a short pulse in a Litium Niobate time-lens.

  3. Pulse Compression using a Tapered Microstructure Optical Fiber

    DTIC Science & Technology

    2006-04-01

    Pulse compression using a tapered microstructure optical fiber Jonathan Hu, Brian S. Marks, and Curtis R. Menyuk University of Maryland Baltimore...R. Menyuk , ”Optimization of the Split-Step Fourier Method in Modeling Optical-Fiber Communications Systems,” J. Lightwave Technol. 21, 61–68 (2003

  4. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOEpatents

    Smirl, A.; Trebino, R.P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques. 2 figs.

  5. Optical frequency modulated pulse power losses, caused by optical fiber material dispersion

    NASA Astrophysics Data System (ADS)

    Ivanov, Dmitry V.; Ivanov, Vladimir A.; Ryabova, Natalia V.; Ryabova, Maria I.; Chernov, Andrei A.; Konkin, Nikita A.

    2017-04-01

    The equations were obtained to estimate the pulse power losses of broadband light pulses caused by material dispersion in an optical fiber. It was found that the dispersion caused by the extension of a signal bandwidth leads to decreasing a signal base as well as the noise immunity of a system, which uses broadband pulses.

  6. Electro-Optical Modulator Bias Control Using Bipolar Pulses

    NASA Technical Reports Server (NTRS)

    Farr, William; Kovalik, Joseph

    2007-01-01

    An improved method has been devised for controlling the DC bias applied to an electro-optical crystal that is part of a Mach-Zehnder modulator that generates low-duty-cycle optical pulses for a pulse-position modulation (PPM) optical data-communication system. In such a system, it is desirable to minimize the transmission of light during the intervals between pulses, and for this purpose, it is necessary to maximize the extinction ratio of the modulator (the ratio between the power transmitted during an "on" period and the power transmitted during an "off" period). The present method is related to prior dither error feedback methods, but unlike in those methods, there is no need for an auxiliary modulation subsystem to generate a dithering signal. Instead, as described below, dither is effected through alternation of the polarity of the modulation signal. The upper part of Figure 1 schematically depicts a Mach-Zehnder modulator. The signal applied to the electro-optical crystal consists of a radio-frequency modulating pulse signal, VRF, superimposed on a DC bias Vbias. Maximum extinction occurs during the off (VRF = 0) period if Vbias is set at a value that makes the two optical paths differ by an odd integer multiple of a half wavelength so that the beams traveling along the two paths interfere destructively at the output beam splitter. Assuming that the modulating pulse signal VRF has a rectangular waveform, maximum transmission occurs during the "on" period if the amplitude of VRF is set to a value, V , that shifts the length of the affected optical path by a half wavelength so that now the two beams interfere constructively at the output beam splitter. The modulating pulse signal is AC-coupled from an amplifier to the electro-optical crystal. Sometimes, two successive pulses occur so close in time that the operating point of the amplifier drifts, one result being that there is not enough time for the signal level to return to ground between pulses. Also, the

  7. Ultrafast optical pulse delivery with fibers for nonlinear microscopy

    PubMed Central

    Kim, Daekeun; Choi, Heejin; Yazdanfar, Siavash; So, Peter T. C.

    2008-01-01

    Nonlinear microscopies including multiphoton excitation fluorescence microscopy and multiple-harmonic generation microscopy have recently gained popularity for cellular and tissue imaging. The optimization of these imaging methods for minimally invasive use will require optical fibers to conduct light into tight space where free space delivery is difficult. The delivery of high peak power laser pulses with optical fibers is limited by dispersion resulting from nonlinear refractive index responses. In this paper, we characterize a variety of commonly used optical fibers in terms of how they affect pulse profile and imaging performance of nonlinear microscopy; the following parameters are quantified: spectral bandwidth and temporal pulse width, two-photon excitation efficiency, and optical resolution. A theoretical explanation for the measured performance of these is also provided. PMID:18816597

  8. Recovering the propagation delay of an optical pulse.

    PubMed

    Tommasi, Federico; Ignesti, Emilio; Fini, Lorenzo; Cavalieri, Stefano

    2014-11-17

    Causality and special relativity pose an upper limit to the amount of advance that an optical pulse can acquire during a superluminal propagation. Such a limit can be circumvented if the pulse, before entering the superluminal medium, is retarded by letting it propagate under normal dispersion. We present an experimental evidence of this fact by showing that a laser pulse propagating in an atomic vapor, quasi resonant with an inverted transition and in conditions of anomalous dispersion, moves faster if it is previously retarded in a cell containing the same medium with no population inversion. Optical transmission lines often need an amplification stage to overcome the signal attenuation and the unavoidable delay respect to propagation at c; in this paper we tailor such stage to provide also an optical controlled recover of such delay. We believe that our results can open exciting prospects for real-life optical data processing and communication.

  9. Attosecond nonlinear optics using gigawatt-scale isolated attosecond pulses

    PubMed Central

    Takahashi, Eiji J.; Lan, Pengfei; Mücke, Oliver D.; Nabekawa, Yasuo; Midorikawa, Katsumi

    2013-01-01

    High-energy isolated attosecond pulses required for the most intriguing nonlinear attosecond experiments as well as for attosecond-pump/attosecond-probe spectroscopy are still lacking at present. Here we propose and demonstrate a robust generation method of intense isolated attosecond pulses, which enable us to perform a nonlinear attosecond optics experiment. By combining a two-colour field synthesis and an energy-scaling method of high-order harmonic generation, the maximum pulse energy of the isolated attosecond pulse reaches as high as 1.3 μJ. The generated pulse with a duration of 500 as, as characterized by a nonlinear autocorrelation measurement, is the shortest and highest-energy pulse ever with the ability to induce nonlinear phenomena. The peak power of our tabletop light source reaches 2.6 GW, which even surpasses that of an extreme-ultraviolet free-electron laser. PMID:24158092

  10. Optical pulse engineering and processing using optical nonlinearities of nanostructured waveguides made of silicon

    NASA Astrophysics Data System (ADS)

    Lavdas, Spyros; You, Jie; Osgood, Richard M.; Panoiu, Nicolae C.

    2015-08-01

    We present recent results pertaining to pulse reshaping and optical signal processing using optical nonlinearities of silicon-based tapered photonic wires and photonic crystal waveguides. In particular, we show how nonlinearity and dispersion engineering of tapered photonic wires can be employed to generate optical similaritons and achieve more than 10× pulse compression. We also discuss the properties of four-wave mixing pulse amplification and frequency conversion efficiency in long-period Bragg waveguides and photonic crystal waveguides. Finally, the influence of linear and nonlinear optical effects on the transmission bit-error rate in uniform photonic wires and photonic crystal waveguides made of silicon is discussed.

  11. Monolithic hybrid optics for focusing ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Fuchs, U.

    2014-03-01

    Almost any application of ultrashort laser pulses involves focusing them in order to reach high intensities and/or small spot sizes as needed for micro-machining or Femto-LASIK. Hence, it is indispensable to be able to understand pulse front distortion caused by real world optics. Focusing causes pulse front distortion due to aberrations, dispersion and diffraction. Thus, the spatio-temporal profile of ultrashort laser is altered, which increases automatically the pulse duration and the focusing spot. Consequently, the main advantage of having ultrashort laser pulses - pulse durations way below 100 fs - can be lost in that one last step of the experimental set-up by focusing them unfavorable. Since compensating for dispersion, aberration and diffraction effects is quite complicated and not always possible, we pursue a different approach. We present a specially designed monolithic hybrid optics comprising refraction and diffraction effects for tight spatial and temporal focusing of ultrashort laser pulses. Both aims can be put into practice by having a high numerical aperture (NA = 0.35) and low internal dispersion at the same time. The focusing properties are very promising, due to a design, which provides diffraction limited focusing for 100 nm bandwidth at 780 nm center wavelength. Thus, pulses with durations as short as 10 fs can be focused without pulse front distortion. The outstanding performance of this optics is shown in theory and experimentally. Above that, such focusing optics are easily adapted to their special purpose - changing the center wavelength, achromatic bandwidth or even correcting for focusing into material is possible.

  12. Acousto-optical imaging using a powerful long pulse laser

    NASA Astrophysics Data System (ADS)

    Rousseau, Guy; Blouin, Alain; Monchalin, Jean-Pierre

    2008-06-01

    Acousto-optical imaging is an emerging biodiagnostic technique which provides an optical spectroscopic signature and a spatial localization of an optically absorbing target embedded in a strongly scattering medium. The transverse resolution of the technique is determined by the lateral extent of ultrasound beam focal zone while the axial resolution is obtained by using short ultrasound pulses. Although very promising for medical diagnostic, the practical application of this technique is presently limited by its poor sensitivity. Moreover, any method to enhance the signal-to-noise ratio must obviously satisfy the in vivo safety limits regarding the acceptable power level of both the ultrasonic pressure wave and the laser beam. In this paper, we propose to improve the sensitivity by using a pulsed single-frequency laser source to raise the optical peak power applied to the scattering medium and to collect more ultrasonically tagged photons. Such a laser source also allows illuminating the tissues mainly during the transit time of the ultrasonic wave to maintain the average optical power below the maximum permissible exposure. In our experiment, a single-frequency Nd:YAG laser emitting 500-μs pulses with a peak power superior to 100 W was used. Photons were tagged in few-cm thick optical phantoms with tone bursts generated by an ultrasonic transducer. Tagged photons were detected with a GaAs photorefractive interferometer characterized by a large optical etendue to process simultaneously a large number of speckle grains. When pumped by high intensity laser pulses, such an interferometer also provides the fast response time essential to obtain an apparatus insensitive to the speckle decorrelation due to mechanical vibrations or tissues movements. The use of a powerful long pulse laser appears promising to enhance the signal level in ultrasound modulated optical imaging. When combined with a photorefractive interferometer of large optical etendue, such a source could

  13. All-optical three-dimensional electron pulse compression

    NASA Astrophysics Data System (ADS)

    Jie Wong, Liang; Freelon, Byron; Rohwer, Timm; Gedik, Nuh; Johnson, Steven G.

    2015-01-01

    We propose an all-optical, three-dimensional electron pulse compression scheme in which Hermite-Gaussian optical modes are used to fashion a three-dimensional optical trap in the electron pulse’s rest frame. We show that the correct choices of optical incidence angles are necessary for optimal compression. We obtain analytical expressions for the net impulse imparted by Hermite-Gaussian free-space modes of arbitrary order. Although we focus on electrons, our theory applies to any charged particle and any particle with non-zero polarizability in the Rayleigh regime. We verify our theory numerically using exact solutions to Maxwell’s equations for first-order Hermite-Gaussian beams, demonstrating single-electron pulse compression factors of \\gt {{10}2} in both longitudinal and transverse dimensions with experimentally realizable optical pulses. The proposed scheme is useful in ultrafast electron imaging for both single- and multi-electron pulse compression, and as a means of circumventing temporal distortions in magnetic lenses when focusing ultrashort electron pulses. Other applications include the creation of flat electron beams and ultrashort electron bunches for coherent terahertz emission.

  14. Spatial and temporal pulse propagation for dispersive paraxial optical systems

    DOE PAGES

    Marcus, G.

    2016-04-01

    The formalism for pulse propagation through dispersive paraxial optical systems first presented by Kostenbauder (IEEE J. Quant. Elec. 261148–1157 (1990)) using 4 × 4 ray-pulse matrices is extended to 6 × 6 matrices and includes non-separable spatial-temporal couplings in both transverse dimensions as well as temporal dispersive effects up to a quadratic phase. The eikonal in a modified Huygens integral in the Fresnell approximation is derived and can be used to propagate pulses through complicated dispersive optical systems within the paraxial approximation. Additionally, a simple formula for the propagation of ultrashort pulses having a Gaussian profile both spatially and temporallymore » is presented.« less

  15. Normalized pulsed energy thresholding in a nonlinear optical loop mirror.

    PubMed

    Nahmias, M A; Shastri, B J; Tait, A N; Eder, M; Rafidi, Nicole; Tian, Yue; Prucnal, P R

    2015-04-10

    We demonstrate for the first time, to the best of our knowledge, that a Sagnac interferometer can threshold the energies of pulses. Pulses below a given threshold T are suppressed, while those above this threshold are normalized. The device contains an in-loop tunable isolator and 10.4 m of a highly doped silica fiber. We derive an analytical model of the nonlinear optical loop mirror's pulse energy transfer function and show that its energy transfer function approximates a step function for very high phase shifts (>π). We reveal some limitations of this approach, showing that a step-function transfer function necessarily results in pulse distortion in fast, nonresonant all-optical devices.

  16. Suspension of Atoms Using Optical Pulses, and Application to Gravimetry

    SciTech Connect

    Hughes, K. J.; Burke, J. H. T.; Sackett, C. A.

    2009-04-17

    Atoms from a {sup 87}Rb condensate are suspended against gravity using repeated reflections from a pulsed optical standing wave. Up to 100 reflections are observed, yielding suspension times of over 100 ms. The local gravitational acceleration can be determined from the pulse rate required to achieve suspension. Further, a gravitationally sensitive atom interferometer was implemented using the suspended atoms. This technique could potentially provide a precision measurement of gravity without requiring the atoms to fall a large distance.

  17. Optical emission spectroscopy observations of fast pulsed capillary discharge plasmas

    NASA Astrophysics Data System (ADS)

    Avaria, G.; Ruiz, M.; Guzmán, F.; Favre, M.; Wyndham, E. S.; Chuaqui, H.; Bhuyan, H.

    2014-05-01

    We present time resolved optical emission spectroscopic (OES) observations of a low energy, pulsed capillary discharage (PCD). The optical emission from the capillary plasma and plasma jets emitted from the capillary volume was recorded with with a SpectraPro 275 spectrograph, fitted with a MCP gated OMA system, with 15 ns time resolution. The discharge was operated with different gases, including argon, nitrogen, hydrogen and methane, in a repetitive pulsed discharge mode at 10-50 Hz, with, 10-12 kV pulses applied at the cathode side. The time evolution of the electron density was measured using Stark broadening of the Hβ line. Several features of the capillary plasma dynamics, such as ionization growth, wall effects and plasma jet evolution, are inferred from the time evolution of the optical emission.

  18. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement.

    PubMed

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun

    2014-11-01

    A compact multifunctional optical correlator system for pulse width measurement of ultrashort ultraviolet (UV) pulses has been designed and experimentally demonstrated. Both autocorrelation and cross-correlation functions are measured using a single nonlinear crystal, and the switching between two measurements requires no adjustment of phase matching and detector. The system can measure UV pulse widths from sub-picoseconds to 100 ps, and it involves no auxiliary pulse in the measurement. The measurement results on a burst-mode picosecond UV laser show a high-quality performance on speed, accuracy, resolution, and dynamic range. The proposed correlator can be applied to measure any ultrashort UV pulses produced through sum-frequency generation or second-harmonic generation.

  19. Predictability of extreme intensity pulses in optically injected semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Alvarez, Nuria Martinez; Borkar, Saurabh; Masoller, Cristina

    2017-06-01

    The predictability of extreme intensity pulses emitted by an optically injected semiconductor laser is studied numerically, by using a well-known rate equation model. We show that symbolic ordinal time-series analysis allows to identify the patterns of intensity oscillations that are likely to occur before an extreme pulse. The method also gives information about patterns which are unlikely to occur before an extreme pulse. The specific patterns identified capture the topology of the underlying chaotic attractor and depend on the model parameters. The methodology proposed here can be useful for analyzing data recorded from other complex systems that generate extreme fluctuations in their output signals.

  20. Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

    PubMed

    Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

    2010-06-15

    We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

  1. ULTRASHORT LIGHT PULSES: Formation of subfemtosecond laser pulses in aperiodically poled nonlinear-optical crystals

    NASA Astrophysics Data System (ADS)

    Shutov, I. V.; Novikov, A. A.; Chirkin, A. S.

    2008-03-01

    The method of synthesis of ultrashort laser pulses in nonlinear aperiodically poled crystals based on the simultaneous generation of several higher optical harmonics is considered. The interaction of four waves with multiple frequencies involving three mutually coupled nonlinear three-frequency processes is studied. It is shown that by introducing intense laser radiation into a crystal, pulses of duration of the order of a few hundreds of attoseconds can be produced at the crystal output.

  2. Methylprednisolone pulse therapy in severe dysthyroid optic neuropathy

    SciTech Connect

    Guy, J.R.; Fagien, S.; Donovan, J.P.; Rubin, M.L. )

    1989-07-01

    Five patients with severe dysthyroid optic neuropathy were treated with intravenous methylprednisolone (1 g daily for 3 consecutive days). Before administration, visual acuity of the more severely affected eyes of each patient was counting fingers at 5 feet, 8/200, 20/400, 20/200, and 20/80. Immediately after completion of pulse therapy, visual acuity improved to 20/25 in four patients and 20/30 in one. Remissions were maintained with oral prednisone and external beam irradiation of the orbit. Pulse methylprednisolone therapy appears to be beneficial in the initial management of severe dysthyroid optic neuropathy.

  3. Polarization-controlled optical ring cavity (PORC) tunable pulse stretcher

    NASA Astrophysics Data System (ADS)

    Williamson, Andrew P.; Kiefer, Johannes

    2016-08-01

    A new concept and a theoretical approach for modeling a tunable polarization-controlled optical ring cavity pulse stretcher is demonstrated. The technique discussed herein permits highly simplified and flexible tuning of the temporal shape of nanosecond duration pulses. Using half-wave plates positioned extra- and intracavity, transmission to reflection ratios across both input faces of a polarization beam splitter can easily be controlled. The resulting models indicate a further reduction in peak intensity of 30%, with respect to conventional dielectric beam splitting optical ring cavities, when configured under equivalent and optimized cavity settings.

  4. Gigahertz planar photoconducting antenna activated by picosecond optical pulses.

    PubMed

    Liu, D W; Thaxter, J B; Bliss, D F

    1995-07-15

    We have generated 1-20-GHz microwave pulses by illuminating an Fe-compensated InP wafer with 50-ps optical pulses at normal incidence. The process of the generation of microwave radiation was monitored and analyzed directly through a 40-GHz sampling oscilloscope with precision. The saturation properties, the waveform evolution, and the optical coupling efficiency of the gigahertz photoconducting antenna are discussed. The flexibility, compactness, and high-resolution features offered by this technique merit new applications for radar communication as well as for other microwave detecting devices.

  5. Gigahertz planar photoconducting antenna activated by picosecond optical pulses

    NASA Astrophysics Data System (ADS)

    Liu, D. W.; Thaxter, J. B.; Bliss, D. F.

    1995-07-01

    We have generated 1-20-GHz microwave pulses by illuminating an Fe-compensated InP wafer with 50-ps optical pulses at normal incidence. The process of the generation of microwave radiation was monitored and analyzed directly through a 40-GHz sampling oscilloscope with precision. The saturation properties, the waveform evolution, and the optical coupling efficiency of the gigahertz photoconducting antenna are discussed. The flexibility, compactness, and high-resolution features offered by this technique merit new applications for radar communication as well as for other microwave detecting devices.

  6. Soft demodulation to the optical pulse position modulated signals

    NASA Astrophysics Data System (ADS)

    Zhou, Tian-hua; Chen, Wei-biao

    2009-07-01

    The optical Pulse Position Modulation (PPM) is applied widely in Free Space Optical communication (FSO) with the low average power and the high peak power. The transmitted PPM information depends on the location of the coming optical pulse signals in fixed period. Both receiver and transmitter should been kept in time slot synchronization and frame synchronization in demodulation. Because the channel is very complex, the received optical pulse width will be stretched randomly. We design and realize one digital PPM modulation receiver with high sensitivity using the technology of PMT, A/D converter, and DSP. It is suitable to the total digital optical receiver with random time slots and random pulse width. The paper will mainly discuss the realization of the soft demodulation behind A/D converter. The key of PPM digital soft modulation is the establishment of the synchronization that involves the segment synchronization, the fame synchronization and the bit synchronization. The synchronization can be obtained by seeking for the frame head in data frames. Based on the estimation of received waveform characteristics, we adopt a matched filter without the best factors firstly. Thereafter, their errors will be self-adapted while finding the synchronization head. Considering the real-time need, we choose the reduced mode of maximum likelihood function judgment finally. In the experiments, results with high sensitivity and low bit error rate have been achieved.

  7. Cross-correlation frequency-resolved optical gating for characterization of an ultrashort optical pulse train

    NASA Astrophysics Data System (ADS)

    Nakano, Yuta; Imasaka, Totaro

    2017-05-01

    A technique involving cross-correlation frequency-resolved optical gating is applied in characterizing an optical pulse train consisting of several spectral components. An optical beat was used as a reference pulse for measuring the relative spectral phase among the spectral components in the test pulse generated by four-wave Raman mixing in hydrogen gas. It was confirmed that a change in the relative phase can be measured by monitoring the shift in the interference fringe and that Raman emissions generated by four-wave Raman mixing are phase locked.

  8. All-optical DAC using counter-propagating optical and electrical pulses in a Mach-Zehnder modulator.

    PubMed

    Lowery, Arthur James

    2014-10-20

    A novel method of converting binary-level electrical pulses into multi-level optical pulses using only a conventional traveling-wave optical modulator is presented. The method provides low inter-pulse interference due to the counter-propagating pulses, low amplitude noise, and a timing jitter determined chiefly by the quality of the optical pulse source. The method only requires one electrical drive per modulator and provides low-jitter variable-amplitude optical pulses that are suitable for shaping into a wide variety of modulation formats using a programmable optical filter.

  9. Novel ultrasensitive plasmonic detector of terahertz pulses enhanced by femtosecond optical pulses

    NASA Astrophysics Data System (ADS)

    Shur, M.; Rudin, S.; Rupper, G.; Muraviev, A.

    2016-09-01

    Plasmonic Field Effect Transistor detectors (first proposed in 1996) have emerged as superior room temperature terahertz (THz) detectors. Recent theoretical and experimental results showed that such detectors are capable of subpicosecond resolution. Their sensitivity can be greatly enhanced by applying the DC drain-to-source current that increases the responsivity due to the enhanced non-linearity of the device but also adds 1/f noise. We now propose, and demonstrate a dramatic responsivity enhancement of these plasmonic THz pulse detectors by applying a femtosecond optical laser pulse superimposed on the THz pulse. The proposed physical mechanism links the enhanced detection to the superposition of the THz pulse field and the rectified optical field. A femtosecond pulse generates a large concentration of the electron-hole pairs shorting the drain and source contacts and, therefore, determining the moment of time when the THz induced charge starts discharging into the transmission line connecting the FET to an oscilloscope. This allows for scanning the THz pulse with the strongly enhanced sensitivity and/or for scanning the response waveform after the THz pulse is over. The experimental results obtained using AlGaAs/InGaAs deep submicron HEMTs are in good agreement with this mechanism. This new technique could find numerous imaging, sensing, and quality control applications.

  10. Measurement of pulse width and amplitude jitter noises of gigahertz optical pulse trains by time-domain demodulation.

    PubMed

    Pottiez, O; Deparis, O; Kiyan, R; Mégret, P; Blondel, M

    2001-11-15

    We propose a technique for measuring both pulse width and amplitude jitter noises of high-repetition-rate optical pulse trains and the cross correlation between these noises as well. The technique is based on time-domain amplitude demodulation of three harmonic components of the detected pulse train. We applied this technique to characterize noises of a gigahertz optical pulse train generated by an actively mode-locked Er-doped fiber laser. Correlation between pulse width jitter and pulse amplitude jitter was observed at low frequencies in this laser. Unlike relaxation oscillation noise, low-frequency noise is free from pulse energy jitter. Owing to its ability to measure pulse width jitter in addition to amplitude and phase jitters, this technique is of great interest for characterizing noises of a wide variety of optical pulse train sources.

  11. Enhancement of terahertz pulse emission by optical nanoantenna.

    PubMed

    Park, Sang-Gil; Jin, Kyong Hwan; Yi, Minwoo; Ye, Jong Chul; Ahn, Jaewook; Jeong, Ki-Hun

    2012-03-27

    Bridging the gap between ultrashort pulsed optical waves and terahertz (THz) waves, the THz photoconductive antenna (PCA) is a major constituent for the emission or detection of THz waves by diverse optical and electrical methods. However, THz PCA still lacks employment of advanced breakthrough technologies for high-power THz emission. Here, we report the enhancement of THz emission power by incorporating optical nanoantennas with a THz photoconductive antenna. The confinement and concentration of an optical pump beam on a photoconductive substrate can be efficiently achieved with optical nanoantennas over a high-index photoconductive substrate. Both numerical and experimental results clearly demonstrate the enhancement of THz wave emission due to high photocarrier generation at the plasmon resonance of nanoantennas. This work opens up many opportunities for diverse integrated photonic elements on a single PCA at THz and optical frequencies.

  12. Computational Modeling of Ultrafast Pulse Propagation in Nonlinear Optical Materials

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M.; Agrawal, Govind P.; Kwak, Dochan (Technical Monitor)

    1996-01-01

    There is an emerging technology of photonic (or optoelectronic) integrated circuits (PICs or OEICs). In PICs, optical and electronic components are grown together on the same chip. rib build such devices and subsystems, one needs to model the entire chip. Accurate computer modeling of electromagnetic wave propagation in semiconductors is necessary for the successful development of PICs. More specifically, these computer codes would enable the modeling of such devices, including their subsystems, such as semiconductor lasers and semiconductor amplifiers in which there is femtosecond pulse propagation. Here, the computer simulations are made by solving the full vector, nonlinear, Maxwell's equations, coupled with the semiconductor Bloch equations, without any approximations. The carrier is retained in the description of the optical pulse, (i.e. the envelope approximation is not made in the Maxwell's equations), and the rotating wave approximation is not made in the Bloch equations. These coupled equations are solved to simulate the propagation of femtosecond optical pulses in semiconductor materials. The simulations describe the dynamics of the optical pulses, as well as the interband and intraband.

  13. Design of Optical Pulse Position Modulation (PPM) Translating Receiver

    SciTech Connect

    Mendez, A J; Hernandez, V J; Gagliardi, R M; Bennett, C V

    2009-06-19

    M-ary pulse position modulation (M-ary PPM) signaling is a means of transmitting multiple bits per symbol in an intensity modulated/direct detection (IM/DD) system. PPM is used in applications with average power limitations. In optical communication systems, PPM becomes challenging to implement at gigabit rates and/or large M, since pulsed signaling requires higher electronic processing bandwidths than the fundamental transmission rate. they have thus been exploring techniques for PPM communications using optical processing. Previous work described a transmitter algorithm that directly translates a bit sequence of N digital bits to the optical pulse position m for any M = 2{sup N}. It has been considerably more difficult to define a similar receiver algorithm that translates the received optical pulse position directly back to a bit sequence with minimal electronic processing. Designs for specific Ms (e.g., 4-ary) have been shown and implemented, but are difficult to scale to larger M. In this work, they present for the first time a generalized PPM translating receiver that is applicable to all M and data rates.

  14. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle.

    PubMed

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-02-24

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core-shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems.

  15. Parallel Memory Addressing Using Coincident Optical Pulses

    DTIC Science & Technology

    1989-09-15

    case reduces to a at the interface between the electronic memory structure more manageable 21n lines controlling processing units and the optical system...Addressing Donald M. Chiarulli, Rami G. Melhem, and Steven P. Levitan University of Pittsburgh omm on-bus, shared-memory .dcoder can process only a single...encoded multiprocessors are the most k address,thuslimitingmemoryaccess to widely used parallel processing single location. Memory interleaving tech

  16. Recycle Rate in a Pulsed, Optically Pumped Rubidium Laser

    SciTech Connect

    Miller, Wooddy S.; Sulham, Clifford V.; Holtgrave, Jeremy C.; Perram, Glen P.

    2010-10-08

    A pulsed, optically pumped rubidium laser operating in analogy to the diode pumped alkali laser (DPAL) system at pump intensities as high as 750 kW/cm{sup 2} has been demonstrated with output energies of up to 13 {mu}J/pulse. Output energy is dramatically limited by spin-orbit relaxation rates under these high intensity pump conditions. More than 250 photons are available for every rubidium atom in the pumped volume, requiring a high number of cycles per atom during the 2-8 ns duration of the pump pulse. At 550 Torr of ethane, the spin-orbit relaxation rate is too slow to effectively utilize all the incident pump photons. Indeed, a linear dependence of output energy on pump pulse duration for fixed pump energy is demonstrated.

  17. Two-optical-cycle pulses in the mid-infrared from an optical parametric amplifier.

    PubMed

    Brida, D; Marangoni, M; Manzoni, C; Silvestri, S De; Cerullo, G

    2008-12-15

    Ultrabroadband mid IR pulses with energy as high as 2 microJ and tunability from 2 to 5 microm are generated as the idler beam of an 800 nm pumped optical parametric amplifier in periodically poled stoichiometric lithium tantalate. After bulk compression in a Ge plate and frequency-resolved-opticle-gating characterization, a pulse duration as low as 25 fs was measured, corresponding to two optical cycles of the 3.6 microm carrier wavelength.

  18. Quasi-Optical 34-GHz Rf Pulse Compressor

    SciTech Connect

    Hirshfield, Jay L

    2007-06-19

    Designs have been carried out on non-high-vacuum, low-power versions of three- and four-mirror quasi-optical passive and active Ka-band pulse compressors, and prototypes built and tested based on these designs. The active element is a quasi-optical grating employing gas discharge tubes in the gratings. Power gains of about 3:1 were observed experimentally for the passive designs, and about 7:1 with the active designs. High-power, high-vacuum versions of the three-and four-mirror quasi-optical pulse compressors were built and tested at low power. These now await installation and testing using multi-MW power from the 34-GHz magnicon.

  19. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement

    DOE PAGES

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; ...

    2014-01-01

    A compact optical correlator system that measures both the autocorrelation between two infrared (IR) lights and the cross-correlation between an IR and an ultraviolet (UV) light using a single nonlinear optical crystal has been designed and experimentally demonstrated. The rapid scanning of optical delay line, switching between auto and cross-correlations, crystal angle tuning, and data acquisition and processing are all computer controlled. Pulse widths of an IR light from a mode-locked laser are measured by the correlator and the results are compared with a direct measurement using a high-speed photodetector system. The correlator has been used to study the parametermore » dependence of the pulse width of a macropulse UV laser designed for laser-assisted hydrogen ion (H-) beam stripping for the Spallation Neutron Source at Oak Ridge National Laboratory.« less

  20. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement

    SciTech Connect

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary D.; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun

    2014-01-01

    A compact optical correlator system that measures both the autocorrelation between two infrared (IR) lights and the cross-correlation between an IR and an ultraviolet (UV) light using a single nonlinear optical crystal has been designed and experimentally demonstrated. The rapid scanning of optical delay line, switching between auto and cross-correlations, crystal angle tuning, and data acquisition and processing are all computer controlled. Pulse widths of an IR light from a mode-locked laser are measured by the correlator and the results are compared with a direct measurement using a high-speed photodetector system. The correlator has been used to study the parameter dependence of the pulse width of a macropulse UV laser designed for laser-assisted hydrogen ion (H-) beam stripping for the Spallation Neutron Source at Oak Ridge National Laboratory.

  1. Optical pulse-burst position modulation for antenna beam forming

    NASA Astrophysics Data System (ADS)

    Shemer, Amir; Zalevsky, Zeev; Zach, Shlomo

    2009-04-01

    We present a realization of an optically controlled pulse-burst position modulator to be used for a radio-frequency photonic circuit aiming to produce beam forming for a Radar-transmitting antenna. The configuration uses a set of fiber ring resonators that contain erbium-doped fiber amplifiers. By controlling the pumping in each loop, the gain of the doped fibers is changed, which results with a change in the resonators" finesses. In the end of each optical path, the optical signal is sampled and converted to an electronic signal while an electronic subtraction is performed between the outputs of the two resonators. Because each resonator has different and controlled finesse, the subtraction results in an output pulse burst with varied position.

  2. Propagation of Optical Pulses in Polarization Maintaining Highly Birefringent Fibers

    NASA Astrophysics Data System (ADS)

    Leiva, Ariel; Olivares, Ricardo

    2008-04-01

    The propagation of Gaussian optical pulses through optical PM-HiBi (Polarization Maintaining Highly Birefringent) fibers is analyzed and simulated. Based upon a model of propagation as described by Marcuse, et al., [1] and Sunnerud, et al., [2], and the use of PMD (Polarization Mode Dispersion) compensators and emulators used by Kogelnik, et al. [2], [3] and Lima, et al. [4], we construct a simple model that allows graphical representation of the distortion experienced by optical pulses when propagating in a PM-HiBi fiber for different initial polarizations. The results of our analysis have the benefit of being identical to the more elaborate models of [1], [2], while also providing the additional advantage of simple graphical representation.

  3. Fiber Optic Solutions for Short Pulse Lasers

    SciTech Connect

    Beach, R; Dawson, J; Liao, Z; Jovanovic, I; Wattellier, B; Payne, S; Barty, C P

    2003-01-29

    For applications requiring high beam quality radiation from efficient, compact and rugged sources, diffraction limited fiber lasers are ideal, and to date have been demonstrated at average CW power levels exceeding 100 W with near diffraction limited: output. For conventional single-core step-index single-mode fibers, this power level represents the sealing limit because of nonlinear and laser damage considerations. Higher average powers would exceed nonlinear process thresholds such as the Raman and stimulated Brillouin scattering limit, or else damage the fiber due to the high intensity level in the fiber's core. The obvious way to increase the average power capability of fibers is to increase the area of their core. Simply expanding the core dimensions of the fiber allows a straightforward power sealing due to enhanced nonlinear and power handling characteristics that scale directly with the core area. Femtosecond, chirped-pulse, fiber lasers with pulse energies greater than 1mJ have been demonstrated in the literature [2] using this technique. This output energy was still limited by the onset of stimulated Raman scattering. We have pursued an alternative and complimentary approach which is to reduce the intensity of light propagating in the core by distributing it more evenly across the core area via careful design of the refractive index profile [3]. We have also sought to address the primary issue that results from scaling the core. The enhanced power handling capability comes at the expense of beam quality, as increasing the core diameter in standard step index fibers permits multiple transverse modes to lase simultaneously. Although this problem of multimode operation can be mitigated to some extent by appropriately designing the fiber's waveguide structure, limitations such as bend radius loss, sensitivity to thermally induced perturbations of the waveguide structure, and refractive index control, all become more stringent as the core diameter grows

  4. Optical gene transfer by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Konig, Karsten; Riemann, Iris; Tirlapur, Uday K.

    2003-07-01

    Targeted transfection of cells is an important technique for gene therapy and related biomedical applications. We delineate how high-intensity (1012 W/cm2) near-infrared (NIR) 80 MHz nanojoule femtosecond laser pulses can create highly localised membrane perforations within a minute focal volume, enabling non-invasive direct transfection of mammalian cells with DNA. We suspended Chinese hamster ovarian (CHO), rat kangaroo kidney epithelial (PtK2) and rat fibroblast cells in 0.5 ml culture medium in a sterile miniaturized cell chamber (JenLab GmbH, Jena, Germany) containing 0.2 μg plasmid DNA vector pEGFP-N1 (4.7 kb), which codes for green fluorescent protein (GFP). The NIR laser beam was introduced into a femtosecond laser scanning microscope (JenLab GmbH, Jena, Germany; focussed on the edge of the cell membrane of a target cell for 16 ms. The integration and expression efficiency of EGFP were assessed in situ by two-photon fluorescence-lifetime imaging using time-correlated single photon counting. The unique capability to transfer foreign DNA safely and efficiently into specific cell types (including stem cells), circumventing mechanical, electrical or chemical means, will have many applications, such as targeted gene therapy and DNA vaccination.

  5. High-Sensitivity Optical Pulse Characterization Using Sagnac Electro-Optic Spectral Shearing Interferometry

    SciTech Connect

    Dorrer, C.; Bromage, J.

    2010-05-04

    An electro-optic spectral shearing interferometer for high-sensitivity optical pulse characterization is described. Two replicas of the test pulse counterpropagate in a Sagnac interferometer with orthogonal polarization states, resulting in two relatively sheared copolarized replicas after temporal phase modulation. The polarization interferometer is intrinsically stable, and its birefringence sets the delay between interfering replicas to reduce the spectrometer resolution requirement. Experimental implementations demonstrate real-time pulse characterization at average powers as low as 1 nWwith spectral shears as high as 280 GHz.

  6. Stochastic pulse switching in a degenerate resonant optical medium

    NASA Astrophysics Data System (ADS)

    Atkins, Ethan P.; Kramer, Peter R.; Kovačič, Gregor; Gabitov, Ildar R.

    2012-04-01

    Using the idealized integrable Maxwell-Bloch model, we describe random optical-pulse polarization switching along an active optical medium in the Λ configuration with disordered occupation numbers of its lower-energy sublevel pair. The description combines complete integrability and stochastic dynamics. For the single-soliton pulse, we derive the statistics of the electric-field polarization ellipse at a given point along the medium in closed form. If the average initial population difference of the two lower sublevels vanishes, we show that the pulse polarization will switch intermittently between the two circular polarizations as it travels along the medium. If this difference does not vanish, the pulse will eventually forever remain in the circular polarization determined by which sublevel is more occupied on average. We also derive the exact expressions for the statistics of the polarization-switching dynamics, such as the probability distribution of the distance between two consecutive switches and the percentage of the distance along the medium the pulse spends in the elliptical polarization of a given orientation in the case of vanishing average initial population difference. We find that the latter distribution is given in terms of the well-known arc sine law.

  7. Phase and intensity characterization of femtosecond pulses from a chirped-pulse amplifier by frequency-resolved optical gating

    SciTech Connect

    Kohler, B.; Yakovlev, V.V.; Wilson, K.R.; Squier, J.; DeLong, K.W.; Trebino, R.

    1995-03-01

    Frequency-resolved optical gating (FROG) measurements were made to characterize pulses from a Ti:sapphire chirped-pulse amplified laser system. By characterizing both the pulse intensity and the phase, the FROG data provided the first direct observation to our knowledge of residual phase distortion in a chirped-pulse amplifier. The FROG technique was also used to measure the regenerative amplifier dispersion and to characterize an amplitude-shaped pulse. The data provide an experimental demonstration of the value of FROG for characterizing complex pulses, including tailored femtosecond pulses for quantum control.

  8. Theory of Pulse Propagation in Optical Directional Couplers

    NASA Astrophysics Data System (ADS)

    Chiang, Kin Seng

    Since the existence of intermodal dispersion or coupling coefficient dispersion in an optical directional coupler was highlighted ten years ago, a number of theoretical studies for the understanding of the significance of this dispersion effect on pulse propagation in a directional coupler under various situations have been reported. This paper provides a review of these studies. Both the normal-mode theory and the coupled-mode theory of the coupler are described. The application of the more popular coupled-mode theory to the study of nonlinear pulse switching, soliton interaction, soliton formation, and active couplers is discussed. Experimental works are also described briefly.

  9. Pulse operation of semiconductor laser with nonlinear optical feedback

    NASA Astrophysics Data System (ADS)

    Guignard, Celine; Besnard, Pascal; Mihaescu, Adrian; MacDonald, K. F.; Pochon, Sebastien; Zheludev, Nikolay I.

    2004-09-01

    A semiconductor laser coupled to a gallium-made non linear mirror may exhibit pulse regime. In order to better understand this coupled cavity, stationary solutions and dynamics are described following the standard Lang and Kobayashi equations for a semiconductor laser submitted to nonlinear optical feedback. It is shown that the nonlinearity distorts the ellipse on which lied the stationary solutions, with a ``higher'' part corresponding to lower reflectivity and a ``lower'' part to higher reflectivity. Bifurcation diagrams and nonlinear analysis are presented while the conditions for pulsed operation are discussed.

  10. Optical levitation and manipulation of stuck particles with pulsed optical tweezers.

    PubMed

    Ambardekar, Amol Ashok; Li, Yong-Qing

    2005-07-15

    We report on optical levitation and manipulation of microscopic particles that are stuck on a glass surface with pulsed optical tweezers. An infrared pulse laser at 1.06 microm was used to generate a large gradient force (up to 10(-9) N) within a short duration (approximately 45 micros) that overcomes the adhesive interaction between the particles and the glass surface. Then a low-power continuous-wave diode laser at 785 nm was used to capture and manipulate the levitated particle. We have demonstrated that both stuck dielectric and biological micrometer-sized particles, including polystyrene beads, yeast cells, and Bacillus cereus bacteria, can be levitated and manipulated with this technique. We measured the single-pulse levitation efficiency for 2.0 microm polystyrene beads as a function of the pulse energy and of the axial displacement from the stuck particle to the pulsed laser focus, which was as high as 88%.

  11. Direct generation of all-optical random numbers from optical pulse amplitude chaos.

    PubMed

    Li, Pu; Wang, Yun-Cai; Wang, An-Bang; Yang, Ling-Zhen; Zhang, Ming-Jiang; Zhang, Jian-Zhong

    2012-02-13

    We propose and theoretically demonstrate an all-optical method for directly generating all-optical random numbers from pulse amplitude chaos produced by a mode-locked fiber ring laser. Under an appropriate pump intensity, the mode-locked laser can experience a quasi-periodic route to chaos. Such a chaos consists of a stream of pulses with a fixed repetition frequency but random intensities. In this method, we do not require sampling procedure and external triggered clocks but directly quantize the chaotic pulses stream into random number sequence via an all-optical flip-flop. Moreover, our simulation results show that the pulse amplitude chaos has no periodicity and possesses a highly symmetric distribution of amplitude. Thus, in theory, the obtained random number sequence without post-processing has a high-quality randomness verified by industry-standard statistical tests.

  12. Acousto-Optic Tunable Filter for Time-Domain Processing of Ultra-Short Optical Pulses,

    DTIC Science & Technology

    The application of acousto - optic tunable filters for shaping of ultra-fast pulses in the time domain is analyzed and demonstrated. With the rapid...advance of acousto - optic tunable filter (AOTF) technology, the opportunity for sophisticated signal processing capabilities arises. AOTFs offer unique

  13. Averaging of Replicated Pulses for Enhanced-Dynamic-Range Single-Shot Measurement of Nanosecond Optical Pulses

    SciTech Connect

    Marciante, J.R.; Donaldson, W.R.; Roides, R.G.

    2007-10-04

    Measuring optical pulse shapes beyond the dynamic range of oscilloscopes is achieved by temporal pulse stacking in a low-loss, passive, fiber-optic network. Optical pulses are averaged with their time-delayed replicas without introducing additional noise or jitter, allowing for high-contrast pulse-shape measurements of single-shot events. A dynamic-range enhancement of three bits is experimentally demonstrated and compared with conventional multi-shot averaging. This technique can be extended to yield an increase of up to seven bits of additional dynamic range over nominal oscilloscope performance.

  14. An optical fiber re-circulating loop for a single shot very short pulse or pulse train measurement

    NASA Astrophysics Data System (ADS)

    Yin, Yan

    1997-05-01

    A signle shot very short electrical pulse is converted into an optical pulse, then is injeted into a re-circulating optical fiber loop. It is tapped out at each turn to produce a pulse train. Each pulse in the train is a copy of the original one. This method generates a repetitive signals from a single shot signal. A sampling oscilloscope then can be used to perform the measurement. It uses the high bandwidth of modern optical fiber technique. The paper will describe the system and present the results of the bench tests. The work has bee done under DOE SBIR grant, DE-FG03-96ER82210/A000.

  15. Femtosecond optical spectroscopy and microscopy with phase coherent pulses

    NASA Astrophysics Data System (ADS)

    Li, Chunqiang

    This dissertation focuses on femtosecond optical spectroscopy and microscopy by using ultrashort laser pulse shaping technology. Collinear phase coherent two-dimensional spectroscopy on the organic dye Coumarin 102 was performed. The collinear phase coherent three-pulse sequences in the near infrared wavelength (800 nm) were generated by an acousto-optic pulse shaper. Coumarin 102 has a broad absorption band of around 400 nm. Two-photon absorption of the 800 nm light in Coumarin 102 is essential to perform the experiment. For comparison another set of experiments with the light frequency doubled to 400 nm was also performed. The results obtained show similar features with different details. The energy level information, e.g. linewidth, can be retrieved from the two-dimensional spectral peaks. With pulse shaping technology the possibility to perform ultrafast laser microscopy aiming at potential biomedical application was also explored. The information utilized to differentiate chemicals is two-photon absorption and the structural information can also be retrieved from self-phase modulation. The nonlinear signal from these experiments is very small compared with input laser power. A heterodyne detection method was performed by creating a spectral hole in the laser spectrum with the pulse shaper. The signal generated is mixed with the local oscillator. The results from Rhodamine 6G, oxyHemoglobin and pheomelanin show the difference and imply promising further development with this method. The last part of this dissertation is a previous work on a novel structure wavelength tunable semiconductor laser based on asymmetric twin waveguide technology. To integrate several optoelectronic devices together, several schemes are available. Asymmetric twin waveguide technology is the only integration platform which does not require material regrowth and quantum well intermixing. The tunable laser based on this technology can be used as a local oscillator in a coherent optical

  16. Optical feedback signal for ultrashort laser pulse ablation of tissue

    SciTech Connect

    Kim, B.-M.; Feit, M.D.; Rubenchik, A.M.; Mammini, B.M.; Da Silva, L.B.

    1997-07-01

    An optical feedback system for controlled precise tissue ablation is discussed. Our setup includes an ultrashort pulse laser (USPL), and a diagnostic system using analysis of either tissue fluorescence or plasma emission luminescence. Current research is focused on discriminating hard and soft tissues such as bone and spinal cord during surgery using either technique. Our experimental observations exhibit considerable spectroscopic contrast between hard and soft tissue, and both techniques offer promise for a practical diagnostic system.

  17. Evaluation of material dispersion using a nanosecond optical pulse radiator.

    PubMed

    Horiguchi, M; Ohmori, Y; Miya, T

    1979-07-01

    To study the material dispersion effects on graded-index fibers, a method for measuring the material dispersion in optical glass fibers has been developed. Nanosecond pulses in the 0.5-1.7-microm region are generated by a nanosecond optical pulse radiator and grating monochromator. These pulses are injected into a GeO(2)-P(2)0(5)-doped silica graded-index fiber. Relative time delay changes between different wavelengths are used to determine material dispersion, core glass refractive index, material group index, and optimum profile parameter of the graded-index fiber. From the measured data, the optimum profile parameter on the GeO(2)-P(2)O(5)-doped silica graded-index fiber could be estimated to be 1.88 at 1.27 microm of the material dispersion free wavelength region and 1.82 at 1.55 microm of the lowest-loss wavelength region in silica-based optical fiber waveguides.

  18. Optical sinc-shaped Nyquist pulses of exceptional quality.

    PubMed

    Soto, Marcelo A; Alem, Mehdi; Amin Shoaie, Mohammad; Vedadi, Armand; Brès, Camille-Sophie; Thévenaz, Luc; Schneider, Thomas

    2013-01-01

    Sinc-shaped Nyquist pulses possess a rectangular spectrum, enabling data to be encoded in a minimum spectral bandwidth and satisfying by essence the Nyquist criterion of zero inter-symbol interference (ISI). This property makes them very attractive for communication systems since data transmission rates can be maximized while the bandwidth usage is minimized. However, most of the pulse-shaping methods reported so far have remained rather complex and none has led to ideal sinc pulses. Here a method to produce sinc-shaped Nyquist pulses of very high quality is proposed based on the direct synthesis of a rectangular-shaped and phase-locked frequency comb. The method is highly flexible and can be easily integrated in communication systems, potentially offering a substantial increase in data transmission rates. Further, the high quality and wide tunability of the reported sinc-shaped pulses can also bring benefits to many other fields, such as microwave photonics, light storage and all-optical sampling.

  19. Optical sinc-shaped Nyquist pulses of exceptional quality

    PubMed Central

    Soto, Marcelo A.; Alem, Mehdi; Amin Shoaie, Mohammad; Vedadi, Armand; Brès, Camille-Sophie; Thévenaz, Luc; Schneider, Thomas

    2013-01-01

    Sinc-shaped Nyquist pulses possess a rectangular spectrum, enabling data to be encoded in a minimum spectral bandwidth and satisfying by essence the Nyquist criterion of zero inter-symbol interference (ISI). This property makes them very attractive for communication systems since data transmission rates can be maximized while the bandwidth usage is minimized. However, most of the pulse-shaping methods reported so far have remained rather complex and none has led to ideal sinc pulses. Here a method to produce sinc-shaped Nyquist pulses of very high quality is proposed based on the direct synthesis of a rectangular-shaped and phase-locked frequency comb. The method is highly flexible and can be easily integrated in communication systems, potentially offering a substantial increase in data transmission rates. Further, the high quality and wide tunability of the reported sinc-shaped pulses can also bring benefits to many other fields, such as microwave photonics, light storage and all-optical sampling. PMID:24301610

  20. EXCESS OPTICAL ENHANCEMENT OBSERVED WITH ARCONS FOR EARLY CRAB GIANT PULSES

    SciTech Connect

    Strader, M. J.; Mazin, B. A.; Spiro Jaeger, G. V.; Gwinn, C. R.; Meeker, S. R.; Szypryt, P.; Van Eyken, J. C.; Marsden, D.; Walter, A. B.; Ulbricht, G.; Johnson, M. D.; O'Brien, K.; Stoughton, C.; Bumble, B.

    2013-12-10

    We observe an extraordinary link in the Crab pulsar between the enhancement of an optical pulse and the timing of the corresponding giant radio pulse. At optical through infrared wavelengths, our observations use the high time resolution of ARray Camera for Optical to Near-IR Spectrophotometry, a unique superconducting energy-resolving photon-counting array at the Palomar 200 inch telescope. At radio wavelengths, we observe with the Robert C. Byrd Green Bank Telescope and the Green Bank Ultimate Pulsar Processing Instrument backend. We see an 11.3% ± 2.5% increase in peak optical flux for pulses that have an accompanying giant radio pulse arriving near the peak of the optical main pulse, in contrast to a 3.2% ± 0.5% increase when an accompanying giant radio pulse arrives soon after the optical peak. We also observe that the peak of the optical main pulse is 2.8% ± 0.8% enhanced when there is a giant radio pulse accompanying the optical interpulse. We observe no statistically significant spectral differences between optical pulses accompanied by and not accompanied by giant radio pulses. Our results extend previous observations of optical-radio correlation to the time and spectral domains. Our refined temporal correlation suggests that optical and radio emission are indeed causally linked, and the lack of spectral differences suggests that the same mechanism is responsible for all optical emission.

  1. Excess optical enhancement observed with arcons for early crab giant pulses

    SciTech Connect

    Strader, M. J.; Johnson, M. D.; Mazin, B. A.; Spiro Jaeger, G. V.; Gwinn, C. R.; Meeker, S. R.; Szypryt, P.; van Eyken, J. C.; Marsden, D.; O'Brien, K.; Walter, A. B.; Ulbricht, G.; Stoughton, C.; Bumble, B.

    2013-11-26

    Here, we observe an extraordinary link in the Crab pulsar between the enhancement of an optical pulse and the timing of the corresponding giant radio pulse. At optical through infrared wavelengths, our observations use the high time resolution of ARray Camera for Optical to Near-IR Spectrophotometry, a unique superconducting energy-resolving photon-counting array at the Palomar 200 inch telescope. At radio wavelengths, we observe with the Robert C. Byrd Green Bank Telescope and the Green Bank Ultimate Pulsar Processing Instrument backend. We see an 11.3% ± 2.5% increase in peak optical flux for pulses that have an accompanying giant radio pulse arriving near the peak of the optical main pulse, in contrast to a 3.2% ± 0.5% increase when an accompanying giant radio pulse arrives soon after the optical peak. We also observe that the peak of the optical main pulse is 2.8% ± 0.8% enhanced when there is a giant radio pulse accompanying the optical interpulse. We also observe no statistically significant spectral differences between optical pulses accompanied by and not accompanied by giant radio pulses. These results extend previous observations of optical-radio correlation to the time and spectral domains. Our refined temporal correlation suggests that optical and radio emission are indeed causally linked, and the lack of spectral differences suggests that the same mechanism is responsible for all optical emission.

  2. Linear optical pulse compression based on temporal zone plates.

    PubMed

    Li, Bo; Li, Ming; Lou, Shuqin; Azaña, José

    2013-07-15

    We propose and demonstrate time-domain equivalents of spatial zone plates, namely temporal zone plates, as alternatives to conventional time lenses. Both temporal intensity zone plates, based on intensity-only temporal modulation, and temporal phase zone plates, based on phase-only temporal modulation, are introduced and studied. Temporal zone plates do not exhibit the limiting tradeoff between temporal aperture and frequency bandwidth (temporal resolution) of conventional linear time lenses. As a result, these zone plates can be ideally designed to offer a time-bandwidth product (TBP) as large as desired, practically limited by the achievable temporal modulation bandwidth (limiting the temporal resolution) and the amount of dispersion needed in the target processing systems (limiting the temporal aperture). We numerically and experimentally demonstrate linear optical pulse compression by using temporal zone plates based on linear electro-optic temporal modulation followed by fiber-optics dispersion. In the pulse-compression experiment based on temporal phase zone plates, we achieve a resolution of ~25.5 ps over a temporal aperture of ~5.77 ns, representing an experimental TBP larger than 226 using a phase-modulation amplitude of only ~0.8π rad. We also numerically study the potential of these devices to achieve temporal imaging of optical waveforms and present a comparative analysis on the performance of different temporal intensity and phase zone plates.

  3. 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.

  4. Holographic frequency resolved optical gating for spatio-temporal characterization of ultrashort optical pulse

    NASA Astrophysics Data System (ADS)

    Mehta, Nikhil; Yang, Chuan; Xu, Yong; Liu, Zhiwen

    2014-09-01

    We introduce a novel method for characterizing the spatio-temporal evolution of ultrashort optical field by recording the spectral hologram of frequency resolved optical gating (FROG) trace. We show that FROG holography enables the measurement of phase (up to an overall constant) and group delay of the pulse which cannot be measured by conventional FROG method. To illustrate our method, we perform numerical simulation to generate holographic collinear FROG (cFROG) trace of a chirped optical pulse and retrieve its complex profile at multiple locations as it propagates through a hypothetical dispersive medium. Further, we experimentally demonstrate our method by retrieving a 67 fs pulse at three axial locations in the vicinity of focus of an objective lens and compute its group delay.

  5. Dual-Pulse Pulse Position Modulation (DPPM) for Deep-Space Optical Communications: Performance and Practicality Analysis

    NASA Technical Reports Server (NTRS)

    Li, Jing; Hylton, Alan; Budinger, James; Nappier, Jennifer; Downey, Joseph; Raible, Daniel

    2012-01-01

    Due to its simplicity and robustness against wavefront distortion, pulse position modulation (PPM) with photon counting detector has been seriously considered for long-haul optical wireless systems. This paper evaluates the dual-pulse case and compares it with the conventional single-pulse case. Analytical expressions for symbol error rate and bit error rate are first derived and numerically evaluated, for the strong, negative-exponential turbulent atmosphere; and bandwidth efficiency and throughput are subsequently assessed. It is shown that, under a set of practical constraints including pulse width and pulse repetition frequency (PRF), dual-pulse PPM enables a better channel utilization and hence a higher throughput than it single-pulse counterpart. This result is new and different from the previous idealistic studies that showed multi-pulse PPM provided no essential information-theoretic gains than single-pulse PPM.

  6. Optical waveguide writing in photochromic material: photoinduced optical properties by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Gutiérrez, J. M.; Camacho-López, S.; Cano-Lara, M.; Rodríguez, A.; Balderas-Navarro, R. E.; Elizalde, L. E.; Ledezma, R.

    2011-09-01

    We report on the interaction of high repetition rate (MHz) Ti: sapphire laser pulses with a spiropyran polymer (MIC1). Such a polymer is photochromic, wich has potential applications in integrated optical devices. A thin film of polymer deposited on a glass substrate is irradiated with ultrashort pulses (66 fs) from a Ti: sapphire laser. We demonstrate that it is possible to induce an absorption band in the visible by the use of femtosecond pulses via a two-photon excitation process; this might be useful to accomplish waveguide-like structures formation with photochromic response.

  7. Effects of pulse frequency on the microstructure, composition and optical properties of pulsed dc reactively sputtered vanadium oxide thin films

    NASA Astrophysics Data System (ADS)

    Dong, Xiang; Wu, Zhiming; Jiang, Yadong; Xu, Xiangdong; Yu, He; Gu, Deen; Wang, Tao

    2014-09-01

    Vanadium oxide (VOx) thin films were prepared on unheated glass substrate by pulsed dc reactive magnetron sputtering using different pulse frequency. Field emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE) measurements were made on the deposited VOx films to characterize the microstructure, composition and optical properties, respectively. It was found that under the same discharge power and argon-oxygen atmosphere, with the increase of pulse frequency, the vertical column-like structure in the films will gradually disappear and the ratio of high-valent VOx to low-valent VOx will obviously elevate. Optical parameters of the VOx films have been obtained by fitting the ellipsometric data (Ψ andΔ) using the Tauc-Lorentz dispersion relation and a multilayer model (air/roughness layer/VOx/glass). The results demonstrated that pulse frequency plays a critical role in determining the transmittance, refractive index, extinction coefficient and optical band gap etc. The correlations between the microstructure, composition, optical properties and pulse frequency are also given by our experiment results. And the mechanisms for the evolution of the microstructure, composition and optical properties with pulse frequency have been discussed. Overall, due to the pulse frequency had a great effect not only on the growth characteristics but also on the optical properties of the VOx films, thus through variation of the pulse frequency during deposition which provide a convenient and efficient approach to control and optimize the performances of the VOx films.

  8. Large area precision optical coatings by pulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Frach, Peter; Gloess, Daniel; Goschurny, Thomas; Drescher, Andy; Hartung, Ullrich; Bartzsch, Hagen; Heisig, Andreas; Grune, Harald; Leischnig, Lothar; Leischnig, Steffen; Bundesmann, Carsten

    2017-05-01

    Pulse magnetron sputtering is very well suited for the deposition of optical coatings. Due to energetic activation during film growth, sputtered films are dense, smooth and show an excellent environmental stability. Films of materials like SiO2, Al2O3, Nb2O5 or Ta2O5 can be produced with very little absorption and scattering losses and are well suited for precision optics. FEP's coating plant PreSensLine, a deposition machine dedicated for the development and deposition of precision optical layer systems will be presented. The coating machine (VON ARDENNE) is equipped with dual magnetron systems (type RM by FEP). Concepts regarding machine design, process technology and process control as well as in situ monitoring are presented to realize the high demands on uniformity, accuracy and reproducibility. Results of gradient and multilayer type precision optical coatings are presented. Application examples are edge filters and special antireflective coatings for the backlight of 3D displays with substrate size up to 300 x 400mm. The machine allows deposition of rugate type gradient layers by rotating a rotary table with substrates between two sources of the dual magnetron system. By combination of the precision drive (by LSA) for the substrate movement and a special pulse parameter variation during the deposition process (available with the pulse unit UBS-C2 of FEP), it is possible to adjust the deposition rate as a function of the substrate position exactly. The aim of a current development is a technology for the uniform coating of 3D-substrates and freeform components as well as laterally graded layers.

  9. Diffraction leveraged modulation of X-ray pulses using MEMS-based X-ray optics

    DOEpatents

    Lopez, Daniel; Shenoy, Gopal; Wang, Jin; Walko, Donald A.; Jung, Il-Woong; Mukhopadhyay, Deepkishore

    2016-08-09

    A method and apparatus are provided for implementing Bragg-diffraction leveraged modulation of X-ray pulses using MicroElectroMechanical systems (MEMS) based diffractive optics. An oscillating crystalline MEMS device generates a controllable time-window for diffraction of the incident X-ray radiation. The Bragg-diffraction leveraged modulation of X-ray pulses includes isolating a particular pulse, spatially separating individual pulses, and spreading a single pulse from an X-ray pulse-train.

  10. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle

    PubMed Central

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-01-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core–shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems. PMID:26907639

  11. Excess optical enhancement observed with arcons for early crab giant pulses

    DOE PAGES

    Strader, M. J.; Johnson, M. D.; Mazin, B. A.; ...

    2013-11-26

    Here, we observe an extraordinary link in the Crab pulsar between the enhancement of an optical pulse and the timing of the corresponding giant radio pulse. At optical through infrared wavelengths, our observations use the high time resolution of ARray Camera for Optical to Near-IR Spectrophotometry, a unique superconducting energy-resolving photon-counting array at the Palomar 200 inch telescope. At radio wavelengths, we observe with the Robert C. Byrd Green Bank Telescope and the Green Bank Ultimate Pulsar Processing Instrument backend. We see an 11.3% ± 2.5% increase in peak optical flux for pulses that have an accompanying giant radio pulsemore » arriving near the peak of the optical main pulse, in contrast to a 3.2% ± 0.5% increase when an accompanying giant radio pulse arrives soon after the optical peak. We also observe that the peak of the optical main pulse is 2.8% ± 0.8% enhanced when there is a giant radio pulse accompanying the optical interpulse. We also observe no statistically significant spectral differences between optical pulses accompanied by and not accompanied by giant radio pulses. These results extend previous observations of optical-radio correlation to the time and spectral domains. Our refined temporal correlation suggests that optical and radio emission are indeed causally linked, and the lack of spectral differences suggests that the same mechanism is responsible for all optical emission.« less

  12. A half-period surface relief grating formed by bicolor interferences in thin azopolymer films

    NASA Astrophysics Data System (ADS)

    Apostoluk, Aleksandra; Fiorini-Debuisschert, Celine; Nunzi, Jean-Michel

    2003-07-01

    All optical poling technique allows orientation of dye molecules in a polymer matrix by purely optical means. The coherent superposition of two beams at fundamental (FUND)and second harmonic (SH)frequencies results in the presence of the polar field E(t) inside the material, able to break the centrosymmetry of the medium. The temporal average cube t of this field E(t) = Eω(t)+E2ω(t), is non-zero, which leads to an orientation-selective excitation of molecules and the second order χ(2)-susceptibility grating is encoded, with a period satisfying the phase matching condition for SH generation. The physical origin of the effect lies in the orientational hole-burning in the initially isotropic distribution of dye molecules (via trans-cis trans photoisomerisation). We investigate other phenomena responsible for the SHG in polymer films like the electron transfer between a polymer matrix (donor of electrons) and a dye molecule (electron acceptor) and processes which accompany polar orientation mechanism like the one-direction photoinduced molecular migration. The stability of the induced polar order after orientation has been also studied and the crosslinkable polymer system has been developed D side chain molecules with ends can thermally react with epoxy groups were randomly inserted in the side groups of the polymer backbone, which leads to the reticulation and enhancement of the rotational stability. After poling the second order nonlinear response exhibits a much longer relaxation time. In the set-up configuration used we monitor non-perturbatively the all optical poling and there is no necessity of taking into account the phase difference between writing beams (fundamental and SH). The periodical modulation of the relative phase provides the desired control on the polar order at the molecular level as well as the possibility of encoding surface relief gratings with a period equal to the half of the period of the χ(2) grating.

  13. Free space optical communication based on pulsed lasers

    NASA Astrophysics Data System (ADS)

    Drozd, Tadeusz; Mierczyk, Zygmunt; Zygmunt, Marek; Wojtanowski, Jacek

    2016-12-01

    Most of the current optical data transmission systems are based on continuous wave (cw) lasers. It results from the tendency to increase data transmission speed, and from the simplicity in implementation (straightforward modulation). Pulsed lasers, which find many applications in a variety of industrial, medical and military systems, in this field are not common. Depending on the type, pulsed lasers can generate instantaneous power which is many times greater when compared with cw lasers. As such, they seem to be very attractive to be used in data transmission technology, especially due to the potentially larger ranges of transmission, or in adverse atmospheric conditions where low power cw-lasersbased transmission is no longer feasible. It is also a very practical idea to implement data transmission capability in the pulsed laser devices that have been around and already used, increasing the functionality of this type of equipment. At the Institute of Optoelectronics at Military University of Technology, a unique method of data transmission based on pulsed laser radiation has been developed. This method is discussed in the paper in terms of both data transmission speed and transmission range. Additionally, in order to verify the theoretical assumptions, modules for voice and data transmission were developed and practically tested which is also reported, including the measurements of Bit Error Rate (BER) and performance vs. range analysis.

  14. Ultrashort pulse laser welding of glasses without optical contacting

    NASA Astrophysics Data System (ADS)

    Richter, Sören; Zimmermann, Felix; Sutter, Dirk; Budnicki, Aleksander; Tünnermann, Andreas; Nolte, Stefan

    2017-02-01

    We report on ultrashort pulse induced welding of fused silica without previously optical contacting of the samples. We used a TruMicro 2020 by TRUMPF delivering bursts of intense ultrashort laser pulses with an individual pulse energy of up to 10 μJ, an intraburst pulse separation of 20 ns and a burst repetition rate of 200 kHz. With this setup we could realize a large pool of molten material with a length of up to 450 μm and a diameter of around 160 μm. If the laser focus is placed near the surface of a glass sample the low viscosity of the hot material induces bulging of the surface and ejection of the molten material. This molten material can be used to fill a gap of up to 3 μm between fused silica samples. We also determined the breaking strength with a three-point bending test. The determined maximal value of 73 MPa is equivalent to 85% of the stability of the pristine bulk material.

  15. Experimental demonstration of fiber optical parametric chirped-pulse amplification

    NASA Astrophysics Data System (ADS)

    Zhou, Yue; Cheung, Kim K. Y.; Chui, P. C.; Wong, Kenneth K. Y.

    2010-02-01

    A fiber optical parametric chirped-pulse amplifier (FOPCPA) is experimentally demonstrated. A 1.76 ps signal at 1542 nm with a peak power of 20 mW is broadened to 40 ps, and then amplified by a 100-ps pulsed pump at 1560 nm. The corresponding idler at 1578 nm is generated as the FOPCPA output. The same medium used to stretch the signal is deployed to compress the idler to 3.8 ps, and another spool of fiber is deployed to further compress the idler to 1.87 ps. The peak power of the compressed idler is 2 W, which corresponds to a gain of 20 dB.

  16. Bipolar optical pulse coding for performance enhancement in BOTDA sensors.

    PubMed

    Soto, Marcelo A; Le Floch, Sébastien; Thévenaz, Luc

    2013-07-15

    A pump signal based on bipolar pulse coding and single-sideband suppressed-carried (SSB-SC) modulation is proposed for Brillouin optical time-domain analysis (BOTDA) sensors. Making a sequential use of the Brillouin gain and loss spectra, the technique is experimentally validated using bipolar complementary-correlation Golay codes along a 100 km-long fiber and 2 m spatial resolution, fully resolving a 2 m hot-spot at the end of the sensing fiber with no distortion introduced by the decoding algorithm. Experimental results, in good agreement with the theory, indicate that bipolar Golay codes provide a higher signal-to-noise ratio enhancement and stronger robustness to pump depletion in comparison to optimum unipolar pulse codes known for BOTDA sensing.

  17. Suppressing spectral diffusion of emitted photons with optical pulses

    SciTech Connect

    Fotso, H. F.; Feiguin, A. E.; Awschalom, D. D.; Dobrovitski, V. V.

    2016-01-22

    In many quantum architectures the solid-state qubits, such as quantum dots or color centers, are interfaced via emitted photons. However, the frequency of photons emitted by solid-state systems exhibits slow uncontrollable fluctuations over time (spectral diffusion), creating a serious problem for implementation of the photon-mediated protocols. Here we show that a sequence of optical pulses applied to the solid-state emitter can stabilize the emission line at the desired frequency. We demonstrate efficiency, robustness, and feasibility of the method analytically and numerically. Taking nitrogen-vacancy center in diamond as an example, we show that only several pulses, with the width of 1 ns, separated by few ns (which is not difficult to achieve) can suppress spectral diffusion. As a result, our method provides a simple and robust way to greatly improve the efficiency of photon-mediated entanglement and/or coupling to photonic cavities for solid-state qubits.

  18. Pulsed radiation-induced attenuation in certain optical fibers

    SciTech Connect

    Weiss, J.D. )

    1992-05-01

    Using the X-ray pulse from the HERMES II simulation machine at Sandia National Laboratories, the pulsed radiation-induced attenuation was measured in two optical fibers considered to be 'nonrad-hard': the 50-micron-core, graded-index fiber from Corning and the plastic (PMMA) fiber from the Mitsubishi Rayon Company. These fibers were exposed to radiation up to doses of 19.5 and 28 krad(Si), respectively. In addition, fits of their post-radiation recovery were made to the geminate recombination model, from which the recombination-rate and generation constants, characteristic of this theory, were determined. These parameters should be useful in determining the response of the fibers to radiation conditions other than those encountered here. 18 refs.

  19. 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

  20. Spontaneously excited pulses in an optically driven semiconductor laser.

    PubMed

    Wieczorek, Sebastian; Lenstra, Daan

    2004-01-01

    In optically injected semiconductor lasers, intrinsic quantum noise alone, namely, the spontaneous emission and the shot noise, are capable of exciting intensity multipulses from a steady state operation. Noisy lasers exhibit self-pulsations in the locking region of the corresponding deterministic system. The interpulse time statistics are studied in parameter regions near k-homoclinic (Shilnikov) bifurcations where the corresponding deterministic model exhibits single-, double-, and triple-pulse excitability. These statistics differ significantly among each other, and they could be used to characterize regions of different multipulse excitability in a real laser device.

  1. Characterization of a Pulsed HF Optical Resonance Transfer Laser.

    DTIC Science & Technology

    1982-10-01

    AD-A 124 708 CHARACTERIZATION OF A PULSED HIE OPTICAL RESONANCE I TRANSFE R LASER(U ) AIR FORCE INST OF TECH WRIGHT -PATTERSON AFA O H SCHOOL OF...these valves failed and the third leaked and had to be replaced. All three needle valves were replaced by stainless steel which should function well...use in an HP environment). The He feed (see figure 7) to the reference cell is controlled by a stainless steel needle valve (N) and a brass bellows

  2. Optical processing deep inside optical materials using counterpropagating pulse-shaped spatial solitons

    NASA Astrophysics Data System (ADS)

    Hisaka, Masaki

    2016-10-01

    Optical processing using a pair of counterpropagating pulse-shaped spatial solitons to control the molecular structure deep inside an optical material is investigated. A femtosecond pulsed laser focused at the surface of a strontium barium niobate single crystal induces a pulse-shaped self-focusing second-harmonic beam. The two counterpropagating beams are involved in a head-on collision. Locally reversed crystal domains are formed at the collision point, assisted by external threshold controls such as crystal temperature and an electric dc field. The nonlinear interaction between the soliton collision and the approximate nonperiodic reversed domains induces a change in the second-harmonic intensity of the scattered and transmitted beams, thereby enabling the detection of locally reversed crystal domains.

  3. 5 Hz, >250 mJ Optical Parametric Chirped-Pulse Amplifier at 1053 nm

    SciTech Connect

    Bagnoud, V.; Begishev, I.A.; Guardalben, M.J.; Puth, J.; Zuegel, J.D.

    2005-07-15

    A 250 mJ, 5 Hz repetition rate optical parametric chirped-pulse amplifier with near-Fourier-transform-limited, 430 fs pulses and a beam that can be focused to near the diffraction limit is demonstrated.

  4. Self-stabilizing optical clock pulse-train generator using SOA and saturable absorber for asynchronous optical packet processing.

    PubMed

    Nakahara, Tatsushi; Takahashi, Ryo

    2013-05-06

    We propose a novel, self-stabilizing optical clock pulse-train generator for processing preamble-free, asynchronous optical packets with variable lengths. The generator is based on an optical loop that includes a semiconductor optical amplifier (SOA) and a high-extinction spin-polarized saturable absorber (SA), with the loop being self-stabilized by balancing out the gain and absorption provided by the SOA and SA, respectively. The optical pulse train is generated by tapping out a small portion of a circulating seed pulse. The convergence of the generated pulse energy is enabled by the loop round-trip gain function that has a negative slope due to gain saturation in the SOA. The amplified spontaneous emission (ASE) of the SOA is effectively suppressed by the SA, and a backward optical pulse launched into the SOA enables overcoming the carrier-recovery speed mismatch between the SOA and SA. Without external control for the loop gain, a stable optical pulse train consisting of more than 50 pulses with low jitter is generated from a single 10-ps seed optical pulse even with a variation of 10 dB in the seed pulse intensity.

  5. Autocorrelation of laser pulses by optical processing of Fabry-Perot spectrograms.

    PubMed

    Colombeau, B; Froehly, C; Vampouille, M

    1980-02-15

    This paper describes the principles and experimental implementation of a new optical technique based on Fourier analysis for second-order statistics of short coherent light pulses. Using only passive filtering operations, we obtained images of the autocorrelation functions of the optical fields of light pulses, derived from ode-locked Nd:YAG laser pulses, with 40-psec to 4-nsec duration. An application of the method to a shaped sequence of 40-psec pulses is reported.

  6. Construction and characterization of ultraviolet acousto-optic based femtosecond pulse shapers

    SciTech Connect

    Mcgrane, Shawn D; Moore, David S; Greenfield, Margo T

    2008-01-01

    We present all the information necessary for construction and characterization of acousto optic pulse shapers, with a focus on ultraviolet wavelengths, Various radio-frequency drive configurations are presented to allow optimization via knowledgeable trade-off of design features. Detailed performance characteristics of a 267 nm acousto-optic modulator (AOM) based pulse shaper are presented, Practical considerations for AOM based pulse shaping of ultra-broad bandwidth (sub-10 fs) amplified femtosecond pulse shaping are described, with particular attention paid to the effects of the RF frequency bandwidth and optical frequency bandwidth on the spatial dispersion of the output laser pulses.

  7. An integrated CMOS detection system for optical short-pulse

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Gun; Hong, Nam-Pyo; Choi, Young-Wan

    2014-03-01

    We present design of a front-end readout system consisting of charge sensitive amplifier (CSA) and pulse shaper for detection of stochastic and ultra-small semiconductor scintillator signal. The semiconductor scintillator is double sided silicon detector (DSSD) or avalanche photo detector (APD) for high resolution and peak signal reliability of γ-ray or X-ray spectroscopy. Such system commonly uses low noise multichannel CSA. Each CSA in multichannel includes continuous reset system based on tens of MΩ and charge-integrating capacitor in feedback loop. The high value feedback resistor requires large area and huge power consumption for integrated circuits. In this paper, we analyze these problems and propose a CMOS short pulse detection system with a novel CSA. The novel CSA is composed of continuous reset system with combination of diode connected PMOS and 100 fF. This structure has linearity with increased input charge quantity from tens of femto-coulomb to pico-coulomb. Also, the front-end readout system includes both slow and fast shapers for detecting CSA output and preventing pile-up distortion. Shaping times of fast and slow shapers are 150 ns and 1.4 μs, respectively. Simulation results of the CMOS detection system for optical short-pulse implemented in 0.18 μm CMOS technology are presented.

  8. Preliminary Optical And Electric Field Pulse Statistics From Storm Overflights During The Altus Cumulus Electrification Study

    NASA Technical Reports Server (NTRS)

    Mach, D. A.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

    2003-01-01

    The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect high resolution optical pulse and electric field data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses with associated electric field changes. Most of these observations were made while close to the top of the storms. We found filtered mean and median 10-10% optical pulse widths of 875 and 830 microns respectively while the 50-50% mean and median optical pulse widths are 422 and 365 microns respectively. These values are similar to previous results as are the 10-90% mean and median rise times of 327 and 265 microns. The peak electrical to optical pulse delay mean and median were 209 and 145 microns which is longer than one would expect from theoretical results. The results of the pulse analysis will contribute to further validation of the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) satellites. Pre-launch estimates of the flash detection efficiency were based on a small sample of optical pulse measurements associated with less than 350 lightning discharges collected by NASA U-2 aircraft in the early 1980s. Preliminary analyses of the ACES measurements show that we have greatly increased the number of optical pulses available for validation of the LIS and other orbital lightning optical sensors. Since the Altus was often close to the cloud tops, many of the optical pulses are from low-energy pulses. From these low-energy pulses, we can determine the fraction of optical lightning pulses below the thresholds of LIS, OTD, and any future satellite-based optical sensors such as the geostationary Lightning Mapping Sensor.

  9. Preliminary Optical And Electric Field Pulse Statistics From Storm Overflights During The Altus Cumulus Electrification Study

    NASA Technical Reports Server (NTRS)

    Mach, D. A.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

    2003-01-01

    The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect high resolution optical pulse and electric field data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses with associated electric field changes. Most of these observations were made while close to the top of the storms. We found filtered mean and median 10-10% optical pulse widths of 875 and 830 microns respectively while the 50-50% mean and median optical pulse widths are 422 and 365 microns respectively. These values are similar to previous results as are the 10-90% mean and median rise times of 327 and 265 microns. The peak electrical to optical pulse delay mean and median were 209 and 145 microns which is longer than one would expect from theoretical results. The results of the pulse analysis will contribute to further validation of the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) satellites. Pre-launch estimates of the flash detection efficiency were based on a small sample of optical pulse measurements associated with less than 350 lightning discharges collected by NASA U-2 aircraft in the early 1980s. Preliminary analyses of the ACES measurements show that we have greatly increased the number of optical pulses available for validation of the LIS and other orbital lightning optical sensors. Since the Altus was often close to the cloud tops, many of the optical pulses are from low-energy pulses. From these low-energy pulses, we can determine the fraction of optical lightning pulses below the thresholds of LIS, OTD, and any future satellite-based optical sensors such as the geostationary Lightning Mapping Sensor.

  10. Simulation of autosoliton optical pulses in high-speed fibreoptic communication systems

    SciTech Connect

    Latkin, A I

    2005-03-31

    The propagation of a pulse in a fibreoptic communication link with periodically included regenerators - nonlinear optical loop mirrors, is studied. The autosoliton propagation regime of the optical pulse is revealed. It is shown that the inclusion of a ring mirror to the communication link leads to a substantial increase in the transmission distance of the pulse at a small negative average dispersion in the link. (optical communication)

  11. Comparison of pulse propagation and gain saturation characteristics among different input pulse shapes in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Barua, Suchi; Das, Narottam; Nordholm, Sven; Razaghi, Mohammad

    2016-01-01

    This paper presents the pulse propagation and gain saturation characteristics for different input optical pulse shapes with different energy levels in semiconductor optical amplifiers (SOAs). A finite-difference beam propagation method (FD-BPM) is used to solve the modified nonlinear Schrödinger equation (MNLSE) for the simulation of nonlinear optical pulse propagation and gain saturation characteristics in the SOAs. In this MNLSE, the gain spectrum dynamics, gain saturation are taken into account those are depend on the carrier depletion, carrier heating, spectral hole-burning, group velocity dispersion, self-phase modulation and two photon absorption. From this simulation, we obtained the output waveforms and spectra for different input pulse shapes considering different input energy levels. It has shown that the output pulse shape has changed due to the variation of input parameters, such as input pulse shape, input pulse width, and input pulse energy levels. It also shown clearly that the peak position of the output waveforms are shifted toward the leading edge which is due to the gain saturation of the SOA. We also compared the gain saturation characteristics in the SOA for different input pulse shapes.

  12. High-Dynamic-Range Single-Shot Cross-Correlator Based on an Optical Pulse Replicator

    SciTech Connect

    Dorrer, C.; Bromage, J.; Zuegel, J.D.

    2008-09-05

    The operation of a single-shot cross-correlator based on a pulse replicator is described. The correlator uses a discrete sequence of sampling pulses that are nonlinearly mixed with the pulse under test. The combination of a high reflector and partial reflector replicates an optical pulse by multiple internal reflections and generates a sequence of spatially displaced and temporally delayed sampling pulses. This principle is used in a cross-correlator characterizing optical pulses at 1053 nm. A dynamic range higher than 60 dB is obtained over a temporal range larger than 200 ps.

  13. Monocycle and doublet pulses generation via photon echo in rare-earth-doped optical crystal

    NASA Astrophysics Data System (ADS)

    Huang, Kai; Zhang, Shuanggen; Ma, Xiurong; Hu, Minglie; Wang, Qingyue

    2016-12-01

    All-optical pulse generation opens up a field for ultrawideband (UWB) applications. However, controllable pulse width and pulse type are still challenging. Here, we present a theoretical model and stimulated results of monocycle and doublet waveforms generation using programmable optical photon echo progress. We synthesized instantaneously monocycle and doublet waveforms by adjustment of pulse width, pulse amplitude, pulse position, and time interval of subpulses. We verified the possible application of the proposed method to design U.S. Federal Communications Commission-compliant UWB waveforms, and therefore, it may provide an avenue for waveform generation.

  14. Improved optical pulse heterodyne demodulation scheme for fiber-optic interferometric sensors

    NASA Astrophysics Data System (ADS)

    Lai, Haiqiang; Wang, Jianfei; Tu, Xiaobo; Meng, Zhou

    2015-10-01

    An improved optical pulse heterodyne demodulation scheme for fiber-optic interferometric sensors is demonstrated. This scheme uses two series-connected Acoustic-optic modulators (AOMs) as intensity modulator and frequency shifter respectively. Compared to the traditional optical heterodyne demodulation structure, this scheme eliminates the polarization-induced signal fading and the noise floor is lowered for using the Michelson-configuration delay structure and Faraday rotation mirrors (FRMs) in the optic architecture of system. At the same time, the architecture of this scheme is not complicated and can be used to complex a large sensor array. Experimental results show that the phase noise floor of this demodulation scheme is flat and reaches -99dB/sqrt(Hz) at frequencies above 300 Hz.

  15. Generation of unipolar optical pulses in a Raman-active medium

    NASA Astrophysics Data System (ADS)

    Arkhipov, R. M.; Arkhipov, M. V.; Belov, P. A.; Tolmachev, Yu A.; Babushkin, I.

    2016-04-01

    Response of a Raman-active media (RAM) to the excitation by a series of ultrashort (few-cycle) optical pulses propagating at a superluminal velocity is studied theoretically. It is shown that under certain conditions rectangular unipolar pulses (video-pulses) can be generated as the RAM response. The duration, shape and amplitude of these video-pulses can be widely tuned by modifying the pump pulse parameters.

  16. Optical pulse evolution in the Stanford free-electron laser and in a tapered wiggler

    NASA Technical Reports Server (NTRS)

    Colson, W. B.

    1982-01-01

    The Stanford free electron laser (FEL) oscillator is driven by a series of electron pulses from a high-quality superconducting linear accelerator (LINAC). The electrons pass through a transverse and nearly periodic magnetic field, a 'wiggler', to oscillate and amplify a superimposed optical pulse. The rebounding optical pulse must be closely synchronized with the succession of electron pulses from the accelerator, and can take on a range of structures depending on the precise degree of synchronism. Small adjustments in desynchronism can make the optical pulse either much shorter or longer than the electron pulse, and can cause significant subpulse structure. The oscillator start-up from low level incoherent fields is discussed. The effects of desynchronism on coherent pulse propagation are presented and compared with recent Stanford experiments. The same pulse propagation effects are studied for a magnet design with a tapered wavelength in which electrons are trapped in the ponderomotive potential.

  17. Lightning Optical Pulse Statistics from Storm Overflights During the Altus Cumulus Electrification Study

    NASA Technical Reports Server (NTRS)

    Mach, D. M.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

    2004-01-01

    The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect time resolved optical pulse data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses. Most of these observations were made while close to the top of the storms. We divided our data into two amplitude groups based on prior NASA U2 aircraft optical data and our pulse characteristics. The group of large pulses with radiance greater than 2.1 mW /sq m sr had mean and median 10 - 10% optical pulse widths of 765 and 735 microns respectively, the 50-50% pulse widths of 396 and 355 microns respectively, and 10-90% rise times of 290 and 260 microns. These values are very similar to the previous U2 based optical results The other group of pulses consisting of slightly more than a quarter of the total pulses observed had radiances less than the minimum values detected in the U2 study. The small pulses were narrower than the large pulses with 5040% mean and median values of 198 and 160 ps respectively. Only 12 % of the flashes contained only small pulses, minimizing the impact of this data on the estimates of detection efficiencies of the orbital instruments, the Lightning Imaging Sensor and Optical Transient Detector.

  18. Lightning Optical Pulse Statistics from Storm Overflights During the Altus Cumulus Electrification Study

    NASA Technical Reports Server (NTRS)

    Mach, D. M.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

    2004-01-01

    The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect time resolved optical pulse data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses. Most of these observations were made while close to the top of the storms. We divided our data into two amplitude groups based on prior NASA U2 aircraft optical data and our pulse characteristics. The group of large pulses with radiance greater than 2.1 mW /sq m sr had mean and median 10 - 10% optical pulse widths of 765 and 735 microns respectively, the 50-50% pulse widths of 396 and 355 microns respectively, and 10-90% rise times of 290 and 260 microns. These values are very similar to the previous U2 based optical results The other group of pulses consisting of slightly more than a quarter of the total pulses observed had radiances less than the minimum values detected in the U2 study. The small pulses were narrower than the large pulses with 5040% mean and median values of 198 and 160 ps respectively. Only 12 % of the flashes contained only small pulses, minimizing the impact of this data on the estimates of detection efficiencies of the orbital instruments, the Lightning Imaging Sensor and Optical Transient Detector.

  19. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    PubMed Central

    Isaienko, Oleksandr; Robel, István

    2016-01-01

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves. PMID:26975881

  20. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    SciTech Connect

    Isaienko, Oleksandr; Robel, Istvan

    2016-03-15

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. Furthermore, the pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.

  1. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    DOE PAGES

    Isaienko, Oleksandr; Robel, Istvan

    2016-03-15

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to themore » oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. Furthermore, the pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.« less

  2. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    NASA Astrophysics Data System (ADS)

    Isaienko, Oleksandr; Robel, István

    2016-03-01

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.

  3. Ultrashort-pulse measurement using noninstantaneous nonlinearities: Raman effects in frequency-resolved optical gating.

    PubMed

    Delong, K W; Ladera, C L; Trebino, R; Kohler, B; Wilson, K R

    1995-03-01

    Ultrashort-pulse-characterization techniques generally require instantaneously responding media. We show that this is not the case for frequency-resolved optical gating (FROG). We include, as an example, the noninstantaneous Raman response of fused silica, which can cause errors in the retrieved pulse width of as much as 8% for a 25-fs pulse in polarization-gate FROG. We present a modified pulse-retrieval algorithm that deconvolves such slow effects and use it to retrieve pulses of any width. In experiments with 45-fs pulses this algorithm achieved better convergence and yielded a shorter pulse than previous FROG algorithms.

  4. Ultrashort-pulse measurement using noninstantaneous nonlinearities: Raman effects in frequency-resolved optical gating

    SciTech Connect

    DeLong, K.W.; Ladera, C.L.; Trebino, R.; Kohler, B.; Wilson, K.R.

    1995-03-01

    Ultrashort-pulse-characterization techniques generally require instantaneously responding media. We show that this is not the case for frequency-resolved optical gating (FROG). We include, as an example, the noninstantaneous Raman response of fused silica, which can cause errors in the retrieved pulse width of as much as 8% for a 25-fs pulse in polarization-gate FROG. We present a modified pulse-retrieval algorithm that deconvolves such slow effects and use it to retrieve pulses of any width. In experiments with 45-fs pulses this algorithm achieved better convergence and yielded a shorter pulse than previous FROG algorithms.

  5. THz generation from optical rectification tilted-pulse-front pumping scheme with laser pulse focused to a line

    NASA Astrophysics Data System (ADS)

    Du, Hai-Wei; Hoshina, Hiromichi; Otani, Chiko

    2015-10-01

    In this study, we investigate THz pulses generated from optical rectification with tilted-pulse-front pumping scheme in which the laser beam is focused to a line in a stoichiometric lithium niobate (sLN) crystal. A cylindrical lens and a common lens are used to focus the pump laser beam to a line. The power law of THz pulse generation and the redshift induced from the sLN crystal are measured. The spectral shapes of the laser pulse are changed by inserting a filter into the pump laser beam, causing the THz radiation to change. The filter is a metal wire with 2 mm diameter. Experimental results show that this method can change the generated THz time waveforms but not their spectra. Such method offers a simple means to change and manipulate THz field generated from optical rectification with tiled-pulse-front pumping scheme.

  6. Fabrication of optical cavities with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Lin, Jintian; Song, Jiangxin; Tang, Jialei; Fang, Wei; Sugioka, Koji; Cheng, Ya

    2014-03-01

    We report on fabrication of three-dimensional (3D) high-quality (Q) whispering-gallery-mode microcavities by femtosecond laser micromachining. The main fabrication procedures include the formation of on-chip freestanding microdisk through selective material removal by femtosecond laser pulses, followed by surface smoothing processes (CO2 laser reflow for amorphous glass and focused ion beam (FIB) sidewall milling for crystalline materials) to improve the Q factors. Fused silica microcavities with 3D geometries are demonstrated with Q factors exceeding 106. A microcavity laser based on Nd:glass has been fabricated, showing a threshold as low as 69μW via free space continuous-wave optical excitation at the room temperature. CaF2 crystalline microcavities with Q factor of ~4.2×104 have also been demonstrated. This technique allows us to fabricate 3D high-Q microcavities in various transparent materials such as glass and crystals, which will benefit a broad spectrum of applications such as nonlinear optics, quantum optics, and bio-sensing.

  7. Geometry dependence of optical pulse broadening in multiple scattering media

    NASA Technical Reports Server (NTRS)

    Thomas, R. W. L.; Holland, A. C.

    1979-01-01

    A Monte Carlo simulation method has been used to evaluate the temporal response at a variety of receivers to an instantaneous laser pulse input to a turbid medium. The results are compared to the description of the ensemble of all transmitted photons for which a diffusion theory was developed. It was shown that the arrival times for all photons transmitted through the cloud are exponentially distributed with a mean time that varies as the product of the cloud thickness and the momentum transfer optical depth. For large optical depths the mean time delay associated with all reflected photons was found to depend only on the cloud thickness. The impulse response function for receivers on the beam axis varied with field of view and for small fields of view it was dominated by single scattering even for optically thick clouds. In these cases, the mean time delay could be up to 10 to the 6th times shorter than that associated with all transmitted photons with a related increase in the maximum modulation frequency.

  8. Directly driven source of multi-gigahertz, sub-picosecond optical pulses

    DOEpatents

    Messerly, Michael J.; Dawson, Jay W.; Barty, Christopher P.J.; Gibson, David J.; Prantil, Matthew A.; Cormier, Eric

    2015-10-20

    A robust, compact optical pulse train source is described, with the capability of generating sub-picosecond micro-pulse sequences, which can be periodic as well as non-periodic, and at repetition rates tunable over decades of baseline frequencies, from MHz to multi-GHz regimes. The micro-pulses can be precisely controlled and formatted to be in the range of many ps in duration to as short as several fs in duration. The system output can be comprised of a continuous wave train of optical micro-pulses or can be programmed to provide gated bursts of macro-pulses, with each macro-pulse consisting of a specific number of micro-pulses or a single pulse picked from the higher frequency train at a repetition rate lower than the baseline frequency. These pulses could then be amplified in energy anywhere from the nJ to MJ range.

  9. Acousto-optic modulation by pulsed optical excitation: implications to imaging in turbid media.

    PubMed

    Paul, Joseph S; Sen, Deep; Dokos, Socrates

    2010-08-15

    We show that the transient response of acoustically modulated optical flux in a turbid medium irradiated by a pulsed point source of light is delayed in time relative to the light-alone flux obtained in the absence of acoustic modulation. The time delay is shown to result from an initial phase of flux reversal, as determined by the time point of the input pulse onset with reference to the ultrasound cycle. Both the time delay and amplitude of modulation are shown to be dependent on the effective attenuation coefficient of the medium. Application of a periodic train of excitation pulses spaced at equal intervals at, or in multiples of, the ultrasound period enables a time-locked detection of the modulated light, without the deleterious effects caused by speckle artifacts.

  10. Effect of Group-Velocity Dispersion on Photon-Number Squeezing of Optical Pulses using Optical Fibers and Spectral Filter

    NASA Astrophysics Data System (ADS)

    Nishizawa, Norihiko; Horio, Takeo; Mori, Masakazu; Goto, Toshio; Yamane, Kazuo

    1999-04-01

    Photon-number squeezing of optical pulses using optical fibers and band-pass spectral filters is numerically analyzed. The evolution of the quantum noise in the optical pulse propagation is calculated in both the spectral and time domains. The mechanism of filtering squeezing and the role of the group-velocity dispersion are investigated.It is shown that the squeezing is realized owing to the interaction between the self-phase modulation and the group-velocity dispersion.

  11. Nanoparticle detection by microfluidic resistive pulse sensor with optical evidence

    NASA Astrophysics Data System (ADS)

    Zhang, Hongpeng; Song, Yongxin; Pan, Xinxiang; Sun, Yuqing; Li, Dongqing; Jiang, Jihai

    2010-12-01

    This paper reports a device that performs nanoparticle detection with a microfluidic differential Resistive Pulse Sensor (RPS). By using a single microfluidic channel with two detecting arm channels placed at the two ends of the sensing section, the microfluidic differential RPS can achieve a high sensitivity allowing the detection of nanometer size particles. Two-stage differential amplification is used to further increase the signal-to-noise ratio. This method is able to detect nanoparticles of 490nm on a microfluidic chip. An 8μm gate and a 2.7μm gate detected the 490 nm particle. The electrical signal was with optical evidence. The result showed 2.7μm chip can realize signal to noise ratio higher than 10. The method described in this paper is simple and can be applied to develop a compact device without the need of bulky, sophisticated electronic instruments or complicated nano-fabrication processes.

  12. Terahertz beam steering using interference of femtosecond optical pulses.

    PubMed

    Uematsu, Koji; Maki, Ken-ichiro; Otani, Chiko

    2012-09-24

    A terahertz (THz) beam steering method is demonstrated by applying the characteristic of grating lobe (GL) radiation from a linear array antenna and the interference of femtosecond optical pulses. A photoconductive device is illuminated by two femtosecond laser beams combined at an angle of less than 0.5°. Considering the interference pattern as a THz point source array, THz GL radiation is generated through the superposition of radiation emitted from all point sources and steered by varying the interval of the interference pattern. The THz beam direction could be changed by 20° at 0.93THz by varying the relative incidence angle of the pump beams by 0.033°.

  13. Soft X-Ray Optics by Pulsed Laser Deposition

    NASA Technical Reports Server (NTRS)

    Fernandez, Felix E.

    1996-01-01

    Mo/Si and C/Co multilayers for soft x-ray optics were designed for spectral regions of interest in possible applications. Fabrication was effected by Pulsed Laser Deposition using Nd:YAG (355 nm) or excimer (248 nm) lasers in order to evaluate the suitability of this technique. Results for Mo/Si structures were not considered satisfactory due mainly to problems with particulate production and target surface modification during Si ablation. These problems may be alleviated by a two-wavelength approach, using separate lasers for each target. Results for C/Co multilayers are much more encouraging, since indication of good layering was observed for extremely thin layers. We expect to continue investigating this possibility. In order to compete with traditional PVD techniques, it is necessary to achieve film coverage uniformity over large enough areas. It was shown that this is feasible, and novel means of achieving it were devised.

  14. Suppressing spectral diffusion of emitted photons with optical pulses

    DOE PAGES

    Fotso, H. F.; Feiguin, A. E.; Awschalom, D. D.; ...

    2016-01-22

    In many quantum architectures the solid-state qubits, such as quantum dots or color centers, are interfaced via emitted photons. However, the frequency of photons emitted by solid-state systems exhibits slow uncontrollable fluctuations over time (spectral diffusion), creating a serious problem for implementation of the photon-mediated protocols. Here we show that a sequence of optical pulses applied to the solid-state emitter can stabilize the emission line at the desired frequency. We demonstrate efficiency, robustness, and feasibility of the method analytically and numerically. Taking nitrogen-vacancy center in diamond as an example, we show that only several pulses, with the width of 1more » ns, separated by few ns (which is not difficult to achieve) can suppress spectral diffusion. As a result, our method provides a simple and robust way to greatly improve the efficiency of photon-mediated entanglement and/or coupling to photonic cavities for solid-state qubits.« less

  15. Soft x ray optics by pulsed laser deposition

    NASA Technical Reports Server (NTRS)

    Fernandez, Felix E.

    1994-01-01

    A series of molybdenum thin film depositions by PLD (Pulsed Laser Deposition) have been carried out, seeking appropriate conditions for multilayer fabrication. Green (532 nm) and UV (355 nm) light pulses, in a wide range of fluences, were used. Relatively large fluences (in comparison with Si) are required to cause evaporation of molybdenum. The optical penetration depths and reflectivities for Mo at these two wavelengths are comparable, which means that results should be, and do appear to be similar for equal fluences. For all fluences above threshold used, a large number of incandescent particles is ejected by the target (either a standard Mo sputtering target or a Mo sheet were tried), together with the plasma plume. Most of these particles are clearly seen to bounce off the substrate. The films were observed with light microscopy using Nomarski and darkfield techniques. There is no evidence of large debris. Smooth films plus micron-sized droplets are usually seen. The concentration of these droplets embedded in the film appears not to vary strongly with the laser fluence employed. Additional characterization with SEM and XRD is under way.

  16. Adaptive optics for ultra short pulsed lasers in UHV environment

    NASA Astrophysics Data System (ADS)

    Deneuville, Francois; Ropert, Laurent; Sauvageot, Paul; Theis, Sébastien

    2015-02-01

    ISP SYSTEM has developed an electro-mechanical deformable mirror compatible with Ultra High Vacuum environment, suitable for ultra short pulsed lasers. The design of the MD-AME deformable mirror is based on force application on numerous locations. μ-AME actuators are driven by stepper motors, and their patented special design allows controlling the force with a very high accuracy. Materials and assembly method have been adapted to UHV constraints and the performances were evaluated on a first application for a beam with a diameter of 250mm. A Strehl ratio above 0.9 was reached for this application. Optical aberrations up to Zernike order 5 can be corrected with a very low residual error as for standard MD-AME mirror. Amplitude can reach up to several hundreds of μm for low order corrections. Hysteresis is lower than 0.1% and linearity better than 99%. Contrary to piezo-electric actuators, the μ-AME actuators avoid print-through effects and they permit to keep the mirror shape stable even unpowered, providing a high resistance to electro-magnetic pulses. The deformable mirror design allows changing easily an actuator or even the membrane if needed, in order to improve the facility availability. They are designed for circular, square or elliptical aperture from 30mm up to 500mm or more, with incidence angle from 0° to 45°. They can be equipped with passive or active cooling for high power lasers with high repetition rate.

  17. Comb spectra and coherent optical pulse propagation in a size-imbalanced coupled ring resonator

    NASA Astrophysics Data System (ADS)

    Suzuki, Ryuta; Tomita, Makoto

    2017-08-01

    Transmission spectra and coherent optical pulse propagation though a size-imbalanced coupled ring resonator are investigated, where the size of the first ring is extremely large and has a narrow free-spectral-range with an extremely high Q-value, and the second ring is small with a moderate Q-value. The system shows characteristic comb spectra due to interference effects between the two resonators. When an arbitrary-shaped coherent pulse propagates through this system, a series of oscillating output pulses appears. It is shown that this pulse train develops into coherent 0π optical pulses.

  18. Optimally enhanced optical emission in laser-induced air plasma by femtosecond double-pulse

    SciTech Connect

    Chen, Anmin; Li, Suyu; Li, Shuchang; Jiang, Yuanfei; Ding, Dajun; Shao, Junfeng; Wang, Tingfeng; Huang, Xuri; Jin, Mingxing

    2013-10-15

    In laser-induced breakdown spectroscopy, a femtosecond double-pulse laser was used to induce air plasma. The plasma spectroscopy was observed to lead to significant increase of the intensity and reproducibility of the optical emission signal compared to femtosecond single-pulse laser. In particular, the optical emission intensity can be optimized by adjusting the delay time of femtosecond double-pulse. An appropriate pulse-to-pulse delay was selected, that was typically about 50 ps. This effect can be especially advantageous in the context of femtosecond laser-induced breakdown spectroscopy, plasma channel, and so on.

  19. Excitability and optical pulse generation in semiconductor lasers driven by resonant tunneling diode photo-detectors.

    PubMed

    Romeira, Bruno; Javaloyes, Julien; Ironside, Charles N; Figueiredo, José M L; Balle, Salvador; Piro, Oreste

    2013-09-09

    We demonstrate, experimentally and theoretically, excitable nanosecond optical pulses in optoelectronic integrated circuits operating at telecommunication wavelengths (1550 nm) comprising a nanoscale double barrier quantum well resonant tunneling diode (RTD) photo-detector driving a laser diode (LD). When perturbed either electrically or optically by an input signal above a certain threshold, the optoelectronic circuit generates short electrical and optical excitable pulses mimicking the spiking behavior of biological neurons. Interestingly, the asymmetric nonlinear characteristic of the RTD-LD allows for two different regimes where one obtain either single pulses or a burst of multiple pulses. The high-speed excitable response capabilities are promising for neurally inspired information applications in photonics.

  20. Characterization of Ultrafast Laser Pulses using a Low-dispersion Frequency Resolved Optical Grating Spectrometer

    NASA Astrophysics Data System (ADS)

    Whitelock, Hope; Bishop, Michael; Khosravi, Soroush; Obaid, Razib; Berrah, Nora

    2016-05-01

    A low dispersion frequency-resolved optical gating (FROG) spectrometer was designed to characterize ultrashort (<50 femtosecond) laser pulses from a commercial regenerative amplifier, optical parametric amplifier, and a home-built non-colinear optical parametric amplifier. This instrument splits a laser pulse into two replicas with a 90:10 intensity ratio using a thin pellicle beam-splitter and then recombines the pulses in a birefringent medium. The instrument detects a wavelength-sensitive change in polarization of the weak probe pulse in the presence of the stronger pump pulse inside the birefringent medium. Scanning the time delay between the two pulses and acquiring spectra allows for characterization of the frequency and time content of ultrafast laser pulses, that is needed for interpretation of experimental results obtained from these ultrafast laser systems. Funded by the DoE-BES, Grant No. DE-SC0012376.

  1. Towards Terawatt Sub-Cycle Long-Wave Infrared Pulses via Chirped Optical Parametric Amplification and Indirect Pulse Shaping

    NASA Astrophysics Data System (ADS)

    Yin, Yanchun; Chew, Andrew; Ren, Xiaoming; Li, Jie; Wang, Yang; Wu, Yi; Chang, Zenghu

    2017-04-01

    We present an approach for both efficient generation and amplification of 4-12 μm pulses by tailoring the phase matching of the nonlinear crystal Zinc Germanium Phosphide (ZGP) in a narrowband-pumped optical parametric chirped pulse amplifier (OPCPA) and a broadband-pumped dual-chirped optical parametric amplifier (DC-OPA), respectively. Preliminary experimental results are obtained for generating 1.8-4.2 μm super broadband spectra, which can be used to seed both the signal of the OPCPA and the pump of the DC-OPA. The theoretical pump-to-idler conversion efficiency reaches 27% in the DC-OPA pumped by a chirped broadband Cr2+:ZnSe/ZnS laser, enabling the generation of  Terawatt-level 4-12 μm pulses with an available large-aperture ZGP. Furthermore, the 4-12 μm idler pulses can be compressed to sub-cycle pulses by compensating the tailored positive chirp of the idler pulses using the bulk compressor NaCl, and by indirectly controlling the higher-order idler phase through tuning the signal (2.4-4.0 μm) phase with a commercially available acousto-optic programmable dispersive filter (AOPDF). A similar approach is also described for generating high-energy 4-12 μm sub-cycle pulses via OPCPA pumped by a 2 μm Ho:YLF laser.

  2. Towards Terawatt Sub-Cycle Long-Wave Infrared Pulses via Chirped Optical Parametric Amplification and Indirect Pulse Shaping.

    PubMed

    Yin, Yanchun; Chew, Andrew; Ren, Xiaoming; Li, Jie; Wang, Yang; Wu, Yi; Chang, Zenghu

    2017-04-03

    We present an approach for both efficient generation and amplification of 4-12 μm pulses by tailoring the phase matching of the nonlinear crystal Zinc Germanium Phosphide (ZGP) in a narrowband-pumped optical parametric chirped pulse amplifier (OPCPA) and a broadband-pumped dual-chirped optical parametric amplifier (DC-OPA), respectively. Preliminary experimental results are obtained for generating 1.8-4.2 μm super broadband spectra, which can be used to seed both the signal of the OPCPA and the pump of the DC-OPA. The theoretical pump-to-idler conversion efficiency reaches 27% in the DC-OPA pumped by a chirped broadband Cr(2+):ZnSe/ZnS laser, enabling the generation of  Terawatt-level 4-12 μm pulses with an available large-aperture ZGP. Furthermore, the 4-12 μm idler pulses can be compressed to sub-cycle pulses by compensating the tailored positive chirp of the idler pulses using the bulk compressor NaCl, and by indirectly controlling the higher-order idler phase through tuning the signal (2.4-4.0 μm) phase with a commercially available acousto-optic programmable dispersive filter (AOPDF). A similar approach is also described for generating high-energy 4-12 μm sub-cycle pulses via OPCPA pumped by a 2 μm Ho:YLF laser.

  3. Optical generation of millimeter-wave pulses using a fiber Bragg grating in a fiber-optics system.

    PubMed

    Ye, Qing; Qu, Ronghui; Fang, Zujie

    2007-04-10

    A scheme is proposed to transform an optical pulse into a millimeter-wave frequency modulation pulse by using a weak fiber Bragg grating (FBG) in a fiber-optics system. The Fourier transformation method is used to obtain the required spectrum response function of the FBG for the Gaussian pulse, soliton pulse, and Lorenz shape pulse. On the condition of the first-order Born approximation of the weak fiber grating, the relation of the refractive index distribution and the spectrum response function of the FBG satisfies the Fourier transformation, and the corresponding refractive index distribution forms are obtained for single-frequency modulation and linear-frequency modulation millimeter-wave pulse generation. The performances of the designed fiber gratings are also studied by a numerical simulation method for a supershort pulse transmission.

  4. 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.

  5. Metrological characterization of the pulsed Rb clock with optical detection

    NASA Astrophysics Data System (ADS)

    Micalizio, S.; Calosso, C. E.; Godone, A.; Levi, F.

    2012-08-01

    We report on the implementation and metrological characterization of a vapour-cell Rb frequency standard working in a pulsed regime. The three main parts of the clock, physics package, optics and electronics, are described in detail in this paper. The prototype is designed and optimized to detect the clock transition in the optical domain. Specifically, the reference atomic transition, excited with a Ramsey scheme, is detected by observing the interference pattern on a laser absorption signal. The metrological analysis includes the observation and characterization of the clock signal and the measurement of frequency stability and drift. In terms of Allan deviation, the measured frequency stability is as low as 1.7 × 10-13τ-1/2, τ being the averaging time, and reaches the value of a few units of 10-15 for τ = 104 s, an unprecedented result for a vapour-cell clock. We discuss the physical effects leading to this result in this paper with particular care to laser and microwave noises transferred to the clock signal. The frequency drift, probably related to temperature, stays below 10-14 per day, and no evidence of flicker floor is observed. We also mention some possible improvements that in principle would lead to a clock stability below the 10-13 level at 1 s and to a drift of a few units of 10-15 per day.

  6. Multipath Time Spreading of Optical Pulses Propagating through a Scattering Medium

    DTIC Science & Technology

    1975-01-01

    profound. Consider a mode locked dye laser capable )f generating 1 picosecond pulses; beam superposition techniques can be "used to produce a...transmitted by very short ( picosecond ) pulses-, multipap h time spreading of the received pulses can produce intersymbol interference increasing the...satisfied this requirement, well. I -A mode locked He:Ne laser provided optical pulses typical of those encountered in opticzl communications systems

  7. Robust Short-Pulse, High-Peak-Power Laser Transmitter for Optical Communications

    NASA Technical Reports Server (NTRS)

    Wright, Malcolm W.

    2009-01-01

    We report on a pulsed fiber based master oscillator power amplifier laser at 1550 nm to support moderate data rates with high peak powers in a compact package suitable for interplanetary optical communications. To accommodate pulse position modulation, the polarization maintaining laser transmitter generates pulses from 0.1 to 1 ns with variable duty cycle over a pulse repetition frequency range of 10 to 100 MHz.

  8. Synthesis of Optical Frequencies and Ultrastable Femtosecond Pulse Trains from an Optical Reference Oscillator

    NASA Astrophysics Data System (ADS)

    Bartels, A.; Ramond, T. M.; Diddams, S. A.; Hollberg, L.

    Recently, atomic clocks based on optical frequency standards have been demonstrated [1,2]. A key element in these clocks is a femtosecond laser that downconverts the petahertz oscillation rate into countable ticks at 1 GHz. When compared to current microwave standards, these new optical clocks are expected to yield an improvement in stability and accuracy by roughly a factor of 1000. Furthermore, it is possible that the lowest noise microwave sources will soon be based on atomically-stabilized optical oscillators that have their frequency converted to the microwave domain via a femtosecond laser. Here, we present tests of the ability of femtosecond lasers to transfer stability from an optical oscillator to their repetition rates as well as to the associated broadband frequency comb. In a first experiment, we phase-lock two lasers to a stabilized laser diode and find that the relative timing jitter in their pulse trains can be on the order of 1 femtosecond in a 100 kHz bandwidth. It is important to distinguish this technique from previous work where a femtosecond laser has been stabilized to a microwave standard [3,4] or another femtosecond laser [5]. Furthermore, we extract highly stable microwave signals with a fractional frequency instability of 2×10-14 in 1 s by photodetection of the laser pulse trains. In a second experiment, we similarly phase-lock the femtosecond laser to an optical oscillator with linewidth less than 1 Hz [6]. The precision with which we can make the femtosecond frequency comb track this reference oscillator is then tested by a heterodyne measurement between a second stable optical oscillator and a mode of the frequency comb that is displaced 76 THz from the 1 Hz-wide reference. From this heterodyne signal we place an upper limit of 150 Hz on the linewidth of the elements of the frequency comb, limited by the noise in the measurement itself.

  9. Acousto-Optic Spectrum Analyzer: Temporal Response and Detection of Pulsed Signals.

    DTIC Science & Technology

    1986-12-01

    ACOUSTO - OPTIC SPECTRUM ANALYZER: TEMPORAL RESPONSE AND I/i DETECTION OF PULSED SIGUALS(U) DEFENCE RESEARCH ESTABLISHMENT OTTANA (ONTARIO) J...8217:. -.....:.-...............--.. - ---:-..--.-..,. ,: i’,.. IJT~c FILE C P National Defe’ se + Deence nationale 0 0 ACOUSTO - OPTIC SPECTRUM ANALYZER: TEMPORAL RESPONSE AND DETECTION 0 OF PULSED...Ottawa |S, .±~ |-----------------------..,---.-- -- - - - rNatiorna! Defen~se Deterice r dornale ACOUSTO - OPTIC SPECTRUM ANALYZER: TEMPORAL RESPONSE

  10. Ultrahigh-speed "orthogonal" TDM transmission with an optical Nyquist pulse train.

    PubMed

    Nakazawa, Masataka; Hirooka, Toshihiko; Ruan, Peng; Guan, Pengyu

    2012-01-16

    We propose a novel "orthogonal" TDM transmission scheme using an optical Nyquist pulse that enables us to achieve an ultrahigh data rate and spectral efficiency simultaneously without any intersymbol interference (ISI). We analytically describe the principle of orthogonal TDM, and demonstrate a 160 Gbaud optical orthogonal TDM transmission using 40 GHz optical Nyquist pulses. Tolerance to GVD and the dispersion slope is significantly improved by virtue of the orthogonality, reduced bandwidth, and minimum ISI.

  11. Fiber Optic Picosecond Laser Pulse Transmission Line for Hydrogen Ion Beam Profile Measurement

    SciTech Connect

    Liu, Yun; Huang, Chunning; Aleksandrov, Alexander V

    2013-01-01

    We present a fiber optic laser pulse transmission line for non-intrusive longitudinal profile measurement of the hydrogen ion (H-) beam at the front-end of the Spallation Neutron Source (SNS) accelerator. The 80.5 MHz, 2.5 ps, multi-killowatt optical pulses are delivered to the accelerator beam line through a large mode area polarization maintaining optical fiber to ensure a high measurement stability. The transmission efficiency, output laser beam quality, pulse jitter and pulse width broadening over a 100-ft fiber line are experimentally investigated. A successful measurement of the H- beam microbunch (~130 ps) profile is obtained. Our experiment is the first demonstration of particle beam profile diagnostics using fiber optic laser pulse transmission line.

  12. Vibration measurement based on the optical cross-correlation technique with femtosecond pulsed laser

    NASA Astrophysics Data System (ADS)

    Han, Jibo; Wu, Tengfei; Zhao, Chunbo; Li, Shuyi

    2016-10-01

    Two vibration measurement methods with femtosecond pulsed laser based on the optical cross-correlation technique are presented independently in this paper. The balanced optical cross-correlation technique can reflect the time jitter between the reference pluses and measurement pluses by detecting second harmonic signals using type II phase-matched nonlinear crystal and balanced amplified photo-detectors. In the first method, with the purpose of attaining the vibration displacement, the time difference of the reference pulses relative to the measurement pluses can be measured using single femtosecond pulsed laser. In the second method, there are a couple of femtosecond pulsed lasers with high pulse repetition frequency. Vibration displacement associated with cavity length can be calculated by means of precisely measuring the pulse repetition frequency. The results show that the range of measurement attains ±150μm for a 500fs pulse. These methods will be suited for vibration displacement measurement, including laboratory use, field testing and industrial application.

  13. New approach for the design of an optical square pulse generator.

    PubMed

    Ngo, Nam Quoc; Binh, Le Nguyen

    2007-06-10

    What is believed to be a new approach for the design and analysis of a reconfigurable optical square pulse generator using the concept of temporal optical integration and the digital signal processing method is presented. The reconfigurable square pulse generator is synthesized using compact active semiconductor-based waveguide technology, and it consists simply of the cascade of a tunable microring resonator (or a tunable all-pole filter) and a tunable asymmetrical Mach-Zehnder interferometer (or a tunable all-zero filter). The reconfigurable generator can convert an input picosecond pulse (i.e., soliton or Gaussian pulse) into an optical square pulse. The pulse width of the generated square pulse can be adjusted by controlling the time delay of a variable delay element in the tunable all-zero filter. The reconfigurable generator can convert an input picosecond pulse train into return-to-zero (RZ) and non-return-to-zero (NRZ) signals with square pulse shapes. The repetition rates of the generated RZ and NRZ signals can be varied by adjusting the bit period of the input picosecond pulse train, the input pulse width, and the time delay of the variable delay element. The effect of the deviation of the parameter values on the generator performance is also studied.

  14. Dispersion management for a sub-10-fs, 10 TW optical parametric chirped-pulse amplifier.

    PubMed

    Tavella, Franz; Nomura, Yutaka; Veisz, Laszlo; Pervak, Vladimir; Marcinkevicius, Andrius; Krausz, Ferenc

    2007-08-01

    We report the amplification of three-cycle, 8.5 fs optical pulses in a near-infrared noncollinear optical parametric chirped-pulse amplifier (OPCPA) up to energies of 80 mJ. Improved dispersion management in the amplifier by means of a combination of reflection grisms and a chirped-mirror stretcher allowed us to recompress the amplified pulses to within 6% of their Fourier limit. The novel ultrabroad, ultraprecise dispersion control technology presented in this work opens the way to scaling multiterawatt technology to even shorter pulses by optimizing the OPCPA bandwidth.

  15. Simultaneous temporal characterization of telecommunication optical pulses and modulators by use of spectrograms.

    PubMed

    Dorrer, Christophe; Kang, Inuk

    2002-08-01

    We demonstrate a simple technique for simultaneous and complete characterization of the optical pulses and temporal modulators commonly used in telecommunication. The electric field of a pulse and the response of a modulator are obtained from the analysis of the two-dimensional spectrogram of the pulse gated by the modulator. The measurement sensitivity is greatly improved compared with the conventional nonlinear optical techniques. Trains of picosecond pulses as weak as 10(-17)J are accurately characterized with an electroabsorption modulator as the temporal gate. The time-resolved transmission and phase of the modulator are also presented.

  16. Broadband noise limit in the photodetection of ultralow jitter optical pulses.

    PubMed

    Sun, Wenlu; Quinlan, Franklyn; Fortier, Tara M; Deschenes, Jean-Daniel; Fu, Yang; Diddams, Scott A; Campbell, Joe C

    2014-11-14

    Applications with optical atomic clocks and precision timing often require the transfer of optical frequency references to the electrical domain with extremely high fidelity. Here we examine the impact of photocarrier scattering and distributed absorption on the photocurrent noise of high-speed photodiodes when detecting ultralow jitter optical pulses. Despite its small contribution to the total photocurrent, this excess noise can determine the phase noise and timing jitter of microwave signals generated by detecting ultrashort optical pulses. A Monte Carlo simulation of the photodetection process is used to quantitatively estimate the excess noise. Simulated phase noise on the 10 GHz harmonic of a photodetected pulse train shows good agreement with previous experimental data, leading to the conclusion that the lowest phase noise photonically generated microwave signals are limited by photocarrier scattering well above the quantum limit of the optical pulse train.

  17. Frequency Conversion of Short Optical Pulses in Negatively Spatially Dispersive Metamaterials

    DTIC Science & Technology

    2015-10-22

    Short Optical Pulses inNegatively Spatially Dispersive Metamaterials We show that particular spatial distributions of nanoscopic plasmonic building...distributions of nanoscopic plasmonic building blocks in metamaterials may enable extraordinary nonlinear-optical frequency-shifted reflectivity and...particular spatial distributions of nanoscopic plasmonic building blocks in metamaterials may enable extraordinary nonlinear-optical frequency-shifted

  18. Optical polarizing neutron devices designed for pulsed neutron sources

    SciTech Connect

    Takeda, M.; Kurahashi, K.; Endoh, Y.; Itoh, S.

    1997-09-01

    We have designed two polarizing neutron devices for pulsed cold neutrons. The devices have been tested at the pulsed neutron source at the Booster Synchrotron Utilization Facility of the National Laboratory for High Energy Physics. These two devices proved to have a practical use for experiments to investigate condensed matter physics using pulsed cold polarized neutrons.

  19. Optical properties of tissue measured using terahertz-pulsed imaging

    NASA Astrophysics Data System (ADS)

    Berry, Elizabeth; Fitzgerald, Anthony J.; Zinov'ev, Nickolay N.; Walker, Gillian C.; Homer-Vanniasinkam, Shervanthi; Sudworth, Caroline D.; Miles, Robert E.; Chamberlain, J. Martyn; Smith, Michael A.

    2003-06-01

    The first demonstrations of terahertz imaging in biomedicine were made several years ago, but few data are available on the optical properties of human tissue at terahertz frequencies. A catalogue of these properties has been established to estimate variability and determine the practicality of proposed medical applications in terms of penetration depth, image contrast and reflection at boundaries. A pulsed terahertz imaging system with a useful bandwidth 0.5-2.5 THz was used. Local ethical committee approval was obtained. Transmission measurements were made through tissue slices of thickness 0.08 to 1 mm, including tooth enamel and dentine, cortical bone, skin, adipose tissue and striated muscle. The mean and standard deviation for refractive index and linear attenuation coefficient, both broadband and as a function of frequency, were calculated. The measurements were used in simple models of the transmission, reflection and propagation of terahertz radiation in potential medical applications. Refractive indices ranged from 1.5 +/- 0.5 for adipose tissue to 3.06 +/- 0.09 for tooth enamel. Significant differences (P < 0.05) were found between the broadband refractive indices of a number of tissues. Terahertz radiation is strongly absorbed in tissue so reflection imaging, which has lower penetration requirements than transmission, shows promise for dental or dermatological applications.

  20. Infrared photoacoustic gas spectroscopy employing pulsed optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Kaucikas, Marius; Kuprionis, Zenonas; Svedas, Vitas; Vaicikauskas, Viktoras

    2005-09-01

    High sensitivity and selectivity of gas/vapour detection are achieved employing registration of laser photoacoustic spectra. The lasers are usually operated in the continuous-wave (CW) single-frequency mode. The tuning range of the single CW laser system is not sufficient to cover spectral bands of variety of gases/vapours of interest. The optical parametric oscillator (OPO) systems are more preferential for multi component laser analyzers allowing the simultaneous measurement of different gases or pollutants. Pumped by the same 7 ns duration pulse of Nd:YAG laser and its harmonics, two OPO systems were tested. One system generates in the 0.7-1.9 μm range and covers overtones of stretching vibrations and combination vibrations of hydrogen atoms in the analyte molecule. Other system generating in the 5-11 μm range covers vibrations of molecular characteristic groups ("fingerprints"). Photoacoustic spectra of nitro compound vapours, e.g. nitromethane, nitroethane, nitropropane, nitrobenzene and nitrotoluene, also spectra of methane and water vapour were measured and compared to simulated spectra derived with the aid of HITRAN data base and to the literature spectral data. Photoacoustic detection thresholds are evaluated from the ratios of measured signal to the registration noise.

  1. A linear optical trap with active medium for experiments with high power laser pulses

    NASA Astrophysics Data System (ADS)

    Mohamed, Tarek; Andler, Guillermo; Schuch, Reinhold

    2015-02-01

    A linear optical trap for circulating high power laser pulses and tuning these pulses to high repetition frequency of several tens of MHz has been developed. A ns excimer pumped dye laser pulse has been injected with help of a Wollaston prism and a synchronized Pockels cell into an optical trap formed by two highly reflecting mirrors in a linear configuration. The test was done at λ = 580 nm, but the optical trap can be used without limitations in a broad band of optical wavelengths (400-700 nm). Power considerations give an increase of the efficiency of the optical trap of about 7 times compared to single passage of the laser pulse through the experimental section. The time structure of the trapped laser pulses can be controlled by changing the distance between the two high reflecting mirrors. The efficiency of the optical trap strongly depends upon optical losses. To compensate the optical losses, an amplifying cell was introduced, and the efficiency was about 60 times higher than that by single passage of the laser pulse through the experimental section.

  2. A linear optical trap with active medium for experiments with high power laser pulses.

    PubMed

    Mohamed, Tarek; Andler, Guillermo; Schuch, Reinhold

    2015-02-01

    A linear optical trap for circulating high power laser pulses and tuning these pulses to high repetition frequency of several tens of MHz has been developed. A ns excimer pumped dye laser pulse has been injected with help of a Wollaston prism and a synchronized Pockels cell into an optical trap formed by two highly reflecting mirrors in a linear configuration. The test was done at λ = 580 nm, but the optical trap can be used without limitations in a broad band of optical wavelengths (400-700 nm). Power considerations give an increase of the efficiency of the optical trap of about 7 times compared to single passage of the laser pulse through the experimental section. The time structure of the trapped laser pulses can be controlled by changing the distance between the two high reflecting mirrors. The efficiency of the optical trap strongly depends upon optical losses. To compensate the optical losses, an amplifying cell was introduced, and the efficiency was about 60 times higher than that by single passage of the laser pulse through the experimental section.

  3. Electromagnetically induced transparency in rubidium vapor prepared by a comb of short optical pulses

    SciTech Connect

    Sautenkov, Vladimir A.; Rostovtsev, Yuri V.; Ye, C.Y.; Welch, George R.; Kocharovskaya, Olga; Scully, Marlan O.

    2005-06-15

    It was shown by Kocharovskaya and Khanin [Sov. Phys. JETP 63, 945 (1986)] that a comb of optical pulses can induce a ground-state atomic coherence and change the optical response of an atomic medium. In our experiment, we studied the propagation of a comb of optical pulses produced by a mode-locked diode laser in rubidium atomic vapor. Electromagnetically induced transparency (EIT) was observed when the pulse repetition rate is a subharmonic of the hyperfine splitting of the ground state. The width of the EIT resonance is determined by the relaxation rate of the ground-state coherence. Possible applications to magnetometery, atomic clocks, and frequency chains are discussed.

  4. Direct Excitation of Propagating Spin Waves by Focused Ultrashort Optical Pulses

    NASA Astrophysics Data System (ADS)

    Au, Y.; Dvornik, M.; Davison, T.; Ahmad, E.; Keatley, P. S.; Vansteenkiste, A.; Van Waeyenberge, B.; Kruglyak, V. V.

    2013-03-01

    An all-optical experiment long utilized to image phonons excited by ultrashort optical pulses has been applied to a magnetic sample. In addition to circular ripples due to surface acoustic waves, we observe an X-shaped pattern formed by propagating spin waves. The emission of spin waves from the optical pulse epicenter in the form of collimated beams is qualitatively reproduced by micromagnetic simulations. We explain the observed pattern in terms of the group velocity distribution of Damon-Eshbach magnetostatic spin waves in the reciprocal space and the wave vector spectrum of the focused ultrafast laser pulse.

  5. Direct excitation of propagating spin waves by focused ultrashort optical pulses.

    PubMed

    Au, Y; Dvornik, M; Davison, T; Ahmad, E; Keatley, P S; Vansteenkiste, A; Van Waeyenberge, B; Kruglyak, V V

    2013-03-01

    An all-optical experiment long utilized to image phonons excited by ultrashort optical pulses has been applied to a magnetic sample. In addition to circular ripples due to surface acoustic waves, we observe an X-shaped pattern formed by propagating spin waves. The emission of spin waves from the optical pulse epicenter in the form of collimated beams is qualitatively reproduced by micromagnetic simulations. We explain the observed pattern in terms of the group velocity distribution of Damon-Eshbach magnetostatic spin waves in the reciprocal space and the wave vector spectrum of the focused ultrafast laser pulse.

  6. Proposal and simulation of differential double-pulse pair Brillouin optical time-domain analysis

    NASA Astrophysics Data System (ADS)

    Tang, Jianguan; Luo, Wenping; Chen, Beiqing; Guo, Huiyong; Zhang, Cui

    2013-09-01

    A differential double-pulse pair Brillouin optical time-domain analysis (DDP-BOTDA) combined with the double-pulsed technique and the differential pulse-width pair technique is proposed and simulated to detect small temperature and strain changes. Using a symmetrical double-pulse pair, the system can detect small Brillouin shift with high spatial resolution and large dynamic range. Sub-meter spatial resolution is decided by the difference between the pulse-width and the peak and valley of the spectrum which is derived from differential pump depletion signals, and detectable Brillouin shift is less than 1 MHz.

  7. THz generation via optical rectification with ultrashort laser pulse focused to a line

    NASA Astrophysics Data System (ADS)

    Stepanov, A. G.; Hebling, J.; Kuhl, J.

    2005-07-01

    We report on efficient THz pulse generation via optical rectification with femtosecond laser pulses focused to a line by a cylindrical lens. This configuration provides phase-matched conditions in the superluminal regime. 35 pJ THz pulses have been generated with this technique in a stoichiometric LiNbO3 crystal pumped by 2 μJ femtosecond laser pulses at room temperature. An unusual superquadratic rise of the THz pulse energy with the laser pulse energy has been observed at high laser energies. This extraordinary energy dependence of the THz generation efficiency is explained by self-focusing of the laser beam in the crystal. Z-scan measurements and comparison of the THz pulse spectra created with laser pulses having different energies confirm this interpretation.

  8. Pulsed laser manipulation of an optically trapped bead: averaging thermal noise and measuring the pulsed force amplitude.

    PubMed

    Lindballe, Thue B; Kristensen, Martin V G; Berg-Sørensen, Kirstine; Keiding, Søren R; Stapelfeldt, Henrik

    2013-01-28

    An experimental strategy for post-eliminating thermal noise on position measurements of optically trapped particles is presented. Using a nanosecond pulsed laser, synchronized to the detection system, to exert a periodic driving force on an optically trapped 10 μm polystyrene bead, the laser pulse-bead interaction is repeated hundreds of times. Traces with the bead position following the prompt displacement from equilibrium, induced by each laser pulse, are averaged and reveal the underlying deterministic motion of the bead, which is not visible in a single trace due to thermal noise. The motion of the bead is analyzed from the direct time-dependent position measurements and from the power spectrum. The results show that the bead is on average displaced 208 nm from the trap center and exposed to a force amplitude of 71 nanoNewton, more than five orders of magnitude larger than the trapping forces. Our experimental method may have implications for microrheology.

  9. Towards Terawatt Sub-Cycle Long-Wave Infrared Pulses via Chirped Optical Parametric Amplification and Indirect Pulse Shaping

    PubMed Central

    Yin, Yanchun; Chew, Andrew; Ren, Xiaoming; Li, Jie; Wang, Yang; Wu, Yi; Chang, Zenghu

    2017-01-01

    We present an approach for both efficient generation and amplification of 4–12 μm pulses by tailoring the phase matching of the nonlinear crystal Zinc Germanium Phosphide (ZGP) in a narrowband-pumped optical parametric chirped pulse amplifier (OPCPA) and a broadband-pumped dual-chirped optical parametric amplifier (DC-OPA), respectively. Preliminary experimental results are obtained for generating 1.8–4.2 μm super broadband spectra, which can be used to seed both the signal of the OPCPA and the pump of the DC-OPA. The theoretical pump-to-idler conversion efficiency reaches 27% in the DC-OPA pumped by a chirped broadband Cr2+:ZnSe/ZnS laser, enabling the generation of  Terawatt-level 4–12 μm pulses with an available large-aperture ZGP. Furthermore, the 4–12 μm idler pulses can be compressed to sub-cycle pulses by compensating the tailored positive chirp of the idler pulses using the bulk compressor NaCl, and by indirectly controlling the higher-order idler phase through tuning the signal (2.4–4.0 μm) phase with a commercially available acousto-optic programmable dispersive filter (AOPDF). A similar approach is also described for generating high-energy 4–12 μm sub-cycle pulses via OPCPA pumped by a 2 μm Ho:YLF laser. PMID:28367966

  10. Experimental study of electro-optical Q-switched pulsed Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    A, Maleki; M Kavosh, Tehrani; H, Saghafifar; M, H. Moghtader Dindarlu

    2016-03-01

    We report the specification of a compact and stable side diode-pumped Q-switched pulsed Nd:YAG laser. We experimentally study and compare the performance of the pulsed Nd:YAG laser in the free-running and Q-switched modes at different pulse repetition rates from 1 Hz to 100 Hz. The laser output energy is stabilized by using a special configuration of the optical resonator. In this laser, an unsymmetrical concave-concave resonator is used and this structure helps the mode volume to be nearly fixed when the pulse repetition rate is increased. According to the experimental results in the Q-switched operation, the laser output energy is nearly constant around 70 mJ with an FWHM pulse width of 7 ns at 100 Hz. The optical-to-optical conversion efficiency in the Q-switched regime is 17.5%.

  11. Parallel Visualization of the optical pulse propagation through a doped optical fiber

    NASA Astrophysics Data System (ADS)

    Santos-Neto, Elizeu; Tenorio, Luiz; Fonseca, Eduardo; Cavalcanti, Solange; Hickmann, Jandir

    2001-06-01

    The numerical simulation of the simultaneous propagation of a pair of light pulses through a nonlinear doped optical fiber has recently provided many interesting results such as cloning, breakup and soliton interactions. This type of propagation is investigated within the framework of a pair of nonlinear Schrödinger equations together with a set of Bloch equations. The numerical simulations of these equations produce an enormous amount of data that are not easily interpreted depending on the resolution that these results are obtained. This problem is circumvented if one uses scientific visualization and the latter is significantly improved by using high performance computing. Therefore, in this work we have implemented an adaptation of both Visualization Tool Kit (VTK an open visualization library) and the Message Passing Interface (MPI) to run these applications on a cluster of computers. The basic idea is to produce a detailed visualization of the numerical data produced by the simulations of the propagation of a pair of optical pulses through nonlinear waveguide improving significantly the physical interpretation of the processes of cloning, breakup and soliton interactions.

  12. Time- and wavelength-interleaved laser pulses: prospects and challenges in optical signal processing

    NASA Astrophysics Data System (ADS)

    Shu, Chester; Lei, Gordon K. P.

    2011-12-01

    We review our recent work on the generation of time- and wavelength-interleaved laser pulses and their applications in optical signal processing. Using phase and amplitude modulation on four continuous-wave lasers at ~1550 nm followed by chirp compensation, we have generated < 6 ps pulses switched sequentially among 4 center wavelengths with a repetition rate of 80 GHz. The pulses are nearly transform limited with a time-bandwidth product ~ 0.464. We applied time- and wavelength-interleaved pulses for new applications in nonlinear processing of communication signals. Fourwavelength DPSK multicasting with simultaneous NRZ-to-RZ pulse format conversion has been achieved with fourwave mixing. In addition, using optical parametric amplification with the interleaved pulses, we have demonstrated reconfigurable 40 Gb/s OTDM demultiplexing, as well as amplitude noise reduction in DPSK wavelength multicast.

  13. Existence and stability of N-pulses on optical fibers with phase-sensitive amplifiers

    NASA Astrophysics Data System (ADS)

    Sandstede, B.; Jones, C. K. R. T.; Alexander, J. C.

    1997-02-01

    The propagation of pulses in optical communication systems in which attenuation is compensated by phase-sensitive amplifiers is investigated. A central issue is whether optical fibers are capable of carrying several pieces of information at the same time. In this paper, multiple pulses are shown to exist for a fourth-order nonlinear diffusion model due to Kutz and co-workers (1994). Moreover, criteria are derived for determining which of these pulses are stable. The pulses arise in a reversible orbit-flip, a homoclinic bifurcation investigated here for the first time. Numerical simulations are used to study multiple pulses far away from the actual bifurcation point. They confirm that properties of the multiple pulses including their stability are surprisingly well-predicted by the analysis carried out near the bifurcation.

  14. Chirped self-similar optical pulses in tapered centrosymmetric nonlinear waveguides doped with resonant impurities

    NASA Astrophysics Data System (ADS)

    He, J. R.; Xu, S. L.; Xue, L.

    2017-06-01

    Exact chirped self-similar optical pulses propagating in tapered centrosymmetric nonlinear waveguides doped with resonant impurities are reported. The propagation behaviors of the pulses are studied by tailoring of the tapering function. Numerical simulations and stability analysis reveal that the tapering can be used to postpone the wave dispersion and the addition of a small cubic self-focusing term to the governing equation could stabilize the chirped bright pulses. An example of possible experimental protocol that may generate the pulses in realistic waveguides is given. The obtained chirped self-similar optical pulses are particularly useful in the design of amplifying or attenuating pulse compressors for chirped solitary waves in tapered centrosymmetric nonlinear waveguides doped with resonant impurities.

  15. Pulse Analyzing System Using Optical Coherence Tomography for Oriental Medical Application

    NASA Astrophysics Data System (ADS)

    Jung, Unsang; Jeon, Mansik; Lee, Changho; Cho, Namhyun; Jeong, Hyosang; Na, Changsu; Kim, Jeehyun

    2011-05-01

    In oriental medicine, the pulse wave of a radial artery is a critical diagnosis factor. An oriental doctor puts a finger on the radial artery to sense the pulse wave of a radial artery. The pulse wave plays an important role because its shape, pressure, and duration determine the pathological status of a patient. Chongumaekbeop, which is a traditional technique for measuring the pulse by using a finger, is sometimes believed to be not reproducible due to the subjective judgment of the measurement location and pulse signal, so we performed a clinical experiment with a developed diagnosis equipment to produce quantitative and reproducible results. In this study, we measured the pulse wave of the radial artery and quantified the speed, intensity, and power of the pulse wave using optical coherence tomography (OCT). We confirmed the applicability of the developed system through an analysis of the pulse wave. We used two OCT systems whose measurement parameters are different because of the measurement limitation and analysis of vector components of pulse movement. We gathered 25 volunteers, compared and analyzed the experiment results with four oriental medicine doctors' diagnosis. The results showed an agreement of 88% in pulse speed, 64% in pulse intensity, and 72% in pulse power when comparing traditional measurements with the system using OCT. We confirmed the dynamical motion detection through the two-dimensional image to ensure the reproducibility of the developed system. Thus, if the OCT system is applied to pulse measurement systems in oriental medicine, it may partially substitute for traditional measurement methods.

  16. Generation of 30 microJ single-cycle terahertz pulses at 100 Hz repetition rate by optical rectification.

    PubMed

    Stepanov, Andrei G; Bonacina, Luigi; Chekalin, Sergei V; Wolf, Jean-Pierre

    2008-11-01

    We report the generation of 30 microJ single-cycle terahertz pulses at 100 Hz repetition rate by phase-matched optical rectification in lithium niobate using 28 mJ femtosecond laser pulses. The phase-matching condition is achieved by tilting the laser pulse intensity front. Temporal, spectral, and propagation properties of the generated terahertz pulses are presented. In addition, we discuss possibilities for further increasing the energy of single-cycle terahertz pulses obtained by optical rectification.

  17. Effect of noise on Frequency-Resolved Optical Gating measurements of ultrashort pulses

    SciTech Connect

    Fittinghoff, D.N.; DeLong, K.W.; Ladera, C.L.; Trebino, R.

    1995-02-01

    We study the effects of noise in Frequency-Resolved Optical Gating measurements of ultrashort pulses. We quantify the measurement accuracy in the presence of additive, muliplicative, and quantization noise, and discuss filtering and pre-processing of the data.

  18. A versatile implementation of pulsed optical excitation in scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Kloth, P.; Thias, T.; Bunjes, O.; von der Haar, J.; Wenderoth, M.

    2016-12-01

    We present a combination of pulsed optical excitation and scanning tunneling microscopy with a highly flexible pulse generation method. A high frequency arbitrary wave generator drives a gigahertz electro-optical modulator, which processes a continuous-wave laser beam of a low-noise laser diode into the desired wave shape. For pump-probe excitation we generate optical pulse series in an all-electronic way. Thereby we can easily adapt parameters like pulse amplitude, width, or repetition cycle to the demands of the experiment. This setup is used to study different dynamic processes at the GaAs(110) surface. Separating thermally induced effects from electrically induced effects allows us to quantify the thermal contribution of the optical excitation in STM experiments. Time-resolved decay spectra of the photo-generated electron-hole pairs demonstrate the nanoscale spatial resolution.

  19. A Multiterawatt Laser Using a High-Contrast, Optical Parametric Chirped-Pulse Presamplifier

    SciTech Connect

    Bagnoud, V.; Puth, J.; Begishev, I.; Guardalben, M.; Zuegel, J.D.; Forget, N.; LeBlanc, C.

    2005-09-30

    A laser has been built that uses optical parametric chirped-pulse preamplification and a glass booster amplifier. We review the performance of the 5-Hz, multijoule OPCPA pump laser, the 370-mJ OPCPA, and the overall laser.

  20. A versatile implementation of pulsed optical excitation in scanning tunneling microscopy.

    PubMed

    Kloth, P; Thias, T; Bunjes, O; von der Haar, J; Wenderoth, M

    2016-12-01

    We present a combination of pulsed optical excitation and scanning tunneling microscopy with a highly flexible pulse generation method. A high frequency arbitrary wave generator drives a gigahertz electro-optical modulator, which processes a continuous-wave laser beam of a low-noise laser diode into the desired wave shape. For pump-probe excitation we generate optical pulse series in an all-electronic way. Thereby we can easily adapt parameters like pulse amplitude, width, or repetition cycle to the demands of the experiment. This setup is used to study different dynamic processes at the GaAs(110) surface. Separating thermally induced effects from electrically induced effects allows us to quantify the thermal contribution of the optical excitation in STM experiments. Time-resolved decay spectra of the photo-generated electron-hole pairs demonstrate the nanoscale spatial resolution.

  1. Design and construction of an ultrafast optical pulse shaper

    NASA Astrophysics Data System (ADS)

    Kudadze, Mawufemor Yao

    The interaction between an ultrafast laser beam and a semiconductor depends critically on the detailed structure of the laser pulse. Precise control of pulse amplitude, phase and frequency as a function of time is necessary to uncover novel physical effects and to perform repeatable experiments. We describe here the design and construction of a pulse shaper that uses a liquid crystal spatial light modulator as a computer programmable mask in a 4f pulse shaper. The effect of design parameters, including focal length of the cylindrical lenses, grating pitch and spatial light modulator pixel width on the performance of the pulse shaper will be presented. Strategies for experimental optimization of the pulse structure in specific experiments through use of a genetic algorithm will also be discussed.

  2. Generation of femtosecond optical vortex pulse in fiber based on an acoustically induced fiber grating.

    PubMed

    Zhang, Wending; Wei, Keyan; Mao, Dong; Wang, Heng; Gao, Feng; Huang, Ligang; Mei, Ting; Zhao, Jianlin

    2017-02-01

    We proposed a method for generation of a femtosecond optical vortex pulse in a two-mode fiber based on an acoustically induced fiber grating (AIFG) driven by a radio frequency source. Theoretical analysis and experimental results demonstrated that the left- and right-handed circular polarization fundamental modes of the femtosecond optical pulse could be converted to the linearly polarized ±1-order optical vortex modes through the AIFG with the mode conversion efficiency of ∼95%. The off-axial interference experiment and the polarization angle-dependent intensity examination were performed to verify the topological charge and the polarization state of the femtosecond optical vortex, respectively.

  3. Generation of broadband mid-infrared pulses from an optical parametric amplifier.

    PubMed

    Brida, D; Manzoni, C; Cirmi, G; Marangoni, M; De Silvestri, S; Cerullo, G

    2007-11-12

    We report on the direct generation of broadband mid-IR pulses from an optical parametric amplifier. Several crystals with extended IR transparency, when pumped at 800 nm, display a broad phase-matching bandwidth around 1 mum, allowing for the generation of idler pulses spanning the 3-5 mum wavelength range. Using LiIO(3), we produce 2muJ pulses tunable in the 3-4 mum range with bandwidth supporting 30-fs transform-limited duration.

  4. Sub-two-cycle light pulses at 1.6 microm from an optical parametric amplifier.

    PubMed

    Brida, D; Cirmi, G; Manzoni, C; Bonora, S; Villoresi, P; De Silvestri, S; Cerullo, G

    2008-04-01

    We generate ultrabroadband pulses, spanning the 1200-2100 nm wavelength range, from an 800 nm pumped optical parametric amplifier (OPA) working at degeneracy. We compress the microjoule-level energy pulses to nearly transform-limited 8.5 fs duration by an adaptive system employing a deformable mirror. To our knowledge, these are the shortest light pulses generated at 1.6 microm.

  5. Coherent transient phenomena in quantum systems by spatially shaping femtosecond optical pulses

    SciTech Connect

    El Gawhary, Omar; Pereira, Silvania F.; Urbach, H. Paul

    2011-03-15

    Providing a femtosecond optical pulse with a proper transverse spatial profile represents a fast and relatively simple method to force a quantum system to follow a prescribed temporal evolution. In the present work, we show that the quantum system presents a surprisingly high sensitivity with respect to the spatial shape of the pulse. We discuss an explicit example where differences on the order of a few nanometers in the initial pulse's spot size induce completely different responses in the system under study.

  6. Transportation of megawatt millijoule laser pulses via optical fibers?

    NASA Astrophysics Data System (ADS)

    Tauer, Johannes; Kofler, Heinrich; Schwarz, Elisabeth; Wintner, Ernst

    2010-04-01

    Laser ignition is considered to be one of the most promising future concepts for internal combustion engines. It combines the legally required reduction of pollutant emissions and higher engine efficiencies. The igniting plasma is generated by a focused pulsed laser beam. Having pulse durations of a few nanoseconds, the pulse energy E p for reliable ignition amounts to the order of 10 mJ. Different methods of laser ignition with an emphasis on fiber-based systems will be discussed and evaluated.

  7. Developments of pulse laser assist optical tweezers (PLAT) for in vivo manipulation

    NASA Astrophysics Data System (ADS)

    Maeda, Saki; Sugiura, Tadao; Minato, Kotaro

    2011-02-01

    Optical tweezers is a technique to trap and to manipulate micron sized objects under a microscope by radiation pressure force exerted by a laser beam. Optical tweezers has been utilized for single-molecular measurements of force exerted by molecular interactions and for cell palpation. To extend applications of optical tweezers we have developed a novel optical tweezers system combined with a pulse laser. We utilize a pulsed laser (Q-switched Nd: YAG laser, wavelength of 1064 nm) to assist manipulations by conventional optical tweezers achieved by a continuous wave (CW) laser. The pulsed laser beam is introduced into the same optics for conventional optical tweezers. In principle, instantaneous radiation force is proportional to instantaneous power of laser beam. As a result, pulsed laser beam generates strong instantaneous force on an object to be manipulated. If the radiation force becomes strong enough to get over an obstacle structure and/or to be released from adhesion, the object will be free from these difficulties. We have named this technique as Pulse Laser beam Assisted optical Tweezers (PLAT). We have successfully demonstrated to manipulate objects surface on a living cell for "in vivo manipulation."

  8. Intense, Ultrashort Pulse, Vector Wave Propagation in Optical Fibers

    NASA Astrophysics Data System (ADS)

    Almanee, Mohammad

    The planned research is initially motivated by experiments on twisted fiber to examine the polarization of the output pulses. The initial polarization launched into the fiber evolves to a new final state that asymptotically moves to one of two opposite circular polarizations. The initial research was to program the vector wave equations of one and coupled solitons in a twisted fiber including the additional nonlinear terms stimulated Raman scattering and self-steepening. The high-twist fiber eliminates small linear birefringence at the expense of introducing circular birefringence manifested in the group velocities. The vector equations are naturally written in the circular polarization basis. To verify the numerical results, I made a sojourn to INAOE in Puebla, Mexico to run an experiment and compare the results. The numerical compare extremely well with the experimental results. For one soliton, the output polarization of the twisted fiber follows the input with high fluctuations. However, for the coupled soliton input, when the input polarization is close to linear, we observe a very abrupt polarization switch from nearly negative circular, -45° to nearly positive circular, 45° over a very narrow range of the input ellipticities. The literature is full of simulations of super-continuum generation using scalar wave equations, but we have not seen any report on the polarization of the output Supercontinuum light. Again, motivated by the experiments on polarization evolution in optical fibers we wanted to study the vector wave equations at higher incident powers to discover what the polarization state of the output waves are in an extreme nonlinear situation.

  9. Method for spatially modulating X-ray pulses using MEMS-based X-ray optics

    DOEpatents

    Lopez, Daniel; Shenoy, Gopal; Wang, Jin; Walko, Donald A.; Jung, Il-Woong; Mukhopadhyay, Deepkishore

    2015-03-10

    A method and apparatus are provided for spatially modulating X-rays or X-ray pulses using microelectromechanical systems (MEMS) based X-ray optics. A torsionally-oscillating MEMS micromirror and a method of leveraging the grazing-angle reflection property are provided to modulate X-ray pulses with a high-degree of controllability.

  10. Bessel-Gauss pulse as an appropriate mathematical model for optically realizable localized waves.

    PubMed

    Reivelt, Kaido; Saari, Peeter

    2004-06-01

    We show that the field of the optically feasible luminal localized wave solutions of the scalar homogeneous wave equation can be modeled by means of Bessel-Gauss pulses. As the Bessel-Gauss pulses have a closed-form expression, this fact may be of great value in numerical simulations of various experimental situations.

  11. Prospects of obtaining terawatt class infrared pulses using standard optical parametric amplification

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyang; Tokita, Shigeki; Tu, Xiaoniu; Zheng, Yanqing; Kawanaka, Junji

    2017-02-01

    We conceptually propose a standard optical parametric amplification system based on YCOB crystal to achieve terawatt (TW) class infrared (IR) pulses with 100 mJ level energy, which would be one order of magnitude more energetic and powerful than currently available IR pulses and suitable to generate high photon flux water window x-rays.

  12. Active lamp pulse driver circuit. [optical pumping of laser media

    NASA Technical Reports Server (NTRS)

    Logan, K. E. (Inventor)

    1983-01-01

    A flashlamp drive circuit is described which uses an unsaturated transistor as a current mode switch to periodically subject a partially ionized gaseous laser excitation flashlamp to a stable, rectangular pulse of current from an incomplete discharge of an energy storage capacitor. A monostable multivibrator sets the pulse interval, initiating the pulse in response to a flash command by providing a reference voltage to a non-inverting terminal of a base drive amplifier; a tap on an emitter resistor provides a feedback signal sensitive to the current amplitude to an inverting terminal of amplifier, thereby controlling the pulse amplitude. The circuit drives the flashlamp to provide a squarewave current flashlamp discharge.

  13. Frequency-resolved optical gating for characterization of VUV pulses using ultrafast plasma mirror switching.

    PubMed

    Itakura, Ryuji; Kumada, Takayuki; Nakano, Motoyoshi; Akagi, Hiroshi

    2015-05-04

    We propose and experimentally demonstrate a method for characterizing vacuum ultraviolet (VUV) pulses based on time-resolved reflection spectroscopy of fused silica pumped by an intense laser pulse. Plasma mirror reflection is used as an ultrafast optical switch, which enables us to measure frequency-resolved optical gating (FROG) traces. The VUV temporal waveform can be retrieved from the measured FROG trace using principal component generalized projections algorithm with modification. The temporal profile of the plasma mirror reflectivity is also extracted simultaneously.

  14. Neodymium lasers as a source of synchronized high-power optical pulses

    NASA Astrophysics Data System (ADS)

    Sizer, Theodore, II; Duling, Irl N., III

    1988-02-01

    The recent considerable progress in the development of solid-state lasers, primarily neodymium-based lasers for use as sources of short, synchronized, high-power optical pulses, is reviewed. The amplification of femtosecond optical pulses using synchronous amplification techniques with these lasers has proved particularly applicable to experimentation. The authors also presents a laser design which combines several advantageous qualities into a single laser cavity.

  15. Stability of pulses on optical fibers with phase-sensitive amplifiers

    NASA Astrophysics Data System (ADS)

    Alexander, J. C.; Grillakis, M. G.; Jones, C. K. R. T.; Sandstede, B.

    Pulse stability is crucial to the effective propagation of information in a soliton-based optical communication system. It is shown in this paper that pulses in optical fibers, for which attenuation is compensated by phase-sensitive amplifiers, are stable over a large range of parameter values. A fourth-order nonlinear diffusion model due to Kutz and co-workers is used. The stability proof invokes a number of mathematical techniques, including the Evans function and Grillakis' functional analytic approach.

  16. Optical pulse dynamics for quantum-dot logic operations in a photonic-crystal waveguide

    SciTech Connect

    Ma, Xun; John, Sajeev

    2011-11-15

    We numerically demonstrate all-optical logic operations with quantum dots (QDs) embedded in a bimodal photonic-crystal waveguide using Maxwell-Bloch equations in a slowly varying envelope approximation (SVEA). The two-level QD excitation level is controlled by one or more femtojoule optical driving pulses passing through the waveguide. Specific logic operations depend on the relative pulse strengths and their detunings from an inhomogeneouslly broadened (about 1% for QD transitions centered at 1.5 {mu}m) QD transition. This excitation controlled two-level medium then determines passage of subsequent probe optical pulses. Envelope equations for electromagnetic waves in the linear dispersion and cutoff waveguide modes are derived to simplify solution of the coupled Maxwell-Bloch equations in the waveguide. These determine the quantum mechanical evolution of the QD excitation and its polarization, driven by classical electromagnetic (EM) pulses near a sharp discontinuity in the EM density of states of the bimodal waveguide. Different configurations of the driving pulses lead to distinctive relations between driving pulse strength and probe pulse passage, representing all-optical logic and, or, and not operations. Simulation results demonstrate that such operations can be done on picosecond time scales and within a waveguide length of about 10 {mu}m in a photonic-band-gap (PBG) optical microchip.

  17. Single-shot high-resolution characterization of optical pulses by spectral phase diversity

    SciTech Connect

    Dorrer, C.; Waxer, L. J.; Kalb, A.; Hill, E. M.; Bromage, J.

    2015-12-15

    The concept of spectral phase diversity is proposed and applied to the temporal characterization of optical pulses. The experimental trace is composed of the measured power of a plurality of ancillary optical pulses derived from the pulse under test by adding known amounts of chromatic dispersion. The spectral phase of the pulse under test is retrieved by minimizing the error between the experimental trace and a trace calculated from the optical spectrum using the known diagnostic parameters. An assembly composed of splitters and dispersive delay fibers has been used to generate 64 ancillary pulses whose instantaneous power can be detected in a single shot with a high-bandwidth photodiode and oscilloscope. Pulse-shape reconstruction for pulses shorter than the photodetection impulse response has been demonstrated.The diagnostic is experimentally shown to accurately characterize pulses from a chirped-pulse–amplification system when its stretcher is detuned from the position for optimal recompression. As a result, various investigations of the performance with respect to the number of ancillary pulses and the range of chromatic dispersion generated in the diagnostic are presented.

  18. Single-shot high-resolution characterization of optical pulses by spectral phase diversity

    DOE PAGES

    Dorrer, C.; Waxer, L. J.; Kalb, A.; ...

    2015-12-15

    The concept of spectral phase diversity is proposed and applied to the temporal characterization of optical pulses. The experimental trace is composed of the measured power of a plurality of ancillary optical pulses derived from the pulse under test by adding known amounts of chromatic dispersion. The spectral phase of the pulse under test is retrieved by minimizing the error between the experimental trace and a trace calculated from the optical spectrum using the known diagnostic parameters. An assembly composed of splitters and dispersive delay fibers has been used to generate 64 ancillary pulses whose instantaneous power can be detectedmore » in a single shot with a high-bandwidth photodiode and oscilloscope. Pulse-shape reconstruction for pulses shorter than the photodetection impulse response has been demonstrated.The diagnostic is experimentally shown to accurately characterize pulses from a chirped-pulse–amplification system when its stretcher is detuned from the position for optimal recompression. As a result, various investigations of the performance with respect to the number of ancillary pulses and the range of chromatic dispersion generated in the diagnostic are presented.« less

  19. All-optical short pulse translation through cross-phase modulation in a VO₂ thin film.

    PubMed

    Fardad, Shima; Das, Susobhan; Salandrino, Alessandro; Breckenfeld, Eric; Kim, Heungsoo; Wu, Judy; Hui, Rongqing

    2016-01-15

    VO2 is a promising material for reconfigurable photonic devices due to the ultrafast changes in electronic and optical properties associated with its dielectric-to-metal phase transition. Based on a fiber-optic, pump-probe setup at 1550 nm wavelength window, and by varying the pump-pulse duration, we show that the material phase transition is primarily caused by the pump-pulse energy. For the first time, we demonstrate that the instantaneous optical phase modulation of probe during pump leading edge can be utilized to create short optical pulses at probe wavelength, through optical frequency discrimination. This circumvents the impact of long recovery time well known for the phase transition of VO2.

  20. Comparison of ultrashort-pulse frequency-resolved-optical-gating traces for three common beam geometries

    SciTech Connect

    DeLong, K.W.; Trebino, R. ); Kane, D.J. )

    1994-09-01

    We recently introduced frequency-resolved optical gating (FROG), a technique for measuring the intensity and phase of an individual, arbitrary, ultrashort laser pulse. FROG can use almost any instantaneous optical nonlinearity, with the most common geometries being polarization gate, self-diffraction, and second-harmonic generation. The experimentally generated FROG trace is intuitive, visually appealing, and can yield quantitative information about the pulse parameters (such as temporal and spectral width and chirp). However, the qualitative and the quantitative features of the FROG trace depend strongly on the geometry used. We compare the FROG traces for several common ultrashort pulses for these three common geometries and, where possible, develop scaling rules that allow one to obtain quantitative information about the pulse directly from the experimental FROG trace. We illuminate the important features of the various FROG traces for transform-limited, linearly chirped, self-phase modulated, and nonlinearly chirped pulses, pulses with simultaneous linear chirp and self-phase modulation, and pulses with simultaneous linear chirp and cubic phase distortion, as well as double pulses, pulses with phase jumps, and pulses with complex intensity and phase substructure.

  1. Kilohertz generation of high contrast polarization states for visible femtosecond pulses via phase-locked acousto-optic pulse shapers

    SciTech Connect

    Seiler, Hélène; Walsh, Brenna; Palato, Samuel; Kambhampati, Patanjali; Thai, Alexandre; Forget, Nicolas; Crozatier, Vincent

    2015-09-14

    We present a detailed analysis of a setup capable of arbitrary amplitude, phase, and polarization shaping of broadband visible femtosecond pulses at 1 kHz via a pair of actively phase stabilized acousto-optic programmable dispersive filters arranged in a Mach-Zehnder interferometer geometry. The setup features phase stability values around λ/225 at 580 nm as well as degrees of polarization of at least 0.9 for any polarization state. Both numbers are important metrics to evaluate a setup's potential for applications based on polarization-shaped femtosecond pulses, such as fully coherent multi-dimensional electronic spectroscopy.

  2. Compact optical system for pulse-to-pulse laser beam quality measurement and applications in laser machining.

    PubMed

    Lambert, Robert W; Cortés-Martínez, Rodolpho; Waddle, Andrew J; Shephard, Jonathan D; Taghizadeh, Mohammad R; Greenaway, Alan H; Hand, Duncan P

    2004-09-10

    Fluctuations in beam quality (M2) have been observed on a pulse-to-pulse basis from an industrial Nd:YAG laser. This was achieved with a compact multiplane imaging method incorporating quadratically distorted diffraction gratings, which enabled simultaneous imaging of nine planes on a single CCD array. With this system, we measured across a range of beam qualities with an associated error (in M2 variation) of the order of 0.7%. Application of the system to fiber-optic beam delivery and laser drilling is demonstrated.

  3. Pulse width dependence of Brillouin frequency in single mode optical fibers.

    PubMed

    Cho, Seok-Beom; Kim, Young-Gyu; Heo, Jin-Seok; Lee, Jung-Ju

    2005-11-14

    Stimulated Brillouin scattering in optical fibers can be used to measure strain or temperature in a distributed manner. Brillouin optical time domain analysis (BOTDA) is the most common sensor system based on the Brillouin scattering. This paper presents the experimental analysis of the characteristics of Brillouin gain spectrum (BGS) influenced by the width of launched pulse. Brillouin strain coefficient is also examined for the different pulse widths, which is important to apply a Brillouin scattering-based sensor to a structural health monitoring. Experimental results showed that not only the Brillouin linewidth and gain but also the Brillouin frequency were dependent on the pulse widths.

  4. Nuclear reactor pulse calibration using a CdZnTe electro-optic radiation detector.

    PubMed

    Nelson, Kyle A; Geuther, Jeffrey A; Neihart, James L; Riedel, Todd A; Rojeski, Ronald A; Saddler, Jeffrey L; Schmidt, Aaron J; McGregor, Douglas S

    2012-07-01

    A CdZnTe electro-optic radiation detector was used to calibrate nuclear reactor pulses. The standard configuration of the Pockels cell has collimated light passing through an optically transparent CdZnTe crystal located between crossed polarizers. The transmitted light was focused onto an IR sensitive photodiode. Calibrations of reactor pulses were performed using the CdZnTe Pockels cell by measuring the change in the photodiode current, repeated 10 times for each set of reactor pulses, set between 1.00 and 2.50 dollars in 0.50 increments of reactivity.

  5. Highly dispersion-tolerant 160 Gbaud optical Nyquist pulse TDM transmission over 525 km.

    PubMed

    Hirooka, Toshihiko; Ruan, Peng; Guan, Pengyu; Nakazawa, Masataka

    2012-07-02

    We demonstrate an optical Nyquist pulse TDM (Nyquist OTDM) transmission at 160 Gbaud with a substantial increase in the dispersion tolerance compared with a conventional OTDM transmission. Optical Nyquist pulses can be bit-interleaved to ultrahigh symbol rate without suffering from intersymbol interference due to its zero-crossing property at every symbol interval. This allows the signal bandwidth to be greatly narrowed compared to typical pulse waveforms such as Gaussian or sech profile. By virtue of this property, a dispersion tolerance over ± 8 ps/nm was successfully realized in 160 Gbaud, 525 km transmission.

  6. Information coding of exciting laser pulses in an optical echo-processor

    SciTech Connect

    Rusanova, I A

    2013-07-31

    We report the possibility of controlling the distribution of quantum bits within an inhomogeneously broadened line of a resonant transition in recording and transforming information in optical echo-processors. We consider the efficiency of realisation of the elementary logic XOR gate based on a two-pulse excitation of a resonant medium with phase memory. The encoded information is incorporated into the temporal shape of laser pulses in the form of amplitude modulation of an 'echelon' of present ('1') and absent ('0') pulse-codes for obtaining more efficient logic elements that reduce the noise in a quantum communication channel. (optical information processing)

  7. Optical short pulse generation at high repetition rate over 80 GHz from a monolithic passively modelocked DBR laser diode

    NASA Astrophysics Data System (ADS)

    Arahira, S.; Matsui, Y.; Kunii, T.; Oshiba, S.; Ogawa, Y.

    1993-05-01

    Optical short pulses at high repetition rate over 80 GHz were successfully generated using a monolithically fabricated passively modelocked distributed Bragg reflector laser diode for the first time. By using linear fibre compression, a transform-limited optical pulse train with a duration of 2.7 ps was obtained. The pulse envelope closely matched a sech(sup 2) waveform.

  8. Self-similar evolutions of parabolic, Hermite-Gaussian, and hybrid optical pulses: Universality and diversity.

    PubMed

    Chen, Shihua; Yi, Lin; Guo, Dong-Sheng; Lu, Peixiang

    2005-07-01

    Three novel types of self-similar solutions, termed parabolic, Hermite-Gaussian, and hybrid pulses, of the generalized nonlinear Schrödinger equation with varying dispersion, nonlinearity, and gain or absorption are obtained. The properties of the self-similar evolutions in various nonlinear media are confirmed by numerical simulations. Despite the diversity of their formations, these self-similar pulses exhibit many universal features which can facilitate significantly the achievement of well-defined linearly chirped output pulses from an optical fiber, an amplifier, or an absorption medium, under certain parametric conditions. The other intrinsic characteristics of each type of self-similar pulses are also discussed.

  9. Microwave-assisted arbitrary optical-pulse generation in a thermal vapor

    NASA Astrophysics Data System (ADS)

    Rajitha K., V.; Dey, Tarak N.

    2016-11-01

    The propagation of a weak optical field through an atomic system in closed Λ configuration is investigated in which the hyperfine levels are coupled by a microwave pulse. Under the three-photon resonance condition, it is observed that a new pulse of the shape of a microwave field is generated at the probe transition while the input probe is absorbed. The generated probe pulse follows the temporal position of the microwave pulse and maintains shape through the propagation. A simple propagation equation for the probe field in the Fourier domain has been employed to study this effect. This shape preservation of the probe pulse is due to the ground state coherence of the hyperfine transitions induced by the weaker intensity of the microwave field. The generation of an arbitrary shaped probe pulse is also possible at comparable strength of control and microwave fields. The intensity and detuning of the microwave field can play an important role to control probe pulse properties such as gain, broadening, and preservation of shape. The mechanism of efficient generation and manipulation of an optical pulse may have important applications in information science and optical communications.

  10. Pulse evolution in nonlinear optical fibers with sliding-frequency filters.

    PubMed

    Beech-Brandt, J J; Smyth, N F

    2001-05-01

    The effect of fiber loss, amplification, and sliding-frequency filters on the evolution of optical pulses in nonlinear optical fibers is considered, this evolution being governed by a perturbed nonlinear Schrödinger (NLS) equation. Approximate ordinary differential equations (ODE's) governing the pulse evolution are obtained using conservation and moment equations for the perturbed NLS equation together with a trial function incorporating a solitonlike pulse with independently varying amplitude and width. In addition, the trial function incorporates the interaction between the pulse and the dispersive radiation shed as the pulse evolves. This interaction must be included in order to obtain approximate ODE's whose solutions are in good agreement with full numerical solutions of the governing perturbed NLS equation. The solutions of the approximate ODE's are compared with full numerical solutions of the perturbed NLS equation and very good agreement is found.

  11. Generation of Non-Uniform Pulses by an Eight Microstructured Optical Fiber Laser

    NASA Astrophysics Data System (ADS)

    Ennejah, Tarek; Bahloul, Faouzi; Attia, Rabah

    2011-06-01

    Mode locking mechanisms in fiber laser have been an active and rich research field in optical communication. In this paper we study the behaviour of an 8FL (eight fiber laser) totally made out of MOF (Microstructured Optical Fiber). We demonstrate that even output from a fiber laser is not necessarily uniform. Due to its ring cavity and NALM (Non linear Amplifying Loop Mirror) transmission properties, the laser generates randomly different non-uniform output pulses. It follows three states of operation: single, bound and multiple pulses were observed. We report the formation of bound pulses where side peaks are higher than the central one. We report also the formation of bound and multiple pulses which damage their bindings and alter their pulses width and separations.

  12. Peculiarities of the propagation of multidimensional extremely short optical pulses in germanene

    NASA Astrophysics Data System (ADS)

    Zhukov, Alexander V.; Bouffanais, Roland; Konobeeva, Natalia N.; Belonenko, Mikhail B.

    2016-09-01

    In this Letter, we study the propagation characteristics of both two-dimensional and three-dimensional extremely short optical pulses in germanene. A distinguishing feature of germanene-in comparison with other graphene-like structures-is the presence of a significant spin-orbit interaction. The account of this interaction has a significant impact on the evolution of extremely short pulses in such systems. Specifically, extremely short optical pulses, consisting of two electric field oscillations, cause the appearance of a tail associated with the excitation of nonlinear waves. Due to the large spin-orbit interaction in germanene, this tail behind the main pulse is much smaller in germanene-based samples as compared to graphene-based ones, thereby making germanene a preferred material for the stable propagation of pulses along the sample.

  13. Optical emission of silicon plasma induced by femtosecond double-pulse laser

    NASA Astrophysics Data System (ADS)

    Chen, Anmin; Wang, Xiaowei; Zhang, Dan; Wang, Ying; Li, Suyu; Jiang, Yuanfei; Jin, Mingxing

    2017-05-01

    In this paper, we present a study on the influence of interpulse delay in laser-induced silicon plasma with femtosecond double-pulse, and two subpulses have different laser energies. The meansured optical emission line collected by a lens is the Si (I) at 390.55 nm. The range of double-pulse interpulse delay is from -150 ps to 150 ps. Unlike the femtosecond double pulses with two same energies, the combination of low + high energies can enhance the spectral emission intensity, while the combination of high + low energies probably reduces the spectral line intensity compared with single-pulse femtosecond laser. The results indicate that the interpulse delay is very important for laser-induced breakdown spectroscopy with femtosecond double-pulse to improve the optical emission intensity.

  14. All-optical pulse regeneration in an ultrafast nonlinear interferometer with Faraday mirror polarization stabilization

    NASA Astrophysics Data System (ADS)

    Savage, Shelby J.; Robinson, Bryan S.; Hamilton, Scott A.; Ippen, Erich P.

    2003-01-01

    We demonstrate the folded ultrafast nonlinear interferometer (FUNI) as a 3R all-optical regenerator. Faraday rotation provides inherent polarization stabilization, and the optical fiber nonlinear medium provides ultrafast operation and switching window tunability. We demonstrate 3R regeneration of 10-Gbit/s data with 5-pJ pulse switching energy and 4-ps timing-jitter tolerance.

  15. All-optical pulse regeneration in an ultrafast nonlinear interferometer with Faraday mirror polarization stabilization.

    PubMed

    Savage, Shelby J; Robinson, Bryan S; Hamilton, Scott A; Ippen, Erich P

    2003-01-01

    We demonstrate the folded ultrafast nonlinear interferometer (FUNI) as a 3R all-optical regenerator. Faraday rotation provides inherent polarization stabilization, and the optical fiber nonlinear medium provides ultrafast operation and switching window tunability. We demonstrate 3R regeneration of 10-Gbit/s data with 5-pJ pulse switching energy and 4-ps timing-jitter tolerance.

  16. Phase-sensitive optical coherence reflectometer with differential phase-shift keying of probe pulses

    SciTech Connect

    Alekseev, A E; Vdovenko, V S; Sergachev, I A; Simikin, D E; Gorshkov, B G; Potapov, V T

    2014-10-31

    We report a new method for reconstructing the signal shape of the external dynamic perturbations along the entire length of the fibre of an optical coherence reflectometer. The method proposed is based on differential phase-shift keying of a probe pulse and demodulation of scattered light by the phase diversity technique. Possibilities of the method are demonstrated experimentally. (fibre-optic sensors)

  17. Generation of optical frequency combs in fibres: an optical pulse analysis

    NASA Astrophysics Data System (ADS)

    Zajnulina, Marina; Böhm, Michael; Blow, Keith; Chavez Boggio, José M.; Rieznik, Andres A.; Haynes, Roger; Roth, Martin M.

    2014-07-01

    The innovation of optical frequency combs (OFCs) generated in passive mode-locked lasers has provided astronomy with unprecedented accuracy for wavelength calibration in high-resolution spectroscopy in research areas such as the discovery of exoplanets or the measurement of fundamental constants. The unique properties of OCFs, namely a highly dense spectrum of uniformly spaced emission lines of nearly equal intensity over the nominal wavelength range, is not only beneficial for high-resolution spectroscopy. Also in the low- to medium-resolution domain, the OFCs hold the promise to revolutionise the calibration techniques. Here, we present a novel method for generation of OFCs. As opposed to the mode-locked laser-based approach that can be complex, costly, and difficult to stabilise, we propose an all optical fibre-based system that is simple, compact, stable, and low-cost. Our system consists of three optical fibres where the first one is a conventional single-mode fibre, the second one is an erbium-doped fibre and the third one is a highly nonlinear low-dispersion fibre. The system is pumped by two equally intense continuous-wave (CW) lasers. To be able to control the quality and the bandwidth of the OFCs, it is crucial to understand how optical solitons arise out of the initial modulated CW field in the first fibre. Here, we numerically investigate the pulse evolution in the first fibre using the technique of the solitons radiation beat analysis. Having applied this technique, we realised that formation of higherorder solitons is supported in the low-energy region, whereas, in the high-energy region, Kuznetsov-Ma solitons appear.

  18. High-speed pulse train amplification in semiconductor optical amplifiers with optimized bias current.

    PubMed

    Xia, Mingjun; Ghafouri-Shiraz, H; Hou, Lianping; Kelly, Anthony E

    2017-02-01

    In this paper, we have experimentally investigated the optimized bias current of semiconductor optical amplifiers (SOAs) to achieve high-speed input pulse train amplification with high gain and low distortion. Variations of the amplified output pulse duration with the amplifier bias currents have been analyzed and, compared to the input pulse duration, the amplified output pulse duration is broadened. As the SOA bias current decreases from the high level (larger than the saturated bias current) to the low level, the broadened pulse duration of the amplified output pulse initially decreases slowly and then rapidly. Based on the analysis, an optimized bias current of SOA for high-speed pulse train amplification is introduced. The relation between the SOA optimized bias current and the parameters of the input pulse train (pulse duration, power, and repetition rate) are experimentally studied. It is found that the larger the input pulse duration, the lower the input pulse power or a higher repetition rate can lead to a larger SOA optimized bias current, which corresponds to a larger optimized SOA gain. The effects of assist light injection and different amplifier temperatures on the SOA optimized bias current are studied and it is found that assist light injection can effectively increase the SOA optimized bias current while SOA has a lower optimized bias current at the temperature 20°C than that at other temperatures.

  19. Further Methods for the Generation of Ultrashort Optical Pulses

    NASA Astrophysics Data System (ADS)

    Hirlimann, C.

    Up to the beginning of the sixties, the shortest measurable time duration was of the order of one nanosecond (10-9 s). Short pulses were produced through the generation of short electrical discharges. After the laser was invented in 1960, the situation quite rapidly changed. In 1965, the picosecond (10-12 s) regime was reached by placing a saturable absorber inside a laser cavity. Twenty years of continuous progress led to the production of light pulses of less than 10 femtoseconds. In the race towards ever shorter pulses, recent developments in the generation of tabletop X-ray lasers have opened the way to dynamical studies in the attosecond (10-18 s)regime [4.1-2]. In the meantime, progress was made on the tunability of the pulsed-laser sources. Today's tunability extends from the near ultraviolet to the near infrared [4.2-6].

  20. Combined Yb/Nd driver for optical parametric chirped pulse amplifiers.

    PubMed

    Michailovas, Kirilas; Baltuska, Andrius; Pugzlys, Audrius; Smilgevicius, Valerijus; Michailovas, Andrejus; Zaukevicius, Audrius; Danilevicius, Rokas; Frankinas, Saulius; Rusteika, Nerijus

    2016-09-19

    We report on the developed front-end/pump system for optical parametric chirped pulse amplifiers. The system is based on a dual output fiber oscillator/power amplifier which seeds and assures all-optical synchronization of femtosecond Yb and picosecond Nd laser amplifiers operating at a central wavelength of 1030 nm and 1064 nm, respectively. At the central wavelength of 1030 nm, the fiber oscillator generates partially stretched 4 ps pulses with the spectrum supporting a <120 fs pulse duration and pulse energy of 0.45 nJ. The energy of generated 1064 nm pulses is 0.15 nJ, which is sufficient for the efficient seeding of high-contrast Nd:YVO chirped pulse regenerative amplifier/post amplifier systems generating 9 mJ pulses compressible to 16 ps duration. The power amplification stages, based on Nd:YAG crystals, provide 62 mJ pulses compressible to 20 ps pulse duration at a repetition rate of 1 kHz. Further energy scaling currently is prevented by limited dimensions of the diffraction gratings, which, because of the fast progress in MLD grating manufacturing technologies is only a temporary obstacle.

  1. Spectral splitting of optical pulses inside a dispersive medium at a temporal boundary

    DOE PAGES

    Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

    2016-11-07

    We show numerically that the spectrum of an optical pulse splits into multiple, widely separated, spectral bands when it arrives at a temporal boundary across which refractive index changes suddenly. At the same time, the pulse breaks into several temporally separated pulses traveling at different speeds. The number of such pulses depends on the dispersive properties of the medium. We study the effect of second- and third-order dispersion in detail but also consider briefly the impact of other higher-order terms. As a result, a temporal waveguide formed with two temporal boundaries can reflect the temporally separated pulses again and again,more » increasing the number of pulses trapped within the temporal waveguide.« less

  2. Spectral splitting of optical pulses inside a dispersive medium at a temporal boundary

    SciTech Connect

    Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

    2016-11-07

    We show numerically that the spectrum of an optical pulse splits into multiple, widely separated, spectral bands when it arrives at a temporal boundary across which refractive index changes suddenly. At the same time, the pulse breaks into several temporally separated pulses traveling at different speeds. The number of such pulses depends on the dispersive properties of the medium. We study the effect of second- and third-order dispersion in detail but also consider briefly the impact of other higher-order terms. As a result, a temporal waveguide formed with two temporal boundaries can reflect the temporally separated pulses again and again, increasing the number of pulses trapped within the temporal waveguide.

  3. Refractive-diffractive dispersion compensation for optical vortex beams with ultrashort pulse durations.

    PubMed

    Musigmann, Manfred; Jahns, Jürgen; Bock, Martin; Grunwald, Ruediger

    2014-11-01

    Wave fields, which are described mathematically by higher order Bessel functions, carry an orbital angular momentum and thus represent particular types of optical vortex beams with helical wavefronts. For the generation of such vortex beams, one may use, for instance, diffractive spiral axicons. Diffraction, however, leads invariably to strong dispersion, which is detrimental for ultrashort pulses since it leads to severe pulse broadening. This pulse broadening can be minimized or reduced completely (at least, in a specific plane of propagation) if the pulses propagate additionally through a medium with normal refractive dispersion. The refractive-diffractive generation of ultrashort vortex pulses was demonstrated earlier for a pulse duration of approximately 8 fs [Opt. Lett.37, 3804 (2012)10.1364/OL.37.003804OPLEDP0146-9592]. Here, we present an analytical description of the generation and propagation of these vortex beams and of the refractive-diffractive compensation of the dispersion.

  4. Self-similar Shape Mode of Optical Pulse Propagation in Medium with non-stationary Absorption

    NASA Astrophysics Data System (ADS)

    Trofimov, Vycheslav A.; Lysak, Tatyana M.; Fedotov, Mihail V.; Prokopenko, Alexander S.

    2015-03-01

    We discuss laser pulse propagation with the self-similar shape in a medium with instantaneous nonlinear absorption. We consider two cases of the laser pulse propagation. First one corresponds to problem of laser-induced plasma generation in silica under action of TW laser pulse. The second one corresponds to femtosecond laser pulse propagation in medium with nanoparticles of noble metals. In both cases the mode of the self-similar shape of pulse is of interest. We discuss also a physical mechanism of non-linear acceleration or slowing-down for laser pulse propagation in a medium with nanoparticles. The last phenomena are important, in particular, for a problem of data processing of all optical method. We used analytical approach for considered problem as well as computer simulation.

  5. Direct ultrashort-pulse intensity and phase retrieval by frequency-resolved optical gating and a computational neural network.

    PubMed

    Krumbügel, M A; Ladera, C L; Delong, K W; Fittinghoff, D N; Sweetser, J N; Trebino, R

    1996-01-15

    Ultrashort-laser-pulse retrieval in frequency-resolved optical gating has previously required an iterative algorithm. Here, however, we show that a computational neural network can directly and rapidly recover the intensity and phase of a pulse.

  6. LASER PLASMA: Experimental confirmation of the erosion origin of pulsed low-threshold surface optical breakdown of air

    NASA Astrophysics Data System (ADS)

    Min'ko, L. Ya; Chumakou, A. N.; Chivel', Yu A.

    1988-08-01

    Nanosecond kinetic spectroscopy techniques were used to identify the erosion origin of pulsed low-threshold surface optical breakdown of air as a result of interaction of microsecond neodymium and CO2 laser pulses with some metals (indium, lead).

  7. Frequency-resolved optical-gating measurements of ultrashort pulses using surface third-harmonic generation

    SciTech Connect

    Tsang, T.; Krumbuegel, M.A.; DeLong, K.W.; Fittinghoff, D.N.; Trebino, R.

    1996-09-01

    We demonstrate what is to our knowledge the first frequency-resolved optical gating (FROG) technique to measure ultrashort pulses from an unamplified Ti:sapphire laser oscillator without direction-of-time ambiguity. This technique utilizes surface third-harmonic generation as the nonlinear-optical effect and, surprisingly, is the most sensitive third-order FROG geometry yet. {copyright} {ital 1996 Optical Society of America.}

  8. Frequency-resolved optical gating measurement of ultrashort pulses by using single nanowire

    NASA Astrophysics Data System (ADS)

    Yu, Jiaxin; Liao, Feng; Gu, Fuxing; Zeng, Heping

    2016-09-01

    The use of ultrashort pulses for fundamental studies and applications has been increasing rapidly in the past decades. Along with the development of ultrashort lasers, exploring new pulse diagnositic approaches with higher signal-to-noise ratio have attracted great scientific and technological interests. In this work, we demonstrate a simple technique of ultrashort pulses characterization with a single semiconductor nanowire. By performing a frequency-resolved optical gating method with a ZnO nanowire coupled to tapered optical microfibers, the phase and amplitude of a pulse series are extracted. The generated signals from the transverse frequency conversion process can be spatially distinguished from the input, so the signal-to-noise ratio is improved and permits lower energy pulses to be identified. Besides, since the nanometer scale of the nonlinear medium provides relaxed phase-matching constraints, a measurement of 300-nm-wide supercontinuum pulses is achieved. This system is highly compatible with standard optical fiber systems, and shows a great potential for applications such as on-chip optical communication.

  9. Frequency-resolved optical gating measurement of ultrashort pulses by using single nanowire

    PubMed Central

    Yu, Jiaxin; Liao, Feng; Gu, Fuxing; Zeng, Heping

    2016-01-01

    The use of ultrashort pulses for fundamental studies and applications has been increasing rapidly in the past decades. Along with the development of ultrashort lasers, exploring new pulse diagnositic approaches with higher signal-to-noise ratio have attracted great scientific and technological interests. In this work, we demonstrate a simple technique of ultrashort pulses characterization with a single semiconductor nanowire. By performing a frequency-resolved optical gating method with a ZnO nanowire coupled to tapered optical microfibers, the phase and amplitude of a pulse series are extracted. The generated signals from the transverse frequency conversion process can be spatially distinguished from the input, so the signal-to-noise ratio is improved and permits lower energy pulses to be identified. Besides, since the nanometer scale of the nonlinear medium provides relaxed phase-matching constraints, a measurement of 300-nm-wide supercontinuum pulses is achieved. This system is highly compatible with standard optical fiber systems, and shows a great potential for applications such as on-chip optical communication. PMID:27609521

  10. Effects of Birefringence and Nonlinearity on Optical Pulse Propagation in New Types of Optical Fibers

    SciTech Connect

    Curtis R. Menyuk; Gary M. Carter

    2005-05-15

    The purpose of this grant was to allow us to complete work that we had already begun on spun optical fibers and to begin studies of holey and photonic crystal optical fibers. The work on spun optical fibers was completed with great success. It led to several publications in collaboration with our co-workers at the Universita di Padova, and the student who carried out this work received a major award from the Universita di Padova. The work on holey and photonic crystal fibers has proceeded more slowly, but, in collaboration with Korean co-workers at the Gwangju Institute of Science and Technology, we have developed three different computational models that allow us to calculate the modes of these fibers: a Galerkin model, a plane wave model, and a multipole model. We have applied these models to the study of mode coupling in periodic gratings. In collaboration with scientists at the Naval Research Laboratory, we have also applied these models to the study of pulse compression in tapered fibers and the development of nonlinear fibers that are capable of handling large powers in high-index and chalcogenide glasses. European and Asian countries have made large investments in the development of these new glass technologies, while the United States has not. As a consequence, the United States is falling behind in what we believe will prove to be a critical area of nanotechnology. It is our view that by investing in this project, the Department of Energy has helped lay the groundwork for future development of special fiber technology in the United States, once the decision has been made that the United States cannot continue to stand on the sidelines as this technology--which appears to have great commercial and military value--is developed elsewhere.

  11. Measuring ultrashort pulses using frequency-resolved optical gating

    SciTech Connect

    Trebino, R.

    1993-12-01

    The purpose of this program is the development of techniques for the measurement of ultrafast events important in gas-phase combustion chemistry. Specifically, goals of this program include the development of fundamental concepts and spectroscopic techniques that will augment the information currently available with ultrafast laser techniques. Of equal importance is the development of technology for ultrafast spectroscopy. For example, methods for the production and measurement of ultrashort pulses at wavelengths important for these studies is an important goal. Because the specific vibrational motion excited in a molecule depends sensitively on the intensity, I(t), and the phase, {psi}(t), of the ultrashort pulse used to excite the motion, it is critical to measure both of these quantities for an individual pulse. Unfortunately, this has remained an unsolved problem for many years. Fortunately, this year, the authors present a technique that achieves this goal.

  12. On the output characteristics of a semiconductor optical amplifier driven by an ultrafast optical time division multiplexing pulse train

    NASA Astrophysics Data System (ADS)

    Zoiros, K. E.; Chasioti, R.; Koukourlis, C. S.; Houbavlis, T.

    2007-03-01

    A comprehensive theoretical analysis of a semiconductor optical amplifier (SOA) that is subject to an ultrafast optical time division multiplexing pulse stream is presented with the help of a simple but efficient model developed for this purpose. The model combines the necessary set of mathematical equations with the appropriate simplifying assumptions to describe in the time domain gain saturation and recovery for the case of multiple incoming pulses. In this manner, analytical expressions can be obtained for the power and chirp profile of the amplified pulses, essentially extending the work that has been performed for a single pulse only. This allows to identify the critical operational parameters and to investigate and evaluate their effect on these two output characteristics. The derived simulation curves are thoroughly studied to specify the limitations imposed on the SOA small signal gain and carrier lifetime as well as on the full-width at half-maximum (FWHM) and energy of the input pulses and, based on a series of logical arguments, to extract useful rules concerning their selection so as to achieve improved performance with respect to the practical applications of all-optical switching and pulse compression. The obtained results indicate that due to the continuous insertion of pulses, the requirements for the SOA small signal gain and the input pulse energy are stringent than those for the case of isolated pulse amplification. The combination of these two parameters determines also the regime in which the amplifier must be biased to operate in order to ensure distortionless pulse amplification and enhanced chirp for efficient pulse compression and it has been found that low saturation is necessary for the former case whilst heavy saturation for the latter. The scopes of the corresponding requirements for the carrier lifetime and the FWHM are also tight but to a less extent and can be simply satisfied with the available photonics technology. These results

  13. Characterization of arbitrary femtosecond pulses using frequency-resolved optical gating

    SciTech Connect

    Kane, D.J. ); Trebino, R. )

    1993-02-01

    The authors introduce a new technique, which they call frequency-resolved optical gating (FROG), for characterizing and displaying arbitrary femtosecond pulses. The method is simple, general, broad-band, and does not require a reference pulse. Using virtually any instantaneous nonlinear-optical effect, FROG involves measuring the spectrum of the signal pulse as a function of the delay between two input pulses. The resulting trace of intensity versus frequency and delay is related to the pulse's spectrogram, a visually intuitive transform containing both time and frequency information. They prove, using phase retrieval concepts, that the FROG trace yields the full intensity l(t) and phase [var phi](t) of an arbitrary ultrashort pulse with no physically significant ambiguities. They argue, in analogy with acoustics problems, that the FROG trace is in many ways as useful a representation of the pulse as the field itself. FROG appears to have temporal resolution limited only by the response of the nonlinear medium. They demonstrate the method using self-diffraction via the electronic Kerr effect in BK-7 glass and few [mu]J, 620 nm, linearly chirped, [approximately]200 fs pulses.

  14. Effect of laser pulse repetition frequency on the optical breakdown threshold of quartz glass

    SciTech Connect

    Kononenko, T V; Konov, V I; Schöneseiffen, S; Dausinger, F

    2013-08-31

    The thresholds of optical breakdown in the volume of quartz glass were measured in relation to the number of pulses under irradiation by ultrashort laser pulses with different pulse repetition frequencies (1 – 400 kHz). Increasing this frequency from 10 to 400 kHz was found to substantially lower the breakdown threshold for 500-fs long pulses (at a wavelength of 1030 nm) and to lower to a smaller degree for 5-ps long pulses (515 nm). A strong frequency dependence of the breakdown threshold is observed under the same conditions as a manifold decrease of the breakdown threshold with increase in the number of pulses in a pulse train. The dependence of the optical breakdown on the number of pulses is attributable to the accumulation of point defects under multiple subthreshold irradiation, which affects the mechanism of collisional ionisation. In this case, the frequency dependence of the breakdown threshold of quartz glass is determined by the engagement of shortlived defects in the ionisation mechanism. (interaction of laser radiation with matter)

  15. High speed ultra short pulse fiber ring laser using photonic crystal fiber nonlinear optical loop mirror

    NASA Astrophysics Data System (ADS)

    Ma, Shaozhen; Li, Wenbo; Hu, Hongyu; Dutta, Niloy K.

    2012-06-01

    A scheme to generate high speed optical pulse train with ultra short pulse width is proposed and experimentally studied. Two-step compression is used in the scheme: 20 GHz and 40 GHz pulse trains generated from a rational harmonic actively mode-locked fiber ring laser is compressed to a full width at half-maximum (FWHM) of ~ 1.5 ps using adiabatic soliton compression with dispersion shifted fibers (DSF). The pulse trains then undergo a pedestal removal process by transmission through a cascaded two photonic crystal fiber (PCF)-nonlinear optical loop mirrors (NOLM) realized using a double-ring structure. The shortest output pulse width obtained was ~ 610 fs for 20 GHz pulse train and ~ 570 fs for 40 GHz pulse train. The signal to noise ratio of the RF spectrum of the output pulse train is larger than 30 dB. Theoretical simulation of the NOLM transmission is conducted using split-step Fourier method. The results show that two cascaded NOLMs can improve the compression result compared to that for a single NOLM transmission.

  16. Evolution of optical force on two-level atom by ultrashort time-domain dark hollow Gaussian pulse

    NASA Astrophysics Data System (ADS)

    Cao, Xiaochao; Wang, Zhaoying; Lin, Qiang

    2017-09-01

    Based on the analytical expression of the ultrashort time-domain dark hollow Gaussian (TDHG) pulse, the optical force on two-level atoms induced by a TDHG pulse is calculated in this paper. The phenomena of focusing or defocusing of the light force is numerical analyzed for different detuning, various duration time, and different order of the ultrashort pulse. The transverse optical force can change from a focusing force to a defocusing force depending on the spatial-temporal coupling effect as the TDHG pulses propagating in free space. Our results also show that the initial phase of the TDHG pulse can significantly changes the envelope of the optical force.

  17. Hybrid Raman/Brillouin-optical-time-domain-analysis-distributed optical fiber sensors based on cyclic pulse coding.

    PubMed

    Taki, M; Signorini, A; Oton, C J; Nannipieri, T; Di Pasquale, F

    2013-10-15

    We experimentally demonstrate the use of cyclic pulse coding for distributed strain and temperature measurements in hybrid Raman/Brillouin optical time-domain analysis (BOTDA) optical fiber sensors. The highly integrated proposed solution effectively addresses the strain/temperature cross-sensitivity issue affecting standard BOTDA sensors, allowing for simultaneous meter-scale strain and temperature measurements over 10 km of standard single mode fiber using a single narrowband laser source only.

  18. Terahertz field enhancement via coherent superposition of the pulse sequences after a single optical-rectification crystal

    NASA Astrophysics Data System (ADS)

    Sajadi, Mohsen; Wolf, Martin; Kampfrath, Tobias

    2014-03-01

    Terahertz electromagnetic pulses are frequently generated by optical rectification of femtosecond laser pulses. In many cases, the efficiency of this process is known to saturate with increasing intensity of the generation beam because of two-photon absorption. Here, we demonstrate two routes to reduce this effect in ZnTe(110) crystals and enhance efficiency, namely, by (i) recycling the generation pulses and by (ii) splitting each generation pulse into two pulses before pumping the crystal. In both methods, the second pulse arrives ˜1 ns after the first one, sufficiently long for optically generated carriers to relax. Enhancement is achieved by coherently superimposing the two resulting terahertz fields.

  19. Terahertz field enhancement via coherent superposition of the pulse sequences after a single optical-rectification crystal

    SciTech Connect

    Sajadi, Mohsen Wolf, Martin; Kampfrath, Tobias

    2014-03-03

    Terahertz electromagnetic pulses are frequently generated by optical rectification of femtosecond laser pulses. In many cases, the efficiency of this process is known to saturate with increasing intensity of the generation beam because of two-photon absorption. Here, we demonstrate two routes to reduce this effect in ZnTe(110) crystals and enhance efficiency, namely, by (i) recycling the generation pulses and by (ii) splitting each generation pulse into two pulses before pumping the crystal. In both methods, the second pulse arrives ∼1 ns after the first one, sufficiently long for optically generated carriers to relax. Enhancement is achieved by coherently superimposing the two resulting terahertz fields.

  20. A broadly tunable autocorrelator for ultra-short, ultra-high power infrared optical pulses

    SciTech Connect

    Szarmes, E.B.; Madey, J.M.J.

    1995-12-31

    We describe the design of a crossed-beam, optical autocorrelator that uses an uncoated, birefringent beamsplitter to split a linearly polarized incident pulse into two orthogonally polarized pulses, and a Type II, SHG crystal to generate the intensity autocorrelation function. The uncoated beamsplitter accommodates extremely broad tunability while precluding any temporal distortion of ultrashort optical pulses at the dielectric interface, and the specific design provides efficient operation between 1 {mu}m and 4 {mu}m. Furthermore, the use of Type II SHG completely eliminates any single-beam doubling, so the autocorrelator can be operated at very shallow crossed-beam angles without generating a background pedestal. The autocorrelator has been constructed and installed in the Mark III laboratory at Duke University as a broadband diagnostic for ongoing compression experiments on the chirped-pulse FEL.

  1. Experimental investigation of pulse generation with one-pump fiber optical parametric amplification.

    PubMed

    Vedadi, Armand A; Shoaie, Mohammad Amin; Brès, Camille-Sophie

    2012-11-19

    In a recent study, the theory of pulse generation with fiber optical parametric amplification using sinusoidal (clock) intensity modulated pump was revisited. This work showed that the pulses generated through such parametric interaction exhibit a shape which depends on the signal detuning with respect to the pump position (i.e. linear phase mismatch). A near Gaussian shape can only be achieved over a small region of the gain spectrum, close to the maximum gain location. Towards the extremities of the gain spectrum, the generated pulses take a near Sinc shape which can have many potential applications such as for all-optical Nyquist limited transmitters and/or receivers. In this paper we experimentally verify the theory at repetition rates up to 40 GHz. We also discuss the impact of noise, pump saturation and walk-off on the generated pulses.

  2. Fluctuations of energy density of short-pulse optical radiation in the turbulent atmosphere.

    PubMed

    Banakh, V A; Smalikho, I N

    2014-09-22

    Fluctuations of energy density of short-pulse optical radiation in the turbulent atmosphere have been studied based on numerical solution of the parabolic wave equation for the complex spectral amplitude of the wave field by the split-step method. It has been shown that under conditions of strong optical turbulence, the relative variance of energy density fluctuations of pulsed radiation of femtosecond duration becomes much less than the relative variance of intensity fluctuations of continuous-wave radiation. The spatial structure of fluctuations of the energy density with a decrease of the pulse duration becomes more large-scale and homogeneous. For shorter pulses the maximal value of the probability density distribution of energy density fluctuations tends to the mean value of the energy density.

  3. Modulation techniques for deep-space pulse-position modulation (PPM) optical communication

    NASA Technical Reports Server (NTRS)

    Rayman, Marc D.; Robinson, Deborah L.

    1988-01-01

    The extremely energy-efficient pulse-position modulation (PPM) format is being actively developed as a basis for optical communications with deep-space probes. Attention is presently given to different modulation schemes for the efficient production of laser pulses over a broad range of repetition rates. Both Q-switching and cavity dumping modulation methods are available for the envisioned diode-pumped Nd:YAG laser source. Numerical calculation results are presented for cavity-dumping.

  4. Highly stable ultrabroadband mid-IR optical parametric chirped-pulse amplifier optimized for superfluorescence suppression.

    PubMed

    Moses, J; Huang, S-W; Hong, K-H; Mücke, O D; Falcão-Filho, E L; Benedick, A; Ilday, F O; Dergachev, A; Bolger, J A; Eggleton, B J; Kärtner, F X

    2009-06-01

    We present a 9 GW peak power, three-cycle, 2.2 microm optical parametric chirped-pulse amplification source with 1.5% rms energy and 150 mrad carrier envelope phase fluctuations. These characteristics, in addition to excellent beam, wavefront, and pulse quality, make the source suitable for long-wavelength-driven high-harmonic generation. High stability is achieved by careful optimization of superfluorescence suppression, enabling energy scaling.

  5. Two and Three Beam Pumped Optical Parametric Amplifier of Chirped Pulses

    NASA Astrophysics Data System (ADS)

    Ališauskas, S.; Butkus, R.; Pyragaitė, V.; Smilgevičius, V.; Stabinis, A.; Piskarskas, A.

    2010-04-01

    We present two and three beam pumped optical parametric amplifier of broadband chirped pulses. The seed pulses from Ti:sapphire oscillator were stretched and amplified in a non-collinear geometry pumping with up to three beams derived from independent laser amplifiers. The signal with ˜90 nm bandwidth was amplified up to 0.72 mJ. The conversion efficiency dependence on intersection angles of pump beams is also revealed.

  6. Optical gain in Si/SiO2 lattice: Experimental evidence with nanosecond pulses

    NASA Astrophysics Data System (ADS)

    Khriachtchev, Leonid; Räsänen, Markku; Novikov, Sergei; Sinkkonen, Juha

    2001-08-01

    Experimental evidence of population inversion and amplified spontaneous emission was found for Si nanocrystallites embedded in SiO2 surrounding under pumping with 5 ns light pulses at 380, 400, and 500 nm. As an important property, our experiments show a short lifetime of the population inversion allowing a generation of short (a few nanosecond) amplified light pulses in the Si/SiO2 lattice. The estimate for optical gain in the present samples is 6 cm-1 at 720 nm.

  7. Generation of high-power ultrashort optical pulses by semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Dudelev, V. V.; Zazulin, S. V.; Kolykhalova, E. D.; Losev, S. N.; Deryagin, A. G.; Kuchinskii, V. I.; Efanov, M. V.; Sokolovskii, G. S.

    2016-12-01

    Fiber-coupled semiconductor lasers have been studied when pumped by high-power short electrical pulses of 5 ns width and leading front duration below 1 ns. In this pumping regime, it is possible to ensure significant sharpening of output pulses, the duration of which decreases below 80 ps for a single-mode laser and below 120 ps for a broad aperture multimode laser at an output peak optical power as high as 1.5 and 27 W, respectively.

  8. Modulation techniques for deep-space pulse-position modulation (PPM) optical communication

    NASA Technical Reports Server (NTRS)

    Rayman, Marc D.; Robinson, Deborah L.

    1988-01-01

    The extremely energy-efficient pulse-position modulation (PPM) format is being actively developed as a basis for optical communications with deep-space probes. Attention is presently given to different modulation schemes for the efficient production of laser pulses over a broad range of repetition rates. Both Q-switching and cavity dumping modulation methods are available for the envisioned diode-pumped Nd:YAG laser source. Numerical calculation results are presented for cavity-dumping.

  9. Dynamics of optical breakdown in air induced by single and double nanosecond laser pulses

    SciTech Connect

    Mahdieh, Mohammad Hossein Akbari Jafarabadi, Marzieh

    2015-12-15

    In this paper, an optical breakdown in air induced by single and double nanosecond laser pulses was studied. A high power Nd:YAG laser beam was used for producing optical breakdown plasma in the air. The dynamics of breakdown plasma were studied using an optical probe beam. A portion of the laser beam was used, as the probe beam and was aligned to propagate (perpendicular to the pump beam) through the breakdown region. The transmission of the probe beam (through the breakdown region) was temporally measured for both single and double pulse irradiations. The results were used to describe the evolution of the induced plasma in both conditions. These results show that the plasma formation time and its absorptivity are strongly dependent on the single or double pulse configurations.

  10. Observation of voids and optical seizing of voids in silica glass with infrared femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Watanabe, Wataru; Toma, Tadamasa; Yamada, Kazuhiro; Nishii, Junji; Hayashi, Ken-ichi; Itoh, Kazuyoshi

    2000-11-01

    Many researchers have investigated the interaction of femtosecond laser pulses with a wide variety of materials. The structural modifications both on the surface and inside the bulk of transparent materials have been demonstrated. When femtosecond laser pulses are focused into glasses with a high numerical-aperture objective, voids are formed. We demonstrate that one can seize and move voids formed by femtosecond laser pulses inside silica glass and also merge two voids into one. We also present clear evidence that a void is a cavity by showing a scanning-electron-microscope image of cleft voids: we clove through the glass along a plane that includes the laser-ablated thin line on the surface and the voids formed inside. The optical seizing and merging of voids are important basic techniques for fabricate micro-optical dynamic devices, such as the rewritable 3-D optical storage.

  11. Dynamic response of ensemble neurons to pulsed optical and electrical excitation in vivo and in vitro

    NASA Astrophysics Data System (ADS)

    Akchurin, Garif G.; Seleverstov, George A.; Kamenskih, Tatyana G.; Akchurin, George G.; Bondarenko, Olga A.

    2002-07-01

    The nonlinear response of the Hodgkin-Huxley model neuron with external electrical pulsed was investigated. Dynamic response of somatic frog nerve on electrical pulsed duration was study in vitro. Transcutaneous millisecond of excitation of the ganglion cell of the human retina by electric uses is used for diagnosis, determination of the extent of optic nerve damage, and also partial restoration of visual function in patients with glaucoma, myopia and different types of optic nerve atrophy. Correlation between the threshold of phosphen formation and duration of the stimulating electric pulses was determined experimentally in normal eyes and in eyes with various pathologies. Comparison of optical and electrical scintillating frequency gives information about the dynamic processes in the normal and pathological retina.

  12. A pulse-front-tilt–compensated streaked optical spectrometer with high throughput and picosecond time resolution

    SciTech Connect

    Katz, J. Boni, R.; Rivlis, R.; Muir, C.; Froula, D. H.

    2016-11-15

    A high-throughput, broadband optical spectrometer coupled to the Rochester optical streak system equipped with a Photonis P820 streak tube was designed to record time-resolved spectra with 1-ps time resolution. Spectral resolution of 0.8 nm is achieved over a wavelength coverage range of 480 to 580 nm, using a 300-groove/mm diffraction grating in conjunction with a pair of 225-mm-focal-length doublets operating at an f/2.9 aperture. Overall pulse-front tilt across the beam diameter generated by the diffraction grating is reduced by preferentially delaying discrete segments of the collimated input beam using a 34-element reflective echelon optic. The introduced delay temporally aligns the beam segments and the net pulse-front tilt is limited to the accumulation across an individual sub-element. The resulting spectrometer design balances resolving power and pulse-front tilt while maintaining high throughput.

  13. Integration of nonlinearity-management and dispersion-management for pulses in fiber-optic links

    NASA Astrophysics Data System (ADS)

    Driben, Rodislav; Malomed, Boris A.; Mahlab, Uri

    2004-03-01

    We introduce a model of a long-haul fiber-optic link that uses a combination of the nonlinearity- and dispersion-compensation (management) to stabilize nonsoliton pulses. The compensation of the accumulated fiber nonlinearity, and simultaneously pulse reshaping, which helps to suppress the inter-symbol interference (ISI, i.e., blurring of blank spaces between adjacent pulses), are performed by second-harmonic-generating modules, which are periodically inserted together with amplifiers. We demonstrate that the dispersion-management (DM), which was not included in an earlier considered model, drastically improves stability of the pulses. The stable-transmission length for an isolated pulse, which was less than 10 fiber spans with the use of the nonlinearity-management only, becomes indefinitely long. It is demonstrated too that the pulse is quite robust against fluctuations of its initial parameters, and the scheme operates efficiently in a very broad parameter range. The interaction between pulses can be safely suppressed for the transmission distance exceeding 16 spans (≃1000 km). The smallest temporal separation between adjacent pulses, which is necessary to prevent the ISI, attains a minimum in the case of moderate DM, similar to known results for the DM solitons. The mutually-induced distortion of co-propagating pulses being accounted for by the emission of radiation, a plausible way to further increase the stable-transmission limit is to introduce bandpass filters.

  14. Estimating of pulsed electric fields using optical measurements.

    SciTech Connect

    Flanagan, Timothy McGuire; Chantler, Gary.

    2013-09-01

    We performed optical electric field measurements ion nanosecond time scales using the electrooptic crystal beta barium borate (BBO). Tests were based on a preliminary bench top design intended to be a proofofprinciple stepping stone towards a modulardesign optical Efield diagnostic that has no metal in the interrogated environment. The long term goal is to field a modular version of the diagnostic in experiments on large scale xray source facilities, or similarly harsh environments.

  15. Stability of aerosol droplets in Bessel beam optical traps under constant and pulsed external forces

    SciTech Connect

    David, Grégory; Esat, Kıvanç; Hartweg, Sebastian; Cremer, Johannes; Chasovskikh, Egor; Signorell, Ruth

    2015-04-21

    We report on the dynamics of aerosol droplets in optical traps under the influence of additional constant and pulsed external forces. Experimental results are compared with simulations of the three-dimensional droplet dynamics for two types of optical traps, the counter-propagating Bessel beam (CPBB) trap and the quadruple Bessel beam (QBB) trap. Under the influence of a constant gas flow (constant external force), the QBB trap is found to be more stable compared with the CPBB trap. By contrast, under pulsed laser excitation with laser pulse durations of nanoseconds (pulsed external force), the type of trap is of minor importance for the droplet stability. It typically needs pulsed laser forces that are several orders of magnitude higher than the optical forces to induce escape of the droplet from the trap. If the droplet strongly absorbs the pulsed laser light, these escape forces can be strongly reduced. The lower stability of absorbing droplets is a result of secondary thermal processes that cause droplet escape.

  16. Ultrasound generation through a fiber optic delivery system using pulsed laser energy

    SciTech Connect

    Carlson, N.M.; Johnson, J.A.

    1990-01-01

    Short duration laser pulses can generate high frequency, broadband ultrasound in a material without contacting the surface. For these noncontacting techniques to be useful on the shop floor, in remote applications, and in harsh environments, a dependable delivery system must be developed. Fiber optic techniques have been used to deliver either moderate laser energy for a large number of pulses or a large laser energy for a few pulses for the purpose of generating acoustic waves. However, transmitting high energy pulses continuously through a fiber is required for practical sensing systems. Fiber optics systems are currently used for a long duration pulses (of the order of milliseconds) in laser welding applications; e.g. a welding systems developed for manufacture of headlamps uses a fiber optic delivery system. The key to the success of this welding systems is the coupling technique used to deliver laser power to the fiber. Because the pulse duration is on the order of several milliseconds, the power density in the fiber is several orders of magnitude below the power densities required for ultrasonic applications. 17 refs., 2 figs.

  17. Dynamic propagation of symmetric Airy pulses with initial chirps in an optical fiber

    NASA Astrophysics Data System (ADS)

    Shi, Xiaohui; Huang, Xianwei; Deng, Yangbao; Tan, Chao; Bai, Yanfeng; Fu, Xiquan

    2017-09-01

    We analytically and numerically investigate the propagation dynamics of initially chirped symmetric Airy pulses in an optical fiber. The results show that the positive chirps act to promote the interference in generating a focal point on the propagation axis, while the negative chirps tend to suppress the focusing effect, as compared to conventional unchirped symmetric Airy pulses. The numerical results demonstrate that the linear propagation of chirped symmetric Airy pulses depend considerably on the chirp parameter and the primary lobe position. In the anomalous dispersion region, positively chirped symmetric Airy pulses first undergo an initial compression, and reach a foci due to the opposite acceleration, and then experience a lossy inversion transformation, and come to the opposite facing focal position. The impact of truncation coefficient and Kerr nonlinearity on the chirped symmetric Airy pulses propagation is also disclosed separately.

  18. Multi-rate soliton pulse train generator based on novel fiber optic components

    NASA Astrophysics Data System (ADS)

    Sova, Raymond Michael

    As data rates for communication, signal processing, and optical sensing systems increase beyond 50 Gb/sec, ultra-fast optical pulse train generators will play a key role in their development. In this research, an all-fiber optical soliton pulse train generator is developed that operates at discrete rates from 50 to 400 Gb/sec with stable subpicosecond pulses. It is based on the following three novel fiber optic components: (1) all-fiber birefringence filter, (2) dual-wavelength fiber ring laser and (3) fiber-based soliton pulse train generation and compression stage. A multi-segment birefringence comb filter is developed to provide discrete tuning of the free spectral range from 0.8 to 3.2 nm and continuous tuning of the absolute position of the transmission peaks over the entire free spectral range. Two, three and four segment filters are constructed and implemented in Lyot and Lyot-Sagnac filter configurations to demonstrate the tuning properties and provide compound filters for use in the dual-wavelength fiber ring laser. Theoretical transmission functions are derived for two-segment filters. The experimental results are in excellent agreement with theoretical models based on the Jones matrix technique. The dual-wavelength laser consists of a PM amplifier, the tunable birefringence filter and a high-Q filter based on saturable absorber properties of un-pumped Erbium-doped fiber. Tunable compound birefringence filters are designed to operate the dual-wavelength laser over the entire erbium amplifier gain region (1530 to 1565 nm) with discrete tuning of the channel separation from 0.8 to 3.2 nm. Stable tunable dual-wavelength single-longitudinal mode operation is demonstrated and initial laser properties such as dual-relaxation oscillations, laser linewidth, polarization, and multi-wavelength stability are characterized. Induced modulation instability in optical fiber is used to generate pulse trains from the fiber ring laser output signal. Through modeling, the

  19. Model for a pulsed terahertz quantum cascade laser under optical feedback.

    PubMed

    Agnew, Gary; Grier, Andrew; Taimre, Thomas; Lim, Yah Leng; Bertling, Karl; Ikonić, Zoran; Valavanis, Alexander; Dean, Paul; Cooper, Jonathan; Khanna, Suraj P; Lachab, Mohammad; Linfield, Edmund H; Davies, A Giles; Harrison, Paul; Indjin, Dragan; Rakić, Aleksandar D

    2016-09-05

    Optical feedback effects in lasers may be useful or problematic, depending on the type of application. When semiconductor lasers are operated using pulsed-mode excitation, their behavior under optical feedback depends on the electronic and thermal characteristics of the laser, as well as the nature of the external cavity. Predicting the behavior of a laser under both optical feedback and pulsed operation therefore requires a detailed model that includes laser-specific thermal and electronic characteristics. In this paper we introduce such a model for an exemplar bound-to-continuum terahertz frequency quantum cascade laser (QCL), illustrating its use in a selection of pulsed operation scenarios. Our results demonstrate significant interplay between electro-optical, thermal, and feedback phenomena, and that this interplay is key to understanding QCL behavior in pulsed applications. Further, our results suggest that for many types of QCL in interferometric applications, thermal modulation via low duty cycle pulsed operation would be an alternative to commonly used adiabatic modulation.

  20. Pulse height response of an optical particle counter to monodisperse aerosols

    NASA Technical Reports Server (NTRS)

    Wilmoth, R. G.; Grice, S. S.; Cuda, V.

    1976-01-01

    The pulse height response of a right angle scattering optical particle counter has been investigated using monodisperse aerosols of polystyrene latex spheres, di-octyl phthalate and methylene blue. The results confirm previous measurements for the variation of mean pulse height as a function of particle diameter and show good agreement with the relative response predicted by Mie scattering theory. Measured cumulative pulse height distributions were found to fit reasonably well to a log normal distribution with a minimum geometric standard deviation of about 1.4 for particle diameters greater than about 2 micrometers. The geometric standard deviation was found to increase significantly with decreasing particle diameter.

  1. Selection of CO laser single nanosecond pulse by electro-optic CdTe shutter

    NASA Astrophysics Data System (ADS)

    Ionin, A. A.; Kinyaevskiy, I. O.; Klimachev, Yu. M.; Kotkov, A. A.; Kozlov, A. Yu.; Kryuchkov, D. S.

    2017-09-01

    To select a single laser pulse from a train of nanosecond pulses emitted by a mode-locked CO laser with wavelengths from ∼5 to 6 μm, an electro-optic shutter based on CdTe Pockels cell was developed. A contrast between the selected pulse and unselected laser emission was equal to 20 and twice as much decreased in a CO laser power amplifier. To increase the contrast, a feasibility of applying a narrow-gap semiconductor as a saturable absorber is discussed.

  2. Pulse Oximetry in the Physics Lab: A Colorful Alternative to Traditional Optics Curricula

    NASA Astrophysics Data System (ADS)

    Kutschera, Ellynne; Dunlap, Justin C.; Byrd, Misti; Norlin, Casey; Widenhorn, Ralf

    2013-11-01

    We designed a physics laboratory exercise around pulse oximetry, a noninvasive medical technique used to assess a patient's blood oxygen saturation. An alternative to a traditional optics and light lab, this exercise teaches the principles of light absorption, spectroscopy, and the properties of light, while simultaneously studying a common medical device. Pulse oximeters are ubiquitous in clinical environments; many people who have undergone surgery or visited a hospital environment have experienced the use of this device, making it a good candidate for an investigative lab. The experiment elicits the creative process of device development from students as they conduct measurements using a blood analog that reconstructs the principles of pulse oximetry.

  3. X-ray and optical pulse interactions via electron trapping in GaAs

    NASA Astrophysics Data System (ADS)

    Durbin, Stephen; Liu, Shih-Chieh; Dichiara, Anthony; Henning, Robert

    2014-03-01

    A highly excited state of GaAs is created by the absorption of an extremely intense focused 80 ps pulse of hard x-rays at the Advanced Photon Source synchrotron. This state is probed by 2 ps laser pulses with photon energies near the semiconducting band gap, which has previously revealed x-ray induced optical transparency. Two unexpected results are found: x-ray induced luminescence is dramatically enhanced when a high intensity laser pulse precedes the x-ray pulse, and the decay of the induced transparency becomes much slower when the intensity of the subsequent probe laser is increased. Both results require that energy be stored in GaAs by the first pulse, and then released by the second pulse. We describe how this can be explained by electron trapping centers in GaAs with trapping lifetimes of a few nanoseconds. We compare these results with lifetime measurements of other excitations produced by ultrafast optical absorption. We also show how minor improvements in focusing will lead to single-pulse x-ray induced temperature jumps of thousands of Kelvin, allowing new x-ray excited dense matter states to be explored. Supported by DOE award DE-SC0004078. The Advanced Photon Source is supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. BioCARS is supported by the NIGMS of the NIH under grant number R24GM111072.

  4. Detection and analysis of multi-dimensional pulse wave based on optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Shen, Yihui; Li, Zhifang; Li, Hui; Chen, Haiyu

    2014-11-01

    Pulse diagnosis is an important method of traditional Chinese medicine (TCM). Doctors diagnose the patients' physiological and pathological statuses through the palpation of radial artery for radial artery pulse information. Optical coherence tomography (OCT) is an useful tool for medical optical research. Current conventional diagnostic devices only function as a pressure sensor to detect the pulse wave - which can just partially reflect the doctors feelings and lost large amounts of useful information. In this paper, the microscopic changes of the surface skin above radial artery had been studied in the form of images based on OCT. The deformation of surface skin in a cardiac cycle which is caused by arterial pulse is detected by OCT. The patient's pulse wave is calculated through image processing. It is found that it is good consistent with the result conducted by pulse analyzer. The real-time patient's physiological and pathological statuses can be monitored. This research provides a kind of new method for pulse diagnosis of traditional Chinese medicine.

  5. Statistical characterization of the internal structure of noiselike pulses using a nonlinear optical loop mirror

    NASA Astrophysics Data System (ADS)

    Pottiez, O.; Paez-Aguirre, R.; Cruz, J. L.; Andrés, M. V.; Kuzin, E. A.

    2016-10-01

    In this work we study statistically the internal structure of noiselike pulses generated by a passively mode-locked fiber laser. For this purpose, we use a technique that allows estimating the distribution of the amplitudes of the sub-pulses in the bunch. The technique takes advantage of the fast response of the optical Kerr effect in a fiber nonlinear optical loop mirror (NOLM). It requires the measurement of the energy transfer characteristic of the pulses through the NOLM, and the numerical resolution of a system of nonlinear algebraic equations. The results yield a strongly asymmetric distribution, with a high-amplitude tail that is compatible with the existence of extreme-intensity sub-pulses in the bunch. Following the recent discovery of pulse-energy rogue waves and spectral rogue waves in the noiselike pulse regime, we propose a new way to look for extreme events in this particular mode of operation of mode-locked fiber lasers, and confirm that rogue wave generation is a key ingredient in the complex dynamics of these unconventional pulses.

  6. Optical pulse shaping for selective excitation of coherent molecular vibrations by stimulated Raman scattering

    NASA Astrophysics Data System (ADS)

    Geddes, Joseph B., III; Marks, Daniel L.; Boppart, Stephen A.

    2009-02-01

    Coherent anti-Stokes Raman scattering (CARS) can be used to identify biological molecules from their vibrational spectra in tissue. A single double-chirped broadband optical pulse can excite a broad spectrum of resonant molecular vibrations in the fingerprint spectral region. Such a pulse also excites nonresonant CARS, particularly from water. We describe a theoretical technique to design an optical pulse to selectively excite coherent vibrations in a target molecular species so that the CARS signal generated is increased. The signal from other molecules is reduced, since the incident pulse does not excite them to have coherent vibrations. As an example, we apply the technique to design pulses to elicit increased CARS signal from a mixture of one or more of the alcohols methanol, ethanol, and isopropanol. We also show how such pulse designs can be used to selectively excite one member of closely related complex biological species. As measured interferometrically, the CARS signal from three phosphodiester stretch modes of DNA can be increased to more than ten times that of the analogous signal from RNA when the pulse design technique is used.

  7. Optical fiber link for transmission of 1-nJ femtosecond laser pulses at 1550 nm.

    PubMed

    Eichhorn, Finn; Olsson, Rasmus Kjelsmark; Buron, Jonas C D; Grüner-Nielsen, Lars; Pedersen, Jens Engholm; Jepsen, Peter Uhd

    2010-03-29

    We report on numerical and experimental characterization of the performance of a fiber link optimized for the delivery of sub-100-fs laser pulses at 1550 nm over several meters of fiber. We investigate the power handling capacity of the link, and demonstrate all-fiber delivery of 1-nJ pulses over a distance of 5.3 m. The fiber link consists of dispersion-compensating fiber (DCF) and standard single-mode fiber. The optical pulses at different positions in the fiber link are measured using frequency-resolved optical gating (FROG). The results are compared with numerical simulations of the pulse propagation based on the generalized nonlinear Schrödinger equation. The high input power capacity of the fiber link allows the splitting and distribution of femtosecond pulses to an array of fibers with applications in multi-channel fiber-coupled terahertz time-domain spectroscopy and imaging systems. We demonstrate THz pulse generation and detection using a distributed fiber link with 32 channels and 2.6 nJ input pulse energy.

  8. Tunable mid-infrared (6.3-12 μm)optical vortex pulse generation.

    PubMed

    Furuki, Kenji; Horikawa, Michael-Tomoki; Ogawa, Azusa; Miyamoto, Katsuhiko; Omatsu, Takashige

    2014-10-20

    We demonstrated widely tunable mid-infrared (6.3-12 μm) optical vortex pulse generation from a ZGP difference frequency generator pumped by a 2 μm optical vortex laser with a cascaded KTP geometry. The mid-infrared vortex output carried the same topological charge as that of the 1 μm pump output without any destruction. A pulse energy of >135 μJ was obtained in the wavelength region of 6.3-7.0 μm.

  9. Imaging carrier and phonon transport in Si using ultrashort optical pulses

    SciTech Connect

    David H. Hurley; O. B. Wright; O. Matsuda; B. E. McCandless; S. Shinde

    2009-01-01

    A series of experiments have been conducted that microscopically image thermal diffusion and surface acoustic phonon propagation within a single crystallite of a polycrystalline Si sample. The experimental approach employs ultrashort optical pulses to generate an electron-hole plasma and a second probe pulse is used to image the evolution of the plasma. By decomposing the signal into a component that varies with delay time and a steady state component that varies with pump modulation frequency, the respective influence of carrier recombination and thermal diffusion are identified. Additionally, the coherent surface acoustic phonon component to the signal is imaged using a Sagnac interferometer to monitor optical phase.

  10. Short optical pulse generated by integrated MQW DBR laser/EA-modulator

    NASA Astrophysics Data System (ADS)

    Chen, Young-Kai; Tanbun-Ek, Tawee; Logan, Ralph A.; Tate, A. R.; Sergent, A. M.; Wecht, K. W.; Sciortino, Paul F., Jr.; Raybon, Gregory; Froberg, Nan M.; Johnson, Anthony M.

    1994-05-01

    We report on the generation of short optical pulses by utilizing the non-linear absorption characteristics of a multiple quantum well (MQW) electro-absorption modulator, which is monolithically integrated with a MQW wavelength-tunable distributed Bragg reflector (DBR) laser on a single chip. Optical pulses as short as 39 ps and 15 ps have been generated at a repetition rate of 3 GHz and 10 GHz, respectively, with a broad tuning range of 5.4 nm near 1554 nm lasing wavelength.

  11. Quantum computers based on electron spins controlled by ultrafast off-resonant single optical pulses.

    PubMed

    Clark, Susan M; Fu, Kai-Mei C; Ladd, Thaddeus D; Yamamoto, Yoshihisa

    2007-07-27

    We describe a fast quantum computer based on optically controlled electron spins in charged quantum dots that are coupled to microcavities. This scheme uses broadband optical pulses to rotate electron spins and provide the clock signal to the system. Nonlocal two-qubit gates are performed by phase shifts induced by electron spins on laser pulses propagating along a shared waveguide. Numerical simulations of this scheme demonstrate high-fidelity single-qubit and two-qubit gates with operation times comparable to the inverse Zeeman frequency.

  12. Ultrafast optical response of the Au-BaO thin film stimulated by femtosecond pulse laser

    NASA Astrophysics Data System (ADS)

    Wu, J. L.; Wang, C. M.; Zhang, G. M.

    1998-06-01

    The pump-probe method was applied to study the dependence of the transient optical transmissivity upon time delay for the Au-BaO composite thin film stimulated by a femtosecond pulsed laser. It was observed that the light absorption of the thin film increased rapidly and then resumed its initial value in several picoseconds. Optical relaxation is a process in which nonequilibrium electrons, excited by laser pulses and originating from Au ultrafine particles, return to the equilibrium state. In this article, the value of the electron-phonon coupling constant g of gold ultrafine particles in the composite thin film was calculated theoretically.

  13. High frequency optical pulse generation by frequency doubling using polarization rotation

    NASA Astrophysics Data System (ADS)

    Liu, Yang

    2016-05-01

    In this work, we propose and experimentally characterize a stable 40 GHz optical pulse generation by frequency doubling using polarization rotation in a phase modulator (PM). Only half the electrical driving frequency is required (i.e. 20 GHz); hence the deployment cost can be reduced. Besides, precise control of the bias of the PM is not required. The generated optical pulses have a high center-mode-suppression-ratio (CMSR) of  >  28 dB. The single sideband (SSB) noise spectrum is also measured, and the time-domain waveforms under different CMSRs are also analyzed and discussed.

  14. Optical modulation of astrocyte network using ultrashort pulsed laser

    NASA Astrophysics Data System (ADS)

    Yoon, Jonghee; Ku, Taeyun; Chong, Kyuha; Ryu, Seung-Wook; Choi, Chulhee

    2012-03-01

    Astrocyte, the most abundant cell type in the central nervous system, has been one of major topics in neuroscience. Even though many tools have been developed for the analysis of astrocyte function, there has been no adequate tool that can modulates astrocyte network without pharmaceutical or genetic interventions. Here we found that ultrashort pulsed laser stimulation can induce label-free activation of astrocytes as well as apoptotic-like cell death in a dose-dependent manner. Upon irradiation with high intensity pulsed lasers, the irradiated cells with short exposure time showed very rapid mitochondria fragmentation, membrane blebbing and cytoskeletal retraction. We applied this technique to investigate in vivo function of astrocyte network in the CNS: in the aspect of neurovascular coupling and blood-brain barrier. We propose that this noninvasive technique can be widely applied for in vivo study of complex cellular network.

  15. [Study on optical emission spectroscopy of pulse corona methane plasma].

    PubMed

    Li, Jin-Ping; Dai, Bin; Fan, Ting

    2009-07-01

    From experiments of methane pulse corona plasma and plasma emission spectrometry, the emission spectra of methane ranging from 370 to 1 100 nm were recorded and marked with CCD (Charge Coupled Device) grating spectrometry. The ionization products of H, C+, CH, C, C2, C3, C4, C5 and hydrocarbon were confirmed through high purity methane (purity 99.99%) ionized by pulse high voltage of 100 kV and 100 Hz under normal temperature and normal pressure. Through analyzing the experimental emission spectrum of methane plasma, the ionization mechanism, i.e. methane gas was ionized into corona plasma by pulse high voltage, was analyzed and the ionization of free radical CHn (n = 3, 2, 1), carbon and hydrocarbons was given as well. Research results show that the dehydrogenation achieved a high level when methane molecules collide inelastically with high energy electrons, and the hydrogen atoms, hydrogen ions and methane free radicals were synthesized into alkenes, alkynes, alkanes and high polymer of carbon with further inelastic collision of high energy electrons. This experimental spectrum and mechanism analysis can be applied to the research on methane conversion.

  16. Pulse-to-pulse alignment based on interference fringes and the second-order temporal coherence function of optical frequency combs for distance measurement.

    PubMed

    Zhu, Jigui; Cui, Pengfei; Guo, Yin; Yang, Linghui; Lin, Jiarui

    2015-05-18

    A pulse-to-pulse alignment method based on interference fringes and the second-order temporal coherence function of optical frequency combs is proposed for absolute distance measurement. The second-order temporal coherence function of the pulse train emitted from optical frequency combs is studied. A numerical model of the function is developed with an assumption of Gaussian pulse and has good agreement with experimental measurements taken by an ordinary Michelson interferometer. The experimental results show an improvement of standard deviation of peak finding results from 27.3 nm to 8.5 nm by the method in ordinary laboratory conditions. The absolute distance measurement with the pulse-to-pulse alignment method is also proposed and experimentally proved.

  17. The role of morphology and coupling of gold nanoparticles in optical breakdown during picosecond pulse exposures

    PubMed Central

    Davletshin, Yevgeniy R

    2016-01-01

    Summary This paper presents a theoretical study of the interaction of a 6 ps laser pulse with uncoupled and plasmon-coupled gold nanoparticles. We show how the one-dimensional assembly of particles affects the optical breakdown threshold of its surroundings. For this purpose we used a fully coupled electromagnetic, thermodynamic and plasma dynamics model for a laser pulse interaction with gold nanospheres, nanorods and assemblies, which was solved using the finite element method. The thresholds of optical breakdown for off- and on-resonance irradiated gold nanosphere monomers were compared against nanosphere dimers, trimers, and gold nanorods with the same overall size and aspect ratio. The optical breakdown thresholds had a stronger dependence on the optical near-field enhancement than on the mass or absorption cross-section of the nanostructure. These findings can be used to advance the nanoparticle-based nanoscale manipulation of matter. PMID:27547604

  18. Direct-detection optical communication with color coded pulse position modulation signaling

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1985-01-01

    The performance characteristics of a direct-detection optical communication system which is based on a laser transmitter which produces single light pulses at selected nonoverlapping optical center frequencies are discussed. The signal format, called color coded pulse position modulation (CCPPM), uses more of the total available response bandwidth characteristics of the photodetector than does ordinary PPM signaling. The advantages of CCPPM signaling are obtained at the expense of an increased optical bandwidth of the transmitted signal and a more complicated transmitter and receiver structure. When the signal format is used in conjunction with block length Reed-Solomon codes, high data rates and reliable high-speed optical communications under conditions of optimal energy efficiency are obtained.

  19. Direct-detection optical communication with color coded pulse position modulation signaling

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1985-01-01

    The performance characteristics of a direct-detection optical communication system which is based on a laser transmitter which produces single light pulses at selected nonoverlapping optical center frequencies are discussed. The signal format, called color coded pulse position modulation (CCPPM), uses more of the total available response bandwidth characteristics of the photodetector than does ordinary PPM signaling. The advantages of CCPPM signaling are obtained at the expense of an increased optical bandwidth of the transmitted signal and a more complicated transmitter and receiver structure. When the signal format is used in conjunction with block length Reed-Solomon codes, high data rates and reliable high-speed optical communications under conditions of optimal energy efficiency are obtained.

  20. Supercontinuum generation in highly nonlinear fibers using amplified noise-like optical pulses.

    PubMed

    Lin, Shih-Shian; Hwang, Sheng-Kwang; Liu, Jia-Ming

    2014-02-24

    Supercontinuum generation in a highly nonlinear fiber pumped by noise-like pulses from an erbium-doped fiber ring laser is investigated. To generate ultrabroad spectra, a fiber amplifier is used to boost the power launched into the highly nonlinear fiber. After amplification, not only the average power of the noise-like pulses is enhanced but the spectrum of the pulses is also broadened due to nonlinear effects in the fiber amplifier. This leads to a reduction of the peak duration in their autocorrelation trace, suggesting a similar extent of pulse compression; by contrast, the pedestal duration increases only slightly, suggesting that the noise-like characteristic is maintained. By controlling the pump power of the fiber amplifier, the compression ratio of the noise-like pulse duration can be adjusted. Due to the pulse compression, supercontinuum generation with a broader spectrum is therefore feasible at a given average power level of the noise-like pulses launched into the highly nonlinear fiber. As a result, supercontinuum generation with an optical spectrum spanning from 1208 to 2111 nm is achieved using a 1-m nonlinear fiber pumped by amplified noise-like pulses of 15.5 MHz repetition rate at an average power of 202 mW.

  1. Optical field emission from resonant gold nanorods driven by femtosecond mid-infrared pulses

    SciTech Connect

    Kusa, F.; Echternkamp, K. E.; Herink, G.; Ropers, C.; Ashihara, S.

    2015-07-15

    We demonstrate strong-field photoelectron emission from gold nanorods driven by femtosecond mid-infrared optical pulses. The maximum photoelectron yield is reached at the localized surface plasmon resonance, indicating that the photoemission is governed by the resonantly-enhanced optical near-field. The wavelength- and field-dependent photoemission yield allows for a noninvasive determination of local field enhancements, and we obtain intensity enhancement factors close to 1300, in good agreement with finite-difference time domain computations.

  2. Ultrasound-modulated optical imaging using a photorefractive interferometer and a powerful long pulse laser

    NASA Astrophysics Data System (ADS)

    Rousseau, Guy; Blouin, Alain; Monchalin, Jean-Pierre

    2009-02-01

    Ultrasound-modulated optical imaging is an emerging biodiagnostic technique which provides the optical spectroscopic signature and the spatial localization of an optically absorbing object embedded in a strongly scattering medium. The transverse resolution of the technique is determined by the lateral extent of ultrasound beam focal zone while the axial resolution is obtained by using short ultrasound pulses. The practical application of this technique is presently limited by its poor sensitivity. Moreover, any method to enhance the signal-to-noise ratio must satisfy the biomedical safety limits. In this paper, we propose to use a pulsed single-frequency laser source to raise the optical peak power applied to the scattering medium and to collect more ultrasonically tagged photons. Such a laser source allows illuminating the tissues mainly during the transit time of the ultrasonic wave. A single-frequency Nd:YAG laser emitting 500-μs pulses with a peak power superior to 100 W was used. Tagged photons were detected with a GaAs photorefractive interferometer characterized by a large optical etendue. When pumped by high intensity laser pulses, such an interferometer provides the fast response time essential to obtain an apparatus insensitive to the speckle decorrelation encountered in biomedical applications. Consequently, the combination of a large-etendue photorefractive interferometer with a high-power pulsed laser could allow obtaining both the sensitivity and the fast response time necessary for biomedical applications. Measurements performed in 30- and 60-mm thick optical phantoms made of titanium dioxide particles dispersed in sunflower oil are presented. Results obtained in 30- and 60-mm thick chicken breast samples are also reported.

  3. Characterization of the shock pulse-induced cavitation bubble activities recorded by an optical fiber hydrophone.

    PubMed

    Kang, Gwansuk; Cho, Sung Chan; Coleman, Andrew John; Choi, Min Joo

    2014-03-01

    A shock pressure pulse used in an extracorporeal shock wave treatment has a large negative pressure (<-5 MPa) which can produce cavitation. Cavitation cannot be measured easily, but may have known therapeutic effects. This study considers the signal recorded for several hundred microseconds using an optical hydrophone submerged in water at the focus of shock pressure field. The signal is characterized by shock pulse followed by a long tail after several microseconds; this signal is regarded as a cavitation-related signal (CRS). An experimental investigation of the CRS was conducted in the shock pressure field produced in water using an optical hydrophone (FOPH2000, RP Acoustics, Germany). The CRS was found to contain characteristic information about the shock pulse-induced cavitation. The first and second collapse times (t1 and t2) were identified in the CRS. The collapse time delay (tc = t2 - t1) increased with the driving shock pressures. The signal amplitude integrated for time from t1 to t2 was highly correlated with tc (adjusted R(2) = 0.990). This finding suggests that a single optical hydrophone can be used to measure shock pulse and to characterize shock pulse-induced cavitation.

  4. High power burst-mode optical parametric amplifier with arbitrary pulse selection.

    PubMed

    Pergament, M; Kellert, M; Kruse, K; Wang, J; Palmer, G; Wissmann, L; Wegner, U; Lederer, M J

    2014-09-08

    We present results from a unique burst-mode femtosecond non-collinear optical parametric amplifier (NOPA) under development for the optical - x-ray pump-probe experiments at the European X-Ray Free-Electron Laser Facility. The NOPA operates at a burst rate of 10 Hz, a duty cycle of 2.5% and an intra-burst repetition rate of up to 4.5 MHz, producing high fidelity 15 fs pulses at a center wavelength of 810 nm. Using dispersive amplification filtering of the super-continuum seed pulses allows for selectable pulse duration up to 75 fs, combined with a tuning range in excess of 100 nm whilst remaining nearly transform limited. At an intra-burst rate of 188 kHz the single pulse energy from two sequential NOPA stages reached 180 µJ, corresponding to an average power of 34W during the burst. Acousto- and electro-optic switching techniques enable the generation of transient free bursts of required length and the selection of arbitrary pulse sequences inside the burst.

  5. Optical Field Ionization of Atoms and Ions Using Ultrashort Laser Pulses

    NASA Astrophysics Data System (ADS)

    Fittinghoff, David Neal

    This dissertation research is an investigation of the strong optical field ionization of atoms and ions by 120-fs, 614-nm laser pulses and 130-fs, 800-nm laser pulses. The experiments have shown ionization that is enhanced above the predictions of sequential tunneling models for He^{+2}, Ne ^{+2} and Ar^ {+2}. The ion yields for He^ {+1}, Ne^{+1} and Ar^{+1} agree well with the theoretical predictions of optical tunneling models. Investigation of the polarization dependence of the ionization indicates that the enhancements are consistent with a nonsequential ionization mechanism in which the linearly polarized field drives the electron wavefunction back toward the ion core and causes double ionization through inelastic e-2e scattering. These investigations have initiated a number of other studies by other groups and are of current scientific interest in the fields of high-irradiance laser -matter interactions and production of high-density plasmas. This work involved: (1) Understanding the characteristic nature of the ion yields produced by tunneling ionization through investigation of analytic solutions for tunneling at optical frequencies. (2) Extensive characterization of the pulses produced by 614-nm and 800-nm ultrashort pulse lasers. Absolute calibration of the irradiance scale produced shows the practicality of the inverse problem--measuring peak laser irradiance using ion yields. (3) Measuring the ion yields (number of ions produced versus irradiance) for three noble gases using linear, circular and elliptical polarizations of laser pulses.

  6. Optical 40 GHz pulse source module based on a monolithically integrated mode locked DBR laser

    NASA Astrophysics Data System (ADS)

    Huettl, B.; Kaiser, R.; Kroh, M.; Schubert, C.; Jacumeit, G.; Heidrich, H.

    2005-11-01

    In this paper the performance characteristics of compact optical 40 GHz pulse laser modules consisting of a monolithic mode-locked MQW DBR laser on GaInAsP/InP are reported. The monolithic devices were fabricated as tunable multi-section buried heterostructure lasers. A DBR grating is integrated at the output port of an extended cavity in order to meet the standardized ITU wavelength channels allocated in the spectral window around 1.55 μm in optical high speed communication networks. The fabricated 40 GHz lasers modules not only emit short optical pulses (< 1.5 ps) with very low amplitude noise (<1.5 %) and phase noise levels (timing jitter: 50 fs) but also enable good pulse-to-pulse phase and long-term stability. A wavelength tuning range of 6 nm is possible and large locking bandwidths between 100 ... 260 MHz are observed. All data have been achieved by operating the lasers in a hybrid mode-locking scheme with a required minimum micro-wave power of only 12 dBm for pulse synchronization. Details on laser chip architecture and module performance are summarized and the results of a stable and error free module performance in first 160 Gb/s (4 x 40 Gb/s OTDM) RZ-DPSK transmission experiments are presented.

  7. Frequency modulation and compression of optical pulses in an optical fibre with a travelling refractive-index wave

    SciTech Connect

    Zolotovskii, I O; Lapin, V A; Sementsov, D I

    2016-01-31

    We have studied the conditions for spectral broadening, frequency modulation and compression (both temporal and spectral) of Gaussian pulses propagating in a fibre with a travelling refractive-index wave. Analytical expressions have been derived for the dependences of pulse duration, chirp and spectral width on the distance travelled through the fibre, parameters of the fibre and radiation launched into it. Based on the numerical analysis we have studied the behaviour of these characteristics by changing the coefficient of the refractive-index modulation and other parameters of the travelling refractive-index wave. (nonlinear optical phenomena)

  8. Pulse Oximetry in the Physics Lab: A Colorful Alternative to Traditional Optics Curricula

    ERIC Educational Resources Information Center

    Kutschera, Ellynne; Dunlap, Justin C.; Byrd, Misti; Norlin, Casey; Widenhorn, Ralf

    2013-01-01

    We designed a physics laboratory exercise around pulse oximetry, a noninvasive medical technique used to assess a patient's blood oxygen saturation. An alternative to a traditional optics and light lab, this exercise teaches the principles of light absorption, spectroscopy, and the properties of light, while simultaneously studying a common…

  9. Multimode analysis of the light emitted from a pulsed optical parametric oscillator

    SciTech Connect

    Nielsen, Anne E. B.; Moelmer, Klaus

    2007-09-15

    We present a multimode treatment of the optical parametric oscillator, which is valid for both pulsed and continuous-wave pump fields. The two-time correlation functions of the output field are derived, and we apply the theory to analyze a scheme for heralded production of nonclassical field states that may be subsequently stored in an atomic quantum memory.

  10. Variable pulse repetition frequency output from an optically injected solid state laser.

    PubMed

    Kane, D M; Toomey, J P

    2011-02-28

    An optically injected solid state laser (OISSL) system is known to generate complex nonlinear dynamics within the parameter space of varying the injection strength of the master laser and the frequency detuning between the master and slave lasers. Here we show that within these complex nonlinear dynamics, a system which can be operated as a source of laser pulses with a pulse repetition frequency (prf) that can be continuously varied by a single control, is embedded. Generation of pulse repetition frequencies ranging from 200 kHz up to 4 MHz is shown to be achievable for an optically injected Nd:YVO4 solid state laser system from analysis of prior experimental and simulation results. Generalizing this to other optically injected solid state laser systems, the upper bound on the repetition frequency is of order the relaxation oscillation frequency for the lasers. The system is discussed in the context of prf versatile laser systems more generally. Proposals are made for the next generation of OISSLs that will increase understanding of the variable pulse repetition frequency operation, and determine its practical limitations. Such variable prf laser systems; both low powered, and, higher powered systems achieved using one or more optical power amplifier stages; have many potential applications from interrogating resonance behaviors in microscale structures, through sensing and diagnostics, to laser processing.

  11. Pulse Oximetry in the Physics Lab: A Colorful Alternative to Traditional Optics Curricula

    ERIC Educational Resources Information Center

    Kutschera, Ellynne; Dunlap, Justin C.; Byrd, Misti; Norlin, Casey; Widenhorn, Ralf

    2013-01-01

    We designed a physics laboratory exercise around pulse oximetry, a noninvasive medical technique used to assess a patient's blood oxygen saturation. An alternative to a traditional optics and light lab, this exercise teaches the principles of light absorption, spectroscopy, and the properties of light, while simultaneously studying a common…

  12. Streak camera measurements of laser pulse temporal dispersion in short graded-index optical fibers

    SciTech Connect

    Lerche, R.A.; Phillips, G.E.

    1981-08-28

    Streak camera measurements were used to determine temporal dispersion in short (5 to 30 meter) graded-index optical fibers. Results show that 50-ps, 1.06-..mu..m and 0.53-..mu..m laser pulses can be propagated without significant dispersion when care is taken to prevent propagation of energy in fiber cladding modes.

  13. Brillouin optical time-domain analysis sensor assisted by Brillouin distributed amplification of pump pulses.

    PubMed

    Urricelqui, Javier; Sagues, Mikel; Loayssa, Alayn

    2015-11-16

    We demonstrate the extension of the measurement range of Brillouin optical time-domain analysis (BOTDA) sensors using a distributed Brillouin amplifier (DBA). The technique is based on injecting a DBA pump wave in the fiber to generate an additional Brillouin interaction that amplifies the BOTDA pump pulses and compensates optical fiber attenuation. This amplification does not introduce any significant noise to the BOTDA's probe wave due to the inherent directionality of the Brillouin gain. Additionally, we deploy a differential pulse-width pair measurement method to avoid measurement errors due to the interplay between the self-phase modulation effect and the changes in the temporal shape of the pulses induced by the transient behavior of Brillouin gain. Experimental proof-of-concept results in a 50-km fiber link demonstrate full compensation of the fiber's attenuation with no penalty on the signal-to-noise ratio of the detected signal.

  14. Efficient graphene saturable absorbers on D-shaped optical fiber for ultrashort pulse generation

    PubMed Central

    Zapata, J. D.; Steinberg, D.; Saito, L. A. M.; de Oliveira, R. E. P.; Cárdenas, A. M.; de Souza, E. A. Thoroh

    2016-01-01

    We demonstrated a method to construct high efficiency saturable absorbers based on the evanescent light field interaction of CVD monolayer graphene deposited on side-polished D-shaped optical fiber. A set of samples was fabricated with two different core-graphene distances (0 and 1 μm), covered with graphene ranging between 10 and 25 mm length. The mode-locking was achieved and the best pulse duration was 256 fs, the shortest pulse reported in the literature with CVD monolayer graphene in EDFL. As result, we find a criterion between the polarization relative extinction ratio in the samples and the pulse duration, which relates the better mode-locking performance with the higher polarization extinction ratio of the samples. This criterion also provides a better understanding of the graphene distributed saturable absorbers and their reproducible performance as optoelectronic devices for optical applications. PMID:26856886

  15. Optical damage performance measurements of multilayer dielectric gratings for high energy short pulse lasers

    NASA Astrophysics Data System (ADS)

    Alessi, D.; Carr, C. W.; Negres, R. A.; Hackel, R. P.; Stanion, K. A.; Cross, D. A.; Guss, G.; Nissen, J. D.; Luthi, R.; Fair, J. E.; Britten, J. A.; Haefner, C.

    2015-02-01

    We investigate the laser damage resistance of multilayer dielectric (MLD) diffraction gratings used in the pulse compressors for high energy, high peak power laser systems such as the Advanced Radiographic Capability (ARC) Petawatt laser on the National Ignition Facility (NIF). Our study includes measurements of damage threshold and damage density (ρ(Φ)) with picosecond laser pulses at 1053 nm under relevant operational conditions. Initial results indicate that sparse defects present on the optic surface from the manufacturing processes are responsible for damage initiation at laser fluences below the damage threshold indicated by the standard R-on-1 test methods, as is the case for laser damage with nanosecond pulse durations. As such, this study supports the development of damage density measurements for more accurate predictions on the damage performance of large area optics.

  16. Dispersion-compensated beam-splitting of femtosecond light pulses: Wave optics analysis.

    PubMed

    Mínguez-Vega, Gladys; Tajahuerce, Enrique; Fernández-Alonso, Mercedes; Climent, Vicent; Lancis, Jesús; Caraquitena, José; Andrés, Pedro

    2007-01-22

    Recently, using parageometrical optics concepts, a hybrid, diffractive-refractive, lens triplet has been suggested to significantly improve the spatiotemporal resolution of light spots in multifocal processing with femtosecond laser pulses. Here, we carry out a rigorous wave-optics analysis, including the spatiotemporal nature of the wave equation, to elucidate both the spatial extent of the diffractive spots and the temporal duration of the pulse at the output plane. Specifically, we show nearly transform-limited behavior of diffraction maxima. Moreover, the temporal broadening of the pulse is related to the group velocity dispersion, which can be pre-compensated for in practical applications. Finally, some numerical simulations of the spatiotemporal wave field at the output plane in a realistic case are provided.

  17. Multi-Pulse Effects in the Damage to the LCLS Reflective Optics

    SciTech Connect

    Ryutov, D

    2004-07-29

    A number of experiments to be performed on the planned Linac Coherent Light Source (LCLS) will have to use various types of reflective optics (see, e.g., [1]). On the other hand, LCLS will operate at a rate of 120 x-ray pulses per second. Therefore, when considering effects leading to the damage to its optics, one has to be concerned not only with a possible damage within one pulse, but also with effects accumulating during many pulses. We identify and analyze two of such effects: a thermal fatigue, and the intensity-dependent radiation damage. The first effect is associated with thermal stresses and deformations that occur in every pulse. The heating of the surface layers of the optics leads to a peculiar distribution of stresses, with a strong concentration near the surface. The quasistatic analysis of this problem was presented in [2]. In the present study, we show that transients in both transverse and longitudinal acoustic perturbations play a significant role and generally worsen the situation. If the maximum stresses approach the yield strength, the thermal fatigue causes degradation of the surface within a few thousands pulses. The second effect is related to formation of clusters of ionized atoms which lead to gross deformation of the lattice and formation of numerous vacancies and interstitials. At maximum LCLS fluxes, the number of displacements per atom may reach values exceeding unity during a few hours of operation of LCLS, meaning degradation of reflective properties of the surface of the optics. We derive constraints on the admissible fluence per pulse and suggest ways for decreasing the impact of the multipulse effects.

  18. High-energy infrared femtosecond pulses generated by dual-chirped optical parametric amplification.

    PubMed

    Fu, Yuxi; Takahashi, Eiji J; Midorikawa, Katsumi

    2015-11-01

    We demonstrate high-energy infrared femtosecond pulse generation by a dual-chirped optical parametric amplification (DC-OPA) scheme [Opt. Express19, 7190 (2011)]. By employing a 100 mJ pump laser, a signal pulse energy exceeding 20 mJ at a wavelength of 1.4 μm was achieved before dispersion compensation. A total output energy of 33 mJ was recorded. Under a further energy scaling condition, the signal pulse was compressed to an almost transform-limited duration of 27 fs using a fused silica prism compressor. Since the DC-OPA scheme is efficient and energy scalable, design parameters for obtaining 100 mJ level infrared pulses are presented, which are suitable as driver lasers for the energy scaling of high-order harmonic generation with sub-keV photon energy.

  19. Pulsed ultrasound modulated optical tomography with harmonic lock-in holography detection.

    PubMed

    Ruan, Haowen; Mather, Melissa L; Morgan, Stephen P

    2013-07-01

    A method that uses digital heterodyne holography reconstruction to extract scattered light modulated by a single-cycle ultrasound (US) burst is demonstrated and analyzed. An US burst is used to shift the pulsed laser frequency by a series of discrete harmonic frequencies which are then locked on a CCD. The analysis demonstrates that the unmodulated light's contribution to the detected signal can be canceled by appropriate selection of the pulse repetition frequency. It is also shown that the modulated signal can be maximized by selecting a pulse sequence which consists of a pulse followed by its inverted counterpart. The system is used to image a 12 mm thick chicken breast with 2 mm wide optically absorbing objects embedded at the midplane. Furthermore, the method can be revised to detect the nonlinear US modulated signal by locking at the second harmonic US frequency.

  20. Visible-pulse generation in gain crystal of near-infrared femtosecond optical parametric oscillator.

    PubMed

    Jeong, Tae-Young; Kim, Seung-Hyun; Kim, Geon-Hee; Yee, Ki-Ju

    2015-10-05

    An optical parametric oscillator (OPO) based on magnesium-oxide-doped periodically poled lithium niobate (MgO:PPLN) is demonstrated to deliver visible femtosecond pulses, which were created through the intra-cavity nonlinear interactions within the PPLN itself. The signal from the OPO produces femtosecond pulses in the near-infrared region tunable from 1050 to 1600 nm. Visible femtosecond pulses in the range of 522-800 nm and those of 455-540 nm, respectively, were generated via second-harmonic generation (SHG) of signal photons and through sum-frequency generation (SFG) of pump and signal photons. Maximum output efficiencies of 9.2% at 614 nm and 8.0% at 522 nm for the SHG and SFG are attained, respectively, where the efficient visible pulse generation relies on the quasi-phase matching with the aid of the higher-order grating momentum.

  1. The Nature of Emission from Optical Breakdown Induced by Pulses of fs and ns Duration

    SciTech Connect

    Carr, C W; Feit, M D; Rubenchik, A M; Demange, P; Kucheyev, S; Shirk, M D; Radousky, H B; Demos, S G

    2004-11-09

    Spectral emission from optical breakdown in the bulk of a transparent dielectric contains information about the nature of the breakdown medium. We have made time resolved measurements of the breakdown induced emission caused by nanosecond and femtosecond infrared laser pulses. We previously demonstrated that the emission due to ns pulses is blackbody in nature allowing determination of the fireball temperature and pressure during and after the damage event. The emission due to femtosecond pulse breakdown is not blackbody in nature; two different spectral distributions being noted. In one case, the peak spectral distribution occurs at the second harmonic of the incident radiation, in the other the distribution is broader and flatter and presumably due to continuum generation. The differences between ns and fs breakdown emission can be explained by the differing breakdown region geometries for the two pulse durations. The possibility to use spectral emission as a diagnostic of the emission region morphology will be discussed.

  2. An optical parametric chirped-pulse amplifier for seeding high repetition rate free-electron lasers

    SciTech Connect

    Höppner, H.; Tanikawa, T.; Schulz, M.; Riedel, R.; Teubner, U.; Faatz, B.; Tavella, F.

    2015-05-15

    High repetition rate free-electron lasers (FEL), producing highly intense extreme ultraviolet and x-ray pulses, require new high power tunable femtosecond lasers for FEL seeding and FEL pump-probe experiments. A tunable, 112 W (burst mode) optical parametric chirped-pulse amplifier (OPCPA) is demonstrated with center frequencies ranging from 720–900 nm, pulse energies up to 1.12 mJ and a pulse duration of 30 fs at a repetition rate of 100 kHz. Since the power scalability of this OPCPA is limited by the OPCPA-pump amplifier, we also demonstrate a 6.7–13.7 kW (burst mode) thin-disk OPCPA-pump amplifier, increasing the possible OPCPA output power to many hundreds of watts. Furthermore, third and fourth harmonic generation experiments are performed and the results are used to simulate a seeded FEL with high-gain harmonic generation.

  3. On the ability of resonant diffraction gratings to differentiate a pulsed optical signal

    SciTech Connect

    Bykov, D. A. Doskolovich, L. L.; Soifer, V. A.

    2012-05-15

    The passage of an optical pulse through a resonant grating is considered. The conditions under which the resonant grating differentiates the envelope of the incident pulse are determined. It is shown that the necessary condition for computing the k-order derivative is the presence of k resonances in the transmission spectrum of the grating in the vicinity of the central frequency of the incident pulse. A method is described for constructing the stacked structure for computing the kth derivative on the basis of repetition of the structure for computing the first derivative. The results of numerical simulation of diffraction of the pulse from the analyzed structure for computing the first, second, and third derivative are presented.

  4. Propagation of ultrashort laser pulses in optically ionized gases

    SciTech Connect

    Morozov, A.; Luo, Y.; Suckewer, S.; Gordon, D. F.; Sprangle, P.

    2010-02-15

    Propagation of 800 nm, 120 fs laser pulses with intensities of 4x10{sup 16} W/cm{sup 2} in supersonic gas jets of N{sub 2} and H{sub 2} is studied using a shear-type interferometer. The plasma density distribution resulting from photoionization is resolved in space and time with simultaneously measured initial neutral density distribution. A distinct difference in laser beam propagation distance is observed when comparing propagation in jets of H{sub 2} and N{sub 2}. This is interpreted in terms of ionization induced refraction, which is stronger when electrons are produced from states of higher ionization potential. Three dimensional particle-in-cell simulations, based on directly solving the Maxwell-Lorentz system of equations, show the roles played by the forward Raman and ionization scattering instabilities, which further affect the propagation distance.

  5. Rejection of false saturation data in optical pulse-oximeter

    NASA Astrophysics Data System (ADS)

    Scalise, Lorenzo; Marchionni, Paolo; Carnielli, Virgilio

    2010-04-01

    Pulse oximetry (PO) is a non-invasive medical device used for monitoring of the arterial oxygen saturation (SaO2) and in particular of haemoglobin oxygenation in blood. Oxygen saturation is commonly used in any setting where the patient blood oxygen saturation is unstable, including Neonatal Intensive Care Unit (NICU). The main factor affecting PO's output data is the presence of voluntary or involuntary motion artifacts or imperfect skin-sensor contact. Various methods have been employed to reject motion artifact but have met with little success. The aim of the present work is to propose a novel measurement procedure for real-time monitoring and validation of the oxygen saturation data as measured in standard pulse oxymeter. The procedure should be able to individuate and reject erroneous saturation data due to incorrect transducer-skin contact or motion artifact. In the case of short sequences of rejected SpO2 data (time duration< 8s), we report on an algorithm able to substitute the sequence of rejected data with the "most-probable" (rescued) SpO2 data. In total we have analyzed 14 patient for a total of 310 hr, 43 min and 15s, equivalent to a total number of samples of 1118595. For our study, we were interested to download heart rate measured with the ECG (HRECG), the heart rate as measured by the pulse oximeter (HRSAT) and the SpO2 value. In order to remove the erroneous SpO2 values reported in the rough data in coincidence of motion artifact (top, right), we have implemented a specific algorithm which provides at the output a new sequence of SpO2 data (validated SpO2 data). With the aim to "rescue" SpO2 value rejected by the previously presented algorithm, we have implemented an algorithm able to provide the "most-probable" SpO2 values in the case of single rejected values or in the case of short sequences of invalidated data (< 8 s). From these data it is possible to observe how in the 6.8% of the observation time the SpO2 data measured by the pulse oximeter

  6. Demonstration of Pulse Switching with > 1011 Prepulse Contrast by Cascaded Optical Parametric Amplification

    NASA Astrophysics Data System (ADS)

    Haefner, Constantin; Jovanovic, Igor; Wattelier, Benoit; Barty, C. P. J.

    The use of chirped-pulse amplification (CPA) in high-energy systems allows the generation of high-peak power and ultrahigh intensity, and has led to intensities greater than 1020 W · cm-2 [1]-[3]. These systems are of especially high interest for exploring high-energy dense plasma physics and for fast ignition in inertial confinement fusion [4]. In these systems the control of the prepulses is crucial as their intensity might perturb the target before the main pulse arrives. Plasma generation thresholds of solid targets are generally of the order of 1010 W · cm-2 and hence require a contrast ratio exceeding 1010 for a 1020 W · cm-2 system. Optical parametric chirped-pulse amplification (OPCPA), a CPA technique which relies on the three-wave mixing process in a nonlinear crystal, has received much attention due to its superior characteristics for broadband amplification in high-power laser system front-ends. In fact, OPCPA operated near degeneracy and thus providing high gain while maintaining broad spectral bandwidth is increasingly replacing Ti:sapphire front-ends in Nd:glass short-pulse lasers [5]-[8]. With respect to the prepulse contrast ratio, an OPCPA system offers enormous advantages. High-gain regenerative amplifiers usually produce a train of prepulses caused by the cavity leakage due to the limited extinction ratio of the intracavity polarizer, and they thus require additional postamplification temporal pulse cleaning techniques (e.g. [9],[10]). OPCPA amplifies only a single pulse out of the oscillator pulse train resulting in a prepulse contrast enhancement equal to the total saturated gain, provided that the pump pulse duration is sufficiently short so that there is no temporal overlap of the pump pulse with preceding or subsequent pulses.

  7. Multiple Scattering Effects on Pulse Propagation in Optically Turbid Media.

    NASA Astrophysics Data System (ADS)

    Joelson, Bradley David

    The effects of multiple scattering in a optically turbid media is examined for an impulse solution to the radiative transfer equation for a variety of geometries and phase functions. In regions where the complexities of the phase function proved too cumbersome for analytic methods Monte Carlo techniques were developed to describe the entire scalar radiance distribution. The determination of a general spread function is strongly dependent on geometry and particular regions where limits can be placed on the variables of the problem. Hence, the general spread function is first simplified by considering optical regions which reduce the complexity of the variable dependence. First, in the small-angle limit we calculate some contracted spread functions along with their moments and then use Monte Carlo techniques to establish the limitations imposed by the small-angle approximation in planar geometry. The point spread function (PSF) for a spherical geometry is calculated for the full angular spread in the forward direction of ocean waters using Monte Carlo methods in the optically thin and moderate depths and analytic methods in the diffusion domain. The angular dependence of the PSF for various ocean waters is examined for a range of optical parameters. The analytic method used in the diffusion calculation is justified by examining the angular dependence of the radiance of a impulse solution in a planar geometry for a prolongated Henyey-Greenstein phase function of asymmetry factor approximately equal to that of the ocean phase functions. The Legendre moments of the radiance are examined in order to examine the viability of the diffusion approximation which assumes a linearly anisotropic angular distribution for the radiance. A realistic lidar calculation is performed for a variety of ocean waters to determine the effects of multiple scattering on the determination of the speed of sound by using the range gated frequency spectrum of the lidar signal. It is shown that the

  8. Spectral Shearing of Quantum Light Pulses by Electro-Optic Phase Modulation

    NASA Astrophysics Data System (ADS)

    Wright, Laura J.; Karpiński, Michał; Söller, Christoph; Smith, Brian J.

    2017-01-01

    Frequency conversion of nonclassical light enables robust encoding of quantum information based upon spectral multiplexing that is particularly well-suited to integrated-optics platforms. Here we present an intrinsically deterministic linear-optics approach to spectral shearing of quantum light pulses and show it preserves the wave-packet coherence and quantum nature of light. The technique is based upon an electro-optic Doppler shift to implement frequency shear of heralded single-photon wave packets by ±200 GHz , which can be scaled to an arbitrary shift. These results demonstrate a reconfigurable method to controlling the spectral-temporal mode structure of quantum light that could achieve unitary operation.

  9. Methods and optical fibers that decrease pulse degradation resulting from random chromatic dispersion

    DOEpatents

    Chertkov, Michael; Gabitov, Ildar

    2004-03-02

    The present invention provides methods and optical fibers for periodically pinning an actual (random) accumulated chromatic dispersion of an optical fiber to a predicted accumulated dispersion of the fiber through relatively simple modifications of fiber-optic manufacturing methods or retrofitting of existing fibers. If the pinning occurs with sufficient frequency (at a distance less than or are equal to a correlation scale), pulse degradation resulting from random chromatic dispersion is minimized. Alternatively, pinning may occur quasi-periodically, i.e., the pinning distance is distributed between approximately zero and approximately two to three times the correlation scale.

  10. Preparation of an exponentially rising optical pulse for efficient excitation of single atoms in free space

    NASA Astrophysics Data System (ADS)

    Dao, Hoang Lan; Aljunid, Syed Abdullah; Maslennikov, Gleb; Kurtsiefer, Christian

    2012-08-01

    We report on a simple method to prepare optical pulses with exponentially rising envelope on the time scale of a few ns. The scheme is based on the exponential transfer function of a fast transistor, which generates an exponentially rising envelope that is transferred first on a radio frequency carrier, and then on a coherent cw laser beam with an electro-optical phase modulator. The temporally shaped sideband is then extracted with an optical resonator and can be used to efficiently excite a single 87Rb atom.

  11. Multilevel optical information recording in silver-containing photosensitive glasses by UV laser pulses

    NASA Astrophysics Data System (ADS)

    Gorbiak, Veronika V.; Sidorov, Alexander I.; Vasilyev, Vladimir N.; Dubrovin, Viktor D.; Nikonorov, Nikolay V.

    2017-04-01

    It is experimentally shown that silver-containing silicate photosensitive glasses can be used for multilevel optical information recording using UV nanosecond laser pulses. Information can be recorded by the creation of luminescent centers, which are neutral silver molecular clusters, or silver nanoparticles with plasmon resonance using additional thermal treatment. It is shown that silver nanoparticles formed in glass have spheroidal shapes and have dielectric shells. Multilevel optical information recording can be performed by modulation of luminescence or absorption intensity varying UV laser irradiation dose. The effect of dopants (Ce, Sb, and Cl) on the recording process is shown. The described methods allow to record optical information in octal and hexadecimal number systems.

  12. Optical Kerr effect of tRNA solution induced by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Kucia, Weronika E.; Sharma, Gargi; Joseph, Cecil S.; Sarbak, Szymon; Oliver, Cameron; Dobek, Andrzej; Giles, Robert H.

    2016-10-01

    The optical Kerr effect (OKE) in a transfer ribonucleic acid (tRNA) solution induced by femtosecond pulses of linearly polarized pump light (λi = 800 nm) and sounded by probe light (λp = 800 nm) was studied. The measurements were performed to find nonlinear optical parameters describing a single molecule (molecular Kerr constant K, mean nonlinear third order optical polarizability cpi) and to compare them with our previous OKE results obtained in ns and ps time range. The OKE experiment has proven to be an efficient method to obtain the nonlinear parameters of single molecules in solution, which reflects dynamic structure changes.

  13. Extreme nonlinear terahertz electro-optics in diamond for ultrafast pulse switching

    NASA Astrophysics Data System (ADS)

    Shalaby, Mostafa; Vicario, Carlo; Hauri, Christoph P.

    2017-03-01

    Polarization switching of picosecond laser pulses is a fundamental concept in signal processing [C. Chen and G. Liu, Annu. Rev. Mater. Sci. 16, 203 (1986); V. R. Almeida et al., Nature 431, 1081 (2004); and A. A. P. Pohl et al., Photonics Sens. 3, 1 (2013)]. Conventional switching devices rely on the electro-optical Pockels effect and work at radio frequencies. The ensuing gating time of several nanoseconds is a bottleneck for faster switches which is set by the performance of state-of-the-art high-voltage electronics. Here we show that by substituting the electric field of several kV/cm provided by modern electronics by the MV/cm field of a single-cycle THz laser pulse, the electro-optical gating process can be driven orders of magnitude faster, at THz frequencies. In this context, we introduce diamond as an exceptional electro-optical material and demonstrate a pulse gating time as fast as 100 fs using sub-cycle THz-induced Kerr nonlinearity. We show that THz-induced switching in the insulator diamond is fully governed by the THz pulse shape. The presented THz-based electro-optical approach overcomes the bandwidth and switching speed limits of conventional MHz/GHz electronics and establishes the ultrafast electro-optical gating technology for the first time in the THz frequency range. We finally show that the presented THz polarization gating technique is applicable for advanced beam diagnostics. As a first example, we demonstrate tomographic reconstruction of a THz pulse in three dimensions.

  14. A nonlinearity-tolerant frequency domain root M-shaped pulse for coherent optical communication systems.

    PubMed

    Xu, Xian; Zhuge, Qunbi; Châtelain, Benoît; Morsy-Osman, Mohamed; Chagnon, Mathieu; Qiu, Meng; Plant, David V

    2013-12-30

    A new intersymbol interference (ISI)-free nonlinearity-tolerant frequency domain root M-shaped pulse (RMP) is derived for dispersion unmanaged coherent optical transmission systems. Beginning with the relationship between pulse shaping and intra-channel nonlinearity effects, we derive closed-form expressions for the proposed pulse. Experimental demonstrations reveal that by employing the proposed pulse at a roll-off factor of 1, the maximum transmission reach of a single-channel 56 Gb/s polarization-division-multiplexed quadrature phase-shift keying (PDM-QPSK) system can be extended by 33% and 17%, when compared to systems using a root raised cosine (RRC) pulse and a root optimized pulse (ROP), respectively. For a single-channel 128 Gb/s polarization-division-multiplexed 16-quadrature amplitude modulation (PDM-16QAM) system, the reach can be extended by 44% and 18%, respectively. Reach increases of 30% and 13% are also observed for a dense wavelength-division multiplexing (DWDM) 504 Gb/s PDM-QPSK transmission system. The tolerance to narrow filtering effect for the three pulses is experimentally studied as well.

  15. Measurement of complex ultrashort laser pulses using frequency-resolved optical gating

    NASA Astrophysics Data System (ADS)

    Xu, Lina

    This thesis contains three components of research: a detailed study of the performance of Frequency-Resolved Optical Gating (FROG) for measuring complex ultrashort laser pulses, a new method for measuring the arbitrary polarization state of an ultrashort laser pulse using Tomographic Ultrafast Retrieval of Transverse Light E-fields (TURTLE) technique, and new approach for measuring two complex pulses simultaneously using PG blind FROG. In recent decades, many techniques for measuring the full intensity and phase of ultrashort laser pulses have been proposed. These techniques include: Spectral Interferometry (SI)[1], Temporal Analysis by Dispersing a Pair of Light E-Field (TADPOLE)[2], Spectral Phase Interferometry for direct electric-field reconstruction (SPIDER)[3], and Frequency-Resolved Optical Gating (FROG)[4]. Each technique is actually a class of techniques that includes different variations on the original idea, such as SEA-SPIDER[5], ZAP SPIDER[6] are two variations of SPIDER. But most of these techniques for measuring ultrashort laser pulses either do not yield the complete time-dependent intensity and phase (e.g., autocorrelation), can at best only measure simple pulses (e.g., SPIDER), or need well characterized reference pulse. In this thesis, we compare the performance of three versions of FROG: second-harmonic-generation (SHG) FROG, polarization-gate (PG) FROG, and cross-correlation FROG (XFROG), the last of which requires a well-characterized reference pulse. We found that the XFROG algorithm converged in all cases and required only one initial guess. The PG FROG algorithm converged for 99% of the moderately complex pulses that we tried, and for over 95% of the most complex pulses (TBP ˜ 100). And the SHG FROG algorithm converged for 95% of the pulses that we tried and for over 80% of the most complex pulses. After some analysis, we found that noise filtering and adding more sampling points to the FROG trace solved the non-converging problems and we

  16. NONLINEAR-OPTICS PHENOMENA: Formation of optical pulses by modulating the resonant quantum transition frequency in a spectrally inhomogeneous medium

    NASA Astrophysics Data System (ADS)

    Polovinkin, V. A.; Radionychev, E. V.

    2010-02-01

    We consider the conversion of monochromatic radiation in the case of resonant interaction with a quantum system under the condition of harmonic modulation of the quantum transition frequency by the action of additional nonresonant radiation due to the Stark or Zeeman effect, taking into account the inhomogeneous broadening of the quantum transition line. It is shown analytically and numerically that resonant radiation can be converted in a train of ultrashort pulses with a peak intensity exceeding manifold the incident wave intensity. The possibility of the additional compression of the produced pulses is studied by compensating the inherent frequency modulation in a medium with a quadratic or programmable dispersion. The optimal values of the radiation — matter interaction parameters are found numerically. It is shown that generation of femtosecond optical pulses of radiation quasi-resonant to the δ transition of the atomic hydrogen Balmer series is possible.

  17. Causal information velocity in fast and slow pulse propagation in an optical ring resonator

    SciTech Connect

    Tomita, Makoto; Uesugi, Hiroyuki; Sultana, Parvin; Oishi, Tohru

    2011-10-15

    We examined the propagation of nonanalytical points encoded on temporally Gaussian-shaped optical pulses in fast and slow light in an optical ring resonator at {lambda} = 1.5 {mu}m. The temporal peak of the Gaussian pulse was either advanced or delayed, reflecting anomalous or normal dispersions in the ring resonator, relevant to under- or overcoupling conditions, respectively. The nonanalytical points were neither advanced nor delayed but appeared as they entered the ring resonator. The nonanalytical points could be interpreted as information; therefore, the experimental results suggested that information velocity is equal to the light velocity in vacuum or the background medium, independent of the group velocity. The transient behaviors at the leading and trailing edges of the nonanalytical points are discussed in terms of optical precursors.

  18. Double-passed, high-energy quasi-phase-matched optical parametric chirped-pulse amplifier

    SciTech Connect

    Jovanovic, I; Forget, N; Brown, C G; Ebbers, C A; Blanc, C L; Barty, C J

    2005-09-19

    Quasi-phase-matched (QPM) optical parametric chirped-pulse amplification (OPCPA) in periodically poled materials such as periodically poled LiNbO{sub 3} (PPLN) and periodically poled KTiOPO{sub 4} (PPKTP) has been shown to exhibit advantages over the OPCPA in bulk nonlinear crystals. [GHH98, RPN02] The use of the maximum material nonlinear coefficient results in ultra-high gain with low pump peak power. Furthermore, propagation of signal, pump, and idler beams along one of the crystal principal axes eliminates the birefringent walk-off, reduces angular sensitivity, and improves beam quality. Relatively high level of parasitic parametric fluorescence (PF) in QPM OPCPA represents an impediment for simple, single-stage, high-gain amplification of optical pulses from nJ to mJ energies. PF in QPM is increased when compared to PF in critical phase matching in bulk crystals as a result of broader angular acceptance of the nonlinear conversion process. PF reduces prepulse contrast and conversion efficiency by competition with the signal pulse for pump pulse energy. Previous experiments with QPM OPCPA have thus resulted in pulse energies limited to tens of {mu}J. [JSE03] Optical parametric amplification of a narrowband signal pulse in PPKTP utilizing two pump beams has been demonstrated at a mJ-level, [FPK03] but the conversion efficiency has been limited by low energy extraction of pump pulse in the first pass of amplification. Additionally, narrow spectral bandwidth was the result of operation far from signal-idler degeneracy. Here we present a novel double-pass, broad-bandwidth QPM OPCPA. 1.2 mJ of amplified signal energy is produced in a single PPKTP crystal utilizing a single 24-mJ pump pulse from a commercial pump laser. [JFE05] To our knowledge, this is the highest energy demonstrated in QPM OPCPA. Double-passed QPM OPCPA exhibits high gain (> 3 x 10{sup 6}), high prepulse contrast (> 3 x 10{sup 7}), high energy stability (3% rms), and excellent beam quality. We

  19. The optical emission spectroscopy of pulsed and pulse- periodic discharges initiated with runaway electrons

    NASA Astrophysics Data System (ADS)

    Lomaev, M.; Sorokin, D.; Tarasenko, V.

    2015-11-01

    We report on the results of measurements of an electron Te and a gas Tg temperatures as well as a reduced electric field strength E/N in the plasma of a high-voltage nanosecond discharge initiated with runaway electrons in a gap with a strongly nonuniform electric field distribution. The foregoing plasma parameters were determined with optical emission spectroscopy techniques. The possibility of using the method for determining Te and E/N in thermodynamically nonequilibrium plasma, which is based on a determination of a ratio of a peak intensities of the ionic (λ = 391.4 nm) and molecular N2 (λ = 394 nm) nitrogen bands, is proved. To measure a gas temperature the optical emission spectroscopy technique based on the measurement of a relative radiation intensity of rotation structure of electronic-vibrational molecular transitions was used, as well.

  20. Optical layer development for thin films thermal conductivity measurement by pulsed photothermal radiometry

    SciTech Connect

    Martan, J.

    2015-01-15

    Measurement of thermal conductivity and volumetric specific heat of optically transparent thin films presents a challenge for optical-based measurement methods like pulsed photothermal radiometry. We present two approaches: (i) addition of an opaque optical layer to the surface and (ii) approximate correction of the mathematical model to incorporate semitransparency of the film. Different single layer and multilayer additive optical layers were tested. The materials of the optical layers were chosen according to analysis and measurement of their optical properties: emissivity and absorption coefficient. Presented are thermal properties’ measurement results for 6 different thin films with wide range of thermal conductivity in three configurations of surface: as deposited, added Ti layer, and added Ti/TiAlSiN layer. Measurements were done in dependence on temperature from room temperature to 500 °C. The obtained thermal effusivity evolution in time after the laser pulse shows different effects of the surface layers: apparent effusivity change and time delay. Suitability of different measurement configurations is discussed and results of high temperature testing of different optical layers are presented.

  1. Miniaturized pulsed laser source for time-domain diffuse optics routes to wearable devices.

    PubMed

    Di Sieno, Laura; Nissinen, Jan; Hallman, Lauri; Martinenghi, Edoardo; Contini, Davide; Pifferi, Antonio; Kostamovaara, Juha; Mora, Alberto Dalla

    2017-08-01

    We validate a miniaturized pulsed laser source for use in time-domain (TD) diffuse optics, following rigorous and shared protocols for performance assessment of this class of devices. This compact source (12×6  mm2) has been previously developed for range finding applications and is able to provide short, high energy (∼100  ps, ∼0.5  nJ) optical pulses at up to 1 MHz repetition rate. Here, we start with a basic level laser characterization with an analysis of suitability of this laser for the diffuse optics application. Then, we present a TD optical system using this source and its performances in both recovering optical properties of tissue-mimicking homogeneous phantoms and in detecting localized absorption perturbations. Finally, as a proof of concept of in vivo application, we demonstrate that the system is able to detect hemodynamic changes occurring in the arm of healthy volunteers during a venous occlusion. Squeezing the laser source in a small footprint removes a key technological bottleneck that has hampered so far the realization of a miniaturized TD diffuse optics system, able to compete with already assessed continuous-wave devices in terms of size and cost, but with wider performance potentialities, as demonstrated by research over the last two decades. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  2. Optical cell cleaning with NIR femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Uchugonova, Aisada; Breunig, Hans Georg; Batista, Ana; König, Karsten

    2015-03-01

    Femtosecond laser microscopes have been used as both micro and nanosurgery tools. The optical knock-out of undesired cells in multiplex cell clusters shall be further reported on in this study. Femtosecond laser-induced cell death is beneficial due to the reduced collateral side effects and therefore can be used to selectively destroy target cells within monolayers, as well as within 3D tissues, all the while preserving cells of interest. This is an important characteristic for the application in stem cell research and cancer treatment. Non-precise damage compromises the viability of neighboring cells by inducing side effects such as stress to the cells surrounding the target due to the changes in the microenvironment, resulting from both the laser and laser-exposed cells. In this study, optimum laser parameters for optical cleaning by isolating single cells and cell colonies are exploited through the use of automated software control. Physiological equilibrium and cellular responses to the laser induced damages are also investigated. Cell death dependence on laser focus, determination and selectivity of intensity/dosage, controllable damage and cell recovery mechanisms are discussed.

  3. co2amp: A software program for modeling the dynamics of ultrashort pulses in optical systems with CO2 amplifiers

    DOE PAGES

    Polyanskiy, Mikhail N.

    2015-01-01

    We describe a computer code for simulating the amplification of ultrashort mid-infrared laser pulses in CO2 amplifiers and their propagation through arbitrary optical systems. This code is based on a comprehensive model that includes an accurate consideration of the CO2 active medium and a physical optics propagation algorithm, and takes into account the interaction of the laser pulse with the material of the optical elements. Finally, the application of the code for optimizing an isotopic regenerative amplifier is described.

  4. Ultrafast single-shot measurement of optical Kerr effect based on supercontinuum pulse.

    PubMed

    Zhang, Jian; Liu, Shenye; Yi, Tao; Wu, Xingzhi; Song, Yinglin; Zhang, Ben; Zhong, Quanjie

    2016-04-01

    We present an ultrafast single-shot measurement method for the optical Kerr effect based on a polarization gating technique. The advantages of this single-shot technique are demonstrated via a 26-ps chirped supercontinuum pulse used to measure the optical Kerr effect for three transparent organic liquids. The single-shot measurement results agree well with those of the time-resolved optical Kerr gate method, as regards both time and intensity. This method facilitates real-time observation of ultrafast optical Kerr responses of samples and simultaneous high-time-resolution data acquisition at ∼260 fs. We demonstrate that the single-shot measurement method is potentially a powerful tool for investigating the optical Kerr effects of unstable samples, and for application to high-power laser systems.

  5. Optical injection using colliding laser pulses: experiments at LBNL

    NASA Astrophysics Data System (ADS)

    Leemans, W. P.; Geddes, C. G. R.; Toth, C.; Faure, J.; van Tilborg, J.; Marcelis, B.; Esarey, E.; Schroeder, C. B.; Fubiani, G.; Shadwick, B. A.; Dugan, G.; Cary, J.; Giacone, R.

    2002-11-01

    Laser driven acceleration in plasmas has succeeded in producing electron beams containing multi-nC's of charge, with some fraction of the electrons having energies in excess of 10's of MeV's but 100 % energy spread. One of the current challenges is to produce electron beams with much reduced energy spread. We report on experimental progress in the laser triggered injection of electrons in a laser wakefield accelerator using the colliding pulse method (E. Esarey et al., Phys. Rev. Lett. 79, 2682 (1997).), (C.B. Schroeder et al., Phys. Rev. E 59, 6037 (1999).). The experiments use the l'OASIS multi-beam 10 Hz high power Ti:Al_2O3 laser system (W.P. Leemans et al., Phys. Plasmas 8, 2510 (2001).). In the present experiments, two counter propagating beams (30^rc angle) are focused onto a high density gas jet. Preliminary results indicate that electron beam properties are affected by the second beam. Details of the experiments will be shown as well as comparisons with simulations.

  6. Generation of a 2.2 nJ picosecond optical pulse with blue-violet wavelength using a GaInN master oscillator power amplifier

    NASA Astrophysics Data System (ADS)

    Koda, Rintaro; Takiguchi, Yoshiro; Kono, Shunsuke; Watanabe, Hideki; Hanzawa, Yasunari; Nakajima, Hiroshi; Shiozaki, Masaki; Sugawara, Nobuhiro; Kuramoto, Masaru; Narui, Hironobu

    2015-07-01

    We report the generation of a picosecond optical pulse with 2.2 nJ pulse energy at blue-violet wavelengths using a GaN-based mode-locked laser diode (MLLD) and a semiconductor optical amplifier (SOA). The picosecond optical pulse generated by MLLD at a frequency of 812 MHz was amplified effectively by SOA. We optimized SOA with a widely flared waveguide structure to generate a high optical pulse energy.

  7. Design of a Multistep Phase Mask for High-Energy Terahertz Pulse Generation by Optical Rectification

    NASA Astrophysics Data System (ADS)

    Avetisyan, Y.; Makaryan, A.; Tadevosyan, V.; Tonouchi, M.

    2017-08-01

    A new scheme for generating high-energy terahertz (THz) pulses based on using a multistep phase mask (MSPM) is suggested and analyzed. The mask is placed on the entrance surface of the nonlinear optical (NLO) crystal eliminating the necessity of the imaging optics. In contrast to the contact grating method, introduction of large amounts of angular dispersion is avoided. The operation principle of the suggested scheme is based on the fact that the MSPM splits a single input beam into many smaller time-delayed "beamlets," which together form a discretely tilted-front laser pulse in NLO crystal. The analysis of THz-pulse generation in ZnTe and lithium niobate (LN) crystals shows that application of ZnTe crystal is more preferable, especially when long-wavelength pump sources are used. The dimensions of the mask's steps required for high-energy THz-pulse generation in ZnTe and LN crystals are calculated. The optimal number of steps is estimated, taking into account individual beamlet's spatial broadening and problems related to the mask fabrication. The proposed method is a promising way to develop high-energy, monolithic, and alignment-free THz-pulse sources.

  8. Third-order nonlinear optical response in transparent solids using ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Dota, K.; Dharmadhikari, J. A.; Mathur, D.; Dharmadhikari, A. K.

    2012-06-01

    The third-order optical nonlinearity, χ (3), is measured in transparent glasses (BK7 and fused silica) and crystals (BaF2 and quartz) using 36-fs, 800-nm laser pulses and the optical Kerr gate (OKE) technique; values are found to lie in the range 1.3-1.7×10-14 esu, in accordance with theoretical estimates. We probe the purely electronic response to the incident ultrashort laser pulse in fused silica and BK7 glass. In BaF2 and quartz, apart from the electronic response we also observe contribution from the nuclear response to the incident ultrashort pulses. We observe oscillatory modulations that persist for ˜400 fs. The response of the media (glasses and crystals) to ultrashort pulses is also measured using two-beam self-diffraction; the diffraction efficiency in the first-order grating is measured to be in the range of 0.06-0.13 %. Third harmonic generation due to self-phase matching in the transient grating geometry is measured as a function of temporal delay between the two incident ultrashort pulses, yielding the autocorrelation signal.

  9. Highly Efficient Tabletop Optical Parametric Chirped Pulse Amplifier at 1 (micron)m

    SciTech Connect

    Jovanovic, I.; Ebbers, C.A.; Comaskey, B.J.; Bonner, R.A.; Morse, E.C.

    2001-12-04

    Optical parametric chirped pulse amplification (OPCPA) is a scalable technology, for ultrashort pulse amplification. Its major advantages include design simplicity, broad bandwidth, tunability, low B-integral, high contrast, and high beam quality. OPCPA is suitable both for scaling to high peak power as well as high average power. We describe the amplification of stretched 100 fs oscillator pulses in a three-stage OPCPA system pumped by a commercial, single-longitudinal-mode, Q-switched Nd:YAG laser. The stretched pulses were centered around 1054 nm with a FWHM bandwidth of 16.5 nm and had an energy of 0.5 nJ. Using our OPCPA system, we obtained an amplified pulse energy of up to 31 mJ at a 10 Hz repetition rate. The overall conversion efficiency from pump to signal is 6%, which is the highest efficiency obtained With a commercial tabletop pump laser to date. The overall conversion efficiency is limited due to the finite temporal overlap of the seed (3 ns) with respect to the duration of the pump (8.5 ns). Within the temporal window of the seed pulse the pump to signal conversion efficiency exceeds 20%. Recompression of the amplified signal was demonstrated to 310 fs, limited by the aberrations initially present in the low energy seed imparted by the pulse stretcher. The maximum gain in our OPCPA system is 6 x 10{sup 7}, obtained through single passing of 40 mm of beta-barium borate. We present data on the beam quality obtained from our system (M{sup 2}=1.1). This relatively simple system replaces a significantly more complex Ti:sapphire regenerative amplifier based CPA system used in the front end of a high energy short pulse laser. Future improvement will include obtaining shorter amplified pulses and higher average power.

  10. Fiber optic cables for transmission of high-power laser pulses

    NASA Astrophysics Data System (ADS)

    Thomes, W. Joe, Jr.; Ott, Melanie N.; Chuska, Richard F.; Switzer, Robert C.; Blair, Diana E.

    2011-09-01

    High power pulsed lasers are commonly deployed in harsh environments, like space flight and military missions, for a variety of systems such as LIDAR, optical communications over long distances, or optical firing of explosives. Fiber coupling of the laser pulse from the laser to where it is needed can often save size, reduce weight, and lead to a more robust and reliable system. Typical fiber optic termination procedures are not sufficient for injection of these high power laser pulses without catastrophic damage to the fiber endface. In the current study, we will review the causes of fiber damage during high power injection and discuss methods used to avoid these issues to permit fiber use with high reliability in these applications. A brief review of the design considerations for high peak power laser pulse injection will be presented to familiarize the audience with all the areas that need to be considered during the design phase. The majority of this paper focuses on the proper fiber polishing methods for high power use with an emphasis on laser polishing of the fibers. Results from recently build fibers will be shown to demonstrate the techniques.

  11. Quasi-stationary convection in a periodic-pulsed optical discharge in high pressure rare gas

    NASA Astrophysics Data System (ADS)

    Zimakov, V. P.; Kuznetsov, V. A.; Solovyov, N. G.; Shemyakin, A. N.; Shilov, A. O.; Yakimov, M. Yu

    2017-02-01

    Unusual convection flows were observed in stabilized pre-breakdown phase of the periodic-pulsed optical discharge (POD) called “quiet” POD. The discharge was a relatively weakly glowing plasma filament sustained by focused λ = 1.064 μm laser pulses with repetition rate of fr = 50÷100 kHz at the intensity several times below than that required for the optical breakdown to occur. No strong shock waves or irregular turbulence around the discharge were observed, in contrast to breakdown types of POD. Significant laser beam refraction measured in the beam cross-section behind the discharge zone was explained by the gas heating in the discharge up to 10 kK, providing high gradients of gas density and refraction index. Intense convective flow was detected on the schlieren images as thermal traces of the laser-induced gas streams flowing from the discharge zone, directed mainly normally to the optical axis. Repeated relaxation of the gas expanding after being rapidly heated by the laser pulse is proposed to explain the effect. The periodic-pulsed discharge located in the elongated beam waist generates an anisotropic heated region with gas streams and vortices, which may form the observed regular convective flow at the late stages of expanding.

  12. Optical field ionization of atoms and ions using ultrashort laser pulses

    SciTech Connect

    Fittinghoff, David Neal

    1993-12-01

    This dissertation research is an investigation of the strong optical field ionization of atoms and ions by 120-fs, 614-run laser pulses and 130-fs, 800-nm laser pulses. The experiments have shown ionization that is enhanced above the predictions of sequential tunneling models for He+2, Ne+2 and Ar+2. The ion yields for He+1, Ne+1 and Ar+1 agree well with the theoretical predictions of optical tunneling models. Investigation of the polarization dependence of the ionization indicates that the enhancements are consistent with a nonsequential ionization mechanism in which the linearly polarized field drives the electron wavefunction back toward the ion core and causes double ionization through inelastic e-2e scattering. These investigations have initiated a number of other studies by other groups and are of current scientific interest in the fields of high-irradiance laser-matter interactions and production of high-density plasmas. This work involved: (1) Understanding the characteristic nature of the ion yields produced by tunneling ionization through investigation of analytic solutions for tunneling at optical frequencies. (2) Extensive characterization of the pulses produced by 614-nm and 800-ran ultrashort pulse lasers. Absolute calibration of the irradiance scale produced shows the practicality of the inverse problem--measuring peak laser irradiance using ion yields. (3) Measuring the ion yields for three noble gases using linear, circular and elliptical polarizations of laser pulses at 614-nm and 800-nm. The measurements are some of the first measurements for pulse widths as low as 120-fs.

  13. Recent developments in high-resolution optical diagnostics of repetitively pulsed laser-target effects

    NASA Astrophysics Data System (ADS)

    Hugenschmidt, Manfred; Althaus, Marion

    1995-05-01

    High energy densities, as required both in research and in industry, are achieved by the use of lasers. Extremely highpower densities are obtained in the pulsed mode with short microsecond(s) -, ns-, or even ultrashort ps- to fs- pulses. The interaction of such powerful laser pulses with any type of solid state, liquid or gaseous materials is then causing rapidly developing, nonstationary, optically nonlinear processes. Experimental investigations of these effects are therefore requiring special measuring techniques with high spatial and temporal resolution. Optical and optronical methods have proven to be particularly useful. Methods based on laser diagnostics, including high speed photography, cinematography, speckle techniques, holography, videography, infrared techniques or arbitrary combinations of these, are therefore considered to be important tools in these laser effect studies. The investigations reported in the present paper are referring to carbon dioxide-laser effects in intensity ranges which are useful for many industrial applications, such as for example in the field of material processing. Basic interest is actually in pulsed, plasma sustained laser target interaction phenomena which occur above critical threshold power densities, specific for each type of material. Surface induced, highly ionized absorption waves are then determining the energy transfer from the coherent laser radiation field towards the targets. The experiments at ISL were aimed at investigating plasma parameters and their influence on the energy transfer rates, by fast optical, electrical and optronical techniques, such as mentioned above. The results to be discussed refer to target effects, basically observed on optically transparent materials, subject to high average power pulsed carbon dioxide-laser radiation, with repetition rates of several tens to hundred pps at multi-MW/cm2 to GW/cm2 peak power densities and average power densities in the multi-kW/cm2-range.

  14. Validity Using Pump-Probe Pulses to Determine the Optical Response of Niobate Crystals

    NASA Technical Reports Server (NTRS)

    Liu, Huimin; Jia, Weiyi

    1997-01-01

    A variety of niobate crystals have found their places in nonlinear optical applications as well as in laser devices. In recent years much attention has been paid to study the ultrafast optical response in a variety of photorefractive crystals such as KTa(1-x)Nb(x)O3 and KNbO3 crystals, glasses, semiconductors and polymers for applications in optical switching, information processing, optical computing, and all-optical device systems. Third-order optical nonlinearity is the most important property for realization of all-optical switching. Therefore experiments have been performed on the third order susceptibility using a variety of techniques such as the third-order harmonic generation, EFISH and degenerate four-wave mixing(DFWM). The latter has been conducted with a variety of pump wavelengths and with nanosecond, picosecond and femtosecond pulses. Niobate crystals, such as potassium niobate KNbO3, potassium tantalate niobate KTN family (KTa(1-x)Nb(x)O3), strontium barium niobate SBN (Sr(x)Ba(1-x)Nb2O6) and potassium-sodium niobate SBN (KNSBN) are attractive due to their photorefractive properties for application in optical storage and processing. The pulsed probe experiments performed on theses materials have suggested two types of time responses. These responses have been associated with an coherent response due to Chi(sup 3), and a long lived component due to excited state population. Recent study of DFWM on KNbO3 and KTN family reveals that the long lived component of those crystals depends on the crystal orientation. A slowly decaying signal is observable when the grating vector K(sub g) is not perpendicular to the C-axis of those photorefractive crystals', otherwise the optical response signal would be only a narrow coherent peak with FWHM equal to the cross-correlation width of the write beam pulses. Based on this understanding, we study the photodynamical process of a variety of niobate crystals using DFWM in a Kg perpindicular to C geometry with a ps

  15. Few-cycle near-infrared pulses from a degenerate 1 GHz optical parametric oscillator.

    PubMed

    McCracken, Richard A; Reid, Derryck T

    2015-09-01

    We report the generation of transform-limited 4.3-cycle (23 fs) pulses at 1.6 μm from a degenerate doubly resonant optical parametric oscillator (OPO) pumped by a 1 GHz mode-locked Ti:sapphire laser. A χ(2) nonlinear envelope equation was used to inform the experimental implementation of intracavity group-delay dispersion compensation, resulting in resonant pulses with a 169 nm full width half-maximum spectral bandwidth, close to the bandwidth predicted by theory.

  16. Pulsed optically-pumped polarized H{sup {minus}} ion source development

    SciTech Connect

    Zelenski, A.N.; Davydenko, V.I.; Dimov, G.I.; Levy, C.D.P.; Oers, W.T.H. van; Schmor, P.W.; Wight, G.W.; Dutto, G.; Sakae, T.

    1995-09-01

    Results are presented of pulsed optically-pumped polarized H{sup {minus}} ion source (OPPIS) development for high energy accelerators. An atomic hydrogen beam intensity of 2 {times} 10{sup 18} atoms/s within the polarizer acceptance was obtained with an atomic H injector at BINP. A pulsed polarized H{sup {minus}} ion current of about 10--20 mA should be obtainable using this injector. Limitations on beam characteristics due to space-charge were studied. A polarization scheme to avoid space-charge limitations is considered, in which charge-exchange and spin-exchange are combined.

  17. Design of a 17.14 GHz quasi-optical pulse compressor

    SciTech Connect

    Petelin, M. I.; Kuzikov, S. V.; Danilov, Yu. Yu.; Granatstein, V. L.; Nusinovich, G. S.

    1999-07-12

    A quasi-optical version of the ring cavity pulse compressor is considered. This concept is based on the coupling of the input wave to a whispering gallery mode of a barrel-like cavity due to helical corrugations of the cavity wall. Low-power tests of the prototype were carried out at 11.4 GHz and demonstrated reasonable agree-ment between experimental data and theoretical predictions. The design of a similar pulse compressor at 17.14 GHz compatible with the 17.14 GHz, 100 MW gyroklystron currently under development at the University of Maryland is presented.

  18. Modulation of extraordinary optical transmission through nanohole arrays using ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Pearce, Kellie; Dehde, Robin; Spreen, Anika; Späth, Christian; Wendl, Maximilian; Schmidt, Jürgen; Kleineberg, Ulf

    2016-04-01

    We use three dimensional finite-difference-time-domain simulations to study the dynamics of extraordinary optical transmission through arrays of nanoholes in 200 nm-thick Au films on silicon nitride substrates. By diving the light source into two identical 5 femtosecond pulses and tuning the relative delay between them, we are able to modulate both the intensity and spectra of the transmitted light on ultrashort time scales. Simulations demonstrate that the intensity and distribution of the electric fields on the surface of the film and within the nanoholes are altered by changing the pulse delay.

  19. Applications of Optical Coherent Transient Technology to Pulse Shaping, Spectral Filtering, Arbitrary Waveform Generation and RF Beamforming

    DTIC Science & Technology

    2006-04-15

    optical pulses: (1) using acousto - optic modulators (AOMs) driven with a chirped RF source, ( 2 ) using EOPMs driven with a chirped RF source, (3) utilizing a...holograms (SSH) have the potential to duplicate the functional operation of acousto - optic (AO) deflectors , but with bandwidths (BW) in excess of 10 GHz... acousto - optic deflector to create a scanned optical signal that was recorded in an OCT crystal. The scanner functionality of the AOD was thus

  20. Formation and stability analysis of parabolic pulses through specialty microstructured optical fibers at 2.1 μm

    NASA Astrophysics Data System (ADS)

    Biswas, P.; Adhikary, P.; Biswas, A.; Ghosh, S. N.

    2016-10-01

    We report a numerical study on formation and stability of parabolic pulses during their propagation through highly nonlinear specialty optical fibers. Here, we have formed a parabolic pulse at wavelength of 2.1 μm from a Gaussian input pulse with 1.9 ps FWHM and 75 W peak power after traveling through only 20 cm length from the input end of a 1 m long chalcogenide glass based microstructured optical fiber (MOF). Dependence on input pulse shapes towards most efficient conversion into self-similar states is reported. The stability in terms of any deviation from dissipative self-similar nature of such pulses has been analyzed by introducing a variable longitudinal loss profile within the spectral loss window of the MOF, and detailed pulse shapes are captured. Moreover, three different dispersion regimes of propagation have been considered to study the suitability to support most stable propagation of the pulse.

  1. Miniaturized pulsed laser source for time-domain diffuse optics routes to wearable devices

    NASA Astrophysics Data System (ADS)

    Di Sieno, Laura; Nissinen, Jan; Hallman, Lauri; Martinenghi, Edoardo; Contini, Davide; Pifferi, Antonio; Kostamovaara, Juha; Mora, Alberto Dalla

    2017-08-01

    We validate a miniaturized pulsed laser source for use in time-domain (TD) diffuse optics, following rigorous and shared protocols for performance assessment of this class of devices. This compact source (12×6 mm2) has been previously developed for range finding applications and is able to provide short, high energy (˜100 ps, ˜0.5 nJ) optical pulses at up to 1 MHz repetition rate. Here, we start with a basic level laser characterization with an analysis of suitability of this laser for the diffuse optics application. Then, we present a TD optical system using this source and its performances in both recovering optical properties of tissue-mimicking homogeneous phantoms and in detecting localized absorption perturbations. Finally, as a proof of concept of in vivo application, we demonstrate that the system is able to detect hemodynamic changes occurring in the arm of healthy volunteers during a venous occlusion. Squeezing the laser source in a small footprint removes a key technological bottleneck that has hampered so far the realization of a miniaturized TD diffuse optics system, able to compete with already assessed continuous-wave devices in terms of size and cost, but with wider performance potentialities, as demonstrated by research over the last two decades.

  2. Single-pulse CARS based multimodal nonlinear optical microscope for bioimaging.

    PubMed

    Kumar, Sunil; Kamali, Tschackad; Levitte, Jonathan M; Katz, Ori; Hermann, Boris; Werkmeister, Rene; Považay, Boris; Drexler, Wolfgang; Unterhuber, Angelika; Silberberg, Yaron

    2015-05-18

    Noninvasive label-free imaging of biological systems raises demand not only for high-speed three-dimensional prescreening of morphology over a wide-field of view but also it seeks to extract the microscopic functional and molecular details within. Capitalizing on the unique advantages brought out by different nonlinear optical effects, a multimodal nonlinear optical microscope can be a powerful tool for bioimaging. Bringing together the intensity-dependent contrast mechanisms via second harmonic generation, third harmonic generation and four-wave mixing for structural-sensitive imaging, and single-beam/single-pulse coherent anti-Stokes Raman scattering technique for chemical sensitive imaging in the finger-print region, we have developed a simple and nearly alignment-free multimodal nonlinear optical microscope that is based on a single wide-band Ti:Sapphire femtosecond pulse laser source. Successful imaging tests have been realized on two exemplary biological samples, a canine femur bone and collagen fibrils harvested from a rat tail. Since the ultra-broad band-width femtosecond laser is a suitable source for performing high-resolution optical coherence tomography, a wide-field optical coherence tomography arm can be easily incorporated into the presented multimodal microscope making it a versatile optical imaging tool for noninvasive label-free bioimaging.

  3. Interband optical pulse injection locking of quantum dot mode-locked semiconductor laser.

    PubMed

    Kim, Jimyung; Delfyett, Peter J

    2008-07-21

    We experimentally demonstrate optical clock recovery from quantum dot mode-locked semiconductor lasers by interband optical pulse injection locking. The passively mode-locked slave laser oscillating on the ground state or the first excited state transition is locked through the injection of optical pulses generated via the opposite transition bands, i.e. the first excited state or the ground state transition from the hybridly mode-locked master laser, respectively. When an optical pulse train generated via the first excited state from the master laser is injected to the slave laser oscillating via ground state, the slave laser shows an asymmetric locking bandwidth around the nominal repetition rate of the slave laser. In the reverse injection case of, i.e. the ground state (master laser) to the first excited state (slave laser), the slave laser does not lock even though both lasers oscillate at the same cavity frequency. In this case, the slave laser only locks to higher injection rates as compared to its own nominal repetition rate, and also shows a large locking bandwidth of 6.7 MHz.

  4. Fiber optic based heart-rate and pulse pressure shape monitor

    NASA Astrophysics Data System (ADS)

    Kokkinos, D.; Dehipawala, S.; Holden, T.; Cheung, E.; Musa, M.; Tremberger, G., Jr.; Schneider, P.; Lieberman, D.; Cheung, T.

    2012-01-01

    Macro-bending fiber optic based heart-rate and pulse pressure shape monitors have been fabricated and tested for non-invasive measurement. Study of fiber bending loss and its stability and variations are very important especially for sensor designs based on optical fiber bending. Wavelengths from 1300 nm to 1550 nm have been used with fabrication based on multimode fiber, single mode fiber, and photonic crystal fiber. The smallest studied curvature would demand the use of single mode standard fibers. The collected data series show high quality suitable for random series analysis. Fractal property of optically measured pulse pressure data has been observed to correlate with physical activity. Correlation to EKG signal suggests that the fabricated monitors are capable of measuring the differential time delays at wrist and leg locations. The difference in time delay could be used to formulate a velocity parameter for diagnostics. The pulse shape information collected by the fiber sensor provides additional parameters for the analysis of the fractal nature of the heart. The application to real time measurement of blood vessel stiffness with this optical non-invasive fiber sensor is discussed.

  5. Optical attosecond pulses and tracking the nonlinear response of bound electrons

    NASA Astrophysics Data System (ADS)

    Hassan, M. Th.; Luu, T. T.; Moulet, A.; Raskazovskaya, O.; Zhokhov, P.; Garg, M.; Karpowicz, N.; Zheltikov, A. M.; Pervak, V.; Krausz, F.; Goulielmakis, E.

    2016-02-01

    The time it takes a bound electron to respond to the electromagnetic force of light sets a fundamental speed limit on the dynamic control of matter and electromagnetic signal processing. Time-integrated measurements of the nonlinear refractive index of matter indicate that the nonlinear response of bound electrons to optical fields is not instantaneous; however, a complete spectral characterization of the nonlinear susceptibility tensors—which is essential to deduce the temporal response of a medium to arbitrary driving forces using spectral measurements—has not yet been achieved. With the establishment of attosecond chronoscopy, the impulsive response of positive-energy electrons to electromagnetic fields has been explored through ionization of atoms and solids by an extreme-ultraviolet attosecond pulse or by strong near-infrared fields. However, none of the attosecond studies carried out so far have provided direct access to the nonlinear response of bound electrons. Here we demonstrate that intense optical attosecond pulses synthesized in the visible and nearby spectral ranges allow sub-femtosecond control and metrology of bound-electron dynamics. Vacuum ultraviolet spectra emanating from krypton atoms, exposed to intense waveform-controlled optical attosecond pulses, reveal a finite nonlinear response time of bound electrons of up to 115 attoseconds, which is sensitive to and controllable by the super-octave optical field. Our study could enable new spectroscopies of bound electrons in atomic, molecular or lattice potentials of solids, as well as light-based electronics operating on sub-femtosecond timescales and at petahertz rates.

  6. Pulse propagation and optically controllable switch in coupled semiconductor-double-quantum-dot nanostructures

    SciTech Connect

    Hamedi, H. R. E-mail: hamid.hamedi@tfai.vu.lt

    2016-05-14

    The problem of pulse propagation is theoretically investigated through a coupled semiconductor-double-quantum-dot (SDQD) nanostructure. Solving the coupled Maxwell–Bloch equations for the SDQD and field simultaneously, the dynamic control of pulse propagation through the medium is numerically explored. It is found that when all the control fields are in exact resonance with their corresponding transitions, a weak Gaussian-shaped probe pulse is transmitted through the medium nearly without any significant absorption and losses so that it can preserve its shape for quite a long propagation distance. In contrast, when one of the control fields is not in resonance with its corresponding transition, the probe pulse will be absorbed by the QD medium after a short distance. Then we consider the probe pulses with higher intensities. It is realized that an intense probe pulse experiences remarkable absorption and broadening during propagation. Finally, we demonstrate that this SDQD system can be employed as an optically controllable switch for the wave propagation to transit from an absorbing phase to a perfect transparency for the probe field. The required time for such switch is also estimated through realistic values.

  7. Interaction of frequency modulated light pulses with rubidium atoms in a magneto-optical trap

    NASA Astrophysics Data System (ADS)

    Bakos, J. S.; Djotyan, G. P.; Ignácz, P. N.; Kedves, M. Á.; Serényi, M.; Sörlei, Zs.; Szigeti, J.; Tóth, Z.

    2006-07-01

    The spatial displacement of the 85Rb atoms in a Magneto-Optical Trap (MOT) under the influence of series of frequency modulated light pulse pairs propagating opposite to each other is measured as a function of the time elapsed after the start of the pulse train, and compared with the results of simulations. Adiabatic excitation and consecutive de-excitation take place between the ground 52S1/2 (F=3) and the 52P3/2 (F'=2, 3, 4) excited levels as the result of the interaction. The displacement of the 85Rb atoms is calculated as the solution of simple equation of motion where the expelling force is that arising from the action of the frequency modulated light pulses. The restoring and friction forces of the MOT are taken into account also. The system of Bloch equations for the density matrix elements is solved numerically for transitions between six working hyperfine levels of the atom interacting with the sequence of the frequency modulated laser pulses. According to these simulations, the momentum transferred by one pulse pair is always smaller than the expected 2ħk, (1) where ħ is the Plank constant and k=2π/λ where λ is the wavelength, (2) having a maximum value in a restricted region of variation of the laser pulse peak intensity and the chirp.

  8. Phase engineered wavelength conversion of ultra-short optical pulses in TI:PPLN waveguides

    NASA Astrophysics Data System (ADS)

    Babazadeh, Amin; Nouroozi, Rahman; Sohler, Wolfgang

    2016-02-01

    A phase engineered all-optical wavelength converter for ultra-short pulses (down to 140 fs) in a Ti-diffused, periodically poled lithium niobate (Ti:PPLN) waveguide is proposed. The phase engineering, due to the phase conjugation between signal and idler (converted signal) pulses which takes place in the cascaded second harmonic generation and difference frequency generation (cSHG/DFG) based wavelength conversion, already leads to shorter idler pulses. The proposed device consists of an unpoled (passive) waveguide section beside of the PPLN waveguide section in order to compensate pulse broadening and phase distortion of the idler pulses induced by the wavelength conversion (in the PPLN section). For example numerical analysis shows that a 140 fs input signal pulse is only broadened by 1.6% in a device with a combination of 20 mm and 6 mm long periodically poled and unpoled waveguide sections. Thus, cSHG/DFG based wavelength converters of a bandwidth of several Tbits/s can be designed.

  9. All-optical UWB doublet pulses generation by using a delay interferometer

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Xu, En-Ming

    2013-06-01

    We demonstrated a simple scheme to generate ultra wideband (UWB) doublet pulses by inputting a dark return-to-zero (RZ) signal into a fiber delay interferometer (FDI). An 0.625-Gbit/s dark-RZ pulse train where the pulse width is 120 ps was inputted into a FDI where the free spectral range (FSR) is 0.16 nm (˜20 GHz, according time delay is ˜50 ps) and the extinction ratio (ER) is 9 dB, and the phase difference of the two fiber arms was changed and controlled by adjusting the operation temperature of the FDI, by do so, UWB doublet pulses were directly generated at an output port of the FDI. The system parameter effects on the output UWB pulses were discussed. Moreover, we also numerically demonstrated that the UWB quadruplet pulses can be generated in the same set by optimizing system parameters. This scheme has some distinct advantages including easy integration, convenient tuning, good stability, and so on. Presented method also accords with the general features in future applied UWB-Over-Fiber communication system, such as, single optical source input, simple configuration and passive device.

  10. Pulse

    MedlinePlus

    ... the underside of the opposite wrist, below the base of the thumb. Press with flat fingers until ... determine if the patient's heart is pumping. Pulse measurement has other uses as well. During or immediately ...

  11. Formation of an optical pulsed discharge in a supersonic air flow by radiation of a repetitively pulsed CO{sub 2} laser

    SciTech Connect

    Malov, Aleksei N; Orishich, Anatolii M

    2012-09-30

    Results of optimisation of repetitively pulsed CO{sub 2}-laser generation are presented for finding physical conditions of forming stable burning of an optical pulsed discharge (OPD) in a supersonic air flow and for studying the influence of pulse parameters on the energy absorption efficiency of laser radiation in plasma. The optical discharge in a supersonic air flow was formed by radiation of a repetitively pulsed CO{sub 2} laser with mechanical Q-switching excited by a discharge with a convective cooling of the working gas. For the first time the influence of radiation pulse parameters on the ignition conditions and stable burning of the OPD in a supersonic air flow was investigated and the efficiency of laser radiation absorption in plasma was studied. The influence of the air flow velocity on stability of plasma production was investigated. It was shown that stable burning of the OPD in a supersonic flow is realised at a high pulse repetition rate where the interval between radiation pulses is shorter than the time of plasma blowing-off. Study of the instantaneous value of the absorption coefficient shows that after a breakdown in a time lapse of 100 - 150 ns, a quasi-stationary 'absorption phase' is formed with the duration of {approx}1.5 ms, which exists independently of air flow and radiation pulse repetition rate. This phase of strong absorption is, seemingly, related to evolution of the ionisation wave. (laser applications and other topics in quantum electronics)

  12. Real-time optical diagnostics of graphene growth induced by pulsed chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Puretzky, Alexander A.; Geohegan, David B.; Pannala, Sreekanth; Rouleau, Christopher M.; Regmi, Murari; Thonnard, Norbert; Eres, Gyula

    2013-06-01

    The kinetics and mechanisms of graphene growth on Ni films at 720-880 °C have been measured using fast pulses of acetylene and real-time optical diagnostics. In situ UV-Raman spectroscopy was used to unambiguously detect isothermal graphene growth at high temperatures, measure the growth kinetics with ~1 s temporal resolution, and estimate the fractional precipitation upon cooldown. Optical reflectivity and videography provided much faster temporal resolution. Both the growth kinetics and the fractional isothermal precipitation were found to be governed by the C2H2 partial pressure in the CVD pulse for a given film thickness and temperature, with up to ~94% of graphene growth occurring isothermally within 1 second at 800 °C at high partial pressures. At lower partial pressures, isothermal graphene growth is shown to continue 10 seconds after the gas pulse. These flux-dependent growth kinetics are described in the context of a dissolution/precipitation model, where carbon rapidly dissolves into the Ni film and later precipitates driven by gradients in the chemical potential. The combination of pulsed-CVD and real-time optical diagnostics opens new opportunities to understand and control the fast, sub-second growth of graphene on various substrates at high temperatures.The kinetics and mechanisms of graphene growth on Ni films at 720-880 °C have been measured using fast pulses of acetylene and real-time optical diagnostics. In situ UV-Raman spectroscopy was used to unambiguously detect isothermal graphene growth at high temperatures, measure the growth kinetics with ~1 s temporal resolution, and estimate the fractional precipitation upon cooldown. Optical reflectivity and videography provided much faster temporal resolution. Both the growth kinetics and the fractional isothermal precipitation were found to be governed by the C2H2 partial pressure in the CVD pulse for a given film thickness and temperature, with up to ~94% of graphene growth occurring isothermally

  13. Complete optical absorption of ultrashort pulses by plasmons in nanostructured graphene (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Martínez Saavedra, José Ramón; Cerullo, Giulio; Pruneri, Valerio; Wall, Simon; García de Abajo, Javier

    2016-10-01

    The peculiar electronic structure of graphene results in a large optoelectronic response that holds great potential for technology. For example, this material exhibits a nearly constant absorption 2.3% over a broad spectral range [1], which can be electrically modulated in the mid-IR by injecting attainable densities of charge carriers. When doped, graphene can sustain plasmons that radically modify its optical response, enabling complete optical absorption for suitably designed patterns [2]. Graphene nanoribbons constitute one of the simplest geometrical patterns that one can produce. They have been extensively studied and their plasmons accurately explained with simple models [3]. When heated to a large electronic temperature, graphene behaves nearly as if is was highly doped, also giving rise to plasmon modes [4]. In this work, we study the possibility of using ultrashort light pulses together with the natural electronic relaxation mechanisms in graphene nanoribbons as a way to tune their optical response. We first discuss the optically induced plasmons of individual nanoribbons when illuminated with ultrashort pulses and then analyze the evolution of the plasmon frequency as a function of the delay between pump and probe. We study the redshift of these plasmons with increasing delay due to electron relaxation. We also investigate the optical response of the ribbon exposed to a train of optical pulses. We further discuss ribbon arrays illuminated from the substrate under total internal reflection conditions, for which we predict complete absorption for a suitable choice of geometrical and illumination parameters. References [1] F. H. L. Koppens, D. E. Chang, and F. J. García de Abajo, Nano Letters 11, 3370-3377 (2011) [2] S. Thongrattanasiri, F. H. L. Koppens, and F. J. García de Abajo, Phys. Rev. Lett. 108, 047401 (2012) [3] I. Silveiro, J. M. Plaza Ortega, and F. J. García de Abajo, Light: Science and Applications 4, e241 (2015) [4] F. J. García de Abajo

  14. Approaching the full octave: noncollinear optical parametric chirped pulse amplification with two-color pumping.

    PubMed

    Herrmann, D; Homann, C; Tautz, R; Scharrer, M; Russell, P St J; Krausz, F; Veisz, L; Riedle, E

    2010-08-30

    We present a new method to broaden the amplification range in optical parametric amplification toward the bandwidth needed for single cycle femtosecond pulses. Two-color pumping of independent stages is used to sequentially amplify the long and short wavelength parts of the ultrabroadband seed pulses. The concept is tested in two related experiments. With multi-mJ pumping pulses with a nearly octave spanning spectrum and an uncompressed energy of 3 mJ are generated at low repetition rate. The spectral phase varies slowly and continuously in the overlap region as shown with 100 kHz repetition rate. This should allow the compression to the Fourier limit of below 5 fs in the high energy system.

  15. Microcavity design for low threshold polariton condensation with ultrashort optical pulse excitation

    SciTech Connect

    Poellmann, C.; Leierseder, U.; Huber, R.; Galopin, E.; Lemaître, A.; Amo, A.; Bloch, J.; Ménard, J.-M.

    2015-05-28

    We present a microcavity structure with a shifted photonic stop-band to enable efficient non-resonant injection of a polariton condensate with spectrally broad femtosecond pulses. The concept is demonstrated theoretically and confirmed experimentally for a planar GaAs/AlGaAs multilayer heterostructure pumped with ultrashort near-infrared pulses while photoluminescence is collected to monitor the optically injected polariton density. As the excitation wavelength is scanned, a regime of polariton condensation can be reached in our structure at a consistently lower fluence threshold than in a state-of-the-art conventional microcavity. Our microcavity design improves the polariton injection efficiency by a factor of 4, as compared to a conventional microcavity design, when broad excitation pulses are centered at a wavelength of λ = 740 nm. Most remarkably, this improvement factor reaches 270 when the excitation wavelength is centered at 750 nm.

  16. Optical limiting property of a liquid malononitrile derivative on 800 nm laser pulses

    NASA Astrophysics Data System (ADS)

    Du, Juan; Wang, Liuheng; Xie, Na; Sun, Li; Wang, Xiaodong; Zhao, Yuxia; Wu, Feipeng

    2016-08-01

    A new liquid malononitrile derivative (LBDBP) has been synthesized by incorporating four tetraethylene glycol groups into the prototype scaffold of 2-[Bis-(4‧-diethylamino-biphenyl-4-yl)-methylene]-malononitrile (BDBP). The linear photophysical properties, optical/thermal stabilities and optical limiting behaviors of LBDBP and BDBP have been investigated. The results show that LBDBP has equivalent optical/thermal stability but much better solubility compared with BDBP. Its saturation concentration in DMF is increased to 0.075 M, while the corresponding datum for BDBP is only 0.01 M. The improved solubility of LBDBP insures a very significant optical limiting behavior. The saturated DMF solution of LBDBP can significantly reduce the intensity fluctuation of laser pulses in an 800 nm laser setup.

  17. Ultrasound-modulated optical imaging using a powerful long pulse laser.

    PubMed

    Rousseau, Guy; Blouin, Alain; Monchalin, Jean-Pierre

    2008-08-18

    Ultrasound-modulated optical imaging (or tomography) is an emerging biodiagnostic technique which provides the optical spectroscopic signature and the localization of an absorbing object embedded in a strongly scattering medium. We propose to improve the sensitivity of the technique by using a pulsed single-frequency laser to raise the optical peak power applied to the scattering medium and thereby collect more ultrasonically tagged photons. Moreover, when the detection of tagged photons is done with a photorefractive interferometer, the high optical peak power reduces the response time of the photorefractive crystal below the speckle field decorrelation time. Results obtained with a GaAs photorefractive interferometer are presented for 30- and 60-mm thick scattering media.

  18. Pulse position modulation for a subcarrier-multiplexed optical fiber transmission system

    NASA Astrophysics Data System (ADS)

    Wickramasinghe, V. R.; Ghassemlooy, Zabih F.

    1996-11-01

    Subcarrier multiplexed (SCM) optical network s offer a near to medium term alternative solution over high cost, evolving digital technology to distribute broadband services. Majority of existing systems are based on analogue optical transmission techniques and their principle disadvantage is the sensitivity to noise and system nonlinearities. Therefore, conventional SCM systems impose stringent noise and linearity requirements and as a result their performance is limited. A simple and attractive solution is to introduce an appropriate second stage modulator in order to improve the receiver sensitivity, hence the system performance.In this paper a SCM optical transmission system employing pulse position modulation as a second stage modulator, for transmission of video, audio and data channels is reported. Signal to noise ratio measurements obtained shows an improvement in optical receiver sensitivity compared with standard SCM systems.

  19. Graphene Oxides as Tunable Broadband Nonlinear Optical Materials for Femtosecond Laser Pulses.

    PubMed

    Jiang, Xiao-Fang; Polavarapu, Lakshminarayana; Neo, Shu Ting; Venkatesan, T; Xu, Qing-Hua

    2012-03-15

    Graphene oxide (GO) thin films on glass and plastic substrates were found to display interesting broadband nonlinear optical properties. We have investigated their optical limiting activity for femtosecond laser pulses at 800 and 400 nm, which could be tuned by controlling the extent of reduction. The as-prepared GO films were found to exhibit excellent broadband optical limiting behaviors, which were significantly enhanced upon partial reduction by using laser irradiation or chemical reduction methods. The laser-induced reduction of GO resulted in enhancement of effective two-photon absorption coefficient at 400 nm by up to ∼19 times and enhancement of effective two- and three-photon absorption coefficients at 800 nm by ∼12 and ∼14.5 times, respectively. The optical limiting thresholds of partially reduced GO films are much lower than those of various previously reported materials. Highly reduced GO films prepared by using the chemical method displayed strong saturable absorption behavior.

  20. Latest results on solarization of optical glasses with pulsed laser radiation

    NASA Astrophysics Data System (ADS)

    Jedamzik, Ralf; Petzold, Uwe

    2017-02-01

    Femtosecond lasers are more and more used for material processing and lithography. Femtosecond laser help to generate three dimensional structures in photoresists without using masks in micro lithography. This technology is of growing importance for the field of backend lithography or advanced packaging. Optical glasses used for beam shaping and inspection tools need to withstand high laser pulse energies. Femtosecond laser radiation in the near UV wavelength range generates solarization effects in optical glasses. In this paper results are shown of femtosecond laser solarization experiments on a broad range of optical glasses from SCHOTT. The measurements have been performed by the Laser Zentrum Hannover in Germany. The results and their impact are discussed in comparison to traditional HOK-4 and UVA-B solarization measurements of the same materials. The target is to provide material selection guidance to the optical designer of beam shaping lens systems.

  1. Consideration of dynamic photothermal effect for evaluation of scanning light sources in optical devices using pulsed source criteria.

    PubMed

    Kim, Do-Hyun

    2014-04-01

    Quantitative evaluation of the potential radiation hazards of scanning light sources in medical optical devices is critical. Currently, point scanning light sources of continuous radiation are treated as pulsed sources, where the dwell time at each point is equal to the pulse duration. This study compares the photothermal effects from scanning light and pulsed sources using numerical calculation for scanning without restricting aperture and with various spot sizes. The calculation results show that the thermal damage threshold of scanning source not restricted by measurement aperture does not significantly differ from that of pulsed source. Temporal temperature response and size-dependent photothermal effect also confirm the similarity between scanning and pulsed sources.

  2. Yb:YAG Innoslab amplifier: efficient high repetition rate subpicosecond pumping system for optical parametric chirped pulse amplification.

    PubMed

    Schulz, M; Riedel, R; Willner, A; Mans, T; Schnitzler, C; Russbueldt, P; Dolkemeyer, J; Seise, E; Gottschall, T; Hädrich, S; Duesterer, S; Schlarb, H; Feldhaus, J; Limpert, J; Faatz, B; Tünnermann, A; Rossbach, J; Drescher, M; Tavella, F

    2011-07-01

    We report on a Yb:YAG Innoslab laser amplifier system for generation of subpicsecond high energy pump pulses for optical parametric chirped pulse amplification (OPCPA) at high repetition rates. Pulse energies of up to 20 mJ (at 12.5 kHz) and repetition rates of up to 100 kHz were attained with pulse durations of 830 fs and average power in excess of 200 W. We further investigate the possibility to use subpicosecond pulses to derive a stable continuum in a YAG crystal for OPCPA seeding.

  3. Self-guiding of laser pulses and spatio-temporal optical vortices in plasma

    NASA Astrophysics Data System (ADS)

    Hine, George; Jhajj, Nihal; Milchberg, Howard

    2016-10-01

    Relativistic self-focusing and self-guiding are processes fundamental to laser-plasma particle acceleration. Recent work in optical filamentation has discovered the existence of spatio-temporal optical vortices (STOVs) and has shown their integral connection to all self-focusing collapse and self-guiding scenarios. Here we show that STOVs are an essential feature of LWFA through their generation by relativistic self-focusing. Three dimensional particle-in-cell (PIC) simulations show the formation of STOVs in the pulse, corresponding to vortical flow of the Poynting vector, which then influences subsequent pulse propagation such as the self-healing of the relativistic self-guiding process. This work is supported by the Department of Energy, the National Science Foundation, and the Air Force Office of Scientific Research.

  4. UWB doublet signal generation and modulation based on DFB laser under optical pulses injection

    NASA Astrophysics Data System (ADS)

    Chen, Dalei; Wang, Rong; Xiang, Peng; Pu, Tao; Fang, Tao; Zhou, Hua; Zhao, Jiyong; Huang, Long; Zhu, Huatao; Wang, Peng

    2016-05-01

    In this paper, a novel scheme to generate ultra-wideband (UWB) doublet signals based on the cross-gain modulation (XGM) effect in the DFB lasers is proposed and experimentally demonstrated, the modulation and transmission of the generated UWB doublet signals are also researched. In the proposed system, a gain-switched laser (GSL) is used as a master laser (ML) and the optical pulses from the ML are optically injected into two paralleled DFB lasers, which are used as slave lasers (SL). Then the outputs from the SLs are detected by a balanced photodiode (BPD) to generate the Bi-phased UWB signals. By properly setting the system parameters, UWB signals with various modulation formats such as on-off keying (OOK), pulse amplitude modulation (PAM) as well as the phase-shift keying (PSK) can be generated. In addition, fiber transmission of the modulated UWB signals is also experimentally investigated.

  5. Nanosecond square high voltage pulse generator for electro-optic switch

    NASA Astrophysics Data System (ADS)

    Feng, Xian-wang; Long, Xing-wu; Tan, Zhong-qi

    2011-07-01

    A scalable square high voltage pulse generator, which has the properties of fast rise time, fast fall time, powerful driving capability, and long lifetime, is presented in this paper by utilizing solid state circuitry. A totem-pole topology is designed to supply a powerful driving capability for the electro-optic (EO) crystal which is of capacitive load. Power MOSFETs are configured in series to sustain high voltage, and proper driving circuits are introduced for the specific MOSFETs configurations. A 3000 V pulse generator with ˜49.04 ns rise time and ˜10.40 ns fall time of the output waveform is presented. This kind of generator is desirable for electro-optic switch. However, it is not specific to EO switch and may have broad applications where high voltage fast switching is required.

  6. An Approximate Numerical Technique for Characterizing Optical Pulse Propagation in Inhomogeneous Biological Tissue

    PubMed Central

    Handapangoda, Chintha C.; Premaratne, Malin

    2008-01-01

    An approximate numerical technique for modeling optical pulse propagation through weakly scattering biological tissue is developed by solving the photon transport equation in biological tissue that includes varying refractive index and varying scattering/absorption coefficients. The proposed technique involves first tracing the ray paths defined by the refractive index profile of the medium by solving the eikonal equation using a Runge-Kutta integration algorithm. The photon transport equation is solved only along these ray paths, minimizing the overall computational burden of the resulting algorithm. The main advantage of the current algorithm is that it enables to discretise the pulse propagation space adaptively by taking optical depth into account. Therefore, computational efficiency can be increased without compromising the accuracy of the algorithm. PMID:18317526

  7. Generation of pulse trains in nonlinear optical fibers through the generalized complex Ginzburg-Landau equation.

    PubMed

    Latchio Tiofack, Camus G; Mohamadou, Alidou; Kofané, Timoléon C; Moubissi, Alain B

    2009-12-01

    We consider a higher-order complex Ginzburg-Landau equation, with the fourth-order dispersion and cubic-quintic nonlinear terms, which can describe the propagation of an ultrashort subpicosecond or femtosecond optical pulse in an optical fiber system. We investigate the modulational instability (MI) of continuous wave solution of this equation. Several types of modulational instability gains are shown to exist in both the anomalous and normal dispersion regimes. We find that depending on the sign of the fourth-order dispersion coefficient, the MI appears for normal and anomalous dispersion regime. Simulations of the full system demonstrate that the development of the MI leads to establishment of a regular or chaotic array of pulses, a chain of well-separated peaks with continuously growing or decaying amplitudes depending on the sign of the loss/gain coefficient and higher-order dispersions terms. Comparison of the calculations with reported numerical results shows a satisfactory agreement.

  8. Generation of efficient THz radiation by optical rectification in DAST crystal using tunable femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Venkatesh, Mottamchetty; Thirupugalmani, K.; Rao, K. S.; Brahadeeswaran, S.; Chaudhary, A. K.

    2017-03-01

    We report the efficient THz generation by optical rectification from an indigenously grown organic DAST crystal using the 140 fs oscillator laser pulses tunable in between 780 and 850 nm. The generated THz pulse profile and powers have been measured using the photoconductive (PC) antennas and pyroelectric detector, respectively. The highest THz peak amplitude and power is obtained at 825 nm central wavelength. We have theoretically explained the enhancement of THz radiation based on the matching of average optical group refractive index and average THz refractive index of the DAST crystal at 825 nm. In addition, the dependence of THz peak amplitude and THz power on laser power have been carried out. The measured quantum conversion efficiency (QCE) of 0.5 and 1.5 THz bands are of the order 3.7 × 10-3, 1.4 × 10-3, respectively. Finally, an attempt has been made to study the effect of polarizations on generated THz signal.

  9. An approximate numerical technique for characterizing optical pulse propagation in inhomogeneous biological tissue.

    PubMed

    Handapangoda, Chintha C; Premaratne, Malin

    2008-01-01

    An approximate numerical technique for modeling optical pulse propagation through weakly scattering biological tissue is developed by solving the photon transport equation in biological tissue that includes varying refractive index and varying scattering/absorption coefficients. The proposed technique involves first tracing the ray paths defined by the refractive index profile of the medium by solving the eikonal equation using a Runge-Kutta integration algorithm. The photon transport equation is solved only along these ray paths, minimizing the overall computational burden of the resulting algorithm. The main advantage of the current algorithm is that it enables to discretise the pulse propagation space adaptively by taking optical depth into account. Therefore, computational efficiency can be increased without compromising the accuracy of the algorithm.

  10. Power enhancement of burst-mode UV pulses using a doubly-resonant optical cavity

    SciTech Connect

    Rahkman, Abdurahim; Notcutt, Mark; Liu, Yun

    2015-11-24

    We report a doubly-resonant enhancement cavity (DREC) that can realize a simultaneous enhancement of two incoming laser beams at different wavelengths and different temporal structures. The double-resonance condition is theoretically analyzed and different DREC locking methods are experimentally investigated. Simultaneous locking of a Fabry-Perot cavity to both an infrared (IR, 1064 nm) and its frequency tripled ultraviolet (UV, 355 nm) pulses has been demonstrated by controlling the frequency difference between the two beams with a fiber optic frequency shifter. The DREC technique opens a new paradigm in the applications of optical cavities to power enhancement of burst-mode lasers with arbitrary macropulse width and repetition rate.

  11. Power enhancement of burst-mode ultraviolet pulses using a doubly resonant optical cavity.

    PubMed

    Rakhman, Abdurahim; Notcutt, Mark; Liu, Yun

    2015-12-01

    We report a doubly resonant enhancement cavity (DREC) that can realize a simultaneous enhancement of two incoming laser beams at different wavelengths and different temporal structures. The double-resonance condition is theoretically analyzed, and different DREC locking methods are experimentally investigated. Simultaneous locking of a Fabry-Perot cavity to both an infrared (1064 nm) and its frequency-tripled ultraviolet (355 nm) pulses has been demonstrated by controlling the frequency difference between the two beams with a fiber-optic frequency shifter. The DREC technique enables novel applications of optical cavities to power enhancement of burst-mode lasers with arbitrary macropulse width and repetition rate.

  12. Distributed optical fiber sensor based on modulated dual-pulse probe signal

    NASA Astrophysics Data System (ADS)

    Sun, Wenhui; Fang, Gaosheng; Chen, Xinwei; Wu, Pengsheng; Wang, Kai

    2016-01-01

    A distributed fiber sensor based on Rayleigh scattering is described which converts vibration-induced optical phase changes into optical intensity variations by using modulated dual-pulses injected into sensing fiber. Phase generated carrier algorithm is used to permit arctangent operation to demodulate the phase information along the sensing fiber. The demonstrated sensor is capable of probing dynamic acoustic or vibration disturbances over 10km of sensing length with spatial resolution of 6m and large signal to noise ratio. The background noise of our system is estimated about 1×10-3 rad/√Hz.

  13. Noncontact single-pulse optical method to measure interfacial properties in intact systems.

    PubMed

    Clark, David C; Kim, Myung K

    2012-12-15

    We introduce a noncontact purely optical approach to measuring the localized surface properties of an interface within a system using a single optical pressure pulse and a time-resolved digital holographic quantitative phase-imaging technique to track the propagating nanometric capillary disturbance. We demonstrate the proposed method's ability to measure the surface energy of deionized water, methanol, and chemical monolayers formed by surfactants with good agreement to published values. The development of this technique boasts immediate application to static and dynamic systems and near-future applications for living biological cell membranes.

  14. Generation of a sequence of frequency-modulated pulses in longitudinally inhomogeneous optical waveguides

    NASA Astrophysics Data System (ADS)

    Zolotovskii, I. O.; Lapin, V. A.; Sementsov, D. I.; Stolyarov, D. A.

    2017-03-01

    The conditions for the generation and efficient amplification of frequency-modulated soliton-like wave packets in longitudinally inhomogeneous active optical waveguides have been studied. The possibility of forming a sequence of pico- and subpicosecond pulses from quasi-continuous radiation in active and passive optical waveguides with the group-velocity dispersion (GVD) changing over the waveguide length is considered. The behavior of a wave packet in the well-developed phase of modulation instability with a change in the waveguide inhomogeneity parameters has been investigated based on the numerical analysis.

  15. Study on the digital position transducer with optical time-delay pulse

    NASA Astrophysics Data System (ADS)

    Mayanagi, M.

    1985-09-01

    A rotary optical position transducer employing a pulse technique time-multiplexor has been studied during the development of a Fly-By-Light (FBL) for the aircraft control system, the aim of which is to offer inherent resistance to environments of electromagnetic interference (EMI), electromagntic pulse (EMP) and lightening. The conventional absolute-type optical digital transducer causes difficulty in the interface technique between the transducer and other devices such as a computer. The transducer system described in this paper, which consists of a rotary position transducer unit, a fiber-optic cable, a light source unit, and an electronics interface unit, can improve this interface technique. The rotary transducer unit is an electrically passive device that is connected through optical fibers to the light source unit and the electronics interface unit, and that has many advantages of fiber-optic techniques. This paper studies basic problems in the development of the rotary transducer system. In particular, a basis for optimizing illumination irradiance and photo-detector characteristics is given, and the intrinsic performance of the transducer is quantitatively examined.

  16. Polarization and dynamical properties of VCSELs-based photonic neuron subject to optical pulse injection

    NASA Astrophysics Data System (ADS)

    Xiang, Shuiying; Wen, Aijun; Zhang, Hao; Li, Jiafu; Guo, Xingxing; Shang, Lei; Lin, Lin

    2016-11-01

    The polarization-resolved nonlinear dynamics of vertical-cavity surface-emitting lasers (VCSELs) subject to orthogonally polarized optical pulse injection are investigated numerically based on the spin flip model. By extensive numerical bifurcation analysis, the responses dynamics of photonic neuron based on VCSELs under the arrival of external stimuli of orthogonally polarized optical pulse injection are mainly discussed. It is found that, several neuron-like dynamics, such as phasic spiking of a single abrupt large amplitude pulse followed with or without subthreshold oscillation, and tonic spiking with multiple periodic pulses, are successfully reproduced in the numerical model of VCSELs. Besides, the effects of stimuli strength, pump current, frequency detuning, as well as the linewidth enhancement factor on the neuron-like response dynamics are examined carefully. The operating parameters ranges corresponding to different neuron-like dynamics are further identified. Thus, the numerical model and simulation results are very useful and interesting for the ultrafast brain-inspired neuromorphic photonics systems based on VCSELs.

  17. Sub-picosecond chirped return-to-zero nonlinear optical pulse propagating in dense dispersion-managed fibre

    NASA Astrophysics Data System (ADS)

    Guo, Shuqin; Le, Zichun; Quan, Bisheng

    2006-01-01

    By numerical simulation, we show that the fourth-order dispersion (FOD) makes sub-picosecond optical pulse broaden as second-order dispersion (SOD), makes optical pulse oscillate simultaneously as third-order dispersion (TOD). Based on above two reasons, sub-picosecond optical pulse will be widely broaden and lead to emission of continuum radiation during propagation. Here, resemble to two- and third-order dispersion compensation, fourth-order dispersion compensation is also suggested in a dispersion-managed optical fiber link, which is realized by arranging two kinds of fiber with opposite dispersion sign in each compensation cell. For sake of avoiding excessively broadening, ultra short scale dispersion compensation cell is required in ultra high speed optical communication system. In a full dispersion compensation optical fiber system which path average dispersion is zero about SOD, TOD, and FOD, even suffering from affection of high order nonlinear like self-steep effect and self-frequency shift, 200 fs gauss optical pulse can stable propagate over 1000 km with an optimal initial chirp. When space between neighboring optical pulse is only 2 picoseconds corresponding to 500 Gbit/s transmitting capacity, eye diagram is very clarity after 1000 km. The results demonstrate that ultra short scale dispersion compensation including FOD is need and effective in ultra-high speed optical communication.

  18. Pair annihilation in laser pulses: Optical versus x-ray free-electron laser regimes

    SciTech Connect

    Ilderton, Anton; Johansson, Petter; Marklund, Mattias

    2011-09-15

    We discuss the theory and phenomenology of pair annihilation, within an ultrashort laser pulse, to a single photon. The signature of this process is the unidirectional emission of single photons with a fixed energy. We show that the cross section is significantly larger than for two-photon pair annihilation in vacuum, with x-ray free-electron laser parameters admitting a much clearer signal than optical beams.

  19. A statistical model of the photomultiplier gain process with applications to optical pulse detection

    NASA Technical Reports Server (NTRS)

    Tan, H. H.

    1982-01-01

    A Markov diffusion model was used to determine an approximate probability density for the random gain. This approximate density preserves the correct second-order statistics and appears to be in reasonably good agreement with experimental data. The receiver operating curve for a pulse counter detector of PMT cathode emission events was analyzed using this density. The error performance of a simple binary direct detection optical communication system was also derived. Previously announced in STAR as N82-25100

  20. A statistical model of the photomultiplier gain process with applications to optical pulse detection

    NASA Technical Reports Server (NTRS)

    Tan, H. H.

    1982-01-01

    A Markov diffusion model was used to determine an approximate probability density for the random gain. This approximate density preserves the correct second-order statistics and appears to be in reasonably good agreement with experimental data. The receiver operating curve for a pulse counter detector of PMT cathode emission events was analyzed using this density. The error performance of a simple binary direct detection optical communication system was also derived.

  1. Management of thermal effects in high-repetition-rate pulsed optical parametric oscillators.

    PubMed

    Godard, Antoine; Raybaut, Myriam; Schmid, Thomas; Lefebvre, Michel; Michel, Anne-Marie; Péalat, Michel

    2010-11-01

    We report on the investigation of thermal effects in high-repetition-rate pulsed optical parametric oscillators emitting in the mid-IR. We find that the thermal load induced by the nonresonant idler absorption plays a critical role in the emergence of thermally induced bistability. We then demonstrate a significant improvement of the conversion efficiency (more than 30%) when a proper axial temperature gradient is applied to the nonlinear crystal by use of a two-zone temperature-controlled oven.

  2. Modification of the velocity distribution of H(2) molecules in a supersonic beam by intense pulsed optical gradients.

    PubMed

    Ramirez-Serrano, Jaime; Strecker, Kevin E; Chandler, David W

    2006-07-07

    We report the acceleration and deceleration of H(2) molecules in a supersonic molecular beam by means of its interaction with an intense optical gradient from a nanosecond far-off-resonant optical pulse. The strong optical gradients are formed in the interference pattern of two intense optical pulses at 532 nm. The velocity distribution of the molecular beam, before and after the applied optical pulse, is measured by a velocity-mapped ion imaging technique. Changes in velocity up to 202 m s(-1)+/- 61 m s(-1) are observed in a molecular beam initially travelling at a mean speed of 563 m s(-1). We report the dependence of this change in velocity with the strength of the optical gradient applied.

  3. An Optical Cryostat for Use in Microscopy Cooled by Stirling-Type Pulse Tube Cryocooler

    NASA Astrophysics Data System (ADS)

    Liubiao, Chen; Qiang, Zhou; Xiaoshuang, Zhu; Yuan, Zhou; Junjie, Wang

    The few products of an optical cryostat for use in microscopy in commercialapplications are generally cooled by liquid nitrogen, liquid helium or cryocoolers such as G-M cryocooler or G-M type pulse tube cryocooler (PTC). Sometimes it is not convenient to use G-M cryocooler or G-M type PTC because of its noise and big size; and in some places, liquid nitrogen, especially liquid helium, is not easily available. To overcome this limitation, an optical cryostat for use in microscopy cooled by a Stirling-type pulse tube cryocooler (SPTC) has been designed, built and tested. The refrigerator system SPTC is an important component of the optical cryostat; it has the advantages of compactness, high efficiency, and low vibration. For simplification and compactness, single-stage configuration with coaxial arrangement was employed in the developed SPTC. In order to lower the vibration, the separated configuration was adopted; its compressor and pulse tube are connected with a flexible connecting tube. At present, a lowest temperature of 20 K could be achieved. The temperature fluctuation can be controlled at ±10 mK by adjusting the input electric power to the compressor; and some considerations for further improvement will also be described in this paper.

  4. Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses

    NASA Astrophysics Data System (ADS)

    Bionta, M. R.; Hartmann, N.; Weaver, M.; French, D.; Nicholson, D. J.; Cryan, J. P.; Glownia, J. M.; Baker, K.; Bostedt, C.; Chollet, M.; Ding, Y.; Fritz, D. M.; Fry, A. R.; Kane, D. J.; Krzywinski, J.; Lemke, H. T.; Messerschmidt, M.; Schorb, S.; Zhu, D.; White, W. E.; Coffee, R. N.

    2014-08-01

    The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10-100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for "measure-and-sort" at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses.

  5. Amplification of 126 nm femtosecond seed pulses in optical-field-induced Ar plasma filamentation

    NASA Astrophysics Data System (ADS)

    Kubodera, Shoichi; Deshimaru, Naoyuki; Kaku, Masanori; Katto, Masahito

    2014-10-01

    We have observed amplification of femtosecond (fs) VUV coherent seed beam at 126 nm by utilizing an optical-field-induced ionization (OFI) high-pressure Ar plasma filamentation. We have produced a low-temperature and high-density Ar plasma filamentation inside a high-pressure Ar cell by irradiating a high-intensity laser with an intensity of approximately 1014 W cm-2. Argon excimer molecules (Ar2*) as an amplifier medium were produced inside the high-pressure cell and were used to amplify a weak VUV ultrashort seed pulse at 126 nm, which was generated by harmonic generation of another short pulse infrared laser at 882 nm. We have measured the amplification characteristics and the OFI plasma diagnosis by utilizing the fs VUV pulses at 126 and 882 nm, respectively. The maximum optical gain value of 1.1 cm-1 was observed. Temporal behaviors of the plasma temperature and density in the nano-second time scale indicated a high-density and low-temperature plasma produced by using the OFI. These plasma behaviors were utilized to reproduce the optical amplification characteristics with our OFI excimer simulation code.

  6. Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses

    SciTech Connect

    Bionta, M. R.; Hartmann, N.; Weaver, M.; French, D.; Glownia, J. M.; Bostedt, C.; Chollet, M.; Ding, Y.; Fritz, D. M.; Fry, A. R.; Krzywinski, J.; Lemke, H. T.; Messerschmidt, M.; Schorb, S.; Zhu, D.; White, W. E.; Nicholson, D. J.; Cryan, J. P.; Baker, K.; Kane, D. J.; and others

    2014-08-15

    The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10–100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for “measure-and-sort” at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses.

  7. Optical design and studies of a tiled single grating pulse compressor for enhanced parametric space and compensation of tiling errors

    NASA Astrophysics Data System (ADS)

    Daiya, D.; Patidar, R. K.; Sharma, J.; Joshi, A. S.; Naik, P. A.; Gupta, P. D.

    2017-04-01

    A new optical design of tiled single grating pulse compressor has been proposed, set-up and studied. The parametric space, i.e. the laser beam diameters that can be accommodated in the pulse compressor for the given range of compression lengths, has been calculated and shown to have up to two fold enhancement in comparison to our earlier proposed optical designs. The new optical design of the tiled single grating pulse compressor has an additional advantage of self compensation of various tiling errors like longitudinal and lateral piston, tip and groove density mismatch, compared to the earlier designs. Experiments have been carried out for temporal compression of 650 ps positively chirped laser pulses, at central wavelength 1054 nm, down to 235 fs in the tiled grating pulse compressor set up with the proposed design. Further, far field studies have been performed to show the desired compensation of the tiling errors takes place in the new compressor.

  8. Noise tolerance in wavelength-selective switching of optical differential quadrature-phase-shift-keying pulse train by collinear acousto-optic devices.

    PubMed

    Goto, Nobuo; Miyazaki, Yasumitsu

    2014-06-01

    Optical switching of high-bit-rate quadrature-phase-shift-keying (QPSK) pulse trains using collinear acousto-optic (AO) devices is theoretically discussed. Since the collinear AO devices have wavelength selectivity, the switched optical pulse trains suffer from distortion when the bandwidth of the pulse train is comparable to the pass bandwidth of the AO device. As the AO device, a sidelobe-suppressed device with a tapered surface-acoustic-wave (SAW) waveguide and a Butterworth-type filter device with a lossy SAW directional coupler are considered. Phase distortion of optical pulse trains at 40 to 100  Gsymbols/s in QPSK format is numerically analyzed. Bit-error-rate performance with additive Gaussian noise is also evaluated by the Monte Carlo method.

  9. Few-cycle pulse laser induced damage threshold determination of ultra-broadband optics.

    PubMed

    Kafka, Kyle R P; Talisa, Noah; Tempea, Gabriel; Austin, Drake R; Neacsu, Catalin; Chowdhury, Enam A

    2016-12-12

    A systematic study of few-cycle pulse laser induced damage threshold (LIDT) determination was performed for commercially-available ultra-broadband optics, (i.e. chirped mirrors, silver mirrors, beamsplitters, etc.) in vacuum and in air, for single and multi-pulse regime (S-on-1). Multi-pulse damage morphology at fluences below the single-pulse LIDT was studied in order to investigate the mechanisms leading to the onset of damage. Stark morphological contrast was observed between multi-pulse damage sites formed in air versus those in vacuum. One effect of vacuum testing compared to air included suppression of laser-induced periodic surface structures (LIPSS) formation, possibly influenced by a reduced presence of damage debris. Another effect of vacuum was occasional lowering of LIDT, which appears to be due to the stress-strain performance of the coating design during laser irradiation and under the external stress of vacuum ambience. A fused silica substrate is also examined, and a non-LIPSS nanostructuring is observed on the surface. Possible mechanisms are discussed.

  10. Enhanced tolerance to pulse extinction ratio in Brillouin optical time domain analysis sensors by dithering of the optical source

    NASA Astrophysics Data System (ADS)

    Iribas, Haritz; Urricelqui, Javier; Sagues, Mikel; Loayssa, Alayn

    2015-09-01

    We demonstrate the relaxation of the stringent requirements placed on the pulse extinction ratio in long-range Brillouin optical time-domain analysis sensors (BOTDA) by modulating the wavelength of the laser source that is used to generate both pump and probe waves. This modulation makes the counter-propagating pulse pedestal and probe waves to become correlated only at certain locations in the fiber, thus reducing the gain experienced by the probe wave, which is precisely the process that limits the performance in long-range BOTDAs. Proof-of-concept experimental results in a 20-km sensing link demonstrate a 6-dB reduction of the required modulator extinction ratio.

  11. Photonic generation of ultra-wideband doublet pulse using a semiconductor-optical-amplifier based polarization-diversified loop.

    PubMed

    Luo, Bowen; Dong, Jianji; Yu, Yuan; Yang, Ting; Zhang, Xinliang

    2012-06-15

    We propose and demonstrate a novel scheme of ultra-wideband (UWB) doublet pulse generation using a semiconductor optical amplifier (SOA) based polarization-diversified loop (PDL) without any assistant light. In our scheme, the incoming gaussian pulse is split into two parts by the PDL, and each of them is intensity modulated by the other due to cross-gain modulation (XGM) in the SOA. Then, both parts are recombined with incoherent summation to form a UWB doublet pulse. Bi-polar UWB doublet pulse generation is demonstrated using an inverted gaussian pulse injection. Moreover, pulse amplitude modulation of UWB doublet is also experimentally demonstrated. Our scheme shows some advantages, such as simple implementation without assistant light and single optical carrier operation with good fiber dispersion tolerance.

  12. Sub-5-ps optical pulse generation from a 1.55-µm distributed-feedback laser diode with nanosecond electric pulse excitation and spectral filtering.

    PubMed

    Chen, Shaoqiang; Sato, Aya; Ito, Takashi; Yoshita, Masahiro; Akiyama, Hidefumi; Yokoyama, Hiroyuki

    2012-10-22

    This paper reports generation of sub-5-ps Fourier-transform limited optical pulses from a 1.55-µm gain-switched single-mode distributed-feedback laser diode via nanosecond electric excitation and a simple spectral-filtering technique. Typical damped oscillations of the whole lasing spectrum were observed in the time-resolved waveform. Through a spectral-filtering technique, the initial relaxation oscillation pulse and the following components in the output pulse can be well separated, and the initial short pulse can be selectively extracted by filtering out the short-wavelength components in the spectrum. Short pulses generated by this simple method are expected to have wide potential applications comparable to mode-locking lasers.

  13. 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.

  14. Pulse power requirements for large aperture optical switches based on plasma electrode Pockels cells

    SciTech Connect

    Rhodes, M.A.; Taylor, J.

    1992-06-01

    We discuss very large-aperture optical switches (greater than 30 [times] 30 cm) as an enabling technology for inertial confinement fusion drivers based on multipass laser amplifiers. Large-scale laser fusion drivers such as the Nova laser have been based on single-pass amplifier designs in part because of the unavailability of a suitable large-aperture switch. We are developing an optical switch based on a Pockels cell employing plasma-electrodes. A plasma-electrode Pockels cell (PEPC) is a longitudinal-mode Pockels cell in which a plasma discharge is formed on each side of an electro-optic crystal (typically KDP or deuterated KDP, often designated KD*P). The plasmas formed on either side of the crystal act as transparent electrodes for a switching-pulse and are intended to allow uniform charging of the entire crystal. The switching-pulse is a nominally rectangular high-voltage pulse equal to the half-wave voltage V[sub x] ( 8 kV for KD*P or 17 kV for KDP) and is applied across the crystal via the plasma-electrodes. When the crystal is charged to V[sub x], the polarization of an incoming, linearly polarized, laser beam is rotated by 90[degree]. When used in conjunction with an appropriate, passive polarizer, an optical switch is thus realized. A switch with a clear aperture of 37 [times] 37 cm is now in construction for the Beamlet laser which will serve as a test bed for this switch as well as other technologies required for an advanced NOVA laser design. In this paper, we discuss the unique power electronics requirements of PEPC optical switches.

  15. Pulse power requirements for large aperture optical switches based on plasma electrode Pockels cells

    SciTech Connect

    Rhodes, M.A.; Taylor, J.

    1992-06-01

    We discuss very large-aperture optical switches (greater than 30 {times} 30 cm) as an enabling technology for inertial confinement fusion drivers based on multipass laser amplifiers. Large-scale laser fusion drivers such as the Nova laser have been based on single-pass amplifier designs in part because of the unavailability of a suitable large-aperture switch. We are developing an optical switch based on a Pockels cell employing plasma-electrodes. A plasma-electrode Pockels cell (PEPC) is a longitudinal-mode Pockels cell in which a plasma discharge is formed on each side of an electro-optic crystal (typically KDP or deuterated KDP, often designated KD*P). The plasmas formed on either side of the crystal act as transparent electrodes for a switching-pulse and are intended to allow uniform charging of the entire crystal. The switching-pulse is a nominally rectangular high-voltage pulse equal to the half-wave voltage V{sub x} ( 8 kV for KD*P or 17 kV for KDP) and is applied across the crystal via the plasma-electrodes. When the crystal is charged to V{sub x}, the polarization of an incoming, linearly polarized, laser beam is rotated by 90{degree}. When used in conjunction with an appropriate, passive polarizer, an optical switch is thus realized. A switch with a clear aperture of 37 {times} 37 cm is now in construction for the Beamlet laser which will serve as a test bed for this switch as well as other technologies required for an advanced NOVA laser design. In this paper, we discuss the unique power electronics requirements of PEPC optical switches.

  16. Pulse shape measurements using single shot-frequency resolved optical gating for high energy (80 J) short pulse (600 fs) laser

    SciTech Connect

    Palaniyappan, S.; Johnson, R.; Shimada, T.; Gautier, D. C.; Letzring, S.; Offermann, D. T.; Fernandez, J. C.; Shah, R. C.; Jung, D.; Hegelich, B. M.; Hoerlein, R.

    2010-10-15

    Relevant to laser based electron/ion accelerations, a single shot second harmonic generation frequency resolved optical gating (FROG) system has been developed to characterize laser pulses (80 J, {approx}600 fs) incident on and transmitted through nanofoil targets, employing relay imaging, spatial filter, and partially coated glass substrates to reduce spatial nonuniformity and B-integral. The device can be completely aligned without using a pulsed laser source. Variations of incident pulse shape were measured from durations of 613 fs (nearly symmetric shape) to 571 fs (asymmetric shape with pre- or postpulse). The FROG measurements are consistent with independent spectral and autocorrelation measurements.

  17. Quantum control of ultracold atoms and molecules via linearly chirped laser pulses and optical frequency combs

    NASA Astrophysics Data System (ADS)

    Collins, Thomas A.

    This work investigates the potential of performing high yield quantum control operations on atomic and molecular systems using frequency modulated laser fields. The effectiveness of a single laser pulse in creating desired superposition states within the valence shell of Rubidium and the utilization of a single pulse train in order to perform internal state cooling of diatomic hetero-nuclear molecules, in this case KRb, are investigated. These methods are an alternative to the current protocol in the field of quantum control which typically calls for the employment of two laser fields, be they single pulses or pulse trains. Manipulation of the state of the valence electron within Rubidium was studied for two different models of the hyperfine levels of the 5s and 5p orbitals: a three level Λ system and the more realistic four level system accounting for all allowed optical transitions. Numerical analysis of the population dynamics that occur within the system during the time of interaction with the pulse was carried out for various values of the field parameters as well as for two different forms of the pulse envelope. Population inversion within the hyperfine levels of the 5s orbital of Rubidium is demonstrated for a single linearly polarized, linearly down chirped, laser pulse of nanosecond duration and beam intensity on the order of kWcm2 . Superpositions of equally populated hyperfine states, a phenomenon which is crucial in the development of qubits, were also observed for certain values of the field parameters. The results of this analysis are applicable to 85Rb and 87Rb and both the D1 and D2 transitions and are valid for the two models used. For the case of internal state cooling, the power spectrum of a standard pulse train was compared to that of a pulse with sinusoidal phase modulation revealing that the envelope of the frequency comb associated with such a pulse train is controllable via the phase modulation. Thus through frequency modulation the

  18. Generation of high-energy self-phase-stabilized pulses by difference-frequency generation followed by optical parametric amplification.

    PubMed

    Manzoni, C; Vozzi, C; Benedetti, E; Sansone, G; Stagira, S; Svelto, O; De Silvestri, S; Nisoli, M; Cerullo, G

    2006-04-01

    We produce ultrabroadband self-phase-stabilized near-IR pulses by a novel approach where a seed pulse, obtained by difference-frequency generation of a hollow-fiber broadened supercontinuum, is amplified by a two-stage optical parametric amplifier. Energies up to 20 microJ with a pulse spectrum extending from 1.2 to 1.6 microm are demonstrated, and a route for substantial energy scaling is indicated.

  19. Applications of Optical Coherent Transient Technology to Pulse Shaping, Spectral Filtering Arbitrary Waveform Generation and RF Beamforming

    DTIC Science & Technology

    2006-04-14

    for creating fast (~MHz/µs) linear frequency chirped optical pulses: (1) using acousto - optic modulators (AOMs) driven with a chirped RF source, ( 2 ...the cavity. The frequencies allowed in a Fabry–Perot cavity are: where =1,2,... and optical path length of cavity 2 qcv q d d = = (29) The...the functional operation of acousto - optic (AO) deflectors , but with bandwidths (BW) in excess of 10 GHz and Time-Bandwidth Prod- ucts (TB) over 103 by

  20. Investigations on optimizing the energy transmission of ultrafast optical pulses in pure water

    NASA Astrophysics Data System (ADS)

    Lukofsky, David

    Many of today's communication and imaging technologies share the common challenge of signal deterioration due to water's large absorption coefficient. As an example, it is water molecules that contaminate the fused silica of optical fibers and account for most of the absorption they exhibit at communication wavelengths. It is also water (in the form of vapor) that makes it challenging to devise practical THz spectroscopic systems. As such, this thesis examines how the transmission of electromagnetic radiation through water could be improved as a stepping stone towards bettering a wide array of communication and imaging applications. Recent time-domain approaches have noted the connection between pulse rise-time and precursor waveform absorption. This thesis represents the first in-depth analysis of precursors using an intuitive frequency-domain approach. It was shown with well-known physical metrics that precursors are a linear effect resulting from the temporal representation of a Beer's law of absorption for broadband pulses. Experimental validation was achieved with a spatial light modulator used in conjunction with Frequency-Resolved-Optical-Gating (FROG) to obtain the first measurement of the amplitude and phase of an optical precursor. The semi-classical two-level atom model was used to infer the transitional dipole moments of the 1447 nm and 2:94 mum vibrational resonances of the medium. These values supported finite-difference-time-domain simulations suggesting how 52 fs sech2 pulses of 220 GW/cm2 peak intensity could propagate with negligible attenuation over 15 absorption lengths when tuned to the 2:94 mum transition of water. Extensive use of 1550 nm lasers in communication systems and the presence of the second vibrational overtone resonance of water at 1447 nm were the motivation for transmission experiments completed at the Naval Research Laboratory (Washington, DC) at this transition. As much as a 500% increase in absolute transmission was observed

  1. Excitation of individual Raman Stokes lines in the visible regime using rectangular-shaped nanosecond optical pulses at 530 nm.

    PubMed

    Chen, Kang Kang; Alam, Shaif-ul; Horak, Peter; Codemard, Christophe A; Malinowski, Andrew; Richardson, David J

    2010-07-15

    We demonstrate the selective excitation of individual Raman Stokes lines of up to the ninth order by pumping with rectangular-shaped optical pulses at 530 nm from a frequency-doubled adaptively pulse shaped fiber master oscillator power amplifier. We achieve extinction ratios of up to 15 dB between selected and adjacent Raman orders in a 1-km-long fiber.

  2. High-Beam-Quality Optical Parametric Chirped-Pulse Amplification in Periodically-Poled KTiOPO4

    SciTech Connect

    Ebbers, C A; Schmidt, J R; Jovanovic, I

    2003-09-25

    We have demonstrated a high-gain optical parametric chirped-pulse amplifier for Nd:glass-based short-pulse laser systems based on periodically poled potassium-titanyl-phosphate. Our amplifier produced high single-pass gain, broad bandwidth, excellent beam quality and stability.

  3. Three-dimensional few-cycle optical Airy pulses in the array of carbon nanotubes with multilevel impurities

    NASA Astrophysics Data System (ADS)

    Konobeeva, Natalia N.; Belonenko, Mikhail B.

    2017-01-01

    Propagation of few-cycle optical Airy pulse through the array of semiconductor carbon nanotubes (CNTs) is considered. CNTs are supposed to contain multilevel impurities. In our study, we have neglected transitions between the valence and the conduction bands. As a result, we have revealed the dependence of the pulse form on the parameters of energy.

  4. Structural and nonlinear optical characterizations of ZnS/ PVP nanocomposites synthesized by pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Divyasree, M. C.; Chandrasekharan, K.

    2017-05-01

    ZnS/Poly Vinyl Pyrrolidone nanocomposites were synthesized by pulsed laser ablation at ambient conditions using an Nd: YAG laser at 532 nm wavelength and 7ns pulse width. Linear optical characterizations were done using UV-Vis spectrophotometer and fluorometer. Both absorption and emission peaks were found to be blue shifted, which could be due to quantum confinement effect. Spherical morphology and the purity in the elemental composition of the sample were confirmed by scanning electron microscope and energy dispersive X-ray spectrometer respectively. Average particle size of the ZnS nanoparticles was found to be 13.45 nm from the Gaussian fitted histogram of transmission electron Microscopy image and the structure was confirmed as hexagonal wurtzite by X-ray diffraction analysis. The nonlinear optical parameters were figured out by z scan analysis with the same laser system. The nanocomposite showed good absorptive and refractive properties in the nonlinear optical regime. Detailed study of the nanocomposite revealed its potential applications in optoelectronics and nonlinear optical device fabrication.

  5. Performance model for optical extraction from a pulsed chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Copeland, D. A.; Bauer, A. H.; Jones, K. D.

    A comprehensive time-dependent gain model for pulsed optical extraction from a flowing oxygen-iodine laser medium is described. Gas flow is treated using an unsteady, premixed, quasi-one-dimensional model which accounts for gas motion and expansion as well as heat release in the cavity. The model uses a simplified, temperature-dependent, chemical kinetics package which consists of several reactions among the 3Sigma, 1Delta, and 1Sigma states of oxygen, atomic and molecular iodine, water, and helium. Hyperfine relaxation effects on the gain and optical extraction from the 3-4 line are treated using a simple four-level laser model. An efficient algorithm for solving the coupled medium and optical extraction equations is described. This gain model, in conjunction with a geometric model of an unstable confocal resonator, is used to examine energy extraction from the medium as a function of pulse repetition rate, duty cycle, and optical mode width. It is shown that the output power may exhibit flow-induced relaxation oscillations and the conditions under which these oscillations occur are discussed.

  6. 2013 R&D 100 Award: 'SHIELD' protects NIF optics from harmful pulses

    ScienceCinema

    Chou, Jason

    2016-07-12

    In the past, it took as long as 12 hours to manually screen 48 critical checkpoints at the National Ignition Facility (NIF) for harmful laser pulses. The screening equipment had to be moved from point to point throughout a facility the size of three football fields. Now with a new technology, called Laser SHIELD (Screening at High-throughput to Identify Energetic Laser Distortion), and with the push of a button, the screening can be done in less than one second. Proper screening of pulses is critical for the operation of high-energy lasers to ensure that the laser does not exceed safe operating conditions for optics. The energetic beams of light are so powerful that, when left uncontrolled, they can shatter the extremely valuable glass inside the laser. If a harmful pulse is found, immediate adjustments can be made in order to protect the optics for the facility. Laser SHIELD is a custom-designed high-throughput screening system built from low-cost and commercially available components found in the telecommunications industry. Its all-fiber design makes it amenable to the unique needs of high-energy laser facilities, including routing to intricate pick-off locations, immunity to electromagnetic interference and low-loss transport (up to several kilometers). The technology offers several important benefits for NIF. First, the facility is able to fire more shots in less time-an efficiency that saves the facility millions of dollars each year. Second, high-energy lasers are more flexible to wavelength changes requested by target physicists. Third, by identifying harmful pulses before they damage the laser's optics, the facility potentially saves hundreds of thousands of dollars in maintenance costs each year.

  7. 2013 R&D 100 Award: 'SHIELD' protects NIF optics from harmful pulses

    SciTech Connect

    Chou, Jason

    2014-04-03

    In the past, it took as long as 12 hours to manually screen 48 critical checkpoints at the National Ignition Facility (NIF) for harmful laser pulses. The screening equipment had to be moved from point to point throughout a facility the size of three football fields. Now with a new technology, called Laser SHIELD (Screening at High-throughput to Identify Energetic Laser Distortion), and with the push of a button, the screening can be done in less than one second. Proper screening of pulses is critical for the operation of high-energy lasers to ensure that the laser does not exceed safe operating conditions for optics. The energetic beams of light are so powerful that, when left uncontrolled, they can shatter the extremely valuable glass inside the laser. If a harmful pulse is found, immediate adjustments can be made in order to protect the optics for the facility. Laser SHIELD is a custom-designed high-throughput screening system built from low-cost and commercially available components found in the telecommunications industry. Its all-fiber design makes it amenable to the unique needs of high-energy laser facilities, including routing to intricate pick-off locations, immunity to electromagnetic interference and low-loss transport (up to several kilometers). The technology offers several important benefits for NIF. First, the facility is able to fire more shots in less time-an efficiency that saves the facility millions of dollars each year. Second, high-energy lasers are more flexible to wavelength changes requested by target physicists. Third, by identifying harmful pulses before they damage the laser's optics, the facility potentially saves hundreds of thousands of dollars in maintenance costs each year.

  8. Arbitrary waveform generator and differentiator employing an integrated optical pulse shaper.

    PubMed

    Liao, Shasha; Ding, Yunhong; Dong, Jianji; Yang, Ting; Chen, Xiaolin; Gao, Dingshan; Zhang, Xinliang

    2015-05-04

    We propose and demonstrate an optical arbitrary waveform generator and high-order photonic differentiator based on a four-tap finite impulse response (FIR) silicon-on-insulator (SOI) on-chip circuit. Based on amplitude and phase modulation of each tap controlled by thermal heaters, we obtain several typical waveforms such as triangular waveform, sawtooth waveform, square waveform and Gaussian waveform, etc., assisted by an optical frequency comb injection. Unlike other proposed schemes, our scheme does not require a spectral disperser which is difficult to fabricate on chip with high resolution. In addition, we demonstrate first-, second- and third-order differentiators based on the optical pulse shaper. Our scheme can switch the differentiator patterns from first- to third-order freely. In addition, our scheme has distinct advantages of compactness, capability for integration with electronics.

  9. Energy and average power scalable optical parametric chirped-pulse amplification in yttrium calcium oxyborate.

    PubMed

    Liao, Zhi M; Jovanovic, Igor; Ebbers, Chris A; Fei, Yiting; Chai, Bruce

    2006-05-01

    Optical parametric chirped-pulse amplification (OPCPA) in nonlinear crystals has the potential to produce extremes of peak and average power but is limited either in energy by crystal growth issues or in average power by crystal thermo-optic characteristics. Recently, large (7.5 cm diameter x 25 cm length) crystals of yttrium calcium oxyborate (YCOB) have been grown and utilized for high-average-power second-harmonic generation. Further, YCOB has the necessary thermo-optic properties required for scaling OPCPA systems to high peak and average power operation for wavelengths near 1 microm. We report what is believed to be the first use of YCOB for OPCPA. Scalability to higher peak and average power is addressed.

  10. Spectral Shearing of Quantum Light Pulses by Electro-Optic Phase Modulation.

    PubMed

    Wright, Laura J; Karpiński, Michał; Söller, Christoph; Smith, Brian J

    2017-01-13

    Frequency conversion of nonclassical light enables robust encoding of quantum information based upon spectral multiplexing that is particularly well-suited to integrated-optics platforms. Here we present an intrinsically deterministic linear-optics approach to spectral shearing of quantum light pulses and show it preserves the wave-packet coherence and quantum nature of light. The technique is based upon an electro-optic Doppler shift to implement frequency shear of heralded single-photon wave packets by ±200  GHz, which can be scaled to an arbitrary shift. These results demonstrate a reconfigurable method to controlling the spectral-temporal mode structure of quantum light that could achieve unitary operation.

  11. All-optical generation of DFT-S-OFDM superchannels using periodic sinc pulses.

    PubMed

    Lowery, Arthur James; Zhu, Chen; Viterbo, Emanuele; Corcoran, Bill

    2014-11-03

    Discrete-Fourier-transform spread (DFT-S) optical Orthogonal Frequency Division Multiplexed (OFDM) signals offer improved nonlinearity performance in long haul optical communications systems, and can be used to form superchannels. In this paper we propose how DFT-S-OFDM superchannels can be generated and demultiplexed using all-optical techniques, and demonstrate the feasibility using numerical simulations. We also discuss how each wavelength channel is similar to recently proposed Orthogonally Time-Division Multiplexed (OrthTDM) systems using periodic-sinc pulses from, for example, a Nyquist laser. The key difference between OrthTDM and DFT-S-OFDM is the synchronization of the symbol boundaries of every modulation tributary; because of this we show that OrthTDM cannot be formed into superchannels that can be demultiplexed without penalties, but DFT-S-OFDM can be.

  12. Single shot damage mechanism of Mo/Si multilayer optics under intense pulsed XUV-exposure.

    PubMed

    Khorsand, A R; Sobierajski, R; Louis, E; Bruijn, S; van Hattum, E D; van de Kruijs, R W E; Jurek, M; Klinger, D; Pelka, J B; Juha, L; Burian, T; Chalupsky, J; Cihelka, J; Hajkova, V; Vysin, L; Jastrow, U; Stojanovic, N; Toleikis, S; Wabnitz, H; Tiedtke, K; Sokolowski-Tinten, K; Shymanovich, U; Krzywinski, J; Hau-Riege, S; London, R; Gleeson, A; Gullikson, E M; Bijkerk, F

    2010-01-18

    We investigated single shot damage of Mo/Si multilayer coatings exposed to the intense fs XUV radiation at the Free-electron LASer facility in Hamburg - FLASH. The interaction process was studied in situ by XUV reflectometry, time resolved optical microscopy, and "post-mortem" by interference-polarizing optical microscopy (with Nomarski contrast), atomic force microscopy, and scanning transmission electron microcopy. An ultrafast molybdenum silicide formation due to enhanced atomic diffusion in melted silicon has been determined to be the key process in the damage mechanism. The influence of the energy diffusion on the damage process was estimated. The results are of significance for the design of multilayer optics for a new generation of pulsed (from atto- to nanosecond) XUV sources.

  13. 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.

  14. Optical nonlinear dynamics in ZnS from femtosecond laser pulses

    SciTech Connect

    Wu, Yu-E; Ren, Mengxin Wang, Zhenhua; Li, Wenhua; Wu, Qiang; Zhang, Xinzheng Xu, Jingjun; Yi, Sanming

    2014-05-15

    A wavelength swapping nondegenerate pump-probe technique to measure the magnitudes of the nonlinear optical dynamics as well as the relaxation time of electrons in high energy levels is presented using a ZnS single crystal wafer as an example. By pumping the sample with 800 nm femtosecond pulses and probing at 400 nm, nondegenerate two-photon absorption (N-2PA) happens exclusively, and the measured curves only show instantaneous features without relaxation tails. The N-2PA coefficient was derived explicitly as 7.52 cm/GW. Additionally, when the wavelengths of the pump and probe beams are swapped, extra information about the relaxation time of the hot electrons excited in the conduction band is obtained. The combined results above are helpful for evaluating the characteristics of an optical switches based on ZnS or other materials with respect to its nonlinear optical dynamic aspect.

  15. Pulsing frequency induced change in optical constants and dispersion energy parameters of WO3 films grown by pulsed direct current magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Punitha, K.; Sivakumar, R.; Sanjeeviraja, C.

    2014-03-01

    In this work, we present the pulsing frequency induced change in the structural, optical, vibrational, and luminescence properties of tungsten oxide (WO3) thin films deposited on microscopic glass and fluorine doped tin oxide (SnO2:F) coated glass substrates by pulsed dc magnetron sputtering technique. The WO3 films deposited on SnO2:F substrate belongs to monoclinic phase. The pulsing frequency has a significant influence on the preferred orientation and crystallinity of WO3 film. The maximum optical transmittance of 85% was observed for the film and the slight shift in transmission threshold towards higher wavelength region with increasing pulsing frequency revealed the systematic reduction in optical energy band gap (3.78 to 3.13 eV) of the films. The refractive index (n) of films are found to decrease (1.832 to 1.333 at 550 nm) with increasing pulsing frequency and the average value of extinction coefficient (k) is in the order of 10-3. It was observed that the dispersion data obeyed the single oscillator of the Wemple-Didomenico model, from which the dispersion energy (Ed) parameters, dielectric constants, plasma frequency, oscillator strength, and oscillator energy (Eo) of WO3 films were calculated and reported for the first time due to variation in pulsing frequency during deposition by pulsed dc magnetron sputtering. The Eo is change between 6.30 and 3.88 eV, while the Ed varies from 25.81 to 7.88 eV, with pulsing frequency. The Raman peak observed at 1095 cm-1 attributes the presence of W-O symmetric stretching vibration. The slight shift in photoluminescence band is attributed to the difference in excitons transition. We have made an attempt to discuss and correlate these results with the light of possible mechanisms underlying the phenomena.

  16. Using phase retrieval to measure the intensity and phase of ultrashort pulses: Frequency-resolved optical gating

    SciTech Connect

    Trebino, R. ); Kane, D.J. )

    1993-05-01

    The authors recently introduced a new technique, frequency-resolved optical gating (FROG). For directly determining the full intensity I(t) and phase [var phi](t) of a single femtosecond pulse. By using almost any instantaneous nonlinear-optical interaction of two replicas of the ultrashort pulse to be measured, FROG involves measuring the spectrum of the signal pulse as a function of the delay between the replicas. The resulting trace of intensity versus frequency and delay yields an intuitive display of the pulse that is similar to the pulse spectrogram, except that the gate is a function of the pulse to be measured. The problem of inverting the FROG trace to obtain the pulse intensity and phase can also be considered a complex two-dimensional phase-retrieval problem. As a result, the FROG trace yields, in principle, an essentially unique pulse intensity and phase. It is shown that this is also the case in practice. An iterative-Fourier-transform algorithm is presented for inverting the FROG trace. The algorithm is unusual in its use of a novel constraint: the mathematical form of the signal field. Without the use of a support constraint, the algorithm performs quite well in practice, even for pulses with serious phase distortions and for experimental data with noise, although it occasionally stagnates when pulses with large intensity fluctuations are used. 49 refs., 15 figs.

  17. Pulse Propagation Effects in Optical 2D Fourier-Transform Spectroscopy: Theory.

    PubMed

    Spencer, Austin P; Li, Hebin; Cundiff, Steven T; Jonas, David M

    2015-04-30

    A solution to Maxwell's equations in the three-dimensional frequency domain is used to calculate rephasing two-dimensional Fourier transform (2DFT) spectra of the D2 line of atomic rubidium vapor in argon buffer gas. Experimental distortions from the spatial propagation of pulses through the sample are simulated in 2DFT spectra calculated for the homogeneous Bloch line shape model. Spectral features that appear at optical densities of up to 3 are investigated. As optical density increases, absorptive and dispersive distortions start with peak shape broadening, progress to peak splitting, and ultimately result in a previously unexplored coherent transient twisting of the split peaks. In contrast to the low optical density limit, where the 2D peak shape for the Bloch model depends only on the total dephasing time, these distortions of the 2D peak shape at finite optical density vary with the waiting time and the excited state lifetime through coherent transient effects. Experiment-specific conditions are explored, demonstrating the effects of varying beam overlap within the sample and of pseudo-time domain filtering. For beam overlap starting at the sample entrance, decreasing the length of beam overlap reduces the line width along the ωτ axis but also reduces signal intensity. A pseudo-time domain filter, where signal prior to the center of the last excitation pulse is excluded from the FID-referenced 2D signal, reduces propagation distortions along the ωt axis. It is demonstrated that 2DFT rephasing spectra cannot take advantage of an excitation-detection transformation that can eliminate propagation distortions in 2DFT relaxation spectra. Finally, the high optical density experimental 2DFT spectrum of rubidium vapor in argon buffer gas [J. Phys. Chem. A 2013, 117, 6279-6287] is quantitatively compared, in line width, in depth of peak splitting, and in coherent transient peak twisting, to a simulation with optical density higher than that reported.

  18. Optical Arbitrary Waveform Generators Based on Temporal and Spectral Shaping of Optical Pulses in Nonlinear Metamaterials

    DTIC Science & Technology

    2011-06-01

    harmonic generation. The outcome of this first theoretical demonstration of pulse shaping technique is the function χ( 2 )(z) which is necessary to obtain...identical waveguides, and both one-dimensional and multidimensional configurations have been considered theoretically as well as experimentally [ 2 –8]. On the...CONFORTI, DE ANGELIS, AND AKYLAS PHYSICAL REVIEW A 83, 043822 (2011) to obtain (as a first-order approximation) iuz + β 2 u+ wx + w + γ1|u|2u = 0, ( 2

  19. Optical study of diffuse bi-directional nanosecond pulsed dielectric barrier discharge in nitrogen.

    PubMed

    Nie, Dongxia; Wang, Wenchun; Yang, Dezheng; Shi, Hengchao; Huo, Yan; Dai, Leyang

    2011-09-01

    In this study, a bi-directional high voltage pulse with 20 ns rising time is employed to generate diffuse glow-like dielectric barrier discharge plasma with very low gas temperature in N2 using needle-plate electrode configuration at atmospheric pressure. Both the diffuse nanosecond pulsed dielectric barrier discharge images and the optical emission spectra of the discharge are recorded successfully under severe electromagnetic interference. The effects of pulse peak voltage, pulse repetition rate, and the concentrations of Ar and O2 on the emission intensities of NO (A2Σ→X2Π), OH (A2Σ→X2Π, 0-0), N2 (C3Πu→B3Πg, 0-0, 337.1 nm), and N2+ (B2Σu+→X2Σg+, 0-0, 391.4 nm) are investigated. The effects of the concentrations of Ar and O2 on the discharge diffuse performance are also studied. It is found that the emission intensities of NO (A2Σ→X2Π), OH (A2Σ→X2Π, 0-0), N2 (C3Πu→B3Πg, 0-0, 337.1 nm), and N2+ (B2Σu+→X2Σg+, 0-0, 391.4 nm) rise with increasing pulse peak voltage, pulse repetition rate, and the concentration of Ar, but decrease with increasing the concentration of O2. The main physicochemical processes involved are also discussed.

  20. Pulse shape effects on the measurement of temperature using a Brillouin-based optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Galindez, Carlos; Madruga, Francisco-Javier; Cobo, Adolfo; Conde, Olga; Lopez-Higuera, Jose-Miguel

    2007-04-01

    Distributed fiber sensing based on Brillouin gain scattering (BGS) principle is a useful way to develop devices capable to measure temperature or/and strain in optical fibers. New effects or technologies that could achieve a larger distance and/or a better spatial resolution are a topic of special interest in this fiber sensing area. The influence of the probe-pulse shape in the interaction between the pulsed light and the continuous wave laser in a pump-probe system is presented. The purpose of this study is to improve the spatial resolution of the measurement without losing stability in the BGS. Also it is showed how the backscattering Brillouin gain is affected by inducing variations on the final value of the BGS intensity; this effect is illustrated by using an experimental set up based on the Brillouin optical time-domain analysis (BOTDA). Theoretical analysis of the probe pulse in the Brillouin shift and intensity value using triangular, sinc and saw tooth shapes around the medium phonon life time (~10ns) are presented; as well as the experimental results and possible applications are explained.

  1. ELECTRO-OPTIC BEAM POSITION AND PULSED POWER MONITORS FOR THE SECOND AXIS OF DARHT.

    SciTech Connect

    M. BRUBAKER; C. EKDAHL; C. YAKYMYSHYN

    2001-05-01

    The second axis of the Dual Axis Radiographic Hydro-Test (DARHT) facility utilizes a long pulse electron beam having a duration in excess of two microseconds. This time scale poses problems for many conventional diagnostics that rely upon electrical cables to transmit signals between the accelerator and recording equipment. Recognizing that transit time isolation is not readily achieved for the long pulse regime, difficulties resulting from ground loops are anticipated. An electro-optic (EO) voltage sensor technology has been developed to address this issue. The EO sensor exploits the Pockels effect in Bi{sub 4}Ge{sub 3}O{sub 12} (BGO) to provide linear modulation of laser light in response to the voltage induced on a pickup electrode. Fiber coupling between the light source, Pockels cell and receiver ensures complete galvanic isolation with improved cost and performance as compared to conventional sensors fitted with fiber optic links. Furthermore, the EO approach requires that only the passive sensor element be located near the accelerator while the light source and receiver can be installed in remote locations. This paper describes the design and development of EO sensors for electron beam and pulsed power monitoring on the second axis of DARHT. Typical calibration and testing data for the sensors is also presented.

  2. On-field distributed first-order PMD measurement based on pOTDR and optical pulse width sweep.

    PubMed

    Franciscangelis, Carolina; Floridia, Claudio; Simões, Glauco C C P; Schmmidt, Fernando; Fruett, Fabiano

    2015-05-18

    A method for PMD distributed localization and estimation based on polarization optical time domain reflectometer technique, pOTDR and pulse width sweep is used on-field for the first time. The method consists in launching light pulses with variable widths in an optical fiber under test and then analyzes the Rayleigh backscattered signal spatial power distribution after passing through a polarizer. Both localization and PMD magnitude are function of OTDR pulse width and can be obtained from the ripple analysis, enabling the characterization of the fiber links.

  3. Shear wave pulse compression for dynamic elastography using phase-sensitive optical coherence tomography

    PubMed Central

    Nguyen, Thu-Mai; Song, Shaozhen; Arnal, Bastien; Wong, Emily Y.; Huang, Zhihong; Wang, Ruikang K.; O’Donnell, Matthew

    2014-01-01

    Abstract. Assessing the biomechanical properties of soft tissue provides clinically valuable information to supplement conventional structural imaging. In the previous studies, we introduced a dynamic elastography technique based on phase-sensitive optical coherence tomography (PhS-OCT) to characterize submillimetric structures such as skin layers or ocular tissues. Here, we propose to implement a pulse compression technique for shear wave elastography. We performed shear wave pulse compression in tissue-mimicking phantoms. Using a mechanical actuator to generate broadband frequency-modulated vibrations (1 to 5 kHz), induced displacements were detected at an equivalent frame rate of 47 kHz using a PhS-OCT. The recorded signal was digitally compressed to a broadband pulse. Stiffness maps were then reconstructed from spatially localized estimates of the local shear wave speed. We demonstrate that a simple pulse compression scheme can increase shear wave detection signal-to-noise ratio (>12  dB gain) and reduce artifacts in reconstructing stiffness maps of heterogeneous media. PMID:24441876

  4. Optical control of electron phase space in plasma accelerators with incoherently stacked laser pulses

    SciTech Connect

    Kalmykov, S. Y. Shadwick, B. A.; Davoine, X.; Lehe, R.; Lifschitz, A. F.

    2015-05-15

    It is demonstrated that synthesizing an ultrahigh-bandwidth, negatively chirped laser pulse by incoherently stacking pulses of different wavelengths makes it possible to optimize the process of electron self-injection in a dense, highly dispersive plasma (n{sub 0}∼10{sup 19} cm{sup −3}). Avoiding transformation of the driving pulse into a relativistic optical shock maintains a quasi-monoenergetic electron spectrum through electron dephasing and boosts electron energy far beyond the limits suggested by existing scaling laws. In addition, evolution of the accelerating bucket in a plasma channel is shown to produce a background-free, tunable train of femtosecond-duration, 35–100 kA, time-synchronized quasi-monoenergetic electron bunches. The combination of the negative chirp and the channel permits acceleration of electrons beyond 1 GeV in a 3 mm plasma with 1.4 J of laser pulse energy, thus offering the opportunity of high-repetition-rate operation at manageable average laser power.

  5. Optical emission spectroscopy of nanosecond repetitively pulsed microplasmas generated in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Orriere, Thomas; Moreau, Eric; Benard, Nicolas; Pai, David

    2015-09-01

    Nanosecond repetitively pulsed (NRP) microplasmas are generated in room temperature air at atmospheric pressure, in order to investigate the enhanced control of discharge properties via the combined effects of spatial confinement and nanosecond repetitive pulsing. Discharges were generated using high-voltage pulses of 15-ns duration applied to a tungsten pin-to-pin reactor, with inter-electrode gap distances (d) from 2 mm down to 0.2 mm. Optical emission spectroscopy and electrical characterization performed on the discharge indicate that heat transfer and plasma chemistry are influenced by the microplasma geometry. Ultrafast gas heating is observed upon deducing the rotational temperature of N2 from the measured emission spectrum of the N2 (C -->B) (0, 2) and (1, 3) transition bands, but use of the microplasma geometry (d = 0.2 mm) results in lower gas temperatures than in larger discharge gaps (d = 2 mm), including at high pulse repetition frequency (30 kHz) where substantial steady-state gas heating can occur. The measured Stark broadening of the Hα transition is significantly greater than for previously studied NRP discharges in air at atmospheric pressure, indicating that the maximum electron number density may be correspondingly much greater, up to 1018 cm-3. Furthermore, for NRP microplasmas, the intensities of emission from excited atomic ions (O+ and N+) are much higher than those of excited neutral atoms (O and N), in contrast to NRP discharges generated in larger discharge gaps.

  6. Evaluation of accuracy and reliability of PulseOn optical heart rate monitoring device.

    PubMed

    Delgado-Gonzalo, Ricard; Parak, Jakub; Tarniceriu, Adrian; Renevey, Philippe; Bertschi, Mattia; Korhonen, Ilkka

    2015-08-01

    PulseOn is a wrist-worn optical heart rate (HR) monitor based on photoplethysmography. It utilizes multi-wavelength technology and optimized sensor geometry to monitor blood flow at different depths of skin tissue, and it dynamically adapts to an optimal measurement depth in different conditions. Movement artefacts are reduced by adaptive movement-cancellation algorithms and optimized mechanics, which stabilize the sensor-to-skin contact. In this paper, we evaluated the accuracy and reliability of PulseOn technology against ECG-derived HR in laboratory conditions during a wide range of physical activities and also during outdoor sports. In addition, we compared the performance to another on-the-shelf wrist-worn consumer product Mio LINK(®). The results showed PulseOn reliability (% of time with error <;10bpm) of 94.5% with accuracy (100% - mean absolute percentage error) 96.6% as compared to ECG (vs 86.6% and 94.4% for Mio LINK(®), correspondingly) during laboratory protocol. Similar or better reliability and accuracy was seen during normal outdoor sports activities. The results show that PulseOn provides reliability and accuracy similar to traditional chest strap ECG HR monitors during cardiovascular exercise.

  7. An optical parametric chirped-pulse amplifier for seeding high repetition rate free-electron lasers

    DOE PAGES

    Höppner, H.; Hage, A.; Tanikawa, T.; ...

    2015-05-15

    High repetition rate free-electron lasers (FEL), producing highly intense extreme ultraviolet and x-ray pulses, require new high power tunable femtosecond lasers for FEL seeding and FEL pump-probe experiments. A tunable, 112 W (burst mode) optical parametric chirped-pulse amplifier (OPCPA) is demonstrated with center frequencies ranging from 720–900 nm, pulse energies up to 1.12 mJ and a pulse duration of 30 fs at a repetition rate of 100 kHz. Since the power scalability of this OPCPA is limited by the OPCPA-pump amplifier, we also demonstrate a 6.7–13.7 kW (burst mode) thin-disk OPCPA-pump amplifier, increasing the possible OPCPA output power to manymore » hundreds of watts. Furthermore, third and fourth harmonic generation experiments are performed and the results are used to simulate a seeded FEL with high-gain harmonic generation.« less

  8. INSTRUMENTS AND METHODS OF INVESTIGATION: Microstructure optical fibers for a new generation of fiber-optic sources and converters of light pulses

    NASA Astrophysics Data System (ADS)

    Zheltikov, Aleksei M.

    2007-07-01

    Breakthroughs in microstructure-fiber technologies are pushing the development of a new class of fiber-optic frequency converters, broadband light sources, and short-pulse lasers. The frequency profile of dispersion and the spatial profile of electromagnetic field distribution in waveguide modes of microstructure fibers can be tailored by modifying the core and cladding design on a micro- and nanoscale, suggesting ways of creating novel fiber-optic devices providing the highly efficient spectral and temporal transformation of laser pulses with pulse widths ranging from dozens of nanoseconds to a few optical cycles (several femtoseconds) within a broad range of peak powers from hundreds of watts to several gigawatts. In new fiber lasers, microstructure fibers provide a precise balance of dispersion within a broad spectral range, allowing the creation of compact all-fiber sources of high-power ultrashort light pulses.

  9. Raman Based Dispersive Systems for Short Pulse Generation and Optical Signal Processing

    NASA Astrophysics Data System (ADS)

    Kalyoncu, Salih Kagan

    Spatiotemporal dispersive systems have been widely utilized for nonlinear optics and optical signal processing applications. This thesis is dedicated to the investigation of dispersive and nonlinear properties of optical fibers, temporal dispersion for real time operation and spatially dispersed pulse shaping systems. In particular, this thesis is focused on Raman based dispersive systems based on such promising techniques as dispersion management, photonic time stretching and space-to-wavelength mapping for synchronous pulse generation and all-optical RF arbitrary waveform generation incorporated with mature MEMS technology. The first part of this thesis discusses a novel technique of using dispersion managed system for synchronous first and second order pulsed Raman lasers that can achieve frequency spacing of up to 1000 cm-1, which are widely utilized for CARS microscopy applications. In particular, I focus on analytical and numerical analysis of pulsed stability derived for Raman lasers by using dispersion-managed telecom fibers and pumping at near 1530 nm telecom wavelengths. I show the evolution of the first and second order Stokes signals at the output for different peak pump power and the net anomalous dispersion combinations. I determine the stability condition for dispersion-managed synchronous Raman lasers up to second order. In the second part of the thesis, the noise performance of the amplified time stretched systems is investigated. Amplified time stretched systems enabling real time applications such as high-speed analog-to-digital converters, RF arbitrary waveform generation and dispersive imaging are performance limited by the noise cumulated in the system. In particular, I analyze the noise performance and hence the effective number of bits (ENOB) performance of time stretch ADCs with distributed and lumped amplifications. I estimate that distributed amplification in time stretch system with >10GHz analog bandwidth exhibit up to 16dB higher SNR

  10. Generation of 8-nJ pulses from a dissipative-soliton fiber laser with a nonlinear optical loop mirror

    PubMed Central

    Zhao, L. M.; Bartnik, A. C.; Tai, Q. Q.; Wise, F. W.

    2013-01-01

    Theoretical and experimental investigations of the behavior of normal-dispersion fiber lasers with nonlinear-optical loop mirrors are presented. The use of a loop mirror causes the laser to generate relatively long, flat-topped pulses. The pulse energy can be high, but the pulse duration is limited to greater than 300 fs. Experimentally, 8-nJ pulses that can be dechirped to 340 fs duration are obtained. The laser is a step toward an all-fiber, environmentally-stable design. PMID:23722797

  11. Complete pulse characterization of quantum dot mode-locked lasers suitable for optical communication up to 160 Gbit/s.

    PubMed

    Schmeckebier, H; Fiol, G; Meuer, C; Arsenijević, D; Bimberg, D

    2010-02-15

    A complete characterization of pulse shape and phase of a 1.3 microm, monolithic-two-section, quantum-dot mode-locked laser (QD-MLL) at a repetition rate of 40 GHz is presented, based on frequency resolved optical gating. We show that the pulse broadening of the QD-MLL is caused by linear chirp for all values of current and voltage investigated here. The chirp increases with the current at the gain section, whereas larger bias at the absorber section leads to less chirp and therefore to shorter pulses. Pulse broadening is observed at very high bias, likely due to the quantum confined stark effect. Passive- and hybrid-QD-MLL pulses are directly compared. Improved pulse intensity profiles are found for hybrid mode locking. Via linear chirp compensation pulse widths down to 700 fs can be achieved independent of current and bias, resulting in a significantly increased overall mode-locking range of 101 MHz. The suitability of QD-MLL chirp compensated pulse combs for optical communication up to 160 Gbit/s using optical-time-division multiplexing are demonstrated by eye diagrams and autocorrelation measurements.

  12. Performance comparison of RZ pulse formats in PDM-16QAM high rates transmissions with optical pre-filtering

    NASA Astrophysics Data System (ADS)

    Silva, E. P.; Carvalho, L. H. H.; Lopes, M. L.; Ribeiro, V. B.; Bordonalli, A. C.; Oliveira, J. C. R. F.

    2013-01-01

    The digitally modulated signals spectral density depends directly on pulse format used for information symbols transmission. The modulated signal spectral occupancy can be modified according to the channel frequency response to facilitate information retrieval at the receiver. New generation of coherent optical transmission systems operating at high rates are subject to various bandwidth restrictions aspects, such as electronic components limitations and optical filtering via ROADMs deployed on networks. As noted in technical literature, the RZ pulse formats have some advantages compared to traditional NRZ pulses in optical fiber transmissions. In particular, RZ pulses have a better performance in situations where nonlinear effects of the fiber severely impact the quality of transmission. Among other situations, this occurs in systems that employ modulation formats for high order QAM (16QAM, 64QAM, etc.). Moreover, since RZ pulses have shorter duty cycle, temporal spread of the transmitted symbols causes less performance degradation due to ISI compared with NRZ pulses. This report presents results of experiments carried out in a 226 km recirculation loop, to evaluate the performance of NRZ, RZ 67%, 50% RZ and RZ 33% pulse shapes in a transmission of DP-16QAM (or PDM-16QAM). As application it is proposed and experimentally demonstrated a transmission system that employ 28 GBaud dual carrier PDM-16QAM channels operating with a total line rate of 448 Gb/s each, utilizing RZ pulse format and carrier narrow pre-filtering to increase spectral efficiency of transmission, aggregating a 400G channel in a 75 GHz WDM grid.

  13. X-ray pulse preserving single-shot optical cross-correlation method for improved experimental temporal resolution

    SciTech Connect

    Beye, M.; Krupin, O.; Hays, G.; Jong, S. de; Lee, S.; Coffee, R.; Holmes, M. R.; Fry, A. R.; White, W. E.; Bostedt, C.; Schlotter, W. F.; Reid, A. H.; Rupp, D.; Lee, W.-S.; Scherz, A. O.; Chuang, Y.-D.; Cryan, J. P.; Glownia, J. M.; Foehlisch, A.; Durr, H. A.

    2012-03-19

    We measured the relative arrival time between an optical pulse and a soft x-ray pulse from a free-electron laser. This femtosecond cross-correlation measurement was achieved by observing the change in optical reflectivity induced through the absorption of a fraction of the x-ray pulse. The main x-ray pulse energy remained available for an independent pump-probe experiment where the sample may be opaque to soft x-rays. The method was employed to correct the two-pulse delay data from a canonical pump-probe experiment and demonstrate 130 {+-} 20 fs (FWHM) temporal resolution. We further analyze possible timing jitter sources and point to future improvements.

  14. Selective detection of intermolecular response in benzonitrile through double-pulse excitation in optical Kerr effect spectroscopy

    NASA Astrophysics Data System (ADS)

    Nikiforov, V. G.; Zharkov, D. K.; Shmelev, A. G.; Leontyev, A. V.; Lobkov, V. S.

    2017-07-01

    We report on the decomposition of the molecular contribution to the optically heterodyne-detected optical Kerr effect (OHD-OKE) in benzonitrile C6H5CN in the process of double-pulse laser excitation. The pump pulses with linear orthogonal polarizations, controllable intensities and timing enable us to manipulate the amplitudes of various molecular responses due to the fact that the OHD-OKE signal is formed by the superposition of independent third-order responses associated with each pump pulse. We apply this technique to detect the intermolecular response selectively by using an excitation scenario with suppression of orientational and intramolecular responses. A detailed comparative analysis of third-order optical responses indicates strongly that the double-pulse excitation of the OHD-OKE is the useful spectroscopic technique to obtain precise information on the intermolecular spectrum in liquids.

  15. Portable optical-resolution photoacoustic microscopy with a pulsed laser diode excitation

    NASA Astrophysics Data System (ADS)

    Zeng, Lvming; Liu, Guodong; Yang, Diwu; Ji, Xuanrong

    2013-02-01

    Optical-resolution photoacoustic microscopy (OR-PAM) has been significantly improved in terms of spatial resolution, detection sensitivity, imaging speed, and penetration depth. However, the popular producibility of OR-PAM system is still limited by the size and cost of solid-state laser excitation. Here, we developed a portable laser-diode-based OR-PAM (LD-OR-PAM) system using a pulsed semiconductor laser source, which was operated at 905 ± 15 nm with a pulse energy as low as 4.9 μJ. The measured lateral resolution has been improved to ˜1.5 μm from hundreds of microns. The compact and inexpensive natures of LD-OR-PAM would promote the potential clinical applications such as in dermatology.

  16. Development of high damage threshold optics for petawatt-class short-pulse lasers

    SciTech Connect

    Stuart, B.C.; Perry, M.D.; Boyd, R.D.

    1995-02-22

    The authors report laser-induced damage threshold measurements on pure and multilayer dielectrics and gold-coated optics at 1053 and 526 nm for pulse durations, {tau}, ranging from 140 fs to 1 ns. Damage thresholds of gold coatings are limited to 500 mJ/cm{sup 2} in the subpicosecond range for 1053-nm pulses. In dielectrics, qualitative differences in the morphology of damage and a departure from the diffusion-dominated {tau}1/2 scaling indicate that damage results from plasma formation and ablation for {tau}{le}10 ps and from conventional melting and boiling for {tau}>50 ps. A theoretical model based on electron production via multiphoton ionization, Joule heating, and collisional (avalanche) ionization is in quantitative agreement with both the pulsewidth and wavelength scaling of experimental results.

  17. Ultrafast pulsed laser deposition of carbon nanostructures: Structural and optical characterization

    NASA Astrophysics Data System (ADS)

    Pervolaraki, M.; Komninou, Ph.; Kioseoglou, J.; Othonos, A.; Giapintzakis, J.

    2013-08-01

    Carbon nanostructured materials were obtained by high-repetition rate pulsed laser ablation of a graphite target using a train of 10-ps duration pulses at 1064 nm in different pressures of high-purity Ar gas. It is demonstrated that their microstructure and optical properties vary as a function of the argon pressure. High-resolution transmission electron microscopy revealed the existence of onion-like carbon nanostructures embedded in a matrix of amorphous carbon nanofoam for samples prepared at 300 Pa. In comparison samples prepared at 30 Pa show evidence of both onion-like and turbostratic carbon coexisting in a matrix of amorphous carbon nanofoam whereas samples prepared in vacuum are continuous films of amorphous carbon. Transient transmission spectroscopy measurements suggested that free carrier absorption is the dominant effect following photo-excitation for probing wavelengths in the range of 550-1000 nm and its magnitude varies among the materials investigated due to their different microstructures.

  18. Optical Spectrum of Main-, Inter-, and Off-Pulse Emission from the Crab Pulsar

    NASA Astrophysics Data System (ADS)

    Carramiñana, Alberto; Čadež, Andrej; Zwitter, Tomaž

    2000-10-01

    A dedicated stroboscopic device was used to obtain optical spectra of the Crab pulsar main pulse and interpulse as well as the spectrum of the underlying nebula when the pulsar is turned off. Since the nebular emission is very inhomogeneous, our ability to effectively subtract the nebular background signal is crucial. No spectral lines intrinsic to the pulsar are detected. The main pulse and the interpulse behave as power laws, both with the same dereddened index α=+0.2+/-0.1. This value was obtained by subtracting the nebular spectrum at the exact position of the pulsar. The underlying nebula is redder, α=-0.4+/-0.1. Its emission lines are split into approaching (~-1200 km s-1) and receding (~+600 km s-1) components. The strength of the emission line components and the flux in the nebular continuum vary on an arcsecond scale. The nebular line and continuum intensities along the north-south slit are given.

  19. Low temperature phase barium borate: A new optical limiter in continuous wave and nano pulsed regime

    NASA Astrophysics Data System (ADS)

    Babeela, C.; Girisun, T. C. Sabari

    2015-11-01

    Low temperature phase barium borate was synthesized by hydrothermal method. XRD analysis confirms the formation of γ-BBO or hydrated barium polyborate (Ba3B6O9(OH)6) which crystallizes in monoclinic system in the P2/c space group. The molecular structure analysis shows the presence of dominant BO4 unit and the hydrated nature of material. γ-BBO exhibits sharp absorption edge at 202 nm and highly transparency in the UV-Visible-NIR region. The peak at 347 nm in the emission spectrum is due to the presence of self-trapped exciton. The third order nonlinear optical properties and limiting behavior of low temperature barium borate in both pulsed and continuous wave regime were studied. The effective 2PA absorption coefficient of γ-BBO under ns pulse excitation is estimated to be 0.38 × 10-10 m/W. The nonlinear absorption coefficient, refractive index and optical susceptibility of the material in cw regime were found to be in the order of 10-5 m W-1, 10-12 m2 W-1, 10-6 esu respectively. In both regimes, low temperature phase barium borate exhibits better optical limiting properties than high temperature phase β-BBO.

  20. RF-modulated pulsed fiber optic lidar transmitter for improved underwater imaging and communications

    NASA Astrophysics Data System (ADS)

    Kimpel, F.; Chen, Y.; Fouron, J.-L.; Akbulut, M.; Engin, D.; Gupta, S.

    2011-03-01

    We present results on the design, development and initial testing of a fiber-optic based RF-modulated lidar transmitter operating at 532nm, for underwater imaging application in littoral waters. The design implementation is based on using state-of-the-art high-speed FPGAs, thereby producing optical waveforms with arbitrary digital-RF-modulated pulse patterns with carrier frequencies >= 3GHz, with a repetition rate of 0.5-1MHz, and with average powers >=5W (at 532nm). Use of RF-modulated bursts above 500MHz, instead of single optical pulse lidar detection, reduces the effect of volumetric backscatter for underwater imaging application, leading to an improved signal-to-noise-ratio (SNR) and contrast, for a given range. Initial underwater target detection tests conducted at Patuxent River Naval Air Station, MD, in a large water-tank facility, validates the advantages of this hybrid-lidar-radar (HLR) approach for improved underwater imaging, over a wide range of turbidity levels and both white and black targets. The compact, robust and power-efficient fiber laser architecture lends very well to lidar sensor integration on unmanned-underwater-vehicle (UUV) platforms. HLR transmitters can also provide similar advantages in active-sensing situations dominated by continuous backscatter, e.g. underwater communications, imaging through smoke and fire environment, rotor-craft landing in degraded visual environment, and pointing-tracking of active-EO sensors through fog.

  1. Fundamental modes of a trapped probe photon in optical fibers conveying periodic pulse trains

    SciTech Connect

    Dikande, Alain M.

    2010-01-15

    Wave modes induced by cross-phase reshaping of a probe photon in the guiding structure of a periodic train of temporal pulses are investigated theoretically with emphasis on exact solutions to the wave equation for the probe. The study has direct connection with recent advances on the issue of light control by light, the focus being on the trapping of a low-power probe by a temporal sequence of periodically matched high-power pulses of a dispersion-managed optical fiber. The problem is formulated in terms of the nonlinear optical fiber equation with averaged dispersion, coupled to a linear equation for the probe including a cross-phase modulation term. Shape-preserving modes which are robust against the dispersion are shown to be induced in the probe, they form a family of mutually orthogonal solitons the characteristic features of which are determined by the competition between the self-phase and cross-phase effects. Considering a specific context of this competition, the theory predicts two degenerate modes representing a train of bright signals and one mode which describes a train of dark signals. When the walk-off between the pump and probe is taken into consideration, these modes have finite-momentum envelopes and none of them is totally transparent vis-a-vis the optical pump soliton.

  2. Optically powered firing system for the Procyon high explosive pulse power system

    SciTech Connect

    Earley, L.; Paul, J.; Rohlev, L.; Goforth, J.; Hall, C.R.

    1995-10-01

    An optically powered fireset has been developed for the Procyon high explosive pulsed-power generator at Los Alamos National Laboratory. The fireset was located inside this flux compression experiment where large magnetic fields are generated. No energy sources were allowed inside the experiment and no wire connections can penetrate through the wall, of the experiment because of the high magnetic fields. The flux compression was achieved with high explosives in the experiment. The fireset was used to remotely charge a 1.2 {micro}f capacitor to 6,500V and to provide a readout of the voltage on the capacitor at the control room. The capacitor was charged by using two 7W fiber coupled GaAlAs laser diodes to illuminate two fiber coupled 12V solar cells. The solar cell outputs were connected in parallel to the input of a DC-DC converter which step up a 12V to 6,500V. A voltmeter, powered by illuminating a third 12V solar cell with 1W laser diode, was used to monitor the charge on the capacitor. The voltage was measured with a divider circuit, then converted to frequency in a V-F converter and transmitted to the control room over a fiber optic link. A fiducial circuit measured the capacitor firing current and provided an optical output timing pulse.

  3. Measurement of spatio-temporal field distribution of THz pulses in electro-optic crystal by interferometry method

    SciTech Connect

    Chizhov, P A; Ushakov, A A; Bukin, V V; Garnov, S V

    2015-05-31

    We propose a scheme for measuring the spatial distribution of the THz pulse electric field strength in an electro-optic crystal using optical interferometry. The resulting images of the field distribution from a test source with a spherical wave front are presented. (extreme light fields and their applications)

  4. Inter-island optical link demonstration using high-data-rate pulse-position modulation

    NASA Astrophysics Data System (ADS)

    Bacher, Michael; Arnold, Felix; Thieme, Björn

    2014-03-01

    The growing data-rate demand on satellite communication systems has led to the increased interest in optical space communication solutions for uplinks and downlinks between satellites and ground stations. As one example for applications that benefit from higher data-rates offered by optical links, RUAG Space studied an uplink scenario from an Unmanned Aerial Vehicle (UAV) to a Geostationary Orbit (GEO), under the European Space Agency project formally known as "Optical Communications Transceiver for Atmospheric Links" (OCTAL). Particularly suitable for optical links through turbulent atmospheres are robust Pulse Position Modulation (PPM) schemes. Communication electronics using a Multi-Pulse PPM (MPPM) scheme have been developed, increasing the data-rate compared to traditional PPM at a constant peak-to-average ratio while allowing a widely configurable data-rate range. The communication system was tested together with a newly developed receiver and transmitter at a wavelength of 1055nm in a field test campaign on the Canary Islands, where the transmitter telescope was located on La Palma while the receiver was installed within the ESA Optical Ground Station on Tenerife. The nearly horizontal link between the two islands with a link distance of 142km allowed validation of relevant system performances under stringent atmospheric conditions. A data-rate of more than 360Mbps could be demonstrated using MPPM, while nearly 220Mbps could be achieved with traditional PPM, well exceeding the targeted data-rate of the studied UAV-to-GEO scenario. Following an introduction on the applied MPPM schemes, the architecture of the test setup is described, different modulation schemes are compared and the test results of this Inter-Island Test Campaign performed in October 2012 are presented.

  5. Study on third-order nonlinear optical properties of 4-methylsulfanyl chalcone derivatives using picosecond pulses

    SciTech Connect

    D'silva, E.D.; Podagatlapalli, G. Krishna; Venugopal Rao, S.; Dharmaprakash, S.M.

    2012-11-15

    Graphical abstract: Photograph and schematic representation of Z-scan experimental setup used to investigate third order nonlinear properties of the chalcone materials. Highlights: ► Br and NO{sub 2} substituted chalcone derivatives were exposed to picosecond laser pulses. ► Third-order nonlinear optical (NLO) properties were investigated. ► Compounds show promising third-order and optical limiting properties. ► These materials found suitable for electrical and optical applications. -- Abstract: In this paper we present results from the experimental study of third-order nonlinear optical (NLO) properties of three molecules of Br and NO{sub 2} substituted chalcone derivatives namely (2E)-1-(4-bromophenyl)-3-[4(methylsulfanyl)phenyl]prop-2-en-1-one (4Br4MSP), (2E)-1-(3-bromophenyl)-3-[4-(methylsulfanyl) phenyl]prop-2-en-1-one (3Br4MSP) and (2E)-3[4(methylsulfanyl) phenyl]-1-(4-nitrophenyl)prop-2-en-1-one (4N4MSP). The NLO properties have been investigated by Z-scan technique using 2 ps laser pulses at 800 nm. The nonlinear refractive indices, nonlinear absorption coefficient, and the magnitude of third-order susceptibility have been determined. The values obtained are of the order of 10{sup −7} cm{sup 2}/GW, 10{sup −3} cm/GW and 10{sup −14} esu respectively. The molecular second hyperpolarizability for the chalcone derivatives is of the order of 10{sup −32} esu. The coupling factor, excited state cross section, ground state cross section etc. were determined. The optical limiting (OL) property was studied. The results suggest that the nonlinear properties investigated for present chalcones are comparable with some of the reported chalcone derivatives and can be desirable for NLO applications.

  6. Mapping cerebral pulse pressure and arterial compliance over the adult lifespan with optical imaging.

    PubMed

    Tan, Chin Hong; Low, Kathy A; Kong, Tania; Fletcher, Mark A; Zimmerman, Benjamin; Maclin, Edward L; Chiarelli, Antonio M; Gratton, Gabriele; Fabiani, Monica

    2017-01-01

    Cerebrovascular health is important for maintaining a high level of cognitive performance, not only in old age, but also throughout the lifespan. Recently, it was first demonstrated that diffuse optical imaging measures of pulse amplitude and arterial compliance can provide estimates of cerebral arterial health throughout the cortex, and were associated with age, estimated cardiorespiratory fitness (eCRF), neuroanatomy and cognitive function in older adults (aged 55-87). The current study replicates and extends the original findings using a broader age range (a new adult sample aged 18-75), longer recording periods (360 s), and a more extensive optical montage (1536 channels). These methodological improvements represent a 5-fold increase in recording time and a 4-fold increase in coverage compared to the initial study. Results show that reliability for both pulse amplitude and compliance measures across recording blocks was very high (r(45) = .99 and .75, respectively). Pulse amplitude and pulse pressure were shown to correlate with age across the broader age range. We also found correlations between arterial health and both cortical and subcortical gray matter volumes. Additionally, we replicated the correlations between arterial compliance and age, eCRF, global brain atrophy, and cognitive flexibility. New regional analyses revealed that higher performance on the operation span (OSPAN) working memory task was associated with greater localized arterial compliance in frontoparietal cortex, but not with global arterial compliance. Further, greater arterial compliance in frontoparietal regions was associated with younger age and higher eCRF. These associations were not present in the visual cortex. The current study not only replicates the initial one in a sample including a much wider age range, but also provides new evidence showing that frontoparietal regions may be especially vulnerable to vascular degeneration during brain aging, with potential functional

  7. Mapping cerebral pulse pressure and arterial compliance over the adult lifespan with optical imaging

    PubMed Central

    Tan, Chin Hong; Low, Kathy A.; Kong, Tania; Fletcher, Mark A.; Zimmerman, Benjamin; Maclin, Edward L.; Chiarelli, Antonio M.; Gratton, Gabriele

    2017-01-01

    Cerebrovascular health is important for maintaining a high level of cognitive performance, not only in old age, but also throughout the lifespan. Recently, it was first demonstrated that diffuse optical imaging measures of pulse amplitude and arterial compliance can provide estimates of cerebral arterial health throughout the cortex, and were associated with age, estimated cardiorespiratory fitness (eCRF), neuroanatomy and cognitive function in older adults (aged 55–87). The current study replicates and extends the original findings using a broader age range (a new adult sample aged 18–75), longer recording periods (360 s), and a more extensive optical montage (1536 channels). These methodological improvements represent a 5-fold increase in recording time and a 4-fold increase in coverage compared to the initial study. Results show that reliability for both pulse amplitude and compliance measures across recording blocks was very high (r(45) = .99 and .75, respectively). Pulse amplitude and pulse pressure were shown to correlate with age across the broader age range. We also found correlations between arterial health and both cortical and subcortical gray matter volumes. Additionally, we replicated the correlations between arterial compliance and age, eCRF, global brain atrophy, and cognitive flexibility. New regional analyses revealed that higher performance on the operation span (OSPAN) working memory task was associated with greater localized arterial compliance in frontoparietal cortex, but not with global arterial compliance. Further, greater arterial compliance in frontoparietal regions was associated with younger age and higher eCRF. These associations were not present in the visual cortex. The current study not only replicates the initial one in a sample including a much wider age range, but also provides new evidence showing that frontoparietal regions may be especially vulnerable to vascular degeneration during brain aging, with potential functional

  8. 500 MW peak power degenerated optical parametric amplifier delivering 52 fs pulses at 97 kHz repetition rate.

    PubMed

    Rothhardt, J; Hädrich, S; Röser, F; Limpert, J; Tünnermann, A

    2008-06-09

    We present a high peak power degenerated parametric amplifier operating at 1030 nm and 97 kHz repetition rate. Pulses of a state-of-the art fiber chirped-pulse amplification (FCPA) system with 840 fs pulse duration and 410 microJ pulse energy are used as pump and seed source for a two stage optical parametric amplifier. Additional spectral broadening of the seed signal in a photonic crystal fiber creates enough bandwidth for ultrashort pulse generation. Subsequent amplification of the broadband seed signal in two 1 mm BBO crystals results in 41 microJ output pulse energy. Compression in a SF 11 prism compressor yields 37 microJ pulses as short as 52 fs. Thus, pulse shortening of more than one order of magnitude is achieved. Further scaling in terms of average power and pulse energy seems possible and will be discussed, since both concepts involved, the fiber laser and the parametric amplifier have the reputation to be immune against thermo-optical effects.

  9. Tunable error-free optical frequency conversion of a 4ps optical short pulse over 25 nm by four-wave mixing in a polarisation-maintaining optical fibre

    NASA Astrophysics Data System (ADS)

    Morioka, T.; Kawanishi, S.; Saruwatari, M.

    1994-05-01

    Error-free, tunable optical frequency conversion of a transform-limited 4.0 ps optical pulse signalis demonstrated at 6.3 Gbit/s using four-wave mixing in a polarization-maintaining optical fibre. The process generates 4.0-4.6 ps pulses over a 25nm range with time-bandwidth products of 0.31-0.43 and conversion power penalties of less than 1.5 dB.

  10. Generation of intense femtosecond optical vortex pulses with blazed-phase grating in chirped-pulse amplification system of Ti:sapphire laser

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Chieh; Nabekawa, Yasuo; Midorikawa, Katsumi

    2016-11-01

    We demonstrate the generation of an intense femtosecond optical vortex (OV) pulse by employing an OV converter set between two laser amplifiers in a chirped-pulse amplification (CPA) system of a Ti:sapphire laser. The OV converter is composed of a liquid-crystal spatial light modulator (LC-SLM) exhibiting a blazed-phase computer-generated hologram, a concave mirror, and a flat mirror in the 4f setup. Owing to the intrinsic nature of the 4f setup, the OV converter is free from chromatic and topological-charge dispersions, which are always induced in a spiral phase plate conventionally used to convert an intense Gaussian laser pulse to an OV pulse, while we can avoid damage to the LC-SLM by the irradiation of a low-energy pulse before the second amplifier. We have increased the throughput of the OV converter to 42% by systematically investigating the diffraction efficiency of the blazed-phase hologram on the LC-SLM, which relaxes the gain condition required for the second amplifier. The combination of the high-throughput OV converter and the two-stage amplification enables us to generate OV pulses with an energy of 1.63 mJ and a pulse duration of 60 fs at a wavelength of 720 nm, at which the gain of the Ti:sapphire laser is only 60% of the peak gain around 800 nm.

  11. Unconstrained pulse pressure monitoring for health management using hetero-core fiber optic sensor

    PubMed Central

    Nishiyama, Michiko; Sonobe, Masako; Watanabe, Kazuhiro

    2016-01-01

    In this paper, we present a pulse pressure waveform sensor that does not constrain a wearer’s daily activity; the sensor uses hetero-core fiber optics. Hetero-core fiber sensors have been found to be sensitive to moderate bending. To detect minute pulse pressure changes from the radial artery at the wrist, we devised a fiber sensor arrangement using three-point bending supports. We analyzed and evaluated the measurement validity using wavelet transformation, which is well-suited for biological signal processing. It was confirmed that the detected pulse waveform had a fundamental mode frequency of around 1.25 Hz over the time-varying waveform. A band-pass filter with a range of frequencies from 0.85 to 1.7 Hz was used to pick up the fundamental mode. In addition, a high-pass filter with 0.85 Hz frequency eliminated arm motion artifacts; consequently, we achieved high signal-to-noise ratio. For unrestricted daily health management, it is desirable that pulse pressure monitoring can be achieved by simply placing a device on the hand without the sensor being noticed. Two types of arrangements were developed and demonstrated in which the pulse sensors were either embedded in a base, such as an armrest, or in a wearable device. A wearable device without cuff pressure using a sensitivity-enhanced fiber sensor was successfully achieved with a sensitivity of 0.07–0.3 dB with a noise floor lower than 0.01 dB for multiple subjects. PMID:27699128

  12. Structural, mechanical and optical properties of nitrogen-implanted titanium at different pulse frequency

    NASA Astrophysics Data System (ADS)

    Raaif, Mohamed; Mohamed, Sodky H.; Abd El-Rahman, Ahmed M.; Kolitsch, Andreas

    2013-04-01

    Plasma-immersion ion implantation (PIII) is a potent method to obtain hard and wear-resistant surface on Ti by nitrogen implantation. This presentation is one part of a sequence of experiments to optimize the microstructure and physical properties of TiN through adapting the plasma-processing parameters. In this work, nitrogen ions were implanted into samples of pure Ti at different nitrogen pulse frequency without using any external source of heating. The nitrogen-implanted surfaces were characterized by X-ray diffraction (XRD), Auger electron spectroscopy (AES), optical microscope, nano-indentation technique, ball-on-disk type tribometer, surface profilemeter, Tafel polarization technique for corrosion performance and ellipsometry. The outcomes show that, nitrogen PIII is an effectual method for nitriding titanium and nitrogen pulse frequency affected the microstructure and physical properties of the treated Ti. X-ray diffraction depicted the formation of α-Ti (N) and the cubic TiN after implanting titanium by nitrogen and the thickness of the nitrided layer increased as the nitrogen pulse frequency increased. The wear and corrosion resistance of the nitrogen-implanted titanium are improved and the friction coefficient decreased from nearly 0.8 for the un-implanted titanium to 0.3 for the implanted titanium, this ascribed to the formation of the titanium nitrided phases. Ellipsometric measurements were carried out on the PIII titanium samples at different nitrogen pulse frequency. The ellipsometric measurements show that, the thickness of the nitrided layer and surface roughness increased while the refractive index decreased with increasing nitrogen pulse frequency.

  13. Unconstrained pulse pressure monitoring for health management using hetero-core fiber optic sensor.

    PubMed

    Nishiyama, Michiko; Sonobe, Masako; Watanabe, Kazuhiro

    2016-09-01

    In this paper, we present a pulse pressure waveform sensor that does not constrain a wearer's daily activity; the sensor uses hetero-core fiber optics. Hetero-core fiber sensors have been found to be sensitive to moderate bending. To detect minute pulse pressure changes from the radial artery at the wrist, we devised a fiber sensor arrangement using three-point bending supports. We analyzed and evaluated the measurement validity using wavelet transformation, which is well-suited for biological signal processing. It was confirmed that the detected pulse waveform had a fundamental mode frequency of around 1.25 Hz over the time-varying waveform. A band-pass filter with a range of frequencies from 0.85 to 1.7 Hz was used to pick up the fundamental mode. In addition, a high-pass filter with 0.85 Hz frequency eliminated arm motion artifacts; consequently, we achieved high signal-to-noise ratio. For unrestricted daily health management, it is desirable that pulse pressure monitoring can be achieved by simply placing a device on the hand without the sensor being noticed. Two types of arrangements were developed and demonstrated in which the pulse sensors were either embedded in a base, such as an armrest, or in a wearable device. A wearable device without cuff pressure using a sensitivity-enhanced fiber sensor was successfully achieved with a sensitivity of 0.07-0.3 dB with a noise floor lower than 0.01 dB for multiple subjects.

  14. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, David A.; Keller, Richard A.

    1985-01-01

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10.sup.-5 cm.sup.-1 has been demonstrated using this technique.

  15. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1982-06-08

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be rlated to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10/sup -5/ cm/sup -1/ has been demonstrated using this technique.

  16. New autocorrelation technique for the IR FEL optical pulse width measurements

    SciTech Connect

    Amirmadhi, F.; Brau, K.A.; Becker, C.

    1995-12-31

    We have developed a new technique for the autocorrelation measurement of optical pulse width at the Vanderbilt University FEL center. This method is based on nonlinear absorption and transmission characteristics of semiconductors such as Ge, Te and InAs suitable for the wavelength range from 2 to over 6 microns. This approach, aside being simple and low cost, removes the phase matching condition that is generally required for the standard frequency doubling technique and covers a greater wavelength range per nonlinear material. In this paper we will describe the apparatus, explain the principal mechanism involved and compare data which have been acquired with both frequency doubling and two-photon absorption.

  17. Power scaling of supercontinuum seeded megahertz-repetition rate optical parametric chirped pulse amplifiers.

    PubMed

    Riedel, R; Stephanides, A; Prandolini, M J; Gronloh, B; Jungbluth, B; Mans, T; Tavella, F

    2014-03-15

    Optical parametric chirped-pulse amplifiers with high average power are possible with novel high-power Yb:YAG amplifiers with kW-level output powers. We demonstrate a compact wavelength-tunable sub-30-fs amplifier with 11.4 W average power with 20.7% pump-to-signal conversion efficiency. For parametric amplification, a beta-barium borate crystal is pumped by a 140 W, 1 ps Yb:YAG InnoSlab amplifier at 3.25 MHz repetition rate. The broadband seed is generated via supercontinuum generation in a YAG crystal.

  18. Measuring quantum coherence in bulk solids using dual phase-locked optical pulses

    PubMed Central

    Hayashi, Shingo; Kato, Keigo; Norimatsu, Katsura; Hada, Masaki; Kayanuma, Yosuke; Nakamura, Kazutaka G.

    2014-01-01

    Electronic and phonon coherence are usually measured in different ways because their time-scales are very different. In this paper we simultaneously measure the electronic and phonon coherence using the interference of the electron-phonon correlated states induced by two phase-locked optical pulses. Interferometric visibility showed that electronic coherence remained in a semiconducting GaAs crystal until ~40 fs; in contrast, electronic coherence disappeared within 10 fs in a semimetallic Bi crystal at room temperature, differing substantially from the long damping time of its phonon coherence, in the picosecond range. PMID:24662682

  19. Characterization of optically pumped semiconductor lasers in pulsed mode as a function of temperature

    NASA Astrophysics Data System (ADS)

    Bai, Yanbo; Wisdom, Jeffrey; Hyland, Patrick; Scholz, Christian; Chilla, Juan

    2017-02-01

    Self-heating of Optically Pumped Semiconductor (OPS) chip has been identified as the major limiting factor of power scaling in OPS-based lasers in continuous wave (cw) mode. In this work, characterization of OPS lasers in short pulse (100 ns) and low duty cycle (1%) regime, where self-heating is negligible, as a function of the heat sink temperature is presented. This data, combined with a rigorous thermal model, allows us to predict OPS chip performance in new cooling configurations for power scaling.

  20. Self-similar optical pulses in competing cubic-quintic nonlinear media with distributed coefficients

    SciTech Connect

    Zhang Jiefang; Tian Qing; Wang Yueyue; Dai Chaoqing; Wu Lei

    2010-02-15

    We present a systematic analysis of the self-similar propagation of optical pulses within the framework of the generalized cubic-quintic nonlinear Schroedinger equation with distributed coefficients. By appropriately choosing the relations between the distributed coefficients, we not only retrieve the exact self-similar solitonic solutions, but also find both the approximate self-similar Gaussian-Hermite solutions and compact solutions. Our analytical and numerical considerations reveal that proper choices of the distributed coefficients could make the unstable solitons stable and could restrict the nonlinear interaction between the neighboring solitons.