Very short intracavity directional coupler for high-speed communication

NASA Astrophysics Data System (ADS)

Griffel, Giora

1993-07-01

We propose a novel intracavity modulator/switch that consists of a directional-coupler located inside a Fabry-Perot cavity. The back mirror of the cavity has a unit reflectivity so that both input and output signals are at the same side. In this way we obtain a two-port, single side element, with coupling length of 83.5 μm, which is the shortest modulation coupler proposed so far. The upper frequency limit due to photon lifetime is 275 GHz, which is well over the bandwidth constraints of microwave lumped structures. A unified approach for the analysis of this device and other similar structures is presented and discussed.

High power regenerative laser amplifier

DOEpatents

Miller, John L.; Hackel, Lloyd A.; Dane, Clifford B.; Zapata, Luis E.

1994-01-01

A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

High power regenerative laser amplifier

DOEpatents

Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.

1994-02-08

A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

Switching of transmission resonances in a two-channels coupler: A Boundary Wall Method scattering study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nunes, A.; Zanetti, F.M.; Lyra, M.L., E-mail: marcelo@fis.ufal.br

2016-10-15

In this work, we study the transmission characteristics of a two-channels coupler model system using the Boundary Wall Method (BWM) to determine the solution of the corresponding scattering problem of an incident plane wave. We show that the BWM provides detailed information regarding the transmission resonances. In particular, we focus on the case of single channel input aiming to explore the energy switching performance of the coupler. We show that the coupler geometry can be tailored to allow for the first transmission resonances to be predominantly transmitted on specific output channels, an important characteristic for the realization of logical operations.more » - Highlights: • The switching performance of a coupled waveguide device is studied via the boundary wall method. • The method efficiently identifies all resonant transmission modes. • Energy switching is controlled and optimized as a function of the device geometry.« less

Stable nonlinear Mach-Zehnder fiber switch

DOEpatents

Digonnet, Michel J. F.; Shaw, H. John; Pantell, Richard H.; Sadowski, Robert W.

1999-01-01

An all-optical fiber switch is implemented within a short Mach-Zehnder interferometer configuration. The Mach-Zehnder switch is constructed to have a high temperature stability so as to minimize temperature gradients and other thermal effects which result in undesirable instability at the output of the switch. The Mach-Zehnder switch of the preferred embodiment is advantageously less than 2 cm in length between couplers to be sufficiently short to be thermally stable, and full switching is accomplished by heavily doping one or both of the arms between the couplers so as to provide a highly nonlinear region within one or both of the arms. A pump input source is used to affect the propagation characteristics of one of the arms to control the output coupling ratio of the switch. Because of the high nonlinearity of the pump input arm, low pump powers can be used, thereby alleviating difficulties and high cost associated with high pump input powers.

A new generation of ultra-dense optical I/O for silicon photonics

NASA Astrophysics Data System (ADS)

Wlodawski, Mitchell S.; Kopp, Victor I.; Park, Jongchul; Singer, Jonathan; Hubner, Eric E.; Neugroschl, Daniel; Chao, Norman; Genack, Azriel Z.

2014-03-01

In response to the optical packaging needs of a rapidly growing silicon photonics market, Chiral Photonics, Inc. (CPI) has developed a new generation of ultra-dense-channel, bi-directional, all-optical, input/output (I/O) couplers that bridge the data transport gap between standard optical fibers and photonic integrated circuits. These couplers, called Pitch Reducing Optical Fiber Arrays (PROFAs), provide a means to simultaneously match both the mode field and channel spacing (i.e. pitch) between an optical fiber array and a photonic integrated circuit (PIC). Both primary methods for optically interfacing with PICs, via vertical grating couplers (VGCs) and edge couplers, can be addressed with PROFAs. PROFAs bring the signal-carrying cores, either multimode or singlemode, of many optical fibers into close proximity within an all-glass device that can provide low loss coupling to on-chip components, including waveguides, gratings, detectors and emitters. Two-dimensional (2D) PROFAs offer more than an order of magnitude enhancement in channel density compared to conventional one-dimensional (1D) fiber arrays. PROFAs can also be used with low vertical profile solutions that simplify optoelectronic packaging while reducing PIC I/O real estate usage requirements. PROFA technology is based on a scalable production process for microforming glass preform assemblies as they are pulled through a small oven. An innovative fiber design, called the "vanishing core," enables tailoring the mode field along the length of the PROFA to meet the coupling needs of disparate waveguide technologies, such as fiber and onchip. Examples of single- and multi-channel couplers fabricated using this technology will be presented.

High speed high dynamic range high accuracy measurement system

DOEpatents

Deibele, Craig E.; Curry, Douglas E.; Dickson, Richard W.; Xie, Zaipeng

2016-11-29

A measuring system includes an input that emulates a bandpass filter with no signal reflections. A directional coupler connected to the input passes the filtered input to electrically isolated measuring circuits. Each of the measuring circuits includes an amplifier that amplifies the signal through logarithmic functions. The output of the measuring system is an accurate high dynamic range measurement.

Bio-isolated dc operational amplifier. [for bioelectric measurements

NASA Technical Reports Server (NTRS)

Lee, R. D. (Inventor)

1974-01-01

A bio-isolated dc operational amplifier is described for use in making bioelectrical measurements of a patient while providing isolation of the patient from electrical shocks. The circuit contains a first operational amplifier coupled to the patient with its output coupled in a forward loop through a first optic coupler to a second operational amplifier. The output of the second operational amplifier is coupled to suitable monitoring circuitry via a feedback circuit including a second optic coupler to the input of the first operational amplifier.

Motor/generator

DOEpatents

Hickam, Christopher Dale [Glasford, IL

2008-05-13

A motor/generator is provided for connecting between a transmission input shaft and an output shaft of a prime mover. The motor/generator may include a motor/generator housing, a stator mounted to the motor/generator housing, a rotor mounted at least partially within the motor/generator housing and rotatable about a rotor rotation axis, and a transmission-shaft coupler drivingly coupled to the rotor. The transmission-shaft coupler may include a clamp, which may include a base attached to the rotor and a plurality of adjustable jaws.

Misalignment tolerant efficient inverse taper coupler for silicon waveguide

NASA Astrophysics Data System (ADS)

Wang, Peng; Michael, Aron; Kwok, Chee Yee; Chen, Ssu-Han

2015-12-01

This paper describes an efficient fiber to submicron silicon waveguide coupling based on an inversely tapered silicon waveguide embedded in a SiO2 waveguide that is suspended in air. The inverse taper waveguide consist of a 50um long and 240nm thick silicon that linearly taper in width from 500nm to 120nm, which is embedded in SiO2. The SiO2 waveguide is 6um wide and 10um long. The simulation results show that the coupling loss of this new approach is 2.7dB including the interface loss at the input and output. The tolerance to fiber misalignment at the input of the coupler is 2um in both horizontal and vertical directions for only 1.5dB additional loss.

Mitigation of multipacting, enhanced by gas condensation on the high power input coupler of a superconducting RF module, by comprehensive warm aging

NASA Astrophysics Data System (ADS)

Wang, Chaoen; Chang, Lung-Hai; Chang, Mei-Hsia; Chen, Ling-Jhen; Chung, Fu-Tsai; Lin, Ming-Chyuan; Liu, Zong-Kai; Lo, Chih-Hung; Tsai, Chi-Lin; Yeh, Meng-Shu; Yu, Tsung-Chi

2017-11-01

Excitation of multipacting, enhanced by gas condensation on cold surfaces of the high power input coupler in a SRF module poses the highest challenge for reliable SRF operation under high average RF power. This could prevent the light source SRF module from being operated with a desired high beam current. Off-line long-term reliability tests have been conducted for the newly constructed 500-MHz SRF KEKB type modules at an accelerating RF voltage of 1.6-MV to enable prediction of their operational reliability in the 3-GeV Taiwan Photon Source (TPS), since prediction from mere production performance by conventional horizontal test is presently unreliable. As expected, operational difficulties resulting from multipacting, enhanced by gas condensation, have been identified in the course of long-term reliability test. Our present hypothesis is that gas condensation can be slowed down by preserving the vacuum pressure at the power coupler close to that reached just after its cool down to liquid helium temperatures. This is achievable by reduction of the power coupler out-gassing rate through comprehensive warm aging. Its feasibility and effectiveness has been experimentally verified in a second long term reliability test. Our success opens the possibility to operate the SRF module free of multipacting trouble and opens a new direction to improve the operational performance of next generation SRF modules in light sources with high beam currents.

Thalamic modulation of cingulate seizure activity via the regulation of gap junctions in mice thalamocingulate slice.

PubMed

Chang, Wei-Pang; Wu, José Jiun-Shian; Shyu, Bai-Chuang

2013-01-01

The thalamus is an important target for deep brain stimulation in the treatment of seizures. However, whether the modulatory effect of thalamic inputs on cortical seizures occurs through the modulation of gap junctions has not been previously studied. Therefore, we tested the effects of different gap junction blockers and couplers in a drug-resistant seizure model and studied the role of gap junctions in the thalamic modulation on cortical seizures. Multielectrode array and calcium imaging were used to record the cortical seizures induced by 4-aminopyridine (250 µM) and bicuculline (5-50 µM) in a novel thalamocingulate slice preparation. Seizure-like activity was significantly attenuated by the pan-gap junction blockers carbenoxolone and octanol and specific neuronal gap junction blocker mefloquine. The gap junction coupler trimethylamine significantly enhanced seizure-like activity. Gap junction blockers did not influence the initial phase of seizure-like activity, but they significantly decreased the amplitude and duration of the maintenance phase. The development of seizures is regulated by extracellular potassium concentration. Carbenoxolone partially restored the amplitude and duration after removing the thalamic inputs. A two-dimensional current source density analysis showed that the sink and source signals shifted to deeper layers after removing the thalamic inputs during the clonic phase. These results indicate that the regulatory mechanism of deep brain stimulation in the thalamus occurs partially though gap junctions.

Thalamic Modulation of Cingulate Seizure Activity Via the Regulation of Gap Junctions in Mice Thalamocingulate Slice

PubMed Central

Chang, Wei-Pang; Wu, José Jiun-Shian; Shyu, Bai-Chuang

2013-01-01

The thalamus is an important target for deep brain stimulation in the treatment of seizures. However, whether the modulatory effect of thalamic inputs on cortical seizures occurs through the modulation of gap junctions has not been previously studied. Therefore, we tested the effects of different gap junction blockers and couplers in a drug-resistant seizure model and studied the role of gap junctions in the thalamic modulation on cortical seizures. Multielectrode array and calcium imaging were used to record the cortical seizures induced by 4-aminopyridine (250 µM) and bicuculline (5–50 µM) in a novel thalamocingulate slice preparation. Seizure-like activity was significantly attenuated by the pan-gap junction blockers carbenoxolone and octanol and specific neuronal gap junction blocker mefloquine. The gap junction coupler trimethylamine significantly enhanced seizure-like activity. Gap junction blockers did not influence the initial phase of seizure-like activity, but they significantly decreased the amplitude and duration of the maintenance phase. The development of seizures is regulated by extracellular potassium concentration. Carbenoxolone partially restored the amplitude and duration after removing the thalamic inputs. A two-dimensional current source density analysis showed that the sink and source signals shifted to deeper layers after removing the thalamic inputs during the clonic phase. These results indicate that the regulatory mechanism of deep brain stimulation in the thalamus occurs partially though gap junctions. PMID:23690968

Fabrication of 8×8 MMI optical coupler in BK7 by ion-exchange

NASA Astrophysics Data System (ADS)

Li, Xia; Li, Xi-Hua; Zhou, Qiang; Jiang, Xiao-Qing; Yang, Jian-Yi; Wang, Ming-Hua

2005-01-01

The planar waveguide optical couplers are of prime importance in optical communication and optical signal processing system. Comparing with the optical fiber coupler (OFC) which fabricated by fused biconical taper technology, the planar waveguide couplers are more compact size, lower loss, better uniformity, easier manufacture and integration. Multimode interference (MMI) couplers have many advantages, such as compact size, wavelength and polarization insensitivity, fabrication tolerances and low loss, etc., which concentrate more and more attention. Conventional MMI devices are based on the uniform index waveguides. When the number of input/output waveguides becomes larger, the intrinsic propagation constant error, which will cause bad uniformity of output power, can"t be neglected. In fact, most waveguide devices are graded-index. With the enhanced compatibility of MMI coupler, the performance can be improved at the same time. Prior study shows that graded-index MMI couplers reach the best performance under certain index contrast. Among many available materials, glass is chosen to be the substrate of the coupler, because of its good features, such as low loss, ease fabrication, cheap cost, and so on. In this paper, an 8×8 MMI optical coupler is designed based on the principle of graded-index MMI. The coupler is composed of a waveguide, which is designed to support a large number of modes, and several access (usually single-mode) waveguides, which are used to launch light into and recover light from that multimode waveguide. The total length of the device is less than 3.5 centimeter, including S-bends which lead the multiple images to the output of the device with the spacing D=250μm to make the device fiber compatible. In this paper, we describe an experimental realization of the 8×8 graded-index MMI optical coupler and the measurement of its performance with the testing laser of the wavelength of 1.55μm. The device is fabricated by ion-exchange on BK7 glass substrate. During the ion-exchange process, a melting mixture of AgNO3 : (KNO3 : NaNO3) (molar ratio, 0.001:1) is used at 350~380°C for different times (range from 8 to 18 hours) to fabricate the coupler. The experimental results show that the performance of the optical coupler is quite promising. For instance, while launching light from No.5 waveguide, the uniformity of the device is approximately 0.72dB. Optimization of design and fabrication is going on to improve the total performance of the optical coupler.

Single Fiber Star Couplers. [optical waveguides for spacecraft communication

NASA Technical Reports Server (NTRS)

Asawa, C. K.

1979-01-01

An ion exchange process was developed and used in the fabrication of state-of-the-art planar star couplers for distribution of optical radiation between optical fibers. An 8 x 8 planar transmission star coupler was packaged for evaluation purposes with sixteen fiber connectors and sixteen pigtails. Likewise a transmission star coupler and an eight-port reflection star coupler with eight-fiber ribbons rigidly attached to these couplers, and a planar coupler with silicon guides and a parallel channel guide with pigtails were also fabricated. Optical measurements of the transmission star couplers are included with a description of the manufacturing process.

A History of the Chemical Innovations in Silver-Halide Materials for Color PhotographyII. Color-Forming Development, Part 5. Coupler Innovations after the 1970's—Two-Equivalent Coupler and DIR Coupler

NASA Astrophysics Data System (ADS)

Oishi, Yasushi

After the 1970's on, several manufacturers including Fuji Film, Konica and Agfa-Gevaert participated in innovating color photographic materials by adding their own coupler chemistry to the technological architecture built by Kodak before then. One area of their major advances was development of the couplers having a coupling-off organic group. One of their functional forms was two-equivalent coupler which made the dye-forming process efficient and made the photosensitive layers slim. And another was DIR coupler which improved dramatically the image quality of color negative materials. In this paper a historical overview of these innovations is constructed from the technical documents, mainly patents.

Multisite silicon neural probes with integrated silicon nitride waveguides and gratings for optogenetic applications.

PubMed

Shim, Euijae; Chen, Yu; Masmanidis, Sotiris; Li, Mo

2016-03-04

Optimal optogenetic perturbation of brain circuit activity often requires light delivery in a precise spatial pattern that cannot be achieved with conventional optical fibers. We demonstrate an implantable silicon-based probe with a compact light delivery system, consisting of silicon nitride waveguides and grating couplers for out-of-plane light emission with high spatial resolution. 473 nm light is coupled into and guided in cm-long waveguide and emitted at the output grating coupler. Using the direct cut-back and out-scattering measurement techniques, the propagation optical loss of the waveguide is measured to be below 3 dB/cm. The grating couplers provide collimated light emission with sufficient irradiance for neural stimulation. Finally, a probe with multisite light delivery with three output grating emitters from a single laser input is demonstrated.

Silicon-based highly-efficient fiber-to-waveguide coupler for high index contrast systems

NASA Astrophysics Data System (ADS)

Nguyen, Victor; Montalbo, Trisha; Manolatou, Christina; Agarwal, Anu; Hong, Ching-yin; Yasaitis, John; Kimerling, L. C.; Michel, Jurgen

2006-02-01

A coupler to efficiently transfer broadband light from a single-mode optical fiber to a single-mode high-index contrast waveguide has been fabricated on a silicon substrate. We utilized a novel coupling scheme, with a vertically asymmetric design consisting of a stepwise parabolic graded index profile combined with a horizontal taper, to simultaneously confine light in both directions. Coupling efficiency has been measured as a function of the device dimensions. The optimal coupling efficiency is achieved for structures whose length equals the focal distance of the graded index and whose input width is close to the mode field diameter of the fiber. The fabricated structure is compact, robust and highly efficient, with an insertion loss of 2.2dB at 1550nm. The coupler exhibits less than 1dB variation in coupling efficiency in the measured spectral range from 1520nmto1620nm. The lowest insertion loss of 1.9dB is measured at 1540nm. The coupler design offers highly efficient coupling for single mode waveguides of core indices up to 2.2.

Proposal for fabrication-tolerant SOI polarization splitter-rotator based on cascaded MMI couplers and an assisted bi-level taper

PubMed Central

Wang, Jing; Qi, Minghao; Xuan, Yi; Huang, Haiyang; Li, You; Li, Ming; Chen, Xin; Jia, Qi; Sheng, Zhen; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Gan, Fuwan

2014-01-01

A novel silicon-on-insulator (SOI) polarization splitter-rotator (PSR) with a large fabrication tolerance is proposed based on cascaded multimode interference (MMI) couplers and an assisted mode-evolution taper. The tapers are designed to adiabatically convert the input TM0 mode into the TE1 mode, which will output as the TE0 mode after processed by the subsequent MMI mode converter, 90-degree phase shifter (PS) and MMI 3 dB coupler. The numerical simulation results show that the proposed device has a < 0.5 dB insertion loss with < −17 dB crosstalk in C optical communication band. Fabrication tolerance analysis is also performed with respect to the deviations of MMI coupler width, PS width, slab height and upper-cladding refractive index, showing that this device could work well even when affected by considerable fabrication errors. With such a robust performance with a large bandwidth, this device offers potential applications for CMOS-compatible polarization diversity, especially in the booming 100 Gb/s coherent optical communications based on silicon photonics technology. PMID:25402029

Proposal for fabrication-tolerant SOI polarization splitter-rotator based on cascaded MMI couplers and an assisted bi-level taper.

PubMed

Wang, Jing; Qi, Minghao; Xuan, Yi; Huang, Haiyang; Li, You; Li, Ming; Chen, Xin; Jia, Qi; Sheng, Zhen; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Gan, Fuwan

2014-11-17

A novel silicon-on-insulator (SOI) polarization splitter-rotator (PSR) with a large fabrication tolerance is proposed based on cascaded multimode interference (MMI) couplers and an assisted mode-evolution taper. The tapers are designed to adiabatically convert the input TM(0) mode into the TE(1) mode, which will output as the TE(0) mode after processed by the subsequent MMI mode converter, 90-degree phase shifter (PS) and MMI 3 dB coupler. The numerical simulation results show that the proposed device has a < 0.5 dB insertion loss with < -17 dB crosstalk in C optical communication band. Fabrication tolerance analysis is also performed with respect to the deviations of MMI coupler width, PS width, slab height and upper-cladding refractive index, showing that this device could work well even when affected by considerable fabrication errors. With such a robust performance with a large bandwidth, this device offers potential applications for CMOS-compatible polarization diversity, especially in the booming 100 Gb/s coherent optical communications based on silicon photonics technology.

Polymer optical fiber tapering using chemical solvent and polishing

NASA Astrophysics Data System (ADS)

Supian, L. S.; Syuhaimi Ab-Rahman, Mohd; Arsad, Norhana

2017-11-01

A method for developing polymer optical fiber (POF) directional coupler is introduced where the initial procedure includes using chemical solvent to remove the cladding, and bare out the core in order to align the unclad center of the fiber with other similar fiber to develop a coupler. The process is safe, simple, inexpensive and require low operation skill. The etched fiber offers improvement to the performance of various POF devices, i.e, couplers and sensors. Instead of relying only on silica or glass fiber, POF now can be used as an alternative to improve the network performance in short distance communication system. The measurement parameters laid out offer great outcomes. However, the couplers intended to be developed is yet to be realized, where deeper research and various experiments are needed in order to develop a simple but optimum performance coupler that can be used for various applications.

Lensless magneto-optic speed sensor

DOEpatents

Veeser, L.R.; Forman, P.R.; Rodriguez, P.J.

1998-02-17

Lensless magneto-optic speed sensor is disclosed. The construction of a viable Faraday sensor has been achieved. Multimode fiber bundles are used to collect the light. If coupled directly into a 100 or 200 {micro}m core fiber, light from a light emitting diode (LED) is sufficient to operate the sensor. In addition, LEDs ensure that no birefringence effects in the input fiber are possible, as the output from such light sources have random polarization. No lens is required since the large diameter optical fibers and thin crystals of materials having high Verdet constants (such as iron garnets) employed permit the collection of a substantial quantity of light. No coupler is required. The maximum amount of light which could reach a detector using a coupler is 25%, while the measured throughput of the fiber-optic bundle without a coupler is about 42%. All of the elements employed in the present sensor are planar, and no particular orientation of these elements is required. The present sensor operates over a wide range of distances from magnetic field sources, and observed signals are large. When a tone wheel is utilized, the signals are independent of wheel speed, and the modulation is observed to be about 75%. No sensitivity to bends in the input or output optical fiber leads was observed. Reliable operation was achieved down to zero frequency, or no wheel rotation. 5 figs.

Lensless Magneto-optic speed sensor

DOEpatents

Veeser, Lynn R.; Forman, Peter R.; Rodriguez, Patrick J.

1998-01-01

Lensless magneto-optic speed sensor. The construction of a viable Faraday sensor has been achieved. Multimode fiber bundles are used to collect the light. If coupled directly into a 100 or 200 .mu.m core fiber, light from a light emitting diode (LED) is sufficient to operate the sensor. In addition, LEDs ensure that no birefringence effects in the input fiber are possible, as the output from such light sources have random polarization. No lens is required since the large diameter optical fibers and thin crystals of materials having high Verdet constants (such as iron garnets) employed permit the collection of a substantial quantity of light. No coupler is required. The maximum amount of light which could reach a detector using a coupler is 25%, while the measured throughput of the fiber-optic bundle without a coupler is about 42%. All of the elements employed in the present sensor are planar, and no particular orientation of these elements is required. The present sensor operates over a wide range of distances from magnetic field sources, and observed signals are large. When a tone wheel is utilized, the signals are independent of wheel speed, and the modulation is observed to be about 75%. No sensitivity to bends in the input or output optical fiber leads was observed. Reliable operation was achieved down to zero frequency, or no wheel rotation.

Studying quick coupler efficiency in working attachment system of single-bucket power shovel

NASA Astrophysics Data System (ADS)

Duganova, E. V.; Zagorodniy, N. A.; Solodovnikov, D. N.; Korneyev, A. S.

2018-03-01

A prototype of a quick-disconnect connector (quick coupler) with an unloaded retention mechanism was developed from the analysis of typical quick couplers used as intermediate elements for power shovels of different manufacturers. A method is presented, allowing building a simulation model of the quick coupler prototype as an alternative to physical modeling for further studies.

Extended-Range Passive RFID and Sensor Tags

NASA Technical Reports Server (NTRS)

Fink, Patrick W.; Kennedy, Timothy F.; Lin, Gregory Y.; Barton, Richard

2012-01-01

Extended-range passive radio-frequency identification (RFID) tags and related sensor tags are undergoing development. A tag of this type incorporates a retroreflective antenna array, so that it reflects significantly more signal power back toward an interrogating radio transceiver than does a comparable passive RFID tag of prior design, which does not incorporate a retroreflective antenna array. Therefore, for a given amount of power radiated by the transmitter in the interrogating transceiver, a tag of this type can be interrogated at a distance greater than that of the comparable passive RFID or sensor tag of prior design. The retroreflective antenna array is, more specifically, a Van Atta array, named after its inventor and first published in a patent issued in 1959. In its simplest form, a Van Atta array comprises two antenna elements connected by a transmission line so that the signal received by each antenna element is reradiated by the other antenna element (see Figure 1). The phase relationships among the received and reradiated signals are such as to produce constructive interference of the reradiated signals; that is, to concentrate the reradiated signal power in a direction back toward the source. Hence, an RFID tag equipped with a Van Atta antenna array automatically tracks the interrogating transceiver. The effective gain of a Van Atta array is the same as that of a traditional phased antenna array having the same number of antenna elements. Additional pairs of antenna elements connected by equal-length transmission lines can be incorporated into a Van Atta array to increase its directionality. Like some RFID tags here-to-fore commercially available, an RFID or sensor tag of the present developmental type includes one-port surface-acoustic-wave (SAW) devices. In simplified terms, the mode of operation of a basic one-port SAW device as used heretofore in an RFID device is the following: An interrogating radio signal is converted, at an input end, from an electrical signal to an acoustic wave that propagates along a surface and encounters multiple reflectors suitably positioned along the surface. Upon returning to the input end, the reflected acoustic wave is re-converted to an electrical signal, which, in turn, is reradiated from an antenna. The distances between the reflectors in the SAW device and the corresponding times between reflections encode the identifying or sensory information onto the reradiated signal. The fundamental problem in the present development is how to combine a Van Atta antenna array (which is inherently a multiple-port device) and one or more one-port SAW device(s) into a single, compact, passive unit that can function as a retroreflective RFID tag. The solution is to use one or more hybrid, half-power 90 couplers. A basic unit of this type, shown in Figure 2, includes a half-power 90 hybrid coupler; two identical SAW devices (SAW1 and SAW2) connected to ports 3 and 4 of the coupler, respectively; and antenna elements connected to ports 1 and 2 of the coupler. Necessarily omitting details for the sake of brevity, it must suffice to report that the phase relationships among the coupler inputs and outputs are such as to couple the incident signal from the antenna elements to the SAW devices and couple the reflected signals from the SAW devices back to the antenna elements in the phase relationships required for a Van Atta array. Hence, the reradiated signal is automatically directed back toward the interrogating transceiver and contains identifying and/or sensory information encoded in time intervals between reflections.

Quad-Chip Double-Balanced Frequency Tripler

NASA Technical Reports Server (NTRS)

Lin, Robert H.; Ward, John S.; Bruneau, Peter J.; Mehdi, Imran; Thomas, Bertrand C.; Maestrini, Alain

2010-01-01

Solid-state frequency multipliers are used to produce tunable broadband sources at millimeter and submillimeter wavelengths. The maximum power produced by a single chip is limited by the electrical breakdown of the semiconductor and by the thermal management properties of the chip. The solution is to split the drive power to a frequency tripler using waveguides to divide the power among four chips, then recombine the output power from the four chips back into a single waveguide. To achieve this, a waveguide branchline quadrature hybrid coupler splits a 100-GHz input signal into two paths with a 90 relative phase shift. These two paths are split again by a pair of waveguide Y-junctions. The signals from the four outputs of the Y-junctions are tripled in frequency using balanced Schottky diode frequency triplers before being recombined with another pair of Y-junctions. A final waveguide branchline quadrature hybrid coupler completes the combination. Using four chips instead of one enables using four-times higher power input, and produces a nearly four-fold power output as compared to using a single chip. The phase shifts introduced by the quadrature hybrid couplers provide isolation for the input and output waveguides, effectively eliminating standing waves between it and surrounding components. This is accomplished without introducing the high losses and expense of ferrite isolators. A practical use of this technology is to drive local oscillators as was demonstrated around 300 GHz for a heterodyne spectrometer operating in the 2-3-THz band. Heterodyne spectroscopy in this frequency band is especially valuable for astrophysics due to the presence of a very large number of molecular spectral lines. Besides high-resolution radar and spectrographic screening applications, this technology could also be useful for laboratory spectroscopy.

High power ferrite microwave switch

NASA Technical Reports Server (NTRS)

Bardash, I.; Roschak, N. K.

1975-01-01

A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

Bi-directional triplexer with butterfly MMI coupler using SU-8 polymer waveguides

NASA Astrophysics Data System (ADS)

Mareš, David; Jeřábek, Vítězslav; Prajzler, Václav

2015-01-01

We report about a design of a bi-directional planar optical multiplex/demultiplex filter (triplexer) for the optical part of planar hybrid WDM bi-directional transceiver in fiber-to-the-home (FTTH) PON applications. The triplex lightwave circuit is based on the Epoxy Novolak Resin SU-8 waveguides on the silica-on-silicon substrate with Polymethylmethacrylate cladding layer. The triplexer is comprised of a linear butterfly concept of multimode interference (MMI) coupler separating downstream optical signals of 1490 nm and 1550 nm. For the upstream channel of 1310 nm, an additional directional coupler (DC) is used to add optical signal of 1310 nm propagating in opposite direction. The optical triplexer was designed and optimized using beam propagation method. The insertion losses, crosstalk attenuation, and extinction ratio for all three inputs/outputs were investigated. The intended triplexer was designed using the parameters of the separated DC and MMI filter to approximate the idealized direct connection of both devices.

Modelling, simulation and applications of longitudinal train dynamics

NASA Astrophysics Data System (ADS)

Cole, Colin; Spiryagin, Maksym; Wu, Qing; Sun, Yan Quan

2017-10-01

Significant developments in longitudinal train simulation and an overview of the approaches to train models and modelling vehicle force inputs are firstly presented. The most important modelling task, that of the wagon connection, consisting of energy absorption devices such as draft gears and buffers, draw gear stiffness, coupler slack and structural stiffness is then presented. Detailed attention is given to the modelling approaches for friction wedge damped and polymer draft gears. A significant issue in longitudinal train dynamics is the modelling and calculation of the input forces - the co-dimensional problem. The need to push traction performances higher has led to research and improvement in the accuracy of traction modelling which is discussed. A co-simulation method that combines longitudinal train simulation, locomotive traction control and locomotive vehicle dynamics is presented. The modelling of other forces, braking propulsion resistance, curve drag and grade forces are also discussed. As extensions to conventional longitudinal train dynamics, lateral forces and coupler impacts are examined in regards to interaction with wagon lateral and vertical dynamics. Various applications of longitudinal train dynamics are then presented. As an alternative to the tradition single wagon mass approach to longitudinal train dynamics, an example incorporating fully detailed wagon dynamics is presented for a crash analysis problem. Further applications of starting traction, air braking, distributed power, energy analysis and tippler operation are also presented.

Synthesis of Hadamard transformers by use of multimode interference optical waveguides.

PubMed

Gupta, Atma Ram; Tsutsumi, Kiyoshi; Nakayama, Junichi

2003-05-20

We propose a synthesis method of optical Hadamard transformer using multimode interference (MMI) couplers. By using the signal transfer matrix of 2 x 2, 4 x 4, and 8 x 8 MMI couplers, we show that sum and difference units of input signals can be synthesized. An interchange unit of two signals can also be synthesized. One synthesis method of Hadamard transformers is a combination of only 2 x 2 units, and the other is a combination of N x N(N > or = 4) units as well as 2 x 2 units. The design examples of operation units are shown, and the size and the output power of Hadamard transformers are estimated.

Widely tunable long-period waveguide grating couplers

NASA Astrophysics Data System (ADS)

Bai, Y.; Liu, Q.; Lor, K. P.; Chiang, K. S.

2006-12-01

We demonstrate experimentally two widely tunable optical couplers formed with parallel long-period polymer waveguide gratings. One of the couplers consists of two parallel gratings and shows a peak coupling efficiency of ~34%. The resonance wavelength of the coupler can be tuned thermally with a sensitivity of 4.7 nm/°C. The experimental results agree well with the coupled-mode analysis. The other coupler consists of an array of ten widely separated gratings. A peak coupling efficiency of ~11% is obtained between the two best matched gratings in the array and the resonance wavelength can be tuned thermally with a sensitivity of -3.8 nm/°C. These couplers have the potential to be further developed into practical broadband add/drop multiplexers and signal dividers.

Improved noise-adding radiometer for microwave receivers

NASA Technical Reports Server (NTRS)

Batelaan, P. D.; Stelzried, C. T.; Goldstein, R. M.

1973-01-01

Use of input switch and noise reference standard is avoided by using noise-adding technique. Excess noise from solid state noise-diode is coupled into receiver through directional coupler and square-wave modulated at low rate. High sensitivity receivers for radioastronomy applications are utilized with greater confidence in stability of radiometer.

Design and development of ultra-wideband 3 dB hybrid coupler for Ion cyclotron resonance frequency heating in tokamak.

PubMed

Yadav, Rana Pratap; Kumar, Sunil; Kulkarni, S V

2014-04-01

Design and development of a high power ultra-wideband, 3 dB tandem hybrid coupler is presented and its application in ICRF heating of the tokamak is discussed. In order to achieve the desired frequency band of 38-112 MHz and 200 kW power handling capability, the 3 dB hybrid coupler is developed using two 3-element 8.34 ± 0.2 dB coupled lines sections in tandem. In multi-element coupled lines, junctions are employed for the joining of coupled elements that produce the undesirable reactance called junction discontinuity effect. The effect becomes prominent in the high power multi-element coupled lines for high frequency (HF) and very high frequency(VHF) applications because of larger structural dimensions. Junction discontinuity effect significantly deteriorates coupling and output performance from the theoretical predictions. For the analysis of junction discontinuity effect and its compensation, a theoretical approach has been developed and generalized for n-element coupled lines section. The theory has been applied in the development of the 3 dB hybrid coupler. The fabricated hybrid coupler has been experimentally characterized using vector network analyzer and obtained results are found in good agreement with developed theory.

Tunable and switchable all-fiber comb filter using a PBS-based two-stage cascaded Mach-Zehnder interferometer

NASA Astrophysics Data System (ADS)

Luo, Zhi-Chao; Luo, Ai-Ping; Xu, Wen-Cheng

2011-08-01

We propose and demonstrate a novel tunable and switchable all-fiber comb filter by employing a polarization beam splitter (PBS)-based two-stage cascaded Mach-Zehnder (M-Z) interferometer. The proposed comb filter consists of a rotatable polarizer, a fiber PBS, a non-3-dB coupler and a 3-dB coupler. By simply adjusting the polarization state of the input light, the dual-function of channel spacing tunable and wavelength switchable (interleaving) operations can be efficiently obtained. The theoretical analysis is verified by the experimental results. A comb filter with both the channel spacing tunable from 0.18 nm to 0.36 nm and the wavelength switchable functions is experimentally demonstrated.

Multilayered photonic integration on SOI platform using waveguide-based bridge structure

NASA Astrophysics Data System (ADS)

Majumder, Saikat; Chakraborty, Rajib

2018-06-01

A waveguide based structure on silicon on insulator platform is proposed for vertical integration in photonic integrated circuits. The structure consists of two multimode interference couplers connected by a single mode (SM) section which can act as a bridge over any other underlying device. Two more SM sections acts as input and output of the first and second multimode couplers respectively. Potential application of this structure is in multilayered photonic links. It is shown that the efficiency of the structure can be improved by making some design modifications. The entire simulation is done using effective-index based matrix method. The feature size chosen are comparable to waveguides fabricated previously so as to fabricate the proposed structure easily.

Effect of external index of refraction on multimode fiber couplers.

PubMed

Wang, G Z; Murphy, K A; Claus, R O

1995-12-20

The dependence of the performance of fused-taper multimode fiber couplers on the refractive index of the material surrounding the taper region has been investigated both theoretically and experimentally. It has been identified that for a 2 × 2 multimode fiber coupler there is a range of output-power-coupling ratios for which the effect of the external refractive index is negligible. When the coupler is tapered beyond this region, the performance becomes dependent on the external index of refraction and lossy. To analyze the multimode coupler-loss mechanism, we develop a two-dimensional ray-optics model that incorporates trapped cladding-mode loss and core-mode loss through frustrated total internal reflection.

Computer-simulation results support the experimental observations. Related issues such as coupler fabrication and packaging are also discussed.

Theoretical and experimental analysis of a linear accelerator endowed with single feed coupler with movable short-circuit.

PubMed

Dal Forno, Massimo; Craievich, Paolo; Penco, Giuseppe; Vescovo, Roberto

2013-11-01

The front-end injection systems of the FERMI@Elettra linac produce high brightness electron beams that define the performance of the Free Electron Laser. The photoinjector mainly consists of the radiofrequency (rf) gun and of two S-band rf structures which accelerate the beam. Accelerating structures endowed with a single feed coupler cause deflection and degradation of the electron beam properties, due to the asymmetry of the electromagnetic field. In this paper, a new type of single feed structure with movable short-circuit is proposed. It has the advantage of having only one waveguide input, but we propose a novel design where the dipolar component is reduced. Moreover, the racetrack geometry allows to reduce the quadrupolar component. This paper presents the microwave design and the analysis of the particle motion inside the linac. A prototype has been machined at the Elettra facility to verify the new coupler design and the rf field has been measured by adopting the bead-pull method. The results are here presented, showing good agreement with the expectations.

Fabry-Perot resonators with transverse coupling on SOI using loop mirrors

NASA Astrophysics Data System (ADS)

Saber, Md Ghulam; Abadía, Nicolás; Wang, Yun; Plant, David V.

2018-05-01

A novel integrated transversely coupled Fabry-Perot resonator using loop mirrors as the end reflectors are demonstrated via simulations and experiments on the silicon-on-insulator (SOI) platform. The resonator is formed by connecting two loop mirrors to the two output ports of a directional coupler to form the resonant cavity and utilizing the other two ports as the input and the output. Depending on which two ports of the directional coupler are mirrored, two configurations of the resonator can be achieved. The impacts of varying the cavity length and the coupling coefficient of the directional coupler on the output characteristics of the resonators are analyzed. A Q-factor of 28086 and an extinction ratio of 10.04 dB with an insertion loss of 1.9 dB is achieved experimentally for a 1038 μm cavity length and an extinction ratio of 18.14 dB and a Q-factor of 5120 with an insertion loss of 2.12 dB is obtained for a cavity length of 376 μm. The reported resonator offers additional freedom to tune the spectral characteristics.

Novel ultra-short and ultra-broadband polarization beam splitter based on a bent directional coupler.

PubMed

Dai, Daoxin; Bowers, John E

2011-09-12

A novel ultra-short polarization beam splitter (PBS) based on a bent directional coupler is proposed by utilizing the evanescent coupling between two bent optical waveguides with different core widths. For the bent directional coupler, there is a significant phase-mismatch for TE polarization while the phase-matching condition is satisfied for TM polarization. Therefore, the TM polarized light can be coupled from the narrow input waveguide to the adjacent wide waveguide while the TE polarization goes through the coupling region without significant coupling. An ultra-short (<10 μm-long) PBS is designed based on silicon-on-insulator nanowires and the length of the bent coupling region is as small as 4.5 μm while the gap width is chosen as 200 nm (large enough to simplify the fabrication). Numerical simulations show that the present PBS has a good fabrication tolerance for the variation of the waveguide width (more than ± 60 nm) and a very broad band (~200 nm) for an extinction ratio of >10 dB.

An air brake model for longitudinal train dynamics studies

NASA Astrophysics Data System (ADS)

Wei, Wei; Hu, Yang; Wu, Qing; Zhao, Xubao; Zhang, Jun; Zhang, Yuan

2017-04-01

Experience of heavy haul train operation shows that heavy haul train fatigue fracture of coupler and its related components, even the accidents are caused by excessive coupler force. The most economical and effective method to study on train longitudinal impulse by reducing the coupler force is simulation method. The characteristics of train air brake system is an important excitation source for the study of longitudinal impulse. It is very difficult to obtain the braking characteristic by the test method, a better way to get the input parameters of the excitation source in the train longitudinal dynamics is modelling the train air brake system. In this paper, the air brake system model of integrated system of air brake and longitudinal dynamics is introduced. This introduce is focus on the locomotive automatic brake valve and vehicle distribution valve model, and the comparative analysis of the simulation and test results of the braking system is given. It is proved that the model can predict the characteristics of train braking system. This method provides a good solution for the excitation source of longitudinal dynamic analysis system.

Multiple channel data acquisition system

DOEpatents

Crawley, H. Bert; Rosenberg, Eli I.; Meyer, W. Thomas; Gorbics, Mark S.; Thomas, William D.; McKay, Roy L.; Homer, Jr., John F.

1990-05-22

A multiple channel data acquisition system for the transfer of large amounts of data from a multiplicity of data channels has a plurality of modules which operate in parallel to convert analog signals to digital data and transfer that data to a communications host via a FASTBUS. Each module has a plurality of submodules which include a front end buffer (FEB) connected to input circuitry having an analog to digital converter with cache memory for each of a plurality of channels. The submodules are interfaced with the FASTBUS via a FASTBUS coupler which controls a module bus and a module memory. The system is triggered to effect rapid parallel data samplings which are stored to the cache memories. The cache memories are uploaded to the FEBs during which zero suppression occurs. The data in the FEBs is reformatted and compressed by a local processor during transfer to the module memory. The FASTBUS coupler is used by the communications host to upload the compressed and formatted data from the module memory. The local processor executes programs which are downloaded to the module memory through the FASTBUS coupler.

Multiple channel data acquisition system

DOEpatents

Crawley, H.B.; Rosenberg, E.I.; Meyer, W.T.; Gorbics, M.S.; Thomas, W.D.; McKay, R.L.; Homer, J.F. Jr.

1990-05-22

A multiple channel data acquisition system for the transfer of large amounts of data from a multiplicity of data channels has a plurality of modules which operate in parallel to convert analog signals to digital data and transfer that data to a communications host via a FASTBUS. Each module has a plurality of submodules which include a front end buffer (FEB) connected to input circuitry having an analog to digital converter with cache memory for each of a plurality of channels. The submodules are interfaced with the FASTBUS via a FASTBUS coupler which controls a module bus and a module memory. The system is triggered to effect rapid parallel data samplings which are stored to the cache memories. The cache memories are uploaded to the FEBs during which zero suppression occurs. The data in the FEBs is reformatted and compressed by a local processor during transfer to the module memory. The FASTBUS coupler is used by the communications host to upload the compressed and formatted data from the module memory. The local processor executes programs which are downloaded to the module memory through the FASTBUS coupler. 25 figs.

Reversing Optical Damage In LiNbO3 Switches

NASA Technical Reports Server (NTRS)

Gee, C. M.; Thurmond, G. D.

1985-01-01

One symptom of optical damage in Ti-diffused LiNbO3 directional-coupler switch reversed by temporarily raising input illumination to higher-thannormal power level. Healing phenomenon used to restore normal operation, increase operating-power rating, and stabilize operating characteristics at lower powers. Higher operating power is tolerated after treatment.

Data-based fault-tolerant control of high-speed trains with traction/braking notch nonlinearities and actuator failures.

PubMed

Song, Qi; Song, Yong-Duan

2011-12-01

This paper investigates the position and velocity tracking control problem of high-speed trains with multiple vehicles connected through couplers. A dynamic model reflecting nonlinear and elastic impacts between adjacent vehicles as well as traction/braking nonlinearities and actuation faults is derived. Neuroadaptive fault-tolerant control algorithms are developed to account for various factors such as input nonlinearities, actuator failures, and uncertain impacts of in-train forces in the system simultaneously. The resultant control scheme is essentially independent of system model and is primarily data-driven because with the appropriate input-output data, the proposed control algorithms are capable of automatically generating the intermediate control parameters, neuro-weights, and the compensation signals, literally producing the traction/braking force based upon input and response data only--the whole process does not require precise information on system model or system parameter, nor human intervention. The effectiveness of the proposed approach is also confirmed through numerical simulations.

Detuning related coupler kick variation of a superconducting nine-cell 1.3 GHz cavity

NASA Astrophysics Data System (ADS)

Hellert, Thorsten; Dohlus, Martin

2018-04-01

Superconducting TESLA-type cavities are widely used to accelerate electrons in long bunch trains, such as in high repetition rate free electron lasers. The TESLA cavity is equipped with two higher order mode couplers and a fundamental power coupler (FPC), which break the axial symmetry of the cavity. The passing electrons therefore experience axially asymmetrical coupler kicks, which depend on the transverse beam position at the couplers and the rf phase. The resulting emittance dilution has been studied in detail in the literature. However, the kick induced by the FPC depends explicitly on the ratio of the forward to the backward traveling waves at the coupler, which has received little attention. The intention of this paper is to present the concept of discrete coupler kicks with a novel approach of separating the field disturbances related to the standing wave and a reflection dependent part. Particular attention is directed to the role of the penetration depth of the FPC antenna, which determines the loaded quality factor of the cavity. The developed beam transport model is compared to dedicated experiments at FLASH and European XFEL. Both the observed transverse coupling and detuning related coupler kick variations are in good agreement with the model. Finally, the expected trajectory variations due to coupler kick variations at European XFEL are investigated and results of numerical studies are presented.

Initial Testing of the Mark-0 X-Band RF Gun at SLAC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlieks, Arnold; Adolphsen, C.; Dolgashev, V.

A new X-band RF gun (Mark-0) has been assembled, tuned and was tested in the ASTA facility at SLAC. This gun has been improved from an earlier gun used in Compton-scattering experiments at SLAC by the introduction of a racetrack dual-input coupler to reduce quadrupole fields. Waveguide-to-coupler irises were also redesigned to reduce surface magnetic fields and therefore peak pulse surface heating. Tests of this photocathode gun will allow us to gain early operational experience for beam tests of a new gun with further improvements (Mark-1) being prepared for SLAC's X-Band Test Area (XTA) program and the LLNL MEGa-ray program.more » Results of current testing up to {approx} 200 MV/m peak surface Electric fields are presented.« less

An efficient self-collimating photonic crystal coupling technique in the RF regime

NASA Astrophysics Data System (ADS)

Sabas, Jerico N.; Mirza, Iftekhar O.; Shi, Shouyuan; Prather, Dennis W.

2010-02-01

In this paper, we present both numerical and experimental results for the waveguiding of light using a low-index-contrast (LIC) self-collimating photonic crystal (SCPhC) in the RF frequency regime. This waveguiding structure utilizes the unique interactions of light with the periodic structure of the photonic crystal (PhC) to propagate a beam of light without divergence. This design also employs materials with a low index contrast (LIC), which reduces the electromagnetic signature of the PhC. This SCPhC was designed by extracting its dispersion contours and numerically simulating it using HFSS, a commercial 3-D, full-wave FEM software. In particular, we addressed the issue of coupling the PhC to a coaxial medium by designing an input/output (I/O) coupler consisting of a coaxial-to-waveguide transition, a rectangular waveguide and a tapered dielectric transition. We fabricated the SCPhC with a rigid polyurethane foam slab and Rexolite polystyrene rods using an automated CNC router to drill the periodic lattice in the slab. We also fabricated the dielectric segments of the I/O couplers with Rexolite slabs using an automated milling machine. Using these I/O couplers and SCPhC slab, we simulated and subsequently measured experimentally an insertion loss, for the entire system, of -3.3 dB through a 24" PhC slab, and a coupling loss of -0.95 dB at each coupler-PhC interface.

All-optical universal logic gates on nonlinear multimode interference coupler using tunable input intensity

NASA Astrophysics Data System (ADS)

Tajaldini, Mehdi; Jafri, Mohd Zubir Mat

2015-04-01

The theory of Nonlinear Modal Propagation Analysis Method (NMPA) have shown significant features of nonlinear multimode interference (MMI) coupler with compact dimension and when launched near the threshold of nonlinearity. Moreover, NMPA have the potential to allow studying the nonlinear MMI based the modal interference to explorer the phenomenon that what happen due to the natural of multimode region. Proposal of all-optical switch based NMPA has approved its capability to achieving the all-optical gates. All-optical gates have attracted increasing attention due to their practical utility in all-optical signal processing networks and systems. Nonlinear multimode interference devices could apply as universal all-optical gates due to significant features that NMPA introduce them. In this Paper, we present a novel Ultra-compact MMI coupler based on NMPA method in low intensity compared to last reports either as a novel design method and potential application for optical NAND, NOR as universal gates on single structure for Boolean logic signal processing devices and optimize their application via studding the contrast ratio between ON and OFF as a function of output width. We have applied NMPA for several applications so that the miniaturization in low nonlinear intensities is their main purpose.

Bidirectional optical coupler for plastic optical fibers.

PubMed

Sugita, Tatsuya; Abe, Tomiya; Hirano, Kouki; Itoh, Yuzo

2005-05-20

We have developed a low-loss bidirectional optical coupler for high-speed optical communication with plastic optical fibers (POFs). The coupler, which is fabricated by an injection molding method that uses poly (methyl methacrylate), has an antisymmetric tapered shape. We show that the coupler has low insertion and branching losses. The tapered shape of the receiving branch reduces beam diameter and increases detection efficiency coupling to a photodetector, whose area is smaller than that of the plastic optical fiber. The possibility of more than 15-m bidirectional transmission with a signaling bit rate up to 500 Mbits/s for simplex step-index POFs is demonstrated.

Light coupling and distribution for Si3N4/SiO2 integrated multichannel single-mode sensing system

NASA Astrophysics Data System (ADS)

Kaźmierczak, Andrzej; Dortu, Fabian; Schrevens, Olivier; Giannone, Domenico; Bouville, David; Cassan, Eric; Gylfason, Kristinn B.; Sohlström, Hans; Sanchez, Benito; Griol, Amadeu; Hill, Daniel

2009-01-01

We present an efficient and highly alignment-tolerant light coupling and distribution system for a multichannel Si3N4/SiO2 single-mode photonics sensing chip. The design of the input and output couplers and the distribution splitters is discussed. Examples of multichannel data obtained with the system are given.

Characteristics of a KA-band third-harmonic peniotron driven by a high-quality linear axis-encircling electron beam

NASA Astrophysics Data System (ADS)

Zhao, Xiaoyun; Tuo, Xianguo; Ge, Qing; Peng, Ying

2017-12-01

We employ a high-quality linear axis-encircling electron beam generated by a Cuccia coupler to drive a Ka-band third-harmonic peniotron and develop a self-consistent nonlinear calculation code to numerically analyze the characteristics of the designed peniotron. It is demonstrated that through a Cuccia coupler, a 6 kV, 0.5 A pencil beam and an input microwave power of 16 kW at 10 GHz can generate a 37 kV, 0.5 A linear axis-encircling beam, and it is characterized by a very low velocity spread. Moreover, the electron beam guiding center deviation can be adjusted easily. Driven by such a beam, a 30 GHz, Ka-band third-harmonic peniotron is predicted to achieve a conversion efficiency of 51.0% and a microwave output power of 9.44 kW; the results are in good agreement with the Magic3D simulation. Using this code, we studied the factors influencing the peniotron performance, and it can provide some guidelines for the design of a Ka-band third-harmonic peniotron driven by a linear electron beam and can promote the application of high-harmonic peniotrons in practice.

Single-mode laser studies: Design and performance of a fixed-wave length source and coupling of lasers to thin-film optical waveguides

NASA Technical Reports Server (NTRS)

Ladany, I.; Hammer, J. M.

1980-01-01

A module developed for the generation of a stable single wavelength to be used for a fiber optic multiplexing scheme is described. The laser is driven with RZ pulses, and the temperature is stabilized thermoelectrically. The unit is capable of maintaining a fixed wavelength within about 6 A as the pulse duty cycle is changed between 0 and 100 percent. This is considered the most severe case, and much tighter tolerances are obtainable for constant input power coding schemes. Using a constricted double heterostructure laser, a wavelength shift of 0.083 A mA is obtained due to laser self-heating by a dc driving current. The thermoelectric unit is capable of maintaining a constant laser heat-sink temperature within 0.02 C. In addition, miniature lenses and couplers are described which allow efficient coupling of single wavelength modes of junction lasers to thin film optical waveguides. The design of the miniature cylinder lenses and the prism coupling techniques allow 2 mW of single wavelength mode junction laser light to b coupled into thin film waveguides using compact assemblies. Selective grating couplers are also studied.

Investigation of Fully Three-Dimensional Helical RF Field Effects on TWT Beam/Circuit Interaction

NASA Technical Reports Server (NTRS)

Kory, Carol L.

2000-01-01

A fully three-dimensional (3D), time-dependent, helical traveling wave-tube (TWT) interaction model has been developed using the electromagnetic particle-in-cell (PIC) code MAFIA. The model includes a short section of helical slow-wave circuit with excitation fed by RF input/output couplers, and electron beam contained by periodic permanent magnet (PPM) focusing. All components of the model are simulated in three dimensions allowing the effects of the fully 3D helical fields on RF circuit/beam interaction to be investigated for the first time. The development of the interaction model is presented, and predicted TWT performance using 2.5D and 3D models is compared to investigate the effect of conventional approximations used in TWT analyses.

Design and characterization of integrated components for SiN photonic quantum circuits.

PubMed

Poot, Menno; Schuck, Carsten; Ma, Xiao-Song; Guo, Xiang; Tang, Hong X

2016-04-04

The design, fabrication, and detailed calibration of essential building blocks towards fully integrated linear-optics quantum computation are discussed. Photonic devices are made from silicon nitride rib waveguides, where measurements on ring resonators show small propagation losses. Directional couplers are designed to be insensitive to fabrication variations. Their offset and coupling lengths are measured, as well as the phase difference between the transmitted and reflected light. With careful calibrations, the insertion loss of the directional couplers is found to be small. Finally, an integrated controlled-NOT circuit is characterized by measuring the transmission through different combinations of inputs and outputs. The gate fidelity for the CNOT operation with this circuit is estimated to be 99.81% after post selection. This high fidelity is due to our robust design, good fabrication reproducibility, and extensive characterizations.

Aspects of the development of ultrabroadband precision directional couplers

NASA Astrophysics Data System (ADS)

Kats, B. M.; Larionov, A. I.; Meshchanov, V. P.

1991-03-01

The synthesis of ultrabroadband coaxial directional couplers (DCs) with improved characteristics is examined. A precision DC with operating ranges of 0.6-12.5 and 1.5-18.0 GHz have been developed and experimentally tested. The device is realized on the basis of coupled coaxial lines of a new type.

Optical source and apparatus for remote sensing

NASA Technical Reports Server (NTRS)

Coyle, Donald Barry (Inventor)

2011-01-01

An optical amplifier is configured to amplify an injected seed optical pulse. The optical amplifier may include two or more gain sections coupled to form a continuous solid waveguide along a primary optical path. Each gain section may include: (i) an optical isolator forming an input to that gain section; (ii) a doped optical fiber having a first end coupled to the optical isolator and having a second end; (iii) a plurality of pump laser diodes; (iv) a controller providing drive signals to each of the plurality, the controller being configured to provide at least pulsed drive signals; and (v) an optical coupler having a first input port coupled to the second end, and a second input port coupled to the plurality and an output port.

"Hot-wire" microfluidic flowmeter based on a microfiber coupler.

PubMed

Yan, Shao-Cheng; Liu, Zeng-Yong; Li, Cheng; Ge, Shi-Jun; Xu, Fei; Lu, Yan-Qing

2016-12-15

Using an optical microfiber coupler (MC), we present a microfluidic platform for strong direct or indirect light-liquid interaction by wrapping a MC around a functionalized capillary. The light propagating in the MC and the liquid flowing in the capillary can be combined and divorced smoothly, keeping a long-distance interaction without the conflict of input and output coupling. Using this approach, we experimentally demonstrate a "hot-wire" microfluidic flowmeter based on a gold-integrated helical MC device. The microfluid inside the glass channel takes away the heat, then cools the MC and shifts the resonant wavelength. Due to the long-distance interaction and high temperature sensitivity, the proposed microfluidic flowmeter shows an ultrahigh flow rate sensitivity of 2.183 nm/(μl/s) at a flow rate of 1 μl/s. The minimum detectable change of the flow rate is around 9 nl/s at 1 μl/s.

FERMILAB CRYOMODULE TEST STAND RF INTERLOCK SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petersen, Troy; Diamond, J. S.; McDowell, D.

2016-10-12

An interlock system has been designed for the Fermilab Cryo-module Test Stand (CMTS), a test bed for the cryo- modules to be used in the upcoming Linac Coherent Light Source 2 (LCLS-II) project at SLAC. The interlock system features 8 independent subsystems, one per superconducting RF cavity and solid state amplifier (SSA) pair. Each system monitors several devices to detect fault conditions such as arcing in the waveguides or quenching of the SRF system. Additionally each system can detect fault conditions by monitoring the RF power seen at the cavity coupler through a directional coupler. In the event of amore » fault condition, each system is capable of removing RF signal to the amplifier (via a fast RF switch) as well as turning off the SSA. Additionally, each input signal is available for re- mote viewing and recording via a Fermilab designed digitizer board and MVME 5500 processor.« less

Design of a high power TM01 mode launcher optimized for manufacturing by milling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dal Forno, Massimo

2016-12-15

Recent research on high-gradient rf acceleration found that hard metals, such as hard copper and hard copper-silver, have lower breakdown rate than soft metals. Traditional high-gradient accelerating structures are manufactured with parts joined by high-temperature brazing. The high temperature used in brazing makes the metal soft; therefore, this process cannot be used to manufacture structures out of hard metal alloys. In order to build the structure with hard metals, the components must be designed for joining without high-temperature brazing. One method is to build the accelerating structures out of two halves, and join them by using a low-temperature technique, atmore » the symmetry plane along the beam axis. The structure has input and output rf power couplers. We use a TM01 mode launcher as a rf power coupler, which was introduced during the Next Linear Collider (NLC) work. The part of the mode launcher will be built in each half of the structure. This paper presents a novel geometry of a mode launcher, optimized for manufacturing by milling. The coupler was designed for the CERN CLIC working frequency f = 11.9942 GHz; the same geometry can be scaled to any other frequency.« less

Nonuniform transmission line codirectional couplers for hybrid MIMIC and superconductive applications

NASA Astrophysics Data System (ADS)

Uysal, Sener; Turner, Charles W.; Watkins, John

1994-03-01

A new design approach for thin-film codirectional quadrature couplers and their applications is described. An in-depth analysis and semi-empirical design curves are presented for these couplers. Forward-wave coupling is achieved by making use of the difference between even- and odd-mode phase velocities. Modified nonuniform codirectional couplers with a dummy channel for continuously decreasing or increasing taper and employing wiggly, serpentined and smooth coupled edges have been designed and tested. It is found that a wiggly coupler can achieve a 50% length reduction compared to a smooth-edge coupler. A further 60% length reduction compared to a wiggly coupler is achieved by a serpentine coupler. Coupler performance for wiggly and serpentined configurations is computed by choosing a realizable phase velocity function for a given coupler length. Either constant 90deg or - 90deg phase shift is possible with these couplers giving significant design flexibility in some applications. The results for a K(sub u)-band Sigma-Delta Magic-T circuit employing a 0 dB wiggly coupler and a - 3 dB smooth-edge coupler are also presented.

49 CFR 179.14 - Coupler vertical restraint system.

Code of Federal Regulations, 2010 CFR

2010-10-01

... mating coupler (or simulated coupler) having only frictional vertical force resistance at the mating interface; or a mating coupler (or simulated coupler) having the capabilities described in paragraph (a) of this section; (2) The testing apparatus shall simulate the vertical coupler performance at the mating...

Incident polarization angle and temperature dependence of polarization and spectral response characteristics in optical fiber couplers.

PubMed

Namihira, Y; Kawazawa, T; Wakabayashi, H

1991-03-20

The incident polarization angle and temperature dependence of the polarization and spectral response characteristics of three different types of fiber coupler are presented. The couplers are (1) the biconicalfused- twisted-taper single-mode fiber (coupler A), (2) the asymmetric-etched-fused-taper wavelength division multiplex (coupler B), and (3) the biconical-polished polarization maintaining fiber (coupler C), respectively. It is confirmed experimentally that the polarization characteristics of couplers A and B vary greatly with temperature, but those of coupler C are independent of temperature. Also, the wavelength dependence characteristics of the power splitting ratio of couplers B and C have almost no change with temperature. However, the wavelength dependence of coupler A is greatly changed with temperature. Comparing couplers A and B, it is postulated that the sinusoidal variations of the polarization state vs the incident polarization angle are due to the stress birefringence caused by the fiber twisting when the fused fiber coupler is fabricated and packaged.

Development of fundamental power coupler for C-ADS superconducting elliptical cavities

NASA Astrophysics Data System (ADS)

Gu, Kui-Xiang; Bing, Feng; Pan, Wei-Min; Huang, Tong-Ming; Ma, Qiang; Meng, Fan-Bo

2017-06-01

5-cell elliptical cavities have been selected for the main linac of the China Accelerator Driven sub-critical System (C-ADS) in the medium energy section. According to the design, each cavity should be driven with radio frequency (RF) energy up to 150 kW by a fundamental power coupler (FPC). As the cavities work with high quality factor and high accelerating gradient, the coupler should keep the cavity from contamination in the assembly procedure. To fulfil the requirements, a single-window coaxial type coupler was designed with the capabilities of handling high RF power, class 10 clean room assembly, and heat load control. This paper presents the coupler design and gives details of RF design, heat load optimization and thermal analysis as well as multipacting simulations. In addition, a primary high power test has been performed and is described in this paper. Supported by China ADS Project (XDA03020000) and National Natural Science Foundation of China (11475203)

49 CFR 179.14 - Coupler vertical restraint system.

Code of Federal Regulations, 2011 CFR

2011-10-01

... system shall be tested under the following conditions: (1) The test coupler shall be tested with a mating coupler (or simulated coupler) having only frictional vertical force resistance at the mating interface; or a mating coupler (or simulated coupler) having the capabilities described in paragraph (a) of this...

Independent Research and Independent Exploratory Development

DTIC Science & Technology

1974-09-01

finish on the back. Some of inhomogeneities is described. Although the results the samples were coated with a wet thermal oxide presented are for...1974 Penitin 73 LB . Stotts and W. M. Coton Improved Bire fringent Optical Coupler An optical coupler for waveguides employing the biref ringence

Computer program for analysis of coupled-cavity traveling wave tubes

NASA Technical Reports Server (NTRS)

Connolly, D. J.; Omalley, T. A.

1977-01-01

A flexible, accurate, large signal computer program was developed for the design of coupled cavity traveling wave tubes. The program is written in FORTRAN IV for an IBM 360/67 time sharing system. The beam is described by a disk model and the slow wave structure by a sequence of cavities, or cells. The computational approach is arranged so that each cavity may have geometrical or electrical parameters different from those of its neighbors. This allows the program user to simulate a tube of almost arbitrary complexity. Input and output couplers, severs, complicated velocity tapers, and other features peculiar to one or a few cavities may be modeled by a correct choice of input data. The beam-wave interaction is handled by an approach in which the radio frequency fields are expanded in solutions to the transverse magnetic wave equation. All significant space harmonics are retained. The program was used to perform a design study of the traveling-wave tube developed for the Communications Technology Satellite. Good agreement was obtained between the predictions of the program and the measured performance of the flight tube.

Mid-IR fused fiber couplers

NASA Astrophysics Data System (ADS)

Stevens, G.; Woodbridge, T.

2016-03-01

We present results from our recent efforts on developing single-mode fused couplers in ZBLAN fibre. We have developed a custom fusion workstation for working with lower melting temperature fibres, such as ZBLAN and chalcogenide fibres. Our workstation uses a precisely controlled electrical heater designed to operate at temperatures between 100 - 250°C as our heat source. The heated region of the fibers was also placed in an inert atmosphere to avoid the formation of microcrystal inclusions during fusion. We firstly developed a process for pulling adiabatic tapers in 6/125 μm ZBLAN fibre. The tapers were measured actively during manufacture using a 2000 nm source. The process was automated so that the heater temperature and motor speed automatically adjusted to pull the taper at constant tension. This process was then further developed so that we could fuse and draw two parallel 6/125 μm ZBLAN fibres, forming a single-mode coupler. Low ratio couplers (1-10%) that could be used as power monitors were manufactured that had an excess loss of 0.76 dB. We have also manufactured 50/50 splitters and wavelength division multiplexers (WDMs). However, the excess loss of these devices was typically 2 - 3 dB. The increased losses were due to localised necking and surface defects forming as the tapers were pulled further to achieve a greater coupling ratio. Initial experiments with chalcogenide fibre have shown that our process can be readily adapted for chalcogenide fibres. A 5% coupler with 1.5 dB insertion loss was manufactured using commercial of the shelf (COTS) fibres.

Performance Evaluation of Photonic Sigma Delta ADCs

DTIC Science & Technology

2010-12-01

resulted in an output at the MZI driver that is too low to drive the MZI itself. It is recommended that a transimpedance amplifier be used instead of...Accumulator The accumulator shown in Figure 1 consists of a single delay, a feedback loop and two amplifiers . The input of the accumulator is the...fiber amplifier (EDFA), an output coupler, an electro–optic modulator, a tunable filter and the fiber that connects these devices together. The piezo

Design of a Ku band miniature multiple beam klystron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bandyopadhyay, Ayan Kumar, E-mail: ayan.bandyopadhyay@gmail.com; Pal, Debasish; Kant, Deepender

2016-03-09

The design of a miniature multiple beam klystron (MBK) working in the Ku-band frequency range is presented in this article. Starting from the main design parameters, design of the electron gun, the input and output couplers and radio frequency section (RF-section) are presented. The design methodology using state of the art commercial electromagnetic design tools, analytical formulae as well as noncommercial design tools are briefly presented in this article.

Thermal-Mechanical Study of 3.9 GHz CW Coupler and Cavity for LCLS-II Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonin, Ivan; Harms, Elvin; Khabiboulline, Timergali

2017-05-01

Third harmonic system was originally developed by Fermilab for FLASH facility at DESY and then was adopted and modified by INFN for the XFEL project [1-3]. In contrast to XFEL project, all cryomodules in LCLS-II project will operate in CW regime with higher RF average power for 1.3 GHz and 3.9 GHz cavities and couplers. Design of the cavity and fundamental power coupler has been modified to satisfy LCLS-II requirements. In this paper we discuss the results of COMSOL thermal and mechanical analysis of the 3.9 GHz coupler and cavity to verify proposed modifica-tion of the design. For the dressedmore » cavity we present simulations of Lorentz force detuning, helium pressure sensitivity df/dP and major mechanical resonances.« less

DEB Type I Reconstitution Package Deployment Manual (RPDM).

DTIC Science & Technology

1981-05-01

Waveguide Assembly (d) 1177H02 TWT Power Amplifier (e) TCM-6RK-I Transmit and Receive Remote Kits 20 C" I--I- CL* Figure 8. Terminal 21 17 February...Twist Six Waveguide to Coax Adapters 1.2.1.1.1(d) TWT Power Amplifier. The power amplifier utilizes a periodic permanent magnetic focused travelling...possible to adjust input power while observing TWT output with a power meter and directional coupler. The capability of controlling the TWT drive

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forno, Massimo Dal; Department of Engineering and Architecture, University of Trieste, Trieste; Craievich, Paolo

The front-end injection systems of the FERMI@Elettra linac produce high brightness electron beams that define the performance of the Free Electron Laser. The photoinjector mainly consists of the radiofrequency (rf) gun and of two S-band rf structures which accelerate the beam. Accelerating structures endowed with a single feed coupler cause deflection and degradation of the electron beam properties, due to the asymmetry of the electromagnetic field. In this paper, a new type of single feed structure with movable short-circuit is proposed. It has the advantage of having only one waveguide input, but we propose a novel design where the dipolarmore » component is reduced. Moreover, the racetrack geometry allows to reduce the quadrupolar component. This paper presents the microwave design and the analysis of the particle motion inside the linac. A prototype has been machined at the Elettra facility to verify the new coupler design and the rf field has been measured by adopting the bead-pull method. The results are here presented, showing good agreement with the expectations.« less

Solid state laser

NASA Technical Reports Server (NTRS)

Rines, Glen A. (Inventor); Moulton, Peter F. (Inventor); Harrison, James (Inventor)

1993-01-01

A wavelength-tunable, injection-seeded, dispersion-compensated, dispersively-pumped solid state laser includes a lasing medium; a highly reflective mirror; an output coupler; at least one isosceles Brewster prism oriented to the minimum deviation angle between the medium and the mirror for directing light of different wavelengths along different paths; means for varying the angle of the highly reflective mirror relative to the light from at least one Brewster angle for selecting a predetermined laser operating wavelength; a dispersion compensation apparatus associated with the lasing medium; a laser injection seeding port disposed between the dispersion compensation apparatus and one of the mirror and coupler and including a reflective surface at an acute non-Brewster angle to the laser beam for introducing a seed input; a dispersion compensation apparatus associated with the laser medium including opposite chirality optical elements; the lasing medium including a pump surface disposed at an acute angle to the laser beam to define a discrete path for the pumping laser beam separate from the pumped laser beam.

Performance of the round window soft coupler for the backward stimulation of the cochlea in a temporal bone model.

PubMed

Gostian, Antoniu-Oreste; Schwarz, David; Mandt, Philipp; Anagiotos, Andreas; Ortmann, Magdalene; Pazen, David; Beutner, Dirk; Hüttenbrink, Karl-Bernd

2016-11-01

The round window vibroplasty is a feasible option for the treatment of conductive, sensorineural and mixed hearing loss. Although clinical data suggest a satisfying clinical outcome with various coupling methods, the most efficient coupling technique of the floating mass transducer to the round window is still a matter of debate. For this, a soft silicone-made coupler has been developed recently that aims to ease and optimize the stimulation of the round window membrane of this middle ear implant. We performed a temporal bone study evaluating the performance of the soft coupler compared to the coupling with individually shaped cartilage, perichondrium and the titanium round window coupler with loads up to 20 mN at the unaltered and fully exposed round window niche. The stimulation of the cochlea was measured by the volume velocities of the stapes footplate detected by a laser Doppler vibrometer. The coupling method was computed as significant factor with cartilage and perichondrium allowing for the highest volume velocities followed by the soft and titanium coupler. Exposure of the round window niche allowed for higher volume velocities while the applied load did not significantly affect the results. The soft coupler allows for a good contact to the round window membrane and an effective backward stimulation of the cochlea. Clinical data are mandatory to evaluate performance of this novel coupling method in vivo.

Overlapping-image multimode interference couplers with a reduced number of self-images for uniform and nonuniform power splitting

NASA Astrophysics Data System (ADS)

Bachmann, M.; Besse, P. A.; Melchior, H.

1995-10-01

Overlapping-image multimode interference (MMI) couplers, a new class of devices, permit uniform and nonuniform power splitting. A theoretical description directly relates coupler geometry to image intensities, positions, and phases. Among many possibilities of nonuniform power splitting, examples of 1 \\times 2 couplers with ratios of 15:85 and 28:72 are given. An analysis of uniform power splitters includes the well-known 2 \\times N and 1 \\times N MMI couplers. Applications of MMI couplers include mode filters, mode splitters-combiners, and mode converters.

A Thick Film Microstrip Butler Matrix for the Frequency Range 1.5-1.7 GHz.

DTIC Science & Technology

1979-09-01

The 1800 hybrid coupler II 4.1.5 The broadside coupler 11 4.1.6 The Podell coupler 12 4.2 Phase shifters 12 4.2.1 The dielectrically loaded line phase...The Podell coupler The Podell coupler8 of Fig 9b overcomes even and odd mode velocity disper- sion by using a sawtooth design on the inner edge. This...8 A. Podell A high directivity microstrip coupler technique. IEEE G-MTT International Microwave Symposium, 33-36 (1970) 9 B. Easter The equivalent

Central Iliac Arteriovenous Anastomosis for Uncontrolled Hypertension: One-Year Results From the ROX CONTROL HTN Trial.

PubMed

Lobo, Melvin D; Ott, Christian; Sobotka, Paul A; Saxena, Manish; Stanton, Alice; Cockcroft, John R; Sulke, Neil; Dolan, Eamon; van der Giet, Markus; Hoyer, Joachim; Furniss, Stephen S; Foran, John P; Witkowski, Adam; Januszewicz, Andrzej; Schoors, Danny; Tsioufis, Konstantinos; Rensing, Benno J; Scott, Benjamin; Ng, G André; Schmieder, Roland E

2017-12-01

Creation of a central iliac arteriovenous anastomosis using a novel nitinol coupler device results in an immediate, significant reduction of blood pressure (BP). We present efficacy and safety findings at 12 months post-coupler insertion. This open-label, multicenter, prospective, randomized trial enrolled patients with a baseline office systolic BP ≥140 mm Hg and average daytime ambulatory BP ≥135/85 mm Hg. Subjects were randomly allocated to coupler implantation and continuing previous pharmacotherapy or to maintain previous treatment alone. At 12 months, 39 patients who had coupler therapy were included in the intention-to-treat analysis. Office-based systolic BP reduced by 25.1±23.3 mm Hg (baseline, 174±18 mm Hg; P <0.0001) post-coupler placement, and office diastolic BP reduced by 20.8±13.3 mm Hg (baseline, 100±13 mm Hg; P <0.0001). Mean 24-hour ambulatory BP reduced by 12.6±17.4/15.3±9.7 mm Hg ( P <0.0001 for both). In a prespecified subset of patients who failed to respond adequately to prior renal denervation, coupler therapy led to highly significant reduction in office systolic/diastolic BP (30.7/24.1 mm Hg) and significant reduction in 24-hour ambulatory systolic/diastolic BP (12.4/14.4 mm Hg) at 12 months (n=9). After coupler therapy, 14 patients (33%) developed ipsilateral venous stenosis; all were treated successfully with venous stenting. These findings confirm the importance of arterial mechanics in the pathophysiology of hypertension and support the clinical use of a central iliac arteriovenous anastomosis. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01642498. © 2017 American Heart Association, Inc.

Full scale tank car coupler impact tests

DOT National Transportation Integrated Search

2003-11-15

Full scale tests were performed to investigate various : aspects of tank car behavior during coupler impacts. A tank car : was equipped with 37 accelerometers and an instrumented : coupler. Two series of full scale coupler impact tests, : comprising ...

All-optical controlled switching of solitons

NASA Astrophysics Data System (ADS)

Man, Wai Sing

1999-11-01

In this dissertation, we have numerically investigated various method of switching solitons using two different nonlinear optical switching devices, namely the twin core nonlinear directional coupler (TCNLDC) and the nonlinear optical loop mirror (NOLM). In the case of TCNLDC, four different schemes were explored where the polarization of the controlling pulse is either parallel or orthogonal to that of the signal soliton, or the controlling pulse may be launched into either of the input ports or it may have a wavelength different from that of the signal. It has been shown that high switching efficiency and distortionless propagation of the signal pulse through the coupler can only be achieved for the case in which the control pulse is launched into the adjacent port of the directional coupler and that its dispersion has equal magnitude but opposite sign as that of the signal. The effect of varying pulse width, walk-off and timing jitter were also investigated for this particular scheme for signal pulse width of 1 ps wide. In the case of NOLM, a control pulse having central wavelength located at the normal dispersion region is used to switch the soliton. The control pulse width and the NOLM's loop length were varied to obtain the switched soliton with minimum distortion and high switching efficiency. In this analysis, Raman effect is included because the control pulse transfers part of its energy to the co-propagating signal pulse in the optical loop. A compact soliton laser has also been developed for this project and its performance was analyzed experimentally and numerically. In our analysis of this soliton laser, we found that the wavelength of the mode-locked pulse can be tuned by varying the polarization elements in the laser and this is entirely due to the birefringence in the laser cavity. In summary, our works have shown that optical solitons can be switched effectively by TCNLDC and NOLM in the high bit-rate and low switching energy regime. (Abstract shortened by UMI.)

Study of the effect of loop inductance on the RF transmission line to cavity coupling coefficient

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lal, Shankar, E-mail: shankar@rrcat.gov.in; Pant, K. K.

2016-08-15

Coupling of RF power is an important aspect in the design and development of RF accelerating structures. RF power coupling employing coupler loops has the advantage of tunability of β, the transmission line to cavity coupling coefficient. Analytical expressions available in literature for determination of size of the coupler loop using Faraday’s law of induction show reasonably good agreement with experimentally measured values of β below critical coupling (β ≤ 1) but show large deviation with experimentally measured values and predictions by simulations for higher values of β. In actual accelerator application, many RF cavities need to be over-coupled withmore » β > 1 for reasons of beam loading compensation, reduction of cavity filling time, etc. This paper discusses a modified analytical formulation by including the effect of loop inductance in the determination of loop size for any desired coupling coefficient. The analytical formulation shows good agreement with 3D simulations and with experimentally measured values. It has been successfully qualified by the design and development of power coupler loops for two 476 MHz pre-buncher RF cavities, which have successfully been conditioned at rated power levels using these coupler loops.« less

Study of the effect of loop inductance on the RF transmission line to cavity coupling coefficient

NASA Astrophysics Data System (ADS)

Lal, Shankar; Pant, K. K.

2016-08-01

Coupling of RF power is an important aspect in the design and development of RF accelerating structures. RF power coupling employing coupler loops has the advantage of tunability of β, the transmission line to cavity coupling coefficient. Analytical expressions available in literature for determination of size of the coupler loop using Faraday's law of induction show reasonably good agreement with experimentally measured values of β below critical coupling (β ≤ 1) but show large deviation with experimentally measured values and predictions by simulations for higher values of β. In actual accelerator application, many RF cavities need to be over-coupled with β > 1 for reasons of beam loading compensation, reduction of cavity filling time, etc. This paper discusses a modified analytical formulation by including the effect of loop inductance in the determination of loop size for any desired coupling coefficient. The analytical formulation shows good agreement with 3D simulations and with experimentally measured values. It has been successfully qualified by the design and development of power coupler loops for two 476 MHz pre-buncher RF cavities, which have successfully been conditioned at rated power levels using these coupler loops.

Formalism of photons in a nonlinear microring resonator

NASA Astrophysics Data System (ADS)

Tran, Quang Loc; Yupapin, Preecha

2018-03-01

In this paper, using short Gaussian pulses input from a monochromatic light source, we simulate the photon distribution and analyse the output gate's signals of PANDA nonlinear ring resonator. The present analysis is restricted to directional couplers characterized by two parameters, the power coupling coefficient κ and power coupling loss γ. Add/drop filters are also employed and investigated for the suitable to implement in the practical communication system. The experiment was conducted by using the combination of Lumerical FDTD Solutions and Lumerical MODE Solutions software.

Guano-Derived Nutrient Subsidies Drive Food Web Structure in Coastal Ponds.

PubMed

Vizzini, Salvatrice; Signa, Geraldina; Mazzola, Antonio

2016-01-01

A stable isotope study was carried out seasonally in three coastal ponds (Marinello system, Italy) affected by different gull guano input to investigate the effect of nutrient subsidies on food web structure and dynamics. A marked 15N enrichment occurred in the pond receiving the highest guano input, indicating that gull-derived fertilization (guanotrophication) had a strong localised effect and flowed across trophic levels. The main food web response to guanotrophication was an overall erosion of the benthic pathway in favour of the planktonic. Subsidized primary consumers, mostly deposit feeders, switched their diet according to organic matter source availability. Secondary consumers and, in particular, fish from the guanotrophic pond, acted as couplers of planktonic and benthic pathways and showed an omnivorous trophic behaviour. Food web structure showed substantial variability among ponds and a marked seasonality in the subsidized one: an overall simplification was evident only in summer when guano input maximises its trophic effects, while higher trophic diversity and complexity resulted when guano input was low to moderate.

Guano-Derived Nutrient Subsidies Drive Food Web Structure in Coastal Ponds

PubMed Central

Vizzini, Salvatrice; Signa, Geraldina; Mazzola, Antonio

2016-01-01

A stable isotope study was carried out seasonally in three coastal ponds (Marinello system, Italy) affected by different gull guano input to investigate the effect of nutrient subsidies on food web structure and dynamics. A marked 15N enrichment occurred in the pond receiving the highest guano input, indicating that gull-derived fertilization (guanotrophication) had a strong localised effect and flowed across trophic levels. The main food web response to guanotrophication was an overall erosion of the benthic pathway in favour of the planktonic. Subsidized primary consumers, mostly deposit feeders, switched their diet according to organic matter source availability. Secondary consumers and, in particular, fish from the guanotrophic pond, acted as couplers of planktonic and benthic pathways and showed an omnivorous trophic behaviour. Food web structure showed substantial variability among ponds and a marked seasonality in the subsidized one: an overall simplification was evident only in summer when guano input maximises its trophic effects, while higher trophic diversity and complexity resulted when guano input was low to moderate. PMID:26953794

Comparison of Psychophysical and Physical Measurements of Real Ear to Coupler Differences.

PubMed

Koning, Raphael; Wouters, Jan; Francart, Tom

2015-01-01

The purpose of the study is to compare real ear to coupler difference (RECD) curves based on physical and psychophysical measures. For the physically measured RECD, the RECD was measured with real ear and coupler measurements for the ear simulator and HA1- and HA2 2-cc couplers. The psychophysically measured RECDs were derived from audiogram measures. RECDs were measured in 19 normally hearing subjects. The coupler measurement was done with the probe microphone and the coupler microphone itself. Psychophysically measured RECDs were derived for all subjects by measuring the audiogram in sound field and with an ER-3A insert phone. Reference data were obtained for the three coupler types. It was possible to derive the RECD curve with psychophysical methods. There was no overall statistical difference between the physically and psychophysically measured RECD curves for the HA2 2-cc coupler and the ear simulator. The standard deviation was, however, much higher for the psychophysically derived RECD, indicating that physically measured RECDs are more precise than psychophysically derived RECDs. For the physical RECD measurements, the coupler microphone should be used for the coupler measurement. Physically measured RECDs were validated on group level by the reliable derivation of the RECD curve from audiogram measures.

Fluoride-fiber-based side-pump coupler for high-power fiber lasers at 2.8  μm.

PubMed

Schäfer, C A; Uehara, H; Konishi, D; Hattori, S; Matsukuma, H; Murakami, M; Shimizu, S; Tokita, S

2018-05-15

A side-pump coupler made of fluoride fibers was fabricated and tested. The tested device had a coupling efficiency of 83% and was driven with an incident pump power of up to 83.5 W, demonstrating high-power operation. Stable laser output of 15 W at a wavelength of around 2.8 μm was achieved over 1 h when using an erbium-doped double-clad fiber as the active medium. To the best of our knowledge, this is the first time a fluoride-glass-fiber-based side-pump coupler has been developed. A test with two devices demonstrated further power scalability.

Fiber-optic polarization diversity detection for rotary probe optical coherence tomography.

PubMed

Lee, Anthony M D; Pahlevaninezhad, Hamid; Yang, Victor X D; Lam, Stephen; MacAulay, Calum; Lane, Pierre

2014-06-15

We report a polarization diversity detection scheme for optical coherence tomography with a new, custom, miniaturized fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the X and Y OCT polarization channels prior to interference and the PM fiber outputs ensure defined X and Y axes after interference. Advantages for this scheme include easier alignment, lower cost, and easier miniaturization compared to designs with free-space bulk optical components. We demonstrate the utility of the detection system to mitigate the effects of rapidly changing polarization states when imaging with rotating fiber optic probes in Intralipid suspension and during in vivo imaging of human airways.

Binary power multiplier for electromagnetic energy

DOEpatents

Farkas, Zoltan D.

1988-01-01

A technique for converting electromagnetic pulses to higher power amplitude and shorter duration, in binary multiples, splits an input pulse into two channels, and subjects the pulses in the two channels to a number of binary pulse compression operations. Each pulse compression operation entails combining the pulses in both input channels and selectively steering the combined power to one output channel during the leading half of the pulses and to the other output channel during the trailing half of the pulses, and then delaying the pulse in the first output channel by an amount equal to half the initial pulse duration. Apparatus for carrying out each of the binary multiplication operation preferably includes a four-port coupler (such as a 3 dB hybrid), which operates on power inputs at a pair of input ports by directing the combined power to either of a pair of output ports, depending on the relative phase of the inputs. Therefore, by appropriately phase coding the pulses prior to any of the pulse compression stages, the entire pulse compression (with associated binary power multiplication) can be carried out solely with passive elements.

Superconducting Prototype Cavities for the Spallation Neutron Source (SNS) Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

G. Ciovati, P. Kneisel , J. Brawley, R. Bundy, I. Campisi, K. Davis; K. Macha; D. Machie

2001-09-01

The Spallation Neutron Source project includes a superconducting linac section in the energy range from 192 MeV to 1000 MeV, operating at a frequency of 805 MHz at 2.1 K. For this energy range two types of cavities are needed with geometrical beta - values of beta= 0.61 and beta= 0.81. An aggressive cavity prototyping program is being pursued at Jlab, which calls for fabricating and testing of four beta= 0.61 cavities and two beta= 0.81 cavities. Both types consist of six cells made from high purity niobium and feature one HOM coupler on each beam pipe and a portmore » for a high power coaxial input coupler. Three of the four beta= 0.61 cavities will be used for a cryomodule test in early 2002. At this time four medium beta cavities and one high beta cavity have been completed at JLab. The first tests on the beta=0.61 cavity and the beta= 0.81 exceeded the design values for gradient and Q - value: E{sub acc} = 1 0.3 MV/m and Q = 5 x 10{sup 9} at 2.1K for beta= 0.61 and E{sub acc} = 12.3 MV/m and Q = 5 x 10{sup 9} at 2.1K for beta= 0.81. One of the medium beta cavities has been equipped with an integrated helium vessel and measurements of the static and dynamic Lorentz force detuning will be done and compared to the ''bare'' cavities. In addition two single cell cavities have been fabricated, equipped with welded-on HOM couplers. They are being used to evaluate the HOM couplers with respect to multipacting, fundamental mode rejection and HOM damping as far as possible in a single cell. This paper will describe the cavity design with respect to electrical and mechanical features, the fabrication efforts and the results obtained with the different cavities existing at the time of this workshop.« less

Theoretical analysis and modeling of a photonic integrated circuit for frequency 8-tupled and 24-tupled millimeter wave signal generation.

PubMed

Hasan, Mehedi; Guemri, Rabiaa; Maldonado-Basilio, Ramón; Lucarz, Frédéric; de Bougrenet de la Tocnaye, Jean-Louis; Hall, Trevor

2014-12-15

A photonic circuit design for implementing frequency 8-tupling and 24-tupling is proposed. The front- and back-end of the circuit comprises 4×4 MMI couplers enclosing an array of four pairs of phase modulators and 2×2 MMI couplers. The proposed design for frequency multiplication requires no optical or electrical filters, the operation is not limited to carefully adjusted modulation indexes, and the drift originated from static DC bias is mitigated by making use of the intrinsic phase relations of multi-mode interference couplers. A transfer matrix approach is used to represent the main building blocks of the design and hence to describe the operation of the frequency 8-tupling and 24-tupling. The concept is theoretically developed and demonstrated by simulations. Ideal and imperfect power imbalances in the multi-mode interference couplers, as well as ideal and imperfect phases of the electric drives to the phase modulators, are analyzed.

Improvements for the stability of heavy-haul couplers with arc surface contact

NASA Astrophysics Data System (ADS)

Wu, Guosong; Wang, Huang; Yao, Yuan

2018-03-01

To investigate the stability mechanism of heavy-haul couplers with arc surface contact, the geometry and force analysis were conducted according to the friction circle theory. To improve the stability of the coupler, four improvements were proposed, which are increasing the secondary lateral stiffness of locomotives, adding a restoring bumpstop at the end of the coupler, increasing the arc surfaces radii and changing the clearance and stiffness of secondary lateral stopping block. A multi-body dynamics model with four heavy-haul locomotives and three detailed couplers were established to simulate the emergency braking. In addition, the coupler yaw instability was tested to investigate the effects of relevant parameters on the coupler stability. The results show that increasing the secondary lateral stiffness of locomotives, adding a bumpstop with a smaller bumpstop gap, increasing the arc surfaces radii, increasing the stiffness and decreasing the clearance of secondary lateral stopping block are conducive to improving the stability of the coupler with arc surface contact.

Reconfigurable nanoscale spin-wave directional coupler

PubMed Central

Wang, Qi; Pirro, Philipp; Verba, Roman; Slavin, Andrei; Hillebrands, Burkard; Chumak, Andrii V.

2018-01-01

Spin waves, and their quanta magnons, are prospective data carriers in future signal processing systems because Gilbert damping associated with the spin-wave propagation can be made substantially lower than the Joule heat losses in electronic devices. Although individual spin-wave signal processing devices have been successfully developed, the challenging contemporary problem is the formation of two-dimensional planar integrated spin-wave circuits. Using both micromagnetic modeling and analytical theory, we present an effective solution of this problem based on the dipolar interaction between two laterally adjacent nanoscale spin-wave waveguides. The developed device based on this principle can work as a multifunctional and dynamically reconfigurable signal directional coupler performing the functions of a waveguide crossing element, tunable power splitter, frequency separator, or multiplexer. The proposed design of a spin-wave directional coupler can be used both in digital logic circuits intended for spin-wave computing and in analog microwave signal processing devices. PMID:29376117

Variable temperature, variable-gap Otto prism coupler for use in a vacuum environment

NASA Astrophysics Data System (ADS)

Cairns, G. F.; O'Prey, S. M.; Dawson, P.

2000-11-01

The field of surface polariton physics really took off with the prism coupling techniques developed by Kretschmann and Raether, and by Otto. This article reports on the construction and operation of a rotatable, in vacuo, variable temperature, Otto coupler with a coupling gap that can be varied by remote control. The specific design attributes of the system offer additional advantages to those of standard Otto systems of (i) temperature variation (ambient to 85 K), and (ii) the use of a valuable, additional reference point, namely the gap-independent reflectance at the Brewster angle at any given, fixed temperature. The instrument is placed firmly in a historical context of developments in the field. The efficacy of the coupler is demonstrated by sample attenuated total reflectance results on films of platinum, niobium, and yttrium barium copper oxide and on aluminum/gallium arsenide (Al/GaAs) Schottky diode structures.

Reconfigurable nanoscale spin-wave directional coupler.

PubMed

Wang, Qi; Pirro, Philipp; Verba, Roman; Slavin, Andrei; Hillebrands, Burkard; Chumak, Andrii V

2018-01-01

Spin waves, and their quanta magnons, are prospective data carriers in future signal processing systems because Gilbert damping associated with the spin-wave propagation can be made substantially lower than the Joule heat losses in electronic devices. Although individual spin-wave signal processing devices have been successfully developed, the challenging contemporary problem is the formation of two-dimensional planar integrated spin-wave circuits. Using both micromagnetic modeling and analytical theory, we present an effective solution of this problem based on the dipolar interaction between two laterally adjacent nanoscale spin-wave waveguides. The developed device based on this principle can work as a multifunctional and dynamically reconfigurable signal directional coupler performing the functions of a waveguide crossing element, tunable power splitter, frequency separator, or multiplexer. The proposed design of a spin-wave directional coupler can be used both in digital logic circuits intended for spin-wave computing and in analog microwave signal processing devices.

Role of reinforcement couplers in serviceability performance of concrete members

NASA Astrophysics Data System (ADS)

Ng, P. L.; Guan, G. X.; Kwan, A. K. H.

2017-10-01

Connection of reinforcing bars by couplers is a common form of reinforcement splicing. However, the variation of stiffness at the location of couplers and the potentially excessive residual slips are suspected to cause adverse impact on the serviceability, especially for structural members subjected to repeated loading. This paper studies the role of couplers in the serviceability performance of concrete members. Relevant provisions in design codes are reviewed and compared. Laboratory tests are conducted to investigate the slip behaviour of couplers. A section analysis approach based on equivalent stiffness model is proposed to account for the effects of couplers, and formulations of crack width calculation are explored for use in structural design.

Substrate integrated waveguide (SIW) 3 dB coupler for K-Band applications

NASA Astrophysics Data System (ADS)

Khalid, Nurehansafwanah; Zuraidah Ibrahim, Siti; Wee, Fwen Hoon; Shazuani Mahmud, Farah

2017-11-01

This paper presented a designed coupler by using Rogers RO4003C with thickness (h) 0.508 mm and relative permittivity (ɛr) 3.55. The four port network coupler operates in K-band (18-27 GHz) and design by using substrate integrated waveguide (SIW) method. The reflection coefficient and isolation coefficient of propose Substrate Integrated Waveguide (SIW) coupler is below than -10 dB. Meanwhile the coupler requirements are phase shift 90° between coupled port and output. SIW are high performance broadband interconnects with excellent immunity to electromagnetic interference and suitable for use in microwave and communication electronics, as well as increase bandwidth systems. The designs of coupler are investigated using CST Microwave Studio simulation tool. This proposed couplers are varied from parameters that cover the frequency range (21 -24 GHz) and better performance of scattering (S-parameter).

30 CFR 77.805 - Cable couplers and connection boxes; minimum design requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Cable couplers and connection boxes; minimum... connection boxes; minimum design requirements. (a)(1) Couplers that are used in medium- or high-voltage power... materials other than metal. (2) Cable couplers shall be adequate for the intended current and voltage. (3...

30 CFR 77.805 - Cable couplers and connection boxes; minimum design requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Cable couplers and connection boxes; minimum... connection boxes; minimum design requirements. (a)(1) Couplers that are used in medium- or high-voltage power... materials other than metal. (2) Cable couplers shall be adequate for the intended current and voltage. (3...

30 CFR 77.805 - Cable couplers and connection boxes; minimum design requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Cable couplers and connection boxes; minimum... WORK AREAS OF UNDERGROUND COAL MINES Surface High-Voltage Distribution § 77.805 Cable couplers and connection boxes; minimum design requirements. (a)(1) Couplers that are used in medium- or high-voltage power...

30 CFR 77.805 - Cable couplers and connection boxes; minimum design requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Cable couplers and connection boxes; minimum... WORK AREAS OF UNDERGROUND COAL MINES Surface High-Voltage Distribution § 77.805 Cable couplers and connection boxes; minimum design requirements. (a)(1) Couplers that are used in medium- or high-voltage power...

30 CFR 77.805 - Cable couplers and connection boxes; minimum design requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Cable couplers and connection boxes; minimum... WORK AREAS OF UNDERGROUND COAL MINES Surface High-Voltage Distribution § 77.805 Cable couplers and connection boxes; minimum design requirements. (a)(1) Couplers that are used in medium- or high-voltage power...

New design of a triplexer using ring resonator integrated with directional coupler based on photonic crystals

NASA Astrophysics Data System (ADS)

Wu, Yaw-Dong; Shih, Tien-Tsorng; Lee, Jian-Jang

2009-11-01

In this paper, we proposed the design of directional coupler integrated with ring resonator based on two-dimensional photonic crystals (2D PCs) to develop a triplexer filter. It can be widely used as the fiber access network element for multiplexer-demultiplexer wavelength selective in fiber-to-the-home (FTTH) communication systems. The directional coupler is chosen to separate the wavelengths of 1490nm and 1310nm. The ring resonator separates the wavelength of 1550nm. The transmission efficiency is larger than 90%. Besides, the total size of propose triplexer is only 19μm×12μm. We present simulation results using the finite-difference time-domain (FDTD) method for the proposed structure.

Fabrication et caracterisation d'hybrides optiques tout-fibre 120° et 90° achromatiques

NASA Astrophysics Data System (ADS)

Khettal, Elyes

This thesis presents the fabrication and characterization of optical hybrids as all-fiber 3 x 3 and 4 x 4 couplers. A hybrid does two things; it splits power equally and acts as an interferometer. As an interferometer, it allows to accurately measure the amplitude and phase of an optical signal with respect to a reference signal. Like in a radio receiver, a local oscillator is used to interfere with the incoming signal to produce a beating signal. The complex amplitude is then rebuilt using the output signals of the hybrid. This is known as coherent detection. Since this thesis is a follow-up to a previous project, the main goal is to improve the fabrication process of the couplers in order to give it a certain level of repeatability and reproducibility. The 3 x 3 coupler will be used as a platform of development since the fabrication process is pretty much the same for both couplers. The secondary objective is to validate the theoretical concepts of a broadband hybrid in the form of an asymmetric 4 x 4 coupler. The theory explaining the functioning these couplers is presented and the experimental parameters necessary to their fabrication are derived. The fabrication method used is that of fusion-tapering that has been used for many years to produce 2 x 2 couplers and fiber tapers. The procedure consists of holding fibers together tangentially and fusing them into a monolithic structure with the help a propane flame. The structure is then tapered by linear motorized stages and the procedure is stopped when the desired optical response is achieved. The component is then securely packaged in a hollow metal tube. The critically step of the procedure is holding the fibers together in a desired pattern - a triangle for 3 x 3 couplers and a square or a diamond for 4 x 4 couplers. New methods to make this step more repeatable are highlighted. Several cross-sections of fused couplers are shown and the level of success of the new methods is discussed. The characterization methods in transmission and phase are described and the experimental results are presented. The transmission spectra of the 3 x 3 coupler that was built are presented. Its performances in phase at several wavelengths of the C band (1530-1565 nm) are measured and analyzed. The built hybrid has low loss (<0,8 dB) and shows a phase drift lower than 5° on about 40 nm. Its ability to measure phase accurately is demonstrated by demodulating a digital QPSK signal. In order to validate the theory of the broadband 4 x 4 hybrid, a new fusion-tapering approach is developed and tested. It is used to make biconical 2 x 2 couplers that allow to test the adiabatic transfer of supermodes, a core concept of broadband hybrids. This however does not yield the expected result and an alternative approach is proposed and tested. This new approach gives more encouraging results, confirming the hypothesis and forecasting a viable way to build broadband hybrids. The main goal of the project cannot be considered as achieved since the procedure to hold the fibers together does not guarantee that they stay in the desired pattern. Since this step is so crucial for the hybrids to work correctly, it casts doubt on whether it is possible to build a broadband hybrid that requires a very precise structure made of four fibers. Despite this, the results show that such a component is possible and the question is only about how to build it.

Design simulations for a small emittance 2.7-cell photo-cathode rf-gun in jector

NASA Astrophysics Data System (ADS)

Yongzhang, Huang

1997-05-01

In order to produce the electron bunch with small emittance which is the key issue in the so-called SASE studies, the design studies on a two-and-half cell photocathode rf-gun has been conducted. The rf gun injector is optimized by using the code of Par mela. As a main result, the optimum is found to be a 2.7-cell cavity. The geometry and the coupling scheme of the requested cavity is studied in more detail with the codes of Mafia and Superfish. The beam iris of each cells is enlarged in order to wide n the mode separations. For the purpose of cancelling the influence of the coupling iris upon the field symmetry, the so-called symmetrical double-side input coupler is studied. The coupler will be assembled to the second cell and the critical matchin g has been achieved in the Mafia-T3 simulation. With this cavity, the final normalized rms emittance reaches the value of 0.81πmm-mrad at a charge of 1nC in the Parmela simulation.

Twist-induced tuning in tapered fiber couplers.

PubMed

Birks, T A

1989-10-01

The power-splitting ratio of fused tapered single-mode fiber couplers can be reversibly tuned by axial twisting without affecting loss. The twist-tuning behavior of a range of different tapered couplers is described. A simple expression for twist-tuning can be derived by representing the effects of twist by a change in the refractive index profile. Good agreement between this expression and experimental results is demonstrated. Repeated tuning over tens of thousands of cycles is found not to degrade coupler performance, and a number of practical applications, including a freely tunable tapered coupler, are described.

A 100 MV cryomodule for CW operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charles Reece

2005-07-10

A cryomodule designed for high-gradient CW operation has been built at Jefferson Lab. The Renascence cryomodule is the final prototype of a design for use in the 12 GeV CEBAF upgrade. The module uses eight 7-cell 1497 MHz cavities to be individually powered by 13 kW klystrons. Specifications call for providing >109 MV CW with < 250 W of dynamic heat at 2.07 K. The module incorporates a new generation of tuners and higher power input waveguides. A mixture of the new HG and LL cavity shapes are used. A new high thermal conductivity RF feedthrough has been developed andmore » used on the 32 HOM coupler probes of Renascence. The cryomodule assembly is complete. Testing is to begin late June. Design features and initial test data will be presented.« less

Optically isolated signal coupler with linear response

DOEpatents

Kronberg, James W.

1994-01-01

An optocoupler for isolating electrical signals that translates an electrical input signal linearly to an electrical output signal. The optocoupler comprises a light emitter, a light receiver, and a light transmitting medium. The light emitter, preferably a blue, silicon carbide LED, is of the type that provides linear, electro-optical conversion of electrical signals within a narrow wavelength range. Correspondingly, the light receiver, which converts light signals to electrical signals and is preferably a cadmium sulfide photoconductor, is linearly responsive to light signals within substantially the same wavelength range as the blue LED.

Transmission Line for 258 GHz Gyrotron DNP Spectrometry

NASA Astrophysics Data System (ADS)

Bogdashov, Alexandr A.; Belousov, Vladimir I.; Chirkov, Alexey V.; Denisov, Gregory G.; Korchagin, Vyacheslav V.; Kornishin, Sergey Yu.; Tai, Evgeny M.

2011-06-01

We describe the design and test results of the transmission line for liquid-state (LS) and solid-state (SS) DNP spectrometers with the second-harmonic 258.6 GHz gyrotron at the Institute of the Biophysical Chemistry Center of Goethe University (Frankfurt). The 13-meter line includes a mode converter, HE11 waveguides, 4 mitre bends, a variable polarizer-attenuator, directional couplers, a water-flow calorimeter and a mechanical switch. A microwave power of about 15 W was obtained in the pure HE11 mode at the spectrometer inputs.

Torso sizing ring construction for hard space suit

NASA Technical Reports Server (NTRS)

Vykukal, H. C.

1986-01-01

A hard suit for use in space or diving applications having an adjustable length torso covering that will fit a large variety of wearers is described. The torso covering comprises an upper section and a lower section which interconnect so that the covering will fit wearers with short torsos. One or more sizing rings may be inserted between the upper and lower sections to accommodate larger torso sizes as required. Since access of the astronaut to the torso covering is preferably through an opening in the back of the upper section (which is closed off by the backpack), the rings slant upward-forward from the lower edge of the opening. The lower edge of the upper covering section has a coupler which slants upward-forward from the lower edge of the back opening. The lower torso section has a similarly slanted coupler which may interfit with the upper section coupler to accommodate the smallest torso size. One or more sizing rings may be inserted between the coupler sections of the upper and lower torso sections to accommodate larger torsos. Each ring has an upper coupler which may interfit with the upper section coupler and a lower coupler which may interfit with the lower section coupler.

DOE Office of Scientific and Technical Information (OSTI.GOV)

J.K. Sekutowicz, P. Kneisel

This paper reports about our efforts to develop a flangeable coaxial coupler for both HOM and fundamental coupling for 9-cell TESLA/ILC-type cavities. The cavities were designed in early 90‘s for pulsed operation with a low duty factor, less than 1 %. The proposed design of the coupler has been done in a way, that the magnetic flux B at the flange connection is minimized and only a field of <5 mT would be present at the accelerating field Eacc of ~ 36 MV/m (B =150 mT in the cavity). Even though we achieved reasonably high Q-values at low field, themore » cavity/coupler combination was limited in the cw mode to only ~ 7 MV/m, where a thermally initiated degradation occurred. We have improved the cooling conditions by initially drilling radial channels every 30 degrees, then every 15 degrees into the shorting plate. The modified prototype performed well up to 9 MV/m in cw mode. This paper reports about our experiences with the further modified coaxial coupler and about test results in cw and low duty cycle pulsed mode, similar to the TESLA/ILC operation conditions.« less

Teletype Tester

NASA Technical Reports Server (NTRS)

1979-01-01

In the United States, more than 12,000 homes of deaf people are equipped with a system that enables the deaf to communicate by telephone. It consists of a teletype machine hooked up to an "acoustic coupler." The deaf person taps out a message on the teletype keyboard and the acoustic coupler converts teletype pulses into audio signals that can be sent over phone lines. At the other end, another coupler reconverts the signals to activate the teletype's printer and provide a readable message. Though a boon to the deaf, the system presents a problem when something goes wrong. It is difficult to pinpoint the trouble because of the multiple units involved-the teletype's keyboard or its printer, the coupler's sending circuit or its receiving circuit. Finding the trouble is time-consuming and it usually involves removing the equipment from service, leaving the deaf person temporarily without communication. Seeking an answer to this difficulty, NASA's Biomedical Applications Team at Research Triangle Institute, North Carolina, circulated a problem statement to NASA field centers. Langley Research Center responded by developing a compactly-packaged portable Teletype Test Unit.

Inexpensive 3dB coupler for POF communication by injection-molding production

NASA Astrophysics Data System (ADS)

Haupt, M.; Fischer, U. H. P.

2011-01-01

POFs (polymer optical fibers) gradually replace traditional communication media such as copper and glass within short distance communication systems. Primarily, this is due to their cost-effectiveness and easy handling. POFs are used in various fields of optical communication, e.g. the automotive sector or in-house communication. So far, however, only a few key components for a POF communication network are available. Even basic components, such as splices and couplers, are fabricated manually. Therefore, these circumstances result in high costs and fluctuations in components' performance. Available couplers have high insertion losses due to their manufacturing method. This can only be compensated by higher power budgets. In order to produce couplers with higher performances new fabrication methods are indispensable. A cheap and effective way to produce couplers for POF communication systems is injection molding. The paper gives an overview of couplers available on market, compares their performances, and shows a way to produce couplers by means of injection molding.

K-Band Substrate Integrated Waveguide (SIW) Coupler

NASA Astrophysics Data System (ADS)

Khalid, N.; Ibrahim, S. Z.; Hoon, W. F.

2018-03-01

This paper presents a designed coupler by using substrate Roger RO4003. The four port network coupler operates at (18-26 GHz) and designed by using substrate integrated waveguide (SIW) method. Substrate Integrated Waveguide (SIW) are high performance broadband interconnects with excellent immunity to electromagnetic interference and suitable in microwave and millimetre-wave electronics applications, as well as wideband systems. The designs of the coupler are investigated using CST Microwave Studio simulation tool. These proposed couplers are capable of covering the frequency range and provide better performance of scattering parameter (S-parameter). This technology is successfully approached for millimetre-wave and microwave applications. Designs and results are presented and discussed in this paper. The overall simulated percentage bandwidth of the proposed coupler is covered from 18 to 26 GHz with percentage bandwidth of 36.36%.

Laser Heterodyne Radiometer for Sensitive Detection of CO2 and CH4

NASA Technical Reports Server (NTRS)

Wilson, Emily L.; Miller, J. Houston

2011-01-01

We propose to develop an inexpensive, miniaturized, passive laser heterodyne radiometer (LHR) using commercially available telecommunications laser components to measure two significant carbon cycle gases in the atmospheric column: carbon dioxide (CO2) and methane (CH4). This instrument would operate in tandem with the passive aerosol sensor currently used in AERONET (an established network of more than 450 ground aerosol monitoring instruments worldwide). Because aerosols induce a radiative effect that influences terrestrial carbon exchange, simultaneous detection of aerosols with these key carbon cycle gases offers a uniquely comprehensive measurement approach that supports the Decadal Survey. Laser heterodyne radiometry is a technique for detecting weak signals that was adapted from radio receiver technology. In a radio receiver, a weak input signal from a radio antenna is mixed with a stronger local oscillator signal. The mixed signal (beat note, or intermediate frequency) has a frequency equal to the difference between the input signal and the local oscillator. The intermediate frequency is amplified and sent to a detector that extracts the audio from the signal. In a laser heterodyne radiometer, the weak input signal is light that has undergone absorption by a trace gas. The local oscillator is a laser at a near-by frequency - in this case a low-cost distributed feedback (DFB) telecommunications laser. These two light waves are superimposed in either a beamsplitter or in a fiber coupler (as is the case in this design). The signals are mixed in the detector, and the RF beat frequency is extracted. Changes in concentration of the trace gas are realized through analyzing changes in the beat frequency amplitude. A schematic of the progression of the LHR development project is shown in the figure below. At the center (within the dashed line), light from the local oscillator is superimposed upon light that has undergone absorption by a trace gas, in a single mode fiber coupler. Superimposed light is mixed in a fast photoreceiver, and the beat signal is analyzed for changes in absorption. The left portion of the figure depicts a progression of light sources that pass through the trace gas, increasing in complexity in the downward direction. On the right side of the figure, RF signal processing progresses from a commercially available spectrum analyzer to a RF receiver, and finally to an RF filter bank to deconvolute portions of the beat frequency more heavily weighted for different altitudes.

Measurement of chalcogenide glass optical dispersion using a mid-infrared prism coupler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiao, Hong; Anheier, Norman C.; Musgraves, Jonathan D.

2011-05-01

Physical properties of chalcogenide glass, including broadband infrared transparency, high refractive index, low glass transition temperature, and nonlinear properties, make them attractive candidates for advanced mid-infrared (3 to 12 {micro}m) optical designs. Efforts focused at developing new chalcogenide glass formulations and processing methods require rapid quantitative evaluation of their optical contents to guide the materials research. However, characterization of important optical parameters such as optical dispersion remains a slow and costly process, generally with limited accuracy. The recent development of a prism coupler at the Pacific Northwest National Laboratory (PNNL) now enables rapid, high precision measurement of refractive indices atmore » discrete wavelengths from the visible to the mid-infrared. Optical dispersion data of several chalcogenide glass families were collected using this method. Variations in the optical dispersion were correlated to glass composition and compared against measurements using other methods. While this work has been focused on facilitating chalcogenide glass synthesis, mid-infrared prism coupler analysis has broader applications to other mid-infrared optical material development efforts, including oxide glasses and crystalline materials.« less

Evaluation of the Repeatability and Accuracy of the Wideband Real-Ear-to-Coupler Difference.

PubMed

Vaisberg, Jonathan M; Folkeard, Paula; Pumford, John; Narten, Philipp; Scollie, Susan

2018-06-01

The real-ear-to-coupler difference (RECD) is an ANSI standardized method for estimating ear canal sound pressure level (SPL) thresholds and assisting in the prediction of real-ear aided responses. It measures the difference in dB between the SPL produced in the ear canal and the SPL produced in an HA-1 2-cc coupler by the same sound source. Recent evidence demonstrates that extended high-frequency bandwidth, beyond the hearing aid bandwidth typically measured, is capable of providing additional clinical benefit. The industry has, in turn, moved toward developing hearing aids and verification equipment capable of producing and measuring extended high-frequency audible output. As a result, a revised RECD procedure conducted using a smaller, 0.4-cc coupler, known as the wideband-RECD (wRECD), has been introduced to facilitate extended high-frequency coupler-based measurements up to 12.5 kHz. This study aimed to (1) compare test-retest repeatability between the RECD and wRECD and (2) measure absolute agreement between the RECD and wRECD when both are referenced to a common coupler. RECDs and wRECDs were measured bilaterally in adult ears by calculating the dB difference in SPL between the ear canal and coupler responses. Real-ear probe microphone measures were completed twice per ear per participant for both foam-tip and customized earmold couplings using the Audioscan Verifit 1 and Verifit 2 fitting systems, followed by measurements in the respective couplers. Twenty-one adults (mean age = 67 yr, range = 19-78) with typical aural anatomy (as determined by measures of impedance and otoscopy) participated in this study, leading to a sample size of 42 ears. Repeatability within RECD and wRECD was assessed for each coupling configuration using a repeated-measures analysis of variance (ANOVA) with test-retest and frequency as within-participants factors. Repeatability between the RECD and wRECD was assessed within each configuration using a repeated-measures ANOVA with test-retest, frequency, and coupler type as within-participants factors. Agreement between the RECD and wRECD was assessed for each coupling configuration using a repeated-measures ANOVA with RECD value, coupler type, and frequency as within-participants factors. Post hoc comparisons with Bonferroni corrections were used when appropriate to locate the frequencies at which differences occurred. A 3-dB criterion was defined to locate differences of clinical significance. Average absolute test-retest differences were within ±3 dB within each coupler and coupling configuration, and between the RECD and wRECD. The RECD and wRECD were in absolute agreement following HA-1-referenced transforms, with most frequencies agreeing within ±1 dB, except at 0.2 kHz for the earmold, and 0.2-0.25 kHz for the foam tip, where the average RECD exceeded the average wRECD by slightly >3 dB. Test-retest repeatability of the RECD (up to 8 kHz) and wRECD (up to 12.5 kHz) is acceptable and similar to previously reported data. The RECD and wRECD are referenced to different couplers, but can be rendered comparable with a simple transform, producing values that are in accordance with the ANSI S3.46-2013 standard. American Academy of Audiology.

Refractive index engineering of high performance coupler for compact photonic integrated circuits

NASA Astrophysics Data System (ADS)

Liu, Lu; Zhou, Zhiping

2017-04-01

High performance couplers are highly desired in many applications, but the design is limited by nearly unchangeable material refractive index. To tackle this issue, refractive index engineering method is investigated, which can be realized by subwavelength grating. Subwavelength gratings are periodical structures with pitches small enough to locally synthesize the refractive index of photonic waveguides, which allows direct control of optical profile as well as easier fabrication process. This review provides an introduction to the basics of subwavelength structures and pay special attention to the design strategies of some representative examples of subwavelength grating devices, including: edge couplers, fiber-chip grating couplers, directional couplers and multimode interference couplers. Benefited from the subwavelength grating which can engineer the refractive index as well as birefringence and dispersion, these devices show better performance when compared to their conventional counterparts.

Ultrashort hybrid metal-insulator plasmonic directional coupler.

PubMed

Noghani, Mahmoud Talafi; Samiei, Mohammad Hashem Vadjed

2013-11-01

An ultrashort plasmonic directional coupler based on the hybrid metal-insulator slab waveguide is proposed and analyzed at the telecommunication wavelength of 1550 nm. It is first analyzed using the supermode theory based on mode analysis via the transfer matrix method in the interaction region. Then the 2D model of the coupler, including transition arms, is analyzed using a commercial finite-element method simulator. The hybrid slab waveguide is composed of a metallic layer of silver and two dielectric layers of silica (SiO2) and silicon (Si). The coupler is optimized to have a minimum coupling length and to transfer maximum power considering the layer thicknesses as optimization variables. The resulting coupling length in the submicrometer region along with a noticeable power transfer efficiency are advantages of the proposed coupler compared to previously reported plasmonic couplers.

Erectable/deployable concepts for large space system technology

NASA Technical Reports Server (NTRS)

Agan, W. E.

1980-01-01

Erectable/deployable space structure concepts particularly relating to the development of a science and applications space platform are presented. Design and operating features for an automatic coupler clevis joint, a side latching detent joint, and a module-to-module auto lock coupler are given. An analysis of the packaging characteristics of stacked subassembly, single fold, hybrid, and double fold concepts is given for various platform structure configurations. Payload carrier systems and assembly techniques are also discussed.

Distributed coupling high efficiency linear accelerator

DOEpatents

Tantawi, Sami G.; Neilson, Jeffrey

2016-07-19

A microwave circuit for a linear accelerator includes multiple monolithic metallic cell plates stacked upon each other so that the beam axis passes vertically through a central acceleration cavity of each plate. Each plate has a directional coupler with coupling arms. A first coupling slot couples the directional coupler to an adjacent directional coupler of an adjacent cell plate, and a second coupling slot couples the directional coupler to the central acceleration cavity. Each directional coupler also has an iris protrusion spaced from corners joining the arms, a convex rounded corner at a first corner joining the arms, and a corner protrusion at a second corner joining the arms.

Effect of twist on single-mode fiber-optic 3 × 3 couplers

NASA Astrophysics Data System (ADS)

Chen, Dandan; Ji, Minning; Peng, Lei

2018-01-01

In the fabricating process of a 3 × 3 fused tapered coupler, the three fibers are usually twisted to be close-contact. The effect of twist on 3 × 3 fused tapered couplers is investigated in this paper. It is found that though a linear 3 × 3 coupler may realize equal power splitting ratio theoretically by twisting a special angle, it is hard to be fabricated actually because the twist angle and the coupler's length must be determined in advance. While an equilateral 3 × 3 coupler can not only realize approximate equal power splitting ratio theoretically but can also be fabricated just by controlling the elongation length. The effect of twist on the equilateral 3 × 3 coupler lies in the relationship between the equal ratio error and the twist angle. The more the twist angle is, the larger the equal ratio error may be. The twist angle usually should be no larger than 90° on one coupling period length in order to keep the equal ratio error small enough. The simulation results agree well with the experimental data.

Arbitrary-ratio power splitter based on nonlinear multimode interference coupler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tajaldini, Mehdi; Young Researchers and Elite Club, Baft Branch, Islamic Azad University, Baft; Jafri, Mohd Zubir Mat

2015-04-24

We propose an ultra-compact multimode interference (MMI) power splitter based on nonlinear effects from simulations using nonlinear modal propagation analysis (NMPA) cooperation with finite difference Method (FDM) to access free choice of splitting ratio. Conventional multimode interference power splitter could only obtain a few discrete ratios. The power splitting ratio may be adjusted continuously while the input set power is varying by a tunable laser. In fact, using an ultra- compact MMI with a simple structure that is launched by a tunable nonlinear input fulfills the problem of arbitrary-ratio in integrated photonics circuits. Silicon on insulator (SOI) is used asmore » the offered material due to the high contrast refractive index and Centro symmetric properties. The high-resolution images at the end of the multimode waveguide in the simulated power splitter have a high power balance, whereas access to a free choice of splitting ratio is not possible under the linear regime in the proposed length range except changes in the dimension for any ratio. The compact dimensions and ideal performance of the device are established according to optimized parameters. The proposed regime can be extended to the design of M×N arbitrary power splitters ratio for programmable logic devices in all optical digital signal processing. The results of this study indicate that nonlinear modal propagation analysis solves the miniaturization problem for all-optical devices based on MMI couplers to achieve multiple functions in a compact planar integrated circuit and also overcomes the limitations of previously proposed methods for nonlinear MMI.« less

Integrated photon sources for quantum information science applications

NASA Astrophysics Data System (ADS)

Fanto, M. L.; Tison, C. C.; Steidle, J. A.; Lu, T.; Wang, Z.; Mogent, N. A.; Rizzo, A.; Thomas, P. M.; Preble, S. F.; Alsing, P. M.; Englund, D. R.

2017-10-01

Ring resonators are used as photon pair sources by taking advantage of the materials second or third order non- linearities through the processes of spontaneous parametric downconversion and spontaneous four wave mixing respectively. Two materials of interest for these applications are silicon for the infrared and aluminum nitride for the ultraviolet through the infrared. When fabricated into ring type sources they are capable of producing pairs of indistinguishable photons but typically suffer from an effective 50% loss. By slightly decoupling the input waveguide from the ring, the drop port coincidence ratio can be significantly increased with the trade-off being that the pump is less efficiently coupled into the ring. Ring resonators with this design have been demonstrated having coincidence ratios of 96% but requiring a factor of 10 increase in the pump power. Through the modification of the coupling design that relies on additional spectral dependence, it is possible to achieve similar coincidence ratios without the increased pumping requirement. This can be achieved by coupling the input waveguide to the ring multiple times, thus creating a Mach-Zehnder interferometer. This coupler design can be used on both sides of the ring resonator so that resonances supported by one of the couplers are suppressed by the other. This is the ideal configuration for a photon-pair source as it can only support the pump photons at the input side while only allowing the generated photons to leave through the output side. Recently, this device has been realized with preliminary results exhibiting the desired spectral dependence and with a coincidence ratio as high as 97% while allowing the pump to be nearly critically coupled to the ring. The demonstrated near unity coincidence ratio infers a near maximal heralding efficiency from the fabricated device. This device has the potential to greatly improve the scalability and performance of quantum computing and communication systems.

Flat-Passband 3 × 3 Interleaving Filter Designed With Optical Directional Couplers in Lattice Structure

NASA Astrophysics Data System (ADS)

Wang, Qi Jie; Zhang, Ying; Soh, Yeng Chai

2005-12-01

This paper presents a novel lattice optical delay-line circuit using 3 × 3 directional couplers to implement three-port optical interleaving filters. It is shown that the proposed circuit can deliver three channels of 2pi/3 phase-shifted interleaving transmission spectra if the coupling ratios of the last two directional couplers are selected appropriately. The other performance requirements of an optical interleaver can be achieved by designing the remaining part of the lattice circuit. A recursive synthesis design algorithm is developed to calculate the design parameters of the lattice circuit that will yield the desired filter response. As illustrative examples, interleavers with maximally flat-top passband transmission and with given transmission performance on passband ripples and passband bandwidth, respectively, are designed to verify the effectiveness of the proposed design scheme.

Extended interaction oversized coaxial relativistic klystron amplifier with gigawatt-level output at Ka band

NASA Astrophysics Data System (ADS)

Li, Shifeng; Duan, Zhaoyun; Huang, Hua; Liu, Zhenbang; He, Hu; Wang, Fei; Wang, Zhanliang; Gong, Yubin

2018-04-01

In this paper, an extended interaction oversized coaxial relativistic klystron amplifier (EIOC-RKA) with Gigawatt-level output at Ka band is proposed. We introduce the oversized coaxial and multi-gap resonant cavities to increase the power capacity and investigate a non-uniform extended interaction output cavity to improve the electronic efficiency of the EIOC-RKA. We develop a high order mode gap in the input and output cavities to easily design and fabricate the input and output couplers. Meanwhile, we design the EIOC-RKA by using the particle-in-cell simulation. In the simulations, we use an electron beam with a current of 6 kA and a voltage of 525 kV, which is focused by a low focusing magnetic flux intensity of 0.5 T. The simulation results demonstrate that the saturated output power is 1.17 GW, the electronic efficiency is 37.1%, and the saturated gain is 57 dB at 30 GHz. The self-oscillation is suppressed by adopting the absorbing materials. The proposed EIOC-RKA has plenty of advantages such as large power capacity, high electronic efficiency, low focusing magnetic, high gain, and simple structure.

SPECIAL ISSUE ON OPTICAL PROCESSING OF INFORMATION: Reversible logic elements as a new field of application of optical solitons

NASA Astrophysics Data System (ADS)

Maimistov, Andrei I.

1995-10-01

An analysis is made of the fundamental concepts of conservative logic. It is shown that the existing optical soliton switches can be converted into logic gates which act as conservative logic elements. A logic device of this type, based on a nonlinear fibre-optic directional coupler, is considered. Polarised solitons are used in this coupler. This use of solitons leads in a natural way to the desirability of developing conservative triple-valued logic.

A traveling-wave forward coupler design for a new accelerating mode in a silicon woodpile accelerator

DOE PAGES

Wu, Ziran; Lee, Chunghun H.; Wootton, Kent P.; ...

2016-03-01

Silicon woodpile photonic crystals provide a base structure that can be used to build a three-dimensional dielectric waveguide system for high-gradient laser driven acceleration. A new woodpile waveguide design that hosts a phase synchronous, centrally confined accelerating mode is proposed. Comparing with previously discovered silicon woodpile accelerating modes, this mode shows advantages in terms of better electron beam loading and higher achievable acceleration gradient. Several traveling-wave coupler design schemes developed for multi-cell RF cavity accelerators are adapted to the woodpile power coupler design for this new accelerating mode. Design of a forward coupled, highly efficient silicon woodpile accelerator is achieved.more » Simulation shows high efficiency of over 75% of the drive laser power coupled to this fundamental accelerating mode, with less than 15% backward wave scattering. The estimated acceleration gradient, when the coupler structure is driven at the damage threshold fluence of silicon at its operating 1.506 μm wavelength, can reach 185 MV/m. Lastly, a 17-layer woodpile waveguide structure was successfully fabricated, and the measured bandgap is in excellent agreement with simulation.« less

A traveling-wave forward coupler design for a new accelerating mode in a silicon woodpile accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Ziran; Lee, Chunghun H.; Wootton, Kent P.

Silicon woodpile photonic crystals provide a base structure that can be used to build a three-dimensional dielectric waveguide system for high-gradient laser driven acceleration. A new woodpile waveguide design that hosts a phase synchronous, centrally confined accelerating mode is proposed. Comparing with previously discovered silicon woodpile accelerating modes, this mode shows advantages in terms of better electron beam loading and higher achievable acceleration gradient. Several traveling-wave coupler design schemes developed for multi-cell RF cavity accelerators are adapted to the woodpile power coupler design for this new accelerating mode. Design of a forward coupled, highly efficient silicon woodpile accelerator is achieved.more » Simulation shows high efficiency of over 75% of the drive laser power coupled to this fundamental accelerating mode, with less than 15% backward wave scattering. The estimated acceleration gradient, when the coupler structure is driven at the damage threshold fluence of silicon at its operating 1.506 μm wavelength, can reach 185 MV/m. Lastly, a 17-layer woodpile waveguide structure was successfully fabricated, and the measured bandgap is in excellent agreement with simulation.« less

Multi-MW K-Band Harmonic Multiplier: RF Source For High-Gradient Accelerator R & D

NASA Astrophysics Data System (ADS)

Solyak, N. A.; Yakovlev, V. P.; Kazakov, S. Yu.; Hirshfield, J. L.

2009-01-01

A preliminary design is presented for a two-cavity harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power at selected frequencies in K-band (18-26.5 GHz) using as an RF driver an XK-5 S-band klystron (2.856 GHz). The device is to be built with a TE111 rotating mode input cavity and interchangeable output cavities running in the TEn11 rotating mode, with n = 7,8,9 at 19.992, 22.848, and 25.704 GHz. An example for a 7th harmonic multiplier is described, using a 250 kV, 20 A injected laminar electron beam; with 10 MW of S-band drive power, 4.7 MW of 20-GHz output power is predicted. Details are described of the magnetic circuit, cavities, and output coupler.

Fiber-chip edge coupler with large mode size for silicon photonic wire waveguides.

PubMed

Papes, Martin; Cheben, Pavel; Benedikovic, Daniel; Schmid, Jens H; Pond, James; Halir, Robert; Ortega-Moñux, Alejandro; Wangüemert-Pérez, Gonzalo; Ye, Winnie N; Xu, Dan-Xia; Janz, Siegfried; Dado, Milan; Vašinek, Vladimír

2016-03-07

Fiber-chip edge couplers are extensively used in integrated optics for coupling of light between planar waveguide circuits and optical fibers. In this work, we report on a new fiber-chip edge coupler concept with large mode size for silicon photonic wire waveguides. The coupler allows direct coupling with conventional cleaved optical fibers with large mode size while circumventing the need for lensed fibers. The coupler is designed for 220 nm silicon-on-insulator (SOI) platform. It exhibits an overall coupling efficiency exceeding 90%, as independently confirmed by 3D Finite-Difference Time-Domain (FDTD) and fully vectorial 3D Eigenmode Expansion (EME) calculations. We present two specific coupler designs, namely for a high numerical aperture single mode optical fiber with 6 µm mode field diameter (MFD) and a standard SMF-28 fiber with 10.4 µm MFD. An important advantage of our coupler concept is the ability to expand the mode at the chip edge without leading to high substrate leakage losses through buried oxide (BOX), which in our design is set to 3 µm. This remarkable feature is achieved by implementing in the SiO 2 upper cladding thin high-index Si 3 N 4 layers. The Si 3 N 4 layers increase the effective refractive index of the upper cladding near the facet. The index is controlled along the taper by subwavelength refractive index engineering to facilitate adiabatic mode transformation to the silicon wire waveguide while the Si-wire waveguide is inversely tapered along the coupler. The mode overlap optimization at the chip facet is carried out with a full vectorial mode solver. The mode transformation along the coupler is studied using 3D-FDTD simulations and with fully-vectorial 3D-EME calculations. The couplers are optimized for operating with transverse electric (TE) polarization and the operating wavelength is centered at 1.55 µm.

Grating-assisted surface acoustic wave directional couplers

NASA Astrophysics Data System (ADS)

Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.

1991-07-01

Physical properties of novel grating-assisted Y directional couplers are examined using the coupled-mode theory. A general formalism for the analysis of the lateral perturbed directional coupler properties is presented. Explicit expressions for waveguide key parameters such as coupling length, grating period, and other structural characterizations, are obtained. The influence of other physical properties such as time and frequency response or cutoff conditions are also analyzed. A plane grating-assisted directional coupler is presented and examined as a basic component in the integrated acoustic technology.

Design and fabrication of multimode interference couplers based on digital micro-mirror system

NASA Astrophysics Data System (ADS)

Wu, Sumei; He, Xingdao; Shen, Chenbo

2008-03-01

Multimode interference (MMI) couplers, based on the self-imaging effect (SIE), are accepted popularly in integrated optics. According to the importance of MMI devices, in this paper, we present a novel method to design and fabricate MMI couplers. A technology of maskless lithography to make MMI couplers based on a smart digital micro-mirror device (DMD) system is proposed. A 1×4 MMI device is designed as an example, which shows the present method is efficient and cost-effective.

An Interdigitated Coupler with Defect Ground Structure

DTIC Science & Technology

2015-07-01

branch-line coupler. In [8], DGS is used to microstrip forward-wave coupler for size–reduction. In fact, DGS have been widely used from the concept put...substantially. REFERENCE [1] Bialkowski M E, Seman N, Leong M S. Design of a compact ultra wideband 3 dB microstrip -slot coupler with high return losses and...Pozar D M. Microwave engineering. John Wiley & Sons, 2009. [4] You S J, Liao W. A multi-layer coupled-line power divider. Antennas , Propagation and EM

Extremely small polarization beam splitter based on a multimode interference coupler with a silicon hybrid plasmonic waveguide.

PubMed

Guan, Xiaowei; Wu, Hao; Shi, Yaocheng; Dai, Daoxin

2014-01-15

A novel polarization beam splitter (PBS) with an extremely small footprint is proposed based on a multimode interference (MMI) coupler with a silicon hybrid plasmonic waveguide. The MMI section, covered with a metal strip partially, is designed to achieve mirror imaging for TE polarization. On the other hand, for TM polarization, there is almost no MMI effect since the higher-order TM modes are hardly excited due to the hybrid plasmonic effect. With this design, the whole PBS including the 1.1 μm long MMI section as well as the output section has a footprint as small as ∼1.8 μm×2.5 μm. Besides, the fabrication process is simple since the waveguide dimension is relatively large (e.g., the input/output waveguides widths w ≥300 nm and the MMI width w(MMI)=800 nm). Numerical simulations show that the designed PBS has a broad band of ∼80 nm for an ER >10 dB as well as a large fabrication tolerance to allow a silicon core width variation of -30 nm<Δw<50 nm and a metal strip width variation of -200 nm<Δw(m)<0.

Photonic generation of ultra-wide-band doublet pulse through monolithic integration of tapered directional coupler and quantum well waveguide.

PubMed

Kuo, Yu-Zheng; Wu, Jui-Pin; Wu, Tsu-Hsiu; Chiu, Yi-Jen

2012-10-22

We proposed and demonstrated a novel scheme of photonic ultra-wide-band (UWB) doublet pulse based on monolithic integration of tapered optical-direction coupler (TODC) and multiple-quantum-well (MQW) waveguide. TODC is formed by a top tapered MQW waveguide vertically integrating with an underneath passive waveguide. Through simultaneous field-driven optical index- and absorption- change in MQW, the partial optical coupling in TODC can be used to get a valley-shaped of optical transmission against voltage. Therefore, doublet-enveloped optical pulse can be realized by high-speed and high-efficient conversion of input electrical pulse. By just adjusting bias through MQW, 1530 nm photonic UWB doublet optical pulse with 75-ps pulse width, below -41.3 dBm power, 125% fractional bandwidth, and 7.5 GHz of -10 dB bandwidth has been demonstrated, fitted into FCC requirement (3.1 GHz~10.6 GHz). Doublet-pulse data transmission generated in optical fiber is also performed for further characterization, exhibiting a successful 1.25 Gb/s error-free transmission. It suggests such optoelectronic integration template can be applied for photonic UWB generation in fiber-based communications.

Generation of continuous-wave single-frequency 1.5 W 378 nm radiation by frequency doubling of a Ti:sapphire laser.

PubMed

Cha, Yong-Ho; Ko, Kwang-Hoon; Lim, Gwon; Han, Jae-Min; Park, Hyun-Min; Kim, Taek-Soo; Jeong, Do-Young

2010-03-20

We have generated continuous-wave single-frequency 1.5 W 378 nm radiation by frequency doubling a high-power Ti:sapphire laser in an external enhancement cavity. An LBO crystal that is Brewster-cut and antireflection coated on both ends is used for a long-term stable frequency doubling. By optimizing the input coupler's reflectivity, we could generate 1.5 W 378 nm radiation from a 5 W 756 nm Ti:sapphire laser. According to our knowledge, this is the highest CW frequency-doubled power of a Ti:sapphire laser.

Probe-tube microphone measures in hearing-impaired children and adults.

PubMed

Barlow, N L; Auslander, M C; Rines, D; Stelmachowicz, P G

1988-10-01

This study was designed to investigate the reliability of real-ear measurements of sound pressure level (SPL) and to compare these values with two coupler measures of SPL. A commercially available probe tube microphone system was used to measure real ear SPL in both children and adults. Test-retest reliability decreased as a function of frequency for both groups and, in general, was slightly poorer for the children. For both groups, coupler to real ear differences were larger for the 2 cm3 coupler than for the reduced volume coupler; however, no significant differences were observed between groups. In addition, a measure of ear canal volume was not found to be a good predictor of coupler to real ear discrepancies.

Heat-driven thermoacoustic cryocooler operating at liquid hydrogen temperature with a unique coupler

NASA Astrophysics Data System (ADS)

Hu, J. Y.; Luo, E. C.; Li, S. F.; Yu, B.; Dai, W.

2008-05-01

A heat-driven thermoacoustic cryocooler is constructed. A unique coupler composed of a tube, reservoir, and elastic diaphragm is introduced to couple a traveling-wave thermoacoustic engine (TE) and two-stage pulse tube refrigerator (PTR). The amplitude of the pressure wave generated in the engine is first amplified in the coupler and the wave then passes into the refrigerator to pump heat. The TE uses nitrogen as its working gas and the PTR still uses helium as its working gas. With this coupler, the efficiency of the system is doubled. The engine and coupler match at a much lower operating frequency, which is of great benefit for the PTR to obtain a lower cooling temperature. The coupling place between the coupler and engine is also optimized. The onset problem is effectively solved. With these improvements, the heat-driven thermoacoustic cryocooler reaches a lowest temperature of 18.1K, which is the demonstration of heat-driven thermoacoustic refrigeration technology used for cooling at liquid hydrogen temperatures.

RF Conditioning and Testing of Fundamental Power Couplers for SNS Superconducting Cavity Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. Stirbet; G.K. Davis; M. A. Drury

The Spallation Neutron Source (SNS) makes use of 33 medium beta (0.61) and 48 high beta (0.81) superconducting cavities. Each cavity is equipped with a fundamental power coupler, which should withstand the full klystron power of 550 kW in full reflection for the duration of an RF pulse of 1.3 msec at 60 Hz repetition rate. Before assembly to a superconducting cavity, the vacuum components of the coupler are submitted to acceptance procedures consisting of preliminary quality assessments, cleaning and clean room assembly, vacuum leak checks and baking under vacuum, followed by conditioning and RF high power testing. Similar acceptancemore » procedures (except clean room assembly and baking) were applied for the airside components of the coupler. All 81 fundamental power couplers for SNS superconducting cavity production have been RF power tested at JLAB Newport News and, beginning in April 2004 at SNS Oak Ridge. This paper gives details of coupler processing and RF high power-assessed performances.« less

Apodized grating coupler using fully-etched nanostructures

NASA Astrophysics Data System (ADS)

Wu, Hua; Li, Chong; Li, Zhi-Yong; Guo, Xia

2016-08-01

A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency. Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer. Project supported by the National Natural Science Foundation of China (Grant Nos. 61222501, 61335004, and 61505003), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111103110019), the Postdoctoral Science Foundation of Beijing Funded Project, China (Grant No. Q6002012201502), and the Science and Technology Research Project of Jiangxi Provincial Education Department, China (Grant No. GJJ150998).

Inverse design of near unity efficiency perfectly vertical grating couplers.

PubMed

Michaels, Andrew; Yablonovitch, Eli

2018-02-19

Efficient coupling between integrated optical waveguides and optical fibers is essential to the success of silicon photonics. While many solutions exist, perfectly vertical grating couplers that scatter light out of a waveguide in the direction normal to the waveguide's top surface are an ideal candidate due to their potential to reduce packaging complexity. Designing such couplers with high efficiencies, however, has proven difficult. In this paper, we use inverse electromagnetic design techniques to optimize a high efficiency two-layer perfectly vertical silicon grating coupler. Our base design achieves a chip-to-fiber coupling efficiency of 99.2% (-0.035 dB) at 1550 nm. Using this base design as a starting point, we run subsequent constrained optimizations to realize vertical couplers with coupling efficiencies over 96% and back reflections of less than -40 dB which can be fabricated using 65 nm-resolution lithography. These results demonstrate a new path forward for designing fabrication-tolerant ultra high efficiency grating couplers.

Seismic Performance of Columns with Grouted Couplers in Idaho Accelerated Bridge Construction Applications

DOT National Transportation Integrated Search

2016-10-16

n Accelerated Bridge Construction (ABC) methods, one way to connect prefabricated columns is by using grouted steel bar couplers. As of October 2016, in the U.S., only Utah DOT allows the use of grouted couplers in plastic hinge locations in seismic ...

49 CFR 238.429 - Safety appliances.

Code of Federal Regulations, 2010 CFR

2010-10-01

...-permanently coupled trainset shall each be equipped with an automatic coupler that couples on impact and... that does not require a person to go between the equipment units. (2) The automatic coupler and... ends of each unit shall be equipped with an automatic coupler that couples on impact and uncouples by...

49 CFR 238.429 - Safety appliances.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-permanently coupled trainset shall each be equipped with an automatic coupler that couples on impact and... that does not require a person to go between the equipment units. (2) The automatic coupler and... ends of each unit shall be equipped with an automatic coupler that couples on impact and uncouples by...

49 CFR 231.16 - Steam locomotives used in switching service.

Code of Federal Regulations, 2013 CFR

2013-10-01

... clearance. No part of locomotive or tender except draft rigging, coupler and attachments, safety chains, buffer block, footboard, brake pipe, signal pipe, steam-heat pipe or arms of uncoupling lever shall... with horn of coupler against buffer block or end sill. (h) Couplers. Locomotives shall be equipped with...

49 CFR 231.16 - Steam locomotives used in switching service.

Code of Federal Regulations, 2011 CFR

2011-10-01

... clearance. No part of locomotive or tender except draft rigging, coupler and attachments, safety chains, buffer block, footboard, brake pipe, signal pipe, steam-heat pipe or arms of uncoupling lever shall... with horn of coupler against buffer block or end sill. (h) Couplers. Locomotives shall be equipped with...

49 CFR 231.16 - Steam locomotives used in switching service.

Code of Federal Regulations, 2014 CFR

2014-10-01

... clearance. No part of locomotive or tender except draft rigging, coupler and attachments, safety chains, buffer block, footboard, brake pipe, signal pipe, steam-heat pipe or arms of uncoupling lever shall... with horn of coupler against buffer block or end sill. (h) Couplers. Locomotives shall be equipped with...

49 CFR 231.16 - Steam locomotives used in switching service.

Code of Federal Regulations, 2012 CFR

2012-10-01

... clearance. No part of locomotive or tender except draft rigging, coupler and attachments, safety chains, buffer block, footboard, brake pipe, signal pipe, steam-heat pipe or arms of uncoupling lever shall... with horn of coupler against buffer block or end sill. (h) Couplers. Locomotives shall be equipped with...

49 CFR 231.16 - Steam locomotives used in switching service.

Code of Federal Regulations, 2010 CFR

2010-10-01

... clearance. No part of locomotive or tender except draft rigging, coupler and attachments, safety chains, buffer block, footboard, brake pipe, signal pipe, steam-heat pipe or arms of uncoupling lever shall... with horn of coupler against buffer block or end sill. (h) Couplers. Locomotives shall be equipped with...

Laser-To-Fibre Couplers In Optical Recording Applications

NASA Astrophysics Data System (ADS)

Ophey, W. G.; Benschop, J. P. H.

1988-02-01

In optical recording, the use of single-mode fibres can considerably increase the coupling efficiency of the laser light into the light path. Important here is the performance of the laser-to-fibre coupler used. A mathematical treatment of different kinds of laser-to-fibre couplers is presented using scalar diffraction theory in order to obtain the field incident on the front end of the fibre. In this case the coupling efficiency of a laser-to-fibre coupler, using an aberrated light source (astigmatism) with an asymmetric far-field pattern, can easily be calculated.

The modeling of MMI structures for signal processing applications

NASA Astrophysics Data System (ADS)

Le, Thanh Trung; Cahill, Laurence W.

2008-02-01

Microring resonators are promising candidates for photonic signal processing applications. However, almost all resonators that have been reported so far use directional couplers or 2×2 multimode interference (MMI) couplers as the coupling element between the ring and the bus waveguides. In this paper, instead of using 2×2 couplers, novel structures for microring resonators based on 3×3 MMI couplers are proposed. The characteristics of the device are derived using the modal propagation method. The device parameters are optimized by using numerical methods. Optical switches and filters using Silicon on Insulator (SOI) then have been designed and analyzed. This device can become a new basic component for further applications in optical signal processing. The paper concludes with some further examples of photonic signal processing circuits based on MMI couplers.

Waveguide silicon nitride grating coupler

NASA Astrophysics Data System (ADS)

Litvik, Jan; Dolnak, Ivan; Dado, Milan

2016-12-01

Grating couplers are one of the most used elements for coupling of light between optical fibers and photonic integrated components. Silicon-on-insulator platform provides strong confinement of light and allows high integration. In this work, using simulations we have designed a broadband silicon nitride surface grating coupler. The Fourier-eigenmode expansion and finite difference time domain methods are utilized in design optimization of grating coupler structure. The fully, single etch step grating coupler is based on a standard silicon-on-insulator wafer with 0.55 μm waveguide Si3N4 layer. The optimized structure at 1550 nm wavelength yields a peak coupling efficiency -2.6635 dB (54.16%) with a 1-dB bandwidth up to 80 nm. It is promising way for low-cost fabrication using complementary metal-oxide- semiconductor fabrication process.

Inverse design of near unity efficiency perfectly vertical grating couplers

NASA Astrophysics Data System (ADS)

Michaels, Andrew; Yablonovitch, Eli

2018-02-01

Efficient coupling between integrated optical waveguides and optical fibers is essential to the success of integrated photonics. While many solutions exist, perfectly vertical grating couplers which scatter light out of a waveguide in the direction normal to the waveguide's top surface are an ideal candidate due to their potential to reduce packaging complexity. Designing such couplers with high efficiency, however, has proven difficult. In this paper, we use electromagnetic inverse design techniques to optimize a high efficiency two-layer perfectly vertical silicon grating coupler. Our base design achieves a chip-to-fiber coupling efficiency of over 99% (-0.04 dB) at 1550 nm. Using this base design, we apply subsequent constrained optimizations to achieve vertical couplers with over 96% efficiency which are fabricable using a 65 nm process.

Double-clad photonic crystal fiber coupler for compact nonlinear optical microscopy imaging.

PubMed

Fu, Ling; Gu, Min

2006-05-15

A 1 x 2 double-clad photonic crystal fiber coupler is fabricated by the fused tapered method, showing a low excess loss of 1.1 dB and a splitting ratio of 97/3 over the entire visible and near-infrared wavelength range. In addition to the property of splitting the laser power, the double-clad feature of the coupler facilitates the separation of a near-infrared single-mode beam from a visible multimode beam, which is ideal for nonlinear optical microscopy imaging. In conjunction with a gradient-index lens, this coupler is used to construct a miniaturized microscope based on two-photon fluorescence and second-harmonic generation. Three-dimensional nonlinear optical images demonstrate potential applications of the coupler to compact all-fiber and nonlinear optical microscopy and endoscopy.

Design of compact surface optical coupler based on vertically curved silicon waveguide for high-numerical-aperture single-mode optical fiber

NASA Astrophysics Data System (ADS)

Atsumi, Yuki; Yoshida, Tomoya; Omoda, Emiko; Sakakibara, Youichi

2017-09-01

A surface optical coupler based on a vertically curved Si waveguide was designed for coupling with high-numerical aperture single-mode optical fibers with a mode-field diameter of 5 µm. This coupler has a quite small device size, with a height of approximately 12 µm, achieved by introducing an effective spot-size converter configured with the combination of an extremely short Si exponential-inverse taper and a dome-structured SiO2 lens formed on the coupler top. The designed coupler shows high-efficiency optical coupling, with a loss of 0.8 dB for TE polarized light, as well as broad-band coupling with a 0.5-dB-loss band of 420 nm.

Analysis of a single ring resonator with 2×2 90-degree multimode waveguide turning couplers

NASA Astrophysics Data System (ADS)

Chiu, C. L.; Liao, Yen-Hsun

2016-02-01

A novel design of a single ring resonator with two low-loss 2×2 90-degree multimode waveguide turning mirror couplers based on a InP structure. The coupling factor of the 2×2 90-degree multimode waveguide turning mirror coupler is inversed for K=0.85 to K=0.15 when one folding is achieved. The 2×2 90-degree turning mirror coupler for K=0.15 is (3/4)Lπ in length. Its length is reduced 3 times than the conventional straight 2×2 multimode waveguide interference coupler (9/4)Lπ in length for K=0.15. The cavity length of the curve waveguide (90-degree arc length) in this ring resonator with two 2×2 90-degree multimode waveguide turning couplers is decreased 1/2 times than with two 2×2 MMI couplers (180-degree arc length). The free spectral range (FSR) is increased 2 times. The output spectral response gets a FSR of 82 GHz for the device and a contrast of 4 dB and FWHM of 0.24 nm for the drop port. The results of numerical analysis calculated by the transfer functions in a single ring resonator are agreement with the experimental results.

Analysis of the rectangular resonator with butterfly MMI coupler using SOI

NASA Astrophysics Data System (ADS)

Kim, Sun-Ho; Park, Jun-Hee; Kim, Eudum; Jeon, Su-Jin; Kim, Ji-Hoon; Choi, Young-Wan

2018-02-01

We propose a rectangular resonator sensor structure with butterfly MMI coupler using SOI. It consists of the rectangular resonator, total internal reflection (TIR) mirror, and the butterfly MMI coupler. The rectangular resonator is expected to be used as bio and chemical sensors because of the advantages of using MMI coupler and the absence of bending loss unlike ring resonators. The butterfly MMI coupler can miniaturize the device compared to conventional MMI by using a linear butterfly shape instead of a square in the MMI part. The width, height, and slab height of the rib type waveguide are designed to be 1.5 μm, 1.5 μm, and 0.9 μm, respectively. This structure is designed as a single mode. When designing a TIR mirror, we considered the Goos-Hänchen shift and critical angle. We designed 3:1 MMI coupler because rectangular resonator has no bending loss. The width of MMI is designed to be 4.5 μm and we optimize the length of the butterfly MMI coupler using finite-difference time-domain (FDTD) method for higher Q-factor. It has the equal performance with conventional MMI even though the length is reduced by 1/3. As a result of the simulation, Qfactor of rectangular resonator can be obtained as 7381.

Technical Note: The Modular Earth Submodel System (MESSy) - a new approach towards Earth System Modeling

NASA Astrophysics Data System (ADS)

Jöckel, P.; Sander, R.; Kerkweg, A.; Tost, H.; Lelieveld, J.

2005-02-01

The development of a comprehensive Earth System Model (ESM) to study the interactions between chemical, physical, and biological processes, requires coupling of the different domains (land, ocean, atmosphere, ...). One strategy is to link existing domain-specific models with a universal coupler, i.e. an independent standalone program organizing the communication between other programs. In many cases, however, a much simpler approach is more feasible. We have developed the Modular Earth Submodel System (MESSy). It comprises (1) a modular interface structure to connect to a , (2) an extendable set of such for miscellaneous processes, and (3) a coding standard. MESSy is therefore not a coupler in the classical sense, but exchanges data between a and several within one comprehensive executable. The internal complexity of the is controllable in a transparent and user friendly way. This provides remarkable new possibilities to study feedback mechanisms (by two-way coupling). Note that the MESSy and the coupler approach can be combined. For instance, an atmospheric model implemented according to the MESSy standard could easily be coupled to an ocean model by means of an external coupler. The vision is to ultimately form a comprehensive ESM which includes a large set of submodels, and a base model which contains only a central clock and runtime control. This can be reached stepwise, since each process can be included independently. Starting from an existing model, process submodels can be reimplemented according to the MESSy standard. This procedure guarantees the availability of a state-of-the-art model for scientific applications at any time of the development. In principle, MESSy can be implemented into any kind of model, either global or regional. So far, the MESSy concept has been applied to the general circulation model ECHAM5 and a number of process boxmodels.

Ultra-compact, flat-top demultiplexer using anti-reflection contra-directional couplers for CWDM networks on silicon.

PubMed

Shi, Wei; Yun, Han; Lin, Charlie; Greenberg, Mark; Wang, Xu; Wang, Yun; Fard, Sahba Talebi; Flueckiger, Jonas; Jaeger, Nicolas A F; Chrostowski, Lukas

2013-03-25

Wavelength-division-multiplexing (WDM) networks with wide channel grids and bandwidths are promising for low-cost, low-power optical interconnects. Wide-bandwidth, single-band (i.e., no free-spectral range) add-drop filters have been developed on silicon using anti-reflection contra-directional couplers with out-of-phase Bragg gratings. Using such filter components, we demonstrate a 4-channel, coarse-WDM demultiplexer with flat passbands of up to 13 nm and an ultra-compact size of 1.2 × 10(-3) mm(2).

Straightforward and accurate technique for post-coupler stabilization in drift tube linac structures

NASA Astrophysics Data System (ADS)

Khalvati, Mohammad Reza; Ramberger, Suitbert

2016-04-01

The axial electric field of Alvarez drift tube linacs (DTLs) is known to be susceptible to variations due to static and dynamic effects like manufacturing tolerances and beam loading. Post-couplers are used to stabilize the accelerating fields of DTLs against tuning errors. Tilt sensitivity and its slope have been introduced as measures for the stability right from the invention of post-couplers but since then the actual stabilization has mostly been done by tedious iteration. In the present article, the local tilt-sensitivity slope TSn' is established as the principal measure for stabilization instead of tilt sensitivity or some visual slope, and its significance is developed on the basis of an equivalent-circuit diagram of the DTL. Experimental and 3D simulation results are used to analyze its behavior and to define a technique for stabilization that allows finding the best post-coupler settings with just four tilt-sensitivity measurements. CERN's Linac4 DTL Tank 2 and Tank 3 have been stabilized successfully using this technique. The final tilt-sensitivity error has been reduced from ±100 %/MHz down to ±3 %/MHz for Tank 2 and down to ±1 %/MHz for Tank 3. Finally, an accurate procedure for tuning the structure using slug tuners is discussed.

Optimization of fiber grating couplers on SOI using advanced search algorithms.

PubMed

Wohlfeil, Benjamin; Zimmermann, Lars; Petermann, Klaus

2014-06-01

A one-dimensional fiber grating coupler is derived from a waveguide with random etches using implementations of particle swarm and genetic algorithms. The resulting gratings yield a theoretical coupling efficiency of up to 1.1 dB and prompt clear design rules for the layout of highly efficient fiber grating couplers.

49 CFR 215.123 - Defective couplers.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., DEPARTMENT OF TRANSPORTATION RAILROAD FREIGHT CAR SAFETY STANDARDS Freight Car Components Draft System § 215.123 Defective couplers. A railroad may not place or continue in service a car, if— (a) The car is... automatically with the adjacent car; (b) The car has a coupler that has a crack in the highly stressed junction...

49 CFR 215.123 - Defective couplers.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., DEPARTMENT OF TRANSPORTATION RAILROAD FREIGHT CAR SAFETY STANDARDS Freight Car Components Draft System § 215.123 Defective couplers. A railroad may not place or continue in service a car, if— (a) The car is... automatically with the adjacent car; (b) The car has a coupler that has a crack in the highly stressed junction...

49 CFR 215.123 - Defective couplers.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., DEPARTMENT OF TRANSPORTATION RAILROAD FREIGHT CAR SAFETY STANDARDS Freight Car Components Draft System § 215.123 Defective couplers. A railroad may not place or continue in service a car, if— (a) The car is... automatically with the adjacent car; (b) The car has a coupler that has a crack in the highly stressed junction...

Experimental study of switching in a rho-i(MQW)-eta vertical coupler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cavailles, J.A.; Erman, M.; Woodbridge, K.

1989-11-01

Electrically controlled switching in a vertically arranged directional coupler with GaAs/GaAIAs multiple quantum well waveguides is demonstrated. Coupling lengths and extinction parameters are determined by using a sample processed in such a way that injection conditions are well defined and that the coupler length can be varied continuously.

Optimization of nonbinary slanted surface-relief gratings as high-efficiency broadband couplers for light guides.

PubMed

Bai, Benfeng; Laukkanen, Janne; Kuittinen, Markku; Siitonen, Samuli

2010-10-01

We propose and investigate the use of slanted surface-relief gratings with nonbinary profiles as high-efficiency broadband couplers for light guides. First, a Chandezon-method-based rigorous numerical formulation is presented for modeling the slanted gratings with overhanging profiles. Then, two typical types of slanted grating couplers--a sinusoidal one and a trapezoidal one--are studied and optimized numerically, both exhibiting a high coupling efficiency of over 50% over the full band of white LED under the normal illumination of unpolarized light. Reasonable structural parameters with nice tolerance have been obtained for the optimized designs. It is found that the performance of the couplers depends little on the grating profile shape, but primarily on the grating period and the slant angle of the ridge. The underlying mechanism is analyzed by the equivalence rules of gratings, which provide useful guidelines for the design and fabrication of the couplers. Preliminary investigation has been performed on the fabrication and replication of the slanted overhanging grating couplers, which shows the feasibility of fabrication with mature microfabrication techniques and the perspective for mass production.

Cross-guide Moreno directional coupler in empty substrate integrated waveguide

NASA Astrophysics Data System (ADS)

Miralles, E.; Belenguer, A.; Esteban, H.; Boria, V.

2017-05-01

Substrate integrated waveguides (SIWs) combine the advantages of rectangular waveguides (low losses) and planar circuits (low cost and low profile). Empty substrate integrated waveguide (ESIW) has been proposed as a novel configuration in SIWs recently. This technology significantly reduces the losses of conventional SIW by removing its inner dielectric. The cross-guide directional coupler is a well-known low-profile design for having a broadband waveguide coupler. In this paper a cross-guide coupler with ESIW technique is proposed. In such a manner, the device can be integrated with microwave circuits and other printed circuit board components. It is the first time that a cross-guide coupler is implemented in ESIW technology. The designed, fabricated, and measured device presents good results as a matter of insertion loss of 1 dB (including transitions), reflection under 20 dB, coupling between 19.5 and 21.5 dB, and directivity higher than 15 dB over targeted frequency range from 12.4 GHz to 18 GHz. The coupler implemented in ESIW improves the directivity when compared to similar solutions in other empty substrate integrated waveguide solutions.

Magnetic field sensor based on cascaded microfiber coupler with magnetic fluid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Lianmin; Su, Delong; Wang, Zhaofang

A kind of magnetic field sensor based on cascaded microfiber coupler with magnetic fluid is proposed and experimentally demonstrated. The magnetic fluid is utilized as the cladding of the fused regions of the cascaded microfiber coupler. As the interference valley wavelength of the sensing structure is sensitive to the ambient variation, considering the magnetic-field-dependent refractive index of magnetic fluid, the proposed structure is employed for magnetic field sensing. The effective coupling length for each coupling region of the as-fabricated cascaded microfiber coupler is 6031 μm. The achieved sensitivity is 125 pm/Oe, which is about three times larger than that of the previouslymore » similar structure based on the single microfiber coupler. Experimental results indicate that the sensing sensitivity can be easily improved by increasing the effective coupling length or cascading more microfiber couplers. The proposed magnetic field sensor is attractive due to its low cost, immunity to electromagnetic interference, as well as high sensitivity, which also has the potentials in other tunable all-fiber photonic devices, such as filter.« less

Fiber pigtailed thin wall capillary coupler for excitation of microsphere WGM resonator.

PubMed

Wang, Hanzheng; Lan, Xinwei; Huang, Jie; Yuan, Lei; Kim, Cheol-Woon; Xiao, Hai

2013-07-01

In this paper, we demonstrate a fiber pigtailed thin wall capillary coupler for excitation of Whispering Gallery Modes (WGMs) of microsphere resonators. The coupler is made by fusion-splicing an optical fiber with a capillary tube and consequently etching the capillary wall to a thickness of a few microns. Light is coupled through the peripheral contact between inserted microsphere and the etched capillary wall. The coupling efficiency as a function of the wall thickness was studied experimentally. WGM resonance with a Q-factor of 1.14 × 10(4) was observed using a borosilicate glass microsphere with a diameter of 71 μm. The coupler operates in the reflection mode and provides a robust mechanical support to the microsphere resonator. It is expected that the new coupler may find broad applications in sensors, optical filters and lasers.

Theoretical and experimental investigations of efficient light coupling with spatially varied all dielectric striped waveguides

NASA Astrophysics Data System (ADS)

Yilmaz, Y. A.; Tandogan, S. E.; Hayran, Z.; Giden, I. H.; Turduev, M.; Kurt, H.

2017-07-01

Integrated photonic systems require efficient, compact, and broadband solutions for strong light coupling into and out of optical waveguides. The present work investigates an efficient optical power transferring the problem between optical waveguides having different widths of in/out terminals. We propose a considerably practical and feasible concept to implement and design an optical coupler by introducing gradually index modulation to the coupler section. The index profile of the coupler section is modulated with a Gaussian function by the help of striped waveguides. The effective medium theory is used to replace the original spatially varying index profile with dielectric stripes of a finite length/width having a constant effective refractive index. 2D and 3D finite-difference time-domain analyzes are utilized to investigate the sampling effect of the designed optical coupler and to determine the parameters that play a crucial role in enhancing the optical power transfer performance. Comparing the coupling performance of conventional benchmark adiabatic and butt couplers with the designed striped waveguide coupler, the corresponding coupling efficiency increases from approximately 30% to 95% over a wide frequency interval. In addition, to realize the realistic optical coupler appropriate to integrated photonic applications, the proposed structure is numerically designed on a silicon-on-insulator wafer. The implemented SOI platform based optical coupler operates in the telecom wavelength regime (λ = 1.55 μm), and the dimensions of the striped coupler are kept as 9.77 μm (along the transverse to propagation direction) and 7.69 μm (along the propagation direction) where the unit distance is fixed to be 465 nm. Finally, to demonstrate the operating design principle, the microwave experiments are conducted and the spot size conversion ratio as high as 7.1:1 is measured, whereas a coupling efficiency over 60% in the frequency range of 5.0-16.0 GHz has been also demonstrated.

Multimode Directional Coupler

NASA Technical Reports Server (NTRS)

Simons, Rainee N. (Inventor); Wintucky, Edwin G. (Inventor)

2016-01-01

A multimode directional coupler is provided. In some embodiments, the multimode directional coupler is configured to receive a primary signal and a secondary signal at a first port of a primary waveguide. The primary signal is configured to propagate through the primary waveguide and be outputted at a second port of the primary waveguide. The multimode directional coupler also includes a secondary waveguide configured to couple the secondary signal from the primary waveguide with no coupling of the primary signal into the secondary waveguide. The secondary signal is configured to propagate through the secondary waveguide and be outputted from a port of the secondary waveguide.

Inductive coupler for downhole components and method for making same

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Sneddon, Cameron; Fox, Joe; Briscoe, Michael A.

2006-10-03

An inductive coupler for downhole components. The inductive coupler includes an annular housing having a recess defined by a bottom portion and two opposing side wall portions. At least one side wall portion includes a lip extending toward but not reaching the other side wall portion. A plurality of generally U-shaped MCEI segments, preferably comprised of ferrite, are disposed in the recess and aligned so as to form a circular trough. The coupler further includes a conductor disposed within the circular trough and a polymer filling spaces between the segments, the annular housing and the conductor.

Thin-Ribbon Tapered Couplers For Dielectric Waveguides

NASA Technical Reports Server (NTRS)

Otoshi, Tom Y.; Shimabukuro, Fred I.; Yeh, Cavour

1996-01-01

Thin-ribbon tapered couplers proposed for launching electro-magnetic waves into dielectric waveguides, which include optical fibers. Intended for use with ribbon dielectric waveguides designed for operation at millimeter or submillimeter wavelengths, made of high-relative-permittivity, low-loss materials and thicknesses comparable to or less than free-space design wavelengths. Coupling efficiencies exceeds those of older tapered couplers.

A coupler for parasitic mode diagnosis in an X-band triaxial klystron amplifier

NASA Astrophysics Data System (ADS)

Zhang, Wei; Ju, Jin-chuan; Zhang, Jun; Qi, Zu-min; Zhong, Hui-huang

2017-10-01

The traditional methods of parasitic mode excitation diagnosis in an X-band triaxial klystron amplifier (TKA) meet two difficulties: limited installation space and vacuum sealing. In order to solve these issues, a simple and compact coupler with good sealing performance, which can prevent air flow between the main and the auxiliary waveguides, is proposed and investigated experimentally. The coupler is designed with the aperture diffraction theory and the finite-different time-domain (FDTD) method. The designed coupler consists of a main coaxial waveguide (for microwave transmission) and a rectangular auxiliary waveguide (for parasitic mode diagnosis). The entire coupler structure has been fabricated by macromolecule polymer which is transparent to microwave signal in frequency range of X-band. The metal coating of about 200 microns has been performed through electroplating technique to ensure that the device operates well at high power. A small aperture is made in the metal coating. Hence, microwave can couple through the hole and the wave-transparent medium, whereas air flow is blocked by the wave-transparent medium. The coupling coefficient is analyzed and simulated with CST software. The coupler model is also included in particle-in-cell (PIC) simulation with CHIPIC software and the associated parasitic mode excitation is studied. A frequency component of 11.46 GHz is observed in the FFT of the electric field of the drift tube and its corresponding competition mode appears as TE61 mode according to the electric field distribution. Besides, a frequency component of 10.8 GHz is also observed in the FFT of the electric field. After optimization of TE61 mode suppression, an experiment of the TKA with the designed coupler is carried out and the parasitic mode excitation at 10.8 GHz is observed through the designed coupler.

Outcomes and reliability of the flow coupler in postoperative monitoring of head and neck free flaps.

PubMed

Fujiwara, Rance J T; Dibble, Jacqueline M; Larson, Scott V; Pierce, Matthew L; Mehra, Saral

2018-04-01

To assess the accuracy and reliability of the flow coupler relative to the implantable arterial Doppler probe in postoperative monitoring of head and neck free flaps. Retrospective single-institution study, April 2015 to March 2017. Both the venous flow coupler and arterial Doppler were employed in 120 consecutive head and neck free flap cases. When Doppler signal loss occurred, flaps were evaluated by physical exam to determine whether signal loss was a true positive necessitating operating room takeback. Sensitivity, specificity, and false positive rate (FPR) were recorded for each device. Logistic regression was conducted to identify user trends over time. Eleven of 120 patients (9.2%) required takeback, 10 from venous thrombosis and one from arterial thrombosis. Permanent signal loss (PSL) occurred in the flow coupler in all takebacks; PSL occurred in the arterial Doppler only in the case of arterial thrombosis. Salvage rate was 9/11 (81.8%). For the flow coupler, sensitivity was 100%, specificity 86.4%, and FPR 13.6%. For the arterial probe, sensitivity was 9.1%, specificity 97.1%, and FPR 2.9%. A 4.1% decrease in false positives with each additional flow coupler use was observed. Monitoring the vein via flow coupler has high sensitivity in identifying vascular compromise compared to the arterial probe, especially for venous thrombosis. There is moderate FPR; this decreases with increased usage and, when supplemented with physical examination, does not result in unnecessary takebacks. The flow coupler can be a valuable tool in postoperative monitoring of head and neck free flaps. 4. Laryngoscope, 128:812-817, 2018. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

Total internal reflection-based planar waveguide solar concentrator with symmetric air prisms as couplers.

PubMed

Xie, Peng; Lin, Huichuan; Liu, Yong; Li, Baojun

2014-10-20

We present a waveguide coupling approach for planar waveguide solar concentrator. In this approach, total internal reflection (TIR)-based symmetric air prisms are used as couplers to increase the coupler reflectivity and to maximize the optical efficiency. The proposed concentrator consists of a line focusing cylindrical lens array over a planar waveguide. The TIR-based couplers are located at the focal line of each lens to couple the focused sunlight into the waveguide. The optical system was modeled and simulated with a commercial ray tracing software (Zemax). Results show that the system used with optimized TIR-based couplers can achieve 70% optical efficiency at 50 × geometrical concentration ratio, resulting in a flux concentration ratio of 35 without additional secondary concentrator. An acceptance angle of ± 7.5° is achieved in the x-z plane due to the use of cylindrical lens array as the primary concentrator.

Design of an rf quadrupole for Landau damping

NASA Astrophysics Data System (ADS)

Papke, K.; Grudiev, A.

2017-08-01

The recently proposed superconducting quadrupole resonator for Landau damping in accelerators is subjected to a detailed design study. The optimization process of two different cavity types is presented following the requirements of the High Luminosity Large Hadron Collider (HL-LHC) with the main focus on quadrupolar strength, surface peak fields, and impedance. The lower order and higher order mode (LOM and HOM) spectrum of the optimized cavities is investigated and different approaches for their damping are proposed. On the basis of an example the first two higher order multipole errors are calculated. Likewise on this example the required rf power and optimal external quality factor for the input coupler is derived.

Copper nanorod array assisted silicon waveguide polarization beam splitter.

PubMed

Kim, Sangsik; Qi, Minghao

2014-04-21

We present the design of a three-dimensional (3D) polarization beam splitter (PBS) with a copper nanorod array placed between two silicon waveguides. The localized surface plasmon resonance (LSPR) of a metal nanorod array selectively cross-couples transverse electric (TE) mode to the coupler waveguide, while transverse magnetic (TM) mode passes through the original input waveguide without coupling. An ultra-compact and broadband PBS compared to all-dielectric devices is achieved with the LSPR. The output ports of waveguides are designed to support either TM or TE mode only to enhance the extinction ratios. Compared to silver, copper is fully compatible with complementary metal-oxide-semiconductor (CMOS) technology.

An alternative way to increase the power gain of resonant rings

NASA Astrophysics Data System (ADS)

Zhuang, Dehao; Liu, Yunqi; Wang, Fang; Lin, Lin; Feng, Liwen; Quan, Shengwen; Liu, Kexin

2018-03-01

Resonant rings which can amplify RF power through the coupling of waves are used for high power breakdown tests, unidirectional filters, or pulse-shaping techniques. Usually, the RF output terminal of a resonant ring is connected to a matched load. For the resonant ring at Peking University, the matched load has been replaced by a waveguide shorting plate to obtain higher conditioning power for the 1.3 GHz capacitive type power couplers. The power gain is increased significantly with this short termination with the same input RF power. Working mechanism analysis, experiments, and results of this modified resonant ring will be presented.

Waferscale nanophotonic circuits made from diamond-on-insulator substrates.

PubMed

Rath, P; Gruhler, N; Khasminskaya, S; Nebel, C; Wild, C; Pernice, W H P

2013-05-06

Wide bandgap dielectrics are attractive materials for the fabrication of photonic devices because they allow broadband optical operation and do not suffer from free-carrier absorption. Here we show that polycrystalline diamond thin films deposited by chemical vapor deposition provide a promising platform for the realization of large scale integrated photonic circuits. We present a full suite of photonic components required for the investigation of on-chip devices, including input grating couplers, millimeter long nanophotonic waveguides and microcavities. In microring resonators we measure loaded optical quality factors up to 11,000. Corresponding propagation loss of 5 dB/mm is also confirmed by measuring transmission through long waveguides.

Conceptual design of a sapphire loaded coupler for superconducting radio-frequency 1.3 GHz cavities

DOE PAGES

Xu, Chen; Tantawi, Sami

2016-02-25

This paper explores a hybrid mode rf structure that served as a superconducting radio-frequency coupler. This application achieves a reflection S (1,1) varying from 0 to -30 db and delivers cw power at 7 KW. The coupler has good thermal isolation between the 2 and 300 K sections due to vacuum separation. Only one single hybrid mode can propagate through each section, and no higher order mode is coupled. The analytical and numerical analysis for this coupler is given and the design is optimized. As a result, the coupling mechanism to the cavity is also discussed.

Highly efficient coupler for dielectric slot waveguides and hybrid plasmonic waveguides

NASA Astrophysics Data System (ADS)

Yu, Jiyao; Ohtera, Yasuo; Yamada, Hirohito

2018-05-01

A compact, highly efficient optical coupler for dielectric slot waveguides and hybrid plasmonic waveguides based on transition layers (air slot grooves) was investigated. The power-coupling efficiency of 75% for the direct coupling case increased to 90% following the insertion of an intermediate section. By performing time-averaged Poynting vector analysis, we successfully separated the factors of transmission, reflection, and radiation at the coupler interface. We found that the insertion of optimal air grooves into the coupler structure contributed to the improvement of coupling performance. The proposed compact structure is characterized by a high transmission efficiency, low reflection, small length, and broad-band spectrum response.

Geometric optimisation of an accurate cosine correcting optic fibre coupler for solar spectral measurement.

PubMed

Cahuantzi, Roberto; Buckley, Alastair

2017-09-01

Making accurate and reliable measurements of solar irradiance is important for understanding performance in the photovoltaic energy sector. In this paper, we present design details and performance of a number of fibre optic couplers for use in irradiance measurement systems employing remote light sensors applicable for either spectrally resolved or broadband measurement. The angular and spectral characteristics of different coupler designs are characterised and compared with existing state-of-the-art commercial technology. The new coupler designs are fabricated from polytetrafluorethylene (PTFE) rods and operate through forward scattering of incident sunlight on the front surfaces of the structure into an optic fibre located in a cavity to the rear of the structure. The PTFE couplers exhibit up to 4.8% variation in scattered transmission intensity between 425 nm and 700 nm and show minimal specular reflection, making the designs accurate and reliable over the visible region. Through careful geometric optimization near perfect cosine dependence on the angular response of the coupler can be achieved. The PTFE designs represent a significant improvement over the state of the art with less than 0.01% error compared with ideal cosine response for angles of incidence up to 50°.

Mode-converting coupler for silicon-on-sapphire devices

NASA Astrophysics Data System (ADS)

Zlatanovic, S.; Offord, B. W.; Owen, M.; Shimabukuro, R.; Jacobs, E. W.

2015-02-01

Silicon-on-sapphire devices are attractive for the mid-infrared optical applications up to 5 microns due to the low loss of both silicon and sapphire in this wavelength band. Designing efficient couplers for silicon-on-sapphire devices presents a challenge due to a highly confined mode in silicon and large values of refractive index of both silicon and sapphire. Here, we present design, fabrication, and measurements of a mode-converting coupler for silicon-on-sapphire waveguides. We utilize a mode converter layout that consists of a large waveguide that is overlays a silicon inverse tapered waveguide. While this geometry was previously utilized for silicon-on-oxide devices, the novelty is in using materials that are compatible with the silicon-on-sapphire platform. In the current coupler the overlaying waveguide is made of silicon nitride. Silicon nitride is the material of choice because of the large index of refraction and low absorption from near-infrared to mid-infrared. The couplers were fabricated using a 0.25 micron silicon-on-sapphire process. The measured coupling loss from tapered lensed silica fibers to the silicon was 4.8dB/coupler. We will describe some challenges in fabrication process and discuss ways to overcome them.

Omnidirectional spin-wave nanograting coupler

PubMed Central

Yu, Haiming; Duerr, G.; Huber, R.; Bahr, M.; Schwarze, T.; Brandl, F.; Grundler, D.

2013-01-01

Magnonics as an emerging nanotechnology offers functionalities beyond current semiconductor technology. Spin waves used in cellular nonlinear networks are expected to speed up technologically, demanding tasks such as image processing and speech recognition at low power consumption. However, efficient coupling to microelectronics poses a vital challenge. Previously developed techniques for spin-wave excitation (for example, by using parametric pumping in a cavity) may not allow for the relevant downscaling or provide only individual point-like sources. Here we demonstrate that a grating coupler of periodically nanostructured magnets provokes multidirectional emission of short-wavelength spin waves with giantly enhanced amplitude compared with a bare microwave antenna. Exploring the dependence on ferromagnetic materials, lattice constants and the applied magnetic field, we find the magnonic grating coupler to be more versatile compared with gratings in photonics and plasmonics. Our results allow one to convert, in particular, straight microwave antennas into omnidirectional emitters for short-wavelength spin waves, which are key to cellular nonlinear networks and integrated magnonics. PMID:24189978

Integrated optics prototype beam combiner for long baseline interferometry in the L and M bands

NASA Astrophysics Data System (ADS)

Tepper, J.; Labadie, L.; Diener, R.; Minardi, S.; Pott, J.-U.; Thomson, R.; Nolte, S.

2017-06-01

Context. Optical long baseline interferometry is a unique way to study astronomical objects at milli-arcsecond resolutions not attainable with current single-dish telescopes. Yet, the significance of its scientfic return strongly depends on a dense coverage of the uv-plane and a highly stable transfer function of the interferometric instrument. In the last few years, integrated optics (IO) beam combiners have facilitated the emergence of 4-telescope interferometers such as PIONIER or GRAVITY, boosting the imaging capabilities of the VLTI. However, the spectral range beyond 2.2 μm is not ideally covered by the conventional silica based IO. Here, we consider new laser-written IO prototypes made of gallium lanthanum sulfide (GLS) glass, a material that permits access to the mid-infrared spectral regime. Aims: Our goal is to conduct a full characterization of our mid-IR IO two-telescope coupler in order to measure the performance levels directly relevant for long-baseline interferometry. We focus in particular on the exploitation of the L and M astronomical bands. Methods: We use a dedicated Michelson-interferometer setup to perform Fourier transform spectroscopy on the coupler and measure its broadband interferometric performance. We also analyze the polarization properties of the coupler, the differential dispersion and phase degradation, as well as the modal behavior and the total throughput. Results: We measure broadband interferometric contrasts of 94.9% and 92.1% for unpolarized light in the L and M bands. Spectrally integrated splitting ratios are close to 50%, but show chromatic dependence over the considered bandwidths. Additionally, the phase variation due to the combiner is measured and does not exceed 0.04 rad and 0.07 rad across the L and M band, respectively. The total throughput of the coupler including Fresnel and injection losses from free-space is 25.4%. Furthermore, differential birefringence is low (<0.2 rad), in line with the high contrasts reported for unpolarized light. Conclusions: The laser-written IO GLS prototype combiners prove to be a reliable technological solution with promising performance for mid-infrared long-baseline interferometry. In the next steps, we will consider more advanced optical functions, as well as a fiber-fed input, and we will revise the optical design parameters in order to further enhance the total throughput and achromatic behavior.

Multiplexing of adjacent vortex modes with the forked grating coupler

NASA Astrophysics Data System (ADS)

Nadovich, Christopher T.; Kosciolek, Derek J.; Crouse, David T.; Jemison, William D.

2017-08-01

For vortex fiber multiplexing to reach practical commercial viability, simple silicon photonic interfaces with vortex fiber will be required. These interfaces must support multiplexing. Toward this goal, an efficient singlefed multimode Forked Grating Coupler (FGC) for coupling two different optical vortex OAM charges to or from the TE0 and TE1 rectangular waveguide modes has been developed. A simple, apodized device implemented with e-beam lithography and a conventional dual-etch processing on SOI wafer exhibits low crosstalk and reasonable mode match. Advanced designs using this concept are expected to further improve performance.

Superconducting Prototype Cavities for the Spallation Neutron Source (SNS) Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peter Kneisel; John Brawley; Richard Bundy

2001-06-01

The Spallation Neutron Source project includes a superconducting linac section in the energy range from 192 MeV to 1000 MeV. For this energy range two types of cavities are needed with geometrical beta - values of beta = 0.61 and beta = 0.81. An aggressive cavity prototyping program is being pursued at Jlab, which calls for fabricating and testing of four beta = 0.61 cavities and two beta = 0.81 cavities. Both types consist of six cells made from high purity niobium and feature one HOM coupler of the TESLA type on each beam pipe and a port for amore » high power coaxial input coupler. Three of the four beta = 0.61 cavities will be used for a cryomodule test at the end of the year 2001. At this time two cavities of each type have been fabricated and the first tests on the beta = 0.61 cavity exceeded the design values for gradient and Q - value: Eacc = 10.3 MV/m and Q = 6.5 x 10{sup 9} at 2.1K. This paper will describe the cavity design with respect to electrical and mechanical features, the fabrication efforts and the results obtained with the different cavities existing at the time of the conference.« less

Antenna unit and radio base station therewith

DOEpatents

Kuwahara, Mikio; Doi, Nobukazu; Suzuki, Toshiro; Ishida, Yuji; Inoue, Takashi; Niida, Sumaru

2007-04-10

Phase and amplitude deviations, which are generated, for example, by cables connecting an array antenna of a CDMA base station and the base station, are calibrated in the baseband. The base station comprises: an antenna apparatus 1; couplers 2; an RF unit 3 that converts a receive signal to a baseband signal, converts a transmit signal to a radio frequency, and performs power control; an A/D converter 4 for converting a receive signal to a digital signal; a receive beam form unit 6 that multiplies the receive signal by semi-fixed weight; a despreader 7 for this signal input; a time-space demodulator 8 for demodulating user data; a despreader 9 for probe signal; a space modulator 14 for user data; a spreader 13 for user signal; a channel combiner 12; a Tx calibrater 11 for controlling calibration of a signal; a D/A converter 10; a unit 16 for calculation of correlation matrix for generating a probe signal used for controlling an Rx calibration system and a TX calibration system; a spreader 17 for probe signal; a power control unit 18; a D/A converter 19; an RF unit 20 for probe signal; an A/D converter 21 for signal from the couplers 2; and a despreader 22.

Design issues for directional coupler- and MMI-based optical microring resonator filters on InP

NASA Astrophysics Data System (ADS)

Themistos, Christos; Kalli, Kyriacos; Komodromos, Michalis; Rajarajan, Muttukrishnan; Rahman, B. M. A.; Grattan, Kenneth T. V.

2004-08-01

The characterization and optimization of optical microring resonator-based optical filters on deeply etched GaInAsP-Inp waveguides, using the finite element-based beam propagation approach is presented here. Design issues for directional coupler- and multimode interference coupler-based devices, such as field evolution, optical power, phase, fabrication tolerance and wavelength dependence have been investigated.

Comparison of Hand-Sewn versus Coupled Venous Anastomoses in Traumatic Lower Extremity Reconstruction.

PubMed

Stranix, John T; Rifkin, William J; Lee, Z-Hye; Anzai, Lavinia; Jacoby, Adam; Ceradini, Daniel J; Thanik, Vishal; Saadeh, Pierre B; Levine, Jamie P

2018-06-15

 Microvascular reconstruction of the lower extremity has the highest reported complication and flap failure rates of any anatomical region. Despite widespread adoption of the mechanical anastomotic venous coupler and encouraging results in other anatomical regions, there are limited reports examining its use in the lower extremity. This study compares outcomes between coupled and hand-sewn venous anastomoses in traumatic lower extremity reconstruction.  Retrospective review of our institutional flap registry from 1979 to 2016 identified soft tissue free flaps performed for the reconstruction of Gustilo type IIIB/IIIC open tibial fractures. Patient demographics, flap characteristics, use of a venous anastomotic coupler, and perioperative outcomes were examined. Analysis was performed using chi-square and Student's t -tests.  A total of 361 patients received a microvascular free flap for coverage of a Gustilo type IIIB or IIIC tibial fracture following traumatic injury. After excluding cases that lacked adequate information on coupler use, 358 free flaps were included in the study. There were 72 (20%) free flaps performed using a venous coupler and 286 (80%) performed with hand-sewn venous anastomoses. There were comparable rates of major complications (22.2 vs. 26.1%; p  = 0.522), total flap failure (6.5%, vs. 10.2%; p  = 0.362), and partial flap failure (9.7 vs. 12.2%; p  = 0.579) between venous coupler and hand-sewn anastomoses, respectively. Furthermore, use of the venous coupler was not associated with increased rates of operative take backs (22.8 vs. 23.0%; p  = 0.974). However, reconstructions performed using a venous coupler were significantly more likely to have a second venous anastomosis performed (37.5 vs. 21.3%; p  = 0.004).  Complication and flap failure rates were similar between reconstructions performed with a venous coupler and those performed with hand-sewn venous anastomoses. These findings suggest that use of the venous anastomotic coupler is safe and effective in lower extremity reconstruction, with comparable outcomes to conventional sutured anastomoses. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

The microvascular anastomotic coupler for venous anastomoses in free flap breast reconstruction improves outcomes

PubMed Central

Rozen, Warren Matthew; Chowdhry, Muhammad; Patel, Nakul Gamanlal; Chow, Whitney T.H.; Griffiths, Matthew; Ramakrishnan, Venkat V.

2016-01-01

Background Venous couplers are ubiquitous around the world and are a useful tool for the reconstructive microsurgeon. A systematic review of coupler performance studies demonstrated a thrombosis rate range of 0% to 3%, whilst the average time of using the device is 5 minutes. There is sparse published data on cost analysis and the impact of operator experience on the anastomotic coupler device success. Improvements in outcomes other than time benefits have also not been shown. This study aims to address these deficiencies in the literature. Methods A retrospective clinical study was undertaken, aiming to compare equivalent groups of patients that had free flap surgery with venous micro-anastomoses with those that had sutured anastomoses. The cohort comprised all patients undergoing microsurgical breast reconstruction at the St Andrew’s Centre for Plastic Surgery & Burns from January 2009 to December 2014. Results Between January 2010 to December 2014, 1,064 patients underwent 1,206 free flap breast reconstructions. The average age of patients was 50 years. Seventy percent of patients underwent mastectomy and immediate reconstruction during this period with the remaining 30% having a delayed reconstruction. The 1,206 free flaps comprised of 83 transverse myocutaneous gracilis (TMG) flaps, and 1,123 deep inferior epigastric artery perforator (DIEP) flaps. In total the coupler was used in 319 flaps, 26% of the cohort. There was a statistically significant clinical benefit in using the anastomotic coupler for venous anastomosis. Overall, the return to theatre rate was 12.69% whilst the overall flap loss rate was 0.75%. The overall coupler failure rate was significantly less at 1.4% whilst sutured vein failure rate was 3.57% (P=0.001). Conclusions The anastomotic coupler for venous anastomosis in free flap surgery is associated with reduced operating times, reduced take-backs to theatre and cost benefits. This is the first study to demonstrate clear clinical benefits to anastomotic couplers, and suggests that these may be the gold standard for venous microanastomosis. With increasing experience with their use and technological advances, these outcomes may continue to improve. PMID:27047776

Concentric ring flywheel with hooked ring carbon fiber separator/torque coupler

DOEpatents

Kuklo, Thomas C.

1999-01-01

A concentric ring flywheel with expandable separators, which function as torque couplers, between the rings to take up the gap formed between adjacent rings due to differential expansion between different radius rings during rotation of the flywheel. The expandable separators or torque couplers include a hook-like section at an upper end which is positioned over an inner ring and a shelf-like or flange section at a lower end onto which the next adjacent outer ring is positioned. As the concentric rings are rotated the gap formed by the differential expansion there between is partially taken up by the expandable separators or torque couplers to maintain torque and centering attachment of the concentric rings.

Design and fabrication of N x N optical couplers based on organic polymer optical waveguides

NASA Astrophysics Data System (ADS)

Krchnavek, Robert R.; Rode, Daniel L.

1994-08-01

In this report, we examine the design and fabrication of a planar, 10x10 optical coupler utilizing photopolymerizable organic polymers. Background information on the theory of operation of the coupler culminating in a set of design equations is presented. The details of the material processing are described, including the preparation of monomer mixtures that result in single-mode polymer waveguides (lambda = 1300 nm) that have core dimensions approximately equal to those of single-mode fiber. This is necessary to insure high coupling efficiency between the planar device and optical fiber. A unique method of aligning and attaching optical fibers to the coupler is demonstrated. This method relies on patterned alignment ways, a transcision cut, and single-mode D-fiber. A theoretical analysis of the in situ monitoring technique used to fabricate the single-mode D-fiber is presented and compared favorably with the experimental results. Finally, the 10x10 coupler is characterized. We have measured an excess loss of approximately 8 dB.

Directional coupler based on an elliptic cylindrical nanowire hybrid plasmonic waveguide.

PubMed

Zeng, Dezheng; Zhang, Li; Xiong, Qiulin; Ma, Junxian

2018-06-01

We present what we believe is a novel directional coupler based on an elliptic cylindrical nanowire hybrid plasmonic waveguide. Using the finite element method, the electric field distributions of y-polarized symmetric and antisymmetric modes of the coupler are compared, and the coupling and transmission characteristics are analyzed; then the optimized separation distance between the two parallel waveguides, 100 nm, is obtained. This optimized architecture fits in the weak coupling regime. Furthermore, the energy transfer is studied, and the performances of the directional coupler are evaluated, including excess loss, coupling degree, and directionality. The results show that when the separation distance is set to 100 nm, the coupling length reaches the shorter value of 1.646 μm, and the propagation loss is as low as 0.076 dB/μm, and the maximum energy transfer can reach 80%. The proposed directional coupler features good energy confinement, ultracompact and low propagation loss, which has potential application in dense photonic-integrated circuits and other photonic devices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bane, K.L.F.; Adolphsen, C.; Li, Z.

In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate fields that will kick the beam transversely and degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental (FM) and higher mode (HM) couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, duemore » to (the asymmetry in) the fundamental RF fields and the other, due to transverse wakefields that are generated by the beam even when it is on axis. In this report we calculate the strength of these kicks and estimate their effect on the ILC beam. The TESLA cavity comprises nine cells, one HM coupler in the upstream end, and one (identical, though rotated) HM coupler and one FM coupler in the downstream end (for their shapes and location see Figs. 1, 2) [1]. The cavity is 1.1 m long, the iris radius 35 mm, and the coupler beam pipe radius 39 mm. Note that the couplers reach closer to the axis than the irises, down to a distance of 30 mm.« less

A 12 GHz wavelength spacing multi-wavelength laser source for wireless communication systems

NASA Astrophysics Data System (ADS)

Peng, P. C.; Shiu, R. K.; Bitew, M. A.; Chang, T. L.; Lai, C. H.; Junior, J. I.

2017-08-01

This paper presents a multi-wavelength laser source with 12 GHz wavelength spacing based on a single distributed feedback laser. A light wave generated from the distributed feedback laser is fed into a frequency shifter loop consisting of 50:50 coupler, dual-parallel Mach-Zehnder modulator, optical amplifier, optical filter, and polarization controller. The frequency of the input wavelength is shifted and then re-injected into the frequency shifter loop. By re-injecting the shifted wavelengths multiple times, we have generated 84 optical carriers with 12 GHz wavelength spacing and stable output power. For each channel, two wavelengths are modulated by a wireless data using the phase modulator and transmitted through a 25 km single mode fiber. In contrast to previously developed schemes, the proposed laser source does not incur DC bias drift problem. Moreover, it is a good candidate for radio-over-fiber systems to support multiple users using a single distributed feedback laser.

Design and Development of Amplitude and phase measurement of RF signal with Digital I-Q Demodulator

NASA Astrophysics Data System (ADS)

Soni, Dipal; Rajnish, Kumar; Verma, Sriprakash; Patel, Hriday; Trivedi, Rajesh; Mukherjee, Aparajita

2017-04-01

ITER-India, working as a nodal agency from India for ITER project [1], is responsible to deliver one of the packages, called Ion Cyclotron Heating & Current Drive (ICH&CD) - Radio Frequency Power Sources (RFPS). RFPS is having two cascaded amplifier chains (10 kW, 130 kW & 1.5 MW) combined to get 2.5 MW RF power output. Directional couplers are inserted at the output of each stage to extract forward power and reflected power as samples for measurement of amplitude and phase. Using passive mixer, forward power and reflected power are down converted to 1MHz Intermediate frequency (IF). This IF signal is used as an input to the Digital IQ Demodulator (DIQDM). DIQDM is realized using National Instruments make PXI hardware & LabVIEW software tool. In this paper, Amplitude and Phase measurement of RF signal with DIQDM technique is described. Also test results with dummy signals and signal generated from low power RF systems is discussed here.

The comparison of two methods to manufacture fused biconical tapered optical fiber coupler

NASA Astrophysics Data System (ADS)

Wang, Yue; Liu, Hairong

2009-08-01

Optical fiber coupler is a directional coupler which is crucial component for optical fiber communication systems. The fused biconical taper is the most important method in facture of optical fiber coupler, with many advantages of low excess loss, precise coupling ratio, good consistency and stability. In this paper we have introduced a new method to manufacture optical fiber coupler. And more over the new manufacture process has been compared with the traditional manufacture method. In the traditional crafts, two optical fibers are parallel placed, and then use the method of tie a knot of the two optical fibers. In the new process, a new program of fiber placement is introduced. Two optical fibers are parallel placed in the middle of the fixture, and then in order to make the bare part of the optical fiber close as much as possible, the new plan using high temperature resistant material bind the both end of the fiber which are not removing the cladding. After many contrast tests, we can see that adopt the improved method of fiber placement, during the process of fiber pulling, the variation of optical power in the directional arm and the coupler arm are more smooth and steady. But the excess loss (EL) generated in the process of pulling is a bit higher than the traditional method of tie a knot. The tests show that the new method of optical fiber placement is feasible in the actual projects for the manufacture of coupler with low coupling ratio, but for the control of the EL still need further studying.

Accurate Time-Dependent Traveling-Wave Tube Model Developed for Computational Bit-Error-Rate Testing

NASA Technical Reports Server (NTRS)

Kory, Carol L.

2001-01-01

The phenomenal growth of the satellite communications industry has created a large demand for traveling-wave tubes (TWT's) operating with unprecedented specifications requiring the design and production of many novel devices in record time. To achieve this, the TWT industry heavily relies on computational modeling. However, the TWT industry's computational modeling capabilities need to be improved because there are often discrepancies between measured TWT data and that predicted by conventional two-dimensional helical TWT interaction codes. This limits the analysis and design of novel devices or TWT's with parameters differing from what is conventionally manufactured. In addition, the inaccuracy of current computational tools limits achievable TWT performance because optimized designs require highly accurate models. To address these concerns, a fully three-dimensional, time-dependent, helical TWT interaction model was developed using the electromagnetic particle-in-cell code MAFIA (Solution of MAxwell's equations by the Finite-Integration-Algorithm). The model includes a short section of helical slow-wave circuit with excitation fed by radiofrequency input/output couplers, and an electron beam contained by periodic permanent magnet focusing. A cutaway view of several turns of the three-dimensional helical slow-wave circuit with input/output couplers is shown. This has been shown to be more accurate than conventionally used two-dimensional models. The growth of the communications industry has also imposed a demand for increased data rates for the transmission of large volumes of data. To achieve increased data rates, complex modulation and multiple access techniques are employed requiring minimum distortion of the signal as it is passed through the TWT. Thus, intersymbol interference (ISI) becomes a major consideration, as well as suspected causes such as reflections within the TWT. To experimentally investigate effects of the physical TWT on ISI would be prohibitively expensive, as it would require manufacturing numerous amplifiers, in addition to acquiring the required digital hardware. As an alternative, the time-domain TWT interaction model developed here provides the capability to establish a computational test bench where ISI or bit error rate can be simulated as a function of TWT operating parameters and component geometries. Intermodulation products, harmonic generation, and backward waves can also be monitored with the model for similar correlations. The advancements in computational capabilities and corresponding potential improvements in TWT performance may prove to be the enabling technologies for realizing unprecedented data rates for near real time transmission of the increasingly larger volumes of data demanded by planned commercial and Government satellite communications applications. This work is in support of the Cross Enterprise Technology Development Program in Headquarters' Advanced Technology & Mission Studies Division and the Air Force Office of Scientific Research Small Business Technology Transfer programs.

Design and Fabrication of NxN Optical Couplers Based on Organic Polymer Opti al WaveGuides

DTIC Science & Technology

1994-08-01

lOxlO optical coupler utilizing photopolymerizable organic polymers. Background information on the theory of operation of the coupler culminating in a...Channel Waveguides Based on Photopolymerizable Di/Tri Acrylates," in Optoelecwonic Interconnects Ii, Ray T. Chen, John A. Neff, Editors, Proc. SPIE 2153, pp...demonstrated that acrylic polymers can be used to fabricate single-mode optical wavguides. The resins that we have formulated are photopolymerizable

Waveguide couplers with new power splitting ratios made possible by cascading of short multimode interference sections

NASA Astrophysics Data System (ADS)

Feng, David J. Y.; Lay, T. S.; Chang, T. Y.

2007-02-01

We show that it is possible to obtain 2 x 2 waveguide couplers with new power splitting ratios for cross coupling of 7%, 64%, 80% and 93% by cascading two short MMI sections. These couplers have simple geometry and low loss. They offer valuable new possibilities for designing waveguide power taps, high-Q ring resonators, ladder-structure optical filters, and loop-mirror partial reflectors.

High-efficiency fiber-to-chip grating couplers realized using an advanced CMOS-compatible silicon-on-insulator platform.

PubMed

Vermeulen, D; Selvaraja, S; Verheyen, P; Lepage, G; Bogaerts, W; Absil, P; Van Thourhout, D; Roelkens, G

2010-08-16

A new generation of Silicon-on-Insulator fiber-to-chip grating couplers which use a silicon overlay to enhance the directionality and thereby the coupling efficiency is presented. Devices are realized on a 200 mm wafer in a CMOS pilot line. The fabricated fiber couplers show a coupling efficiency of -1.6 dB and a 3 dB bandwidth of 80 nm.

A grating coupler with a trapezoidal hole array for perfectly vertical light coupling between optical fibers and waveguides

NASA Astrophysics Data System (ADS)

Mizutani, Akio; Eto, Yohei; Kikuta, Hisao

2017-12-01

A grating coupler with a trapezoidal hole array was designed and fabricated for perfectly vertical light coupling between a single-mode optical fiber and a silicon waveguide on a silicon-on-insulator (SOI) substrate. The grating coupler with an efficiency of 53% was computationally designed at a 1.1-µm-thick buried oxide (BOX) layer. The grating coupler and silicon waveguide were fabricated on the SOI substrate with a 3.0-µm-thick BOX layer by a single full-etch process. The measured coupling efficiency was 24% for TE-polarized light at 1528 nm wavelength, which was 0.69 times of the calculated coupling efficiency for the 3.0-µm-thick BOX layer.

Concentric ring flywheel with hooked ring carbon fiber separator/torque coupler

DOEpatents

Kuklo, T.C.

1999-07-20

A concentric ring flywheel with expandable separators, which function as torque couplers, between the rings to take up the gap formed between adjacent rings due to differential expansion between different radius rings during rotation of the flywheel. The expandable separators or torque couplers include a hook-like section at an upper end which is positioned over an inner ring and a shelf-like or flange section at a lower end onto which the next adjacent outer ring is positioned. As the concentric rings are rotated the gap formed by the differential expansion there between is partially taken up by the expandable separators or torque couplers to maintain torque and centering attachment of the concentric rings. 2 figs.

Copper nanorod array assisted silicon waveguide polarization beam splitter

PubMed Central

Kim, Sangsik; Qi, Minghao

2014-01-01

We present the design of a three-dimensional (3D) polarization beam splitter (PBS) with a copper nanorod array placed between two silicon waveguides. The localized surface plasmon resonance (LSPR) of a metal nanorod array selectively cross-couples transverse electric (TE) mode to the coupler waveguide, while transverse magnetic (TM) mode passes through the original input waveguide without coupling. An ultra-compact and broadband PBS compared to all-dielectric devices is achieved with the LSPR. The output ports of waveguides are designed to support either TM or TE mode only to enhance the extinction ratios. Compared to silver, copper is fully compatible with complementary metal-oxide-semiconductor (CMOS) technology. PMID:24787839

High-Q resonant cavities for terahertz quantum cascade lasers.

PubMed

Campa, A; Consolino, L; Ravaro, M; Mazzotti, D; Vitiello, M S; Bartalini, S; De Natale, P

2015-02-09

We report on the realization and characterization of two different designs for resonant THz cavities, based on wire-grid polarizers as input/output couplers, and injected by a continuous-wave quantum cascade laser (QCL) emitting at 2.55 THz. A comparison between the measured resonators parameters and the expected theoretical values is reported. With achieved quality factor Q ≈ 2.5 × 10(5), these cavities show resonant peaks as narrow as few MHz, comparable with the typical Doppler linewidth of THz molecular transitions and slightly broader than the free-running QCL emission spectrum. The effects of the optical feedback from one cavity to the QCL are examined by using the other cavity as a frequency reference.

Monolithic InP strictly non-blocking 8×8 switch for high-speed WDM optical interconnection.

PubMed

Kwack, Myung-Joon; Tanemura, Takuo; Higo, Akio; Nakano, Yoshiaki

2012-12-17

A strictly non-blocking 8 × 8 switch for high-speed WDM optical interconnection is realized on InP by using the phased-array scheme for the first time. The matrix switch architecture consists of over 200 functional devices such as star couplers, phase-shifters and so on without any waveguide cross-section. We demonstrate ultra-broad optical bandwidth covering the entire C-band through several Input/Output ports combination with extinction ratio performance of more than 20dB. Also, nanoseconds reconfiguration time was successfully achieved by dynamic switching experiment. Error-free transmission was verified for 40-Gbps (10-Gbps × 4ch) WDM signal.

Coupler for remote manipulators

NASA Technical Reports Server (NTRS)

Rudmann, A. A.

1980-01-01

Reliable, low-cost coupler alines and grasps moving and rotating objects. Coupling mechanism may be used in handling of radio-active materials or in underwater explorations and other remote manipulators.

Venous coupler use for free-flap breast reconstructions: specific analyses of TMG and DIEP flaps.

PubMed

Bodin, Frédéric; Brunetti, Stefania; Dissaux, Caroline; Erik, A Sauleau; Facca, Sybille; Bruant-Rodier, Catherine; Liverneaux, Philippe

2015-05-01

The purpose of this report was to present the results of comparisons of anastomotic data and flap complications in the use of venous coupler in breast reconstruction with the transverse musculocutaneous gracilis (TMG) flap and the deep inferior epigastric perforator (DIEP) flap. Over a three-year period, 95 patients suffering from breast cancer were treated with mastectomy and breast reconstruction using free flaps. We performed 121 mechanical venous anastomoses for 105 flap procedures (80 DIEP and 25 TMG). The coupler size, anastomotic duration, number of anastomoses and postoperative complications were assessed for the entire series. The coupling device was perfectly suitable for all end-to-end anastomoses between the vein(s) of the flap and the internal mammary vein(s). No venous thrombosis occurred. The mean anastomotic time did not significantly differ between the DIEP (330 seconds) and TMG flap procedures (352 seconds) (P = 0.069). Additionally, there were no differences in coupling time observed following a comparison of seven coupler sizes (P = 0.066). The mean coupler size used during the TMG flap procedure was smaller than that used with the DIEP (2.4 mm versus 2.8 mm) (P < 0.001). The mean size was also smaller when double venous anastomoses were required compared to single anastomosis (2.4 mm versus 2.9 mm) (P < 0.001). The double branching was more frequent with the TMG flap (28%) than with the DIEP flap (11%). The coupler size used was smaller for the TMG procedure and when double venous anastomosis was performed. Additionally, anastomotic time was not affected by the flap type or coupler size used or by anastomosis number. © 2014 Wiley Periodicals, Inc.

Wet-chemical fabrication of a single leakage-channel grating coupler

NASA Astrophysics Data System (ADS)

Weisenbach, Lori; Zelinski, Brian J. J.; Roncone, Ronald L.; Burke, James J.

1995-04-01

We demonstrate the fabrication of a unique optical device, the single leakage-channel grating coupler, using sol-gel techniques. Design specifications are outlined to establish the material criteria for the sol-gel compositions. Material choice and preparation are described. We evaluate the characteristics and performance of the single leakage-channel grating coupler by comparing the predicted and the measured branching ratios. The branching ratio of the solution-derived device is within 3% of the theoretically predicted value.

A study of polaritonic transparency in couplers made from excitonic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Mahi R.; Racknor, Chris

2015-03-14

We have studied light matter interaction in quantum dot and exciton-polaritonic coupler hybrid systems. The coupler is made by embedding two slabs of an excitonic material (CdS) into a host excitonic material (ZnO). An ensemble of non-interacting quantum dots is doped in the coupler. The bound exciton polariton states are calculated in the coupler using the transfer matrix method in the presence of the coupling between the external light (photons) and excitons. These bound exciton-polaritons interact with the excitons present in the quantum dots and the coupler is acting as a reservoir. The Schrödinger equation method has been used tomore » calculate the absorption coefficient in quantum dots. It is found that when the distance between two slabs (CdS) is greater than decay length of evanescent waves the absorption spectrum has two peaks and one minimum. The minimum corresponds to a transparent state in the system. However, when the distance between the slabs is smaller than the decay length of evanescent waves, the absorption spectra has three peaks and two transparent states. In other words, one transparent state can be switched to two transparent states when the distance between the two layers is modified. This could be achieved by applying stress and strain fields. It is also found that transparent states can be switched on and off by applying an external control laser field.« less

Matrix isolation apparatus with extended sample collection capability

DOEpatents

Reedy, Gerald T.

1987-01-01

A gas-sample collection device provides for the matrix isolation of increased amounts of a sample material for spectrographic analysis from a gas chromatographic separation. The device includes an evacuated sample collection chamber containing a disc-like specular carousel having a generally circular lateral surface upon which the sample is deposited in an inert gas matrix for infrared (IR) spectral analysis. The evacuated sample chamber is mounted in a fixed manner and is coupled to and supports a rotating cryostatic coupler which, in turn, supports the specular carousel within the collection chamber. A rotational drive system connected to the cryostatic coupler provides for its rotational displacement as well as that of the sample collecting carousel. In addition, rotation of the cryostatic coupler effects vertical displacement of the carousel to permit the collection of an extended sample band in a helical configuration on the entire lateral surface of the carousel. The various components of the carousel's angular/linear displacement drive system are located exterior to the cryostatic coupler for easy access and improved operation. The cryostatic coupler includes a 360.degree. rotary union assembly for permitting the delivery of a high pressure working fluid to the cryostatic coupler in a continuous flow manner for maintaining the specular carousel at a low temperature, e.g., 10.degree.-20.degree. K., for improved uninterrupted gas sample collection and analysis.

RF conditioning and beam experiments on 400 keV RFQ accelerator at BARC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Shrikrishna; Rao, S.V.L.S.; Kumar, Rajesh, E-mail: sgupta@barc.gov.in

2014-07-01

A 400 keV Radio-frequency quadrupole accelerator (RFQ) has been designed, developed and tested at BARC. This will be used as a neutron generator (via D-T reaction). The RFQ operates at a resonant frequency of 350 MHz and needs an RF power of ∼ 60 kW to accelerate the deuteron beam to 400 keV within a length of 1.03 m. Though the RFQ is designed for deuteron beam, it was tested by accelerating both the proton and deuteron beams to their designed values of 200 and 400 keV respectively. The proton and deuteron beam experiments required peak RF power of approx.more » 15 kW and 60 kW respectively at 350 MHz. The RF power from the tetrode amplifier and coaxial transmission lines is coupled to the cavity by a coaxial loop coupler. As the coupler and cavity operated at vacuum of better than 2e-6 torr, extensive RF conditioning of the cavity and coupler was performed to reach at the desired power levels. (author)« less

Microstructure analysis in the coupling region of fiber coupler with a novel electrical micro-heater

NASA Astrophysics Data System (ADS)

Shuai, Cijun; Gao, Chengde; Nie, Yi; Hu, Huanlong; Peng, Shuping

2011-12-01

Fused-tapered fiber coupler is widely used in optical-fiber communication, optical-fiber sensor and optical signal processing. Its optical performance is mainly determined by the glass properties in the coupling region. In this study, the effect of fused biconical taper (FBT) process on glass microstructure of fiber coupler was investigated by testing the microstructure of the cross-section of coupling region. The fiber coupler is fabricated with a novel home-designed electrical heater. Our experimental results show that the boundary between fiber core and fiber cladding become vague or indistinct after FBT under transmission electron microscopy (TEM) and Ge 2+ in fiber core diffuses into fiber cladding. Crystallizations are observed in coupling region under scanning electron microscope (SEM) and microscopic infrared (IR), and the micro crystallizations become smaller with the drawing speed increasing. The wave number of fiberglass increases after FBT and it is in proportion to the drawing speed. The analysis of the microstructure in the coupling region explored the mechanism of the improvement in the performance of fiber couplers which can be used for the guidance of fabrication process.

Coupling analysis of non-circular-symmetric modes and design of orientation-insensitive few-mode fiber couplers

NASA Astrophysics Data System (ADS)

Li, Jiaxiong; Du, Jiangbing; Ma, Lin; Li, Ming-Jun; Jiang, Shoulin; Xu, Xiao; He, Zuyuan

2017-01-01

We study the coupling between two identical weakly-coupled few-mode fibers based on coupled-mode theory. The coupling behavior of non-circular-symmetric modes, such as LP11 and LP21, is investigated analytically and numerically. By carefully choosing the fiber core separation and coupler length, we can design orientation-insensitive fiber couplers for non-circular-symmetric modes at arbitrary coupling ratios. Based on the design method, we propose an orientation-insensitive two-mode fiber coupler at 850 nm working as a mode multiplexer/demultiplexer for two-mode transmission using standard single-mode fiber. Within the band from 845 to 855 nm, the insertion losses of LP01 and LP11 modes are less than 0.03 dB and 0.24 dB, respectively. When the two-mode fiber coupler is used as mode demultiplexer, the LP01/LP11 and LP11/LP01 extinction ratios in the separated branches are respectively above 12.6 dB and 21.2 dB. Our design method can be extended to two-mode communication or sensing systems at other wavelengths.

Element for use in an inductive coupler for downhole drilling components

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Fox, Joe; Sneddon, Cameron

2006-08-29

The present invention includes an element for use in an inductive coupler in a downhole component. The element includes a plurality of ductile, generally U-shaped leaves that are electrically conductive. The leaves are less than about 0.0625" thick and are separated by an electrically insulating material. These leaves are aligned so as to form a generally circular trough. The invention also includes an inductive coupler for use in downhole components, the inductive coupler including an annular housing having a recess with a magnetically conductive, electrically insulating (MCEI) element disposed in the recess. The MCEI element includes a plurality of segments where each segment further includes a plurality of ductile, generally U-shaped electrically conductive leaves. Each leaf is less than about 0.0625" thick and separated from the otherwise adjacent leaves by electrically insulating material. The segments and leaves are aligned so as to form a generally circular trough. The inductive coupler further includes an insulated conductor disposed within the generally circular trough. A polymer fills spaces between otherwise adjacent segments, the annular housing, insulated conductor, and further fills the circular trough.

A universal Model-R Coupler to facilitate the use of R functions for model calibration and analysis

USGS Publications Warehouse

Wu, Yiping; Liu, Shuguang; Yan, Wende

2014-01-01

Mathematical models are useful in various fields of science and engineering. However, it is a challenge to make a model utilize the open and growing functions (e.g., model inversion) on the R platform due to the requirement of accessing and revising the model's source code. To overcome this barrier, we developed a universal tool that aims to convert a model developed in any computer language to an R function using the template and instruction concept of the Parameter ESTimation program (PEST) and the operational structure of the R-Soil and Water Assessment Tool (R-SWAT). The developed tool (Model-R Coupler) is promising because users of any model can connect an external algorithm (written in R) with their model to implement various model behavior analyses (e.g., parameter optimization, sensitivity and uncertainty analysis, performance evaluation, and visualization) without accessing or modifying the model's source code.

Efficient shortcut techniques in evanescently coupled waveguides

NASA Astrophysics Data System (ADS)

Paul, Koushik; Sarma, Amarendra K.

2016-10-01

Shortcut to Adiabatic Passage (SHAPE) technique, in the context of coherent control of atomic systems has gained considerable attention in last few years. It is primarily because of its ability to manipulate population among the quantum states infinitely fast compared to the adiabatic processes. Two methods in this regard have been explored rigorously, namely the transitionless quantum driving and the Lewis-Riesenfeld invariant approach. We have applied these two methods to realize SHAPE in adiabatic waveguide coupler. Waveguide couplers are integral components of photonic circuits, primarily used as switching devices. Our study shows that with appropriate engineering of the coupling coefficient and propagation constants of the coupler it is possible to achieve efficient and complete power switching. We also observed that the coupler length could be reduced significantly without affecting the coupling efficiency of the system.

Design of microstrip components by computer

NASA Technical Reports Server (NTRS)

Cisco, T. C.

1972-01-01

Development of computer programs for component analysis and design aids used in production of microstrip components is discussed. System includes designs for couplers, filters, circulators, transformers, power splitters, diode switches, and attenuators.

A Novel Multimode Waveguide Coupler for Accurate Power Measurement of Traveling Wave Tube Harmonic Frequencies

NASA Technical Reports Server (NTRS)

Wintucky, Edwin G.; Simons, Rainee N.

2014-01-01

This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from two dissimilar waveguides is capable of isolating the power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT). In addition to accurate power measurements at harmonic frequencies, a potential application of the MDC is in the design of a beacon source for atmospheric propagation studies at millimeter-wave frequencies.

Wireless power transfer magnetic couplers

DOEpatents

Wu, Hunter; Gilchrist, Aaron; Sealy, Kylee

2016-01-19

A magnetic coupler is disclosed for wireless power transfer systems. A ferrimagnetic component is capable of guiding a magnetic field. A wire coil is wrapped around at least a portion of the ferrimagnetic component. A screen is capable of blocking leakage magnetic fields. The screen may be positioned to cover at least one side of the ferrimagnetic component and the coil. A distance across the screen may be at least six times an air gap distance between the ferrimagnetic component and a receiving magnetic coupler.

A Proposal for a High-Voltage Transmission Line Directional Coupler

DOE PAGES

Olsen, R. G.; Li, Zhi

2017-02-01

Directional couplers are devices generally used in high frequency transmission lines and waveguides that respond to forward and reverse traveling waves separately. Hence they can be used to either measure standing wave ratio in the steady state or to determine the direction of a propagating transient wave. Here, a design is proposed for a directional coupler to be used on multimode high voltage transmission lines. Its performance is analyzed and several suggestions are made for improving its design.

Effect of Electrode Loss on the Dynamic Range of Linearized Directional Coupler Modulators

DTIC Science & Technology

2006-02-01

Coupler Modulators George A. Brost , Richard Michalak, Paul Payson, and Kevin Magde Abstract—Numerical simulations were used to study the effect of...RANGE OF LINEARIZED DIRECTIONAL COUPLER MODULATORS In-House N/A 62204F LINKI SN 01 George A. Brost , Richard Michalak, Paul Payson and Kevin Magde AFRL...Fazio Nash BROST et al.: EFFECT OF ELECTRODE LOSS ON THE DYNAMIC RANGE OF LINEARIZED DCMs 515 Fig. 1. Frequency dependence of SFDR for the 1 2 DCM (s

Passive radio frequency peak power multiplier

DOEpatents

Farkas, Zoltan D.; Wilson, Perry B.

1977-01-01

Peak power multiplication of a radio frequency source by simultaneous charging of two high-Q resonant microwave cavities by applying the source output through a directional coupler to the cavities and then reversing the phase of the source power to the coupler, thereby permitting the power in the cavities to simultaneously discharge through the coupler to the load in combination with power from the source to apply a peak power to the load that is a multiplication of the source peak power.

Fast and Scalable Fabrication of Microscopic Optical Surfaces and its Application for Optical Interconnect Devices

NASA Astrophysics Data System (ADS)

Summitt, Christopher Ryan

The use of optical interconnects is a promising solution to the increasing demand for high speed mass data transmission used in integrated circuits as well as device to device data transfer applications. For the purpose, low cost polymer waveguides are a popular choice for routing signal between devices due to their compatibility with printed circuit boards. In optical interconnect, coupling from an external light source to such waveguides is a critical step, thus a variety of couplers have been investigated such as grating based couplers [1,2], evanescent couplers [3], and embedded mirrors [4-6]. These couplers are inherently micro-optical components which require fast and scalable fabrication for mass production with optical quality surfaces/structures. Low NA laser direct writing has been used for fast fabrication of structures such as gratings and Fresnel lenses using a linear laser direct writing scheme, though the length scale of such structures are an order of magnitude larger than the spot size of the focused laser of the tool. Nonlinear writing techniques such as with 2-photon absorption offer increased write resolution which makes it possible to fabricate sub-wavelength structures as well as having a flexibility in feature shape. However it does not allow a high speed fabrication and in general are not scalable due to limitations of speed and area induced by the tool's high NA optics. To overcome such limitations primarily imposed by NA, we propose a new micro-optic fabrication process which extends the capabilities of 1D, low NA, and thus fast and scalable, laser direct writing to fabricate a structure having a length scale close to the tool's spot size, for example, a mirror based and 45 degree optical coupler with optical surface quality. The newly developed process allows a high speed fabrication with a write speed of 2600 mm²/min by incorporating a mask based lithography method providing a blank structure which is critical to creating a 45 degree slope to form the coupler surface. In this method, instead of using an entire exposure in a pixelated manner, only a portion of the Gaussian profile is used, allowing a reduced surface roughness and better control of the surface shape than previously possible with this low NA beam. The surface figure of the mirror is well controlled below 0.04 waves in root-mean-square (RMS) at 1.55 mum wavelength, with mirror angle of 45+/-1 degrees. The coupling efficiency is evaluated using a set of polymer waveguides fabricated on the same substrate as the complete proof of concept device. Device insertion loss was measured using a custom built optical test station and a detailed loss analysis was completed to characterize the optical coupling efficiency of the mirror. Surface roughness and angle were also experimentally confirmed. This process opens up a pathway towards large volume fabrication of free-form and high aspect ratio optical components which have not yet pursued, along with well-defined optical structures on a single substrate. In this dissertation, in Chapter 1, we provide an overview of optical surface fabrication in conjunction with current state of the art on fabrication of free form surfaces in macro and microscopic length scale. The need for optical interconnects is introduced and fabrication methods of micro-optical couplers are reviewed in Chapter 2. In Chapter 3, the complete fabrication process of a mirror based coupler is presented including a custom alignment procedure. In Chapter 4, we provide the integration procedure of the optical couplers with waveguides. In Chapter 5, the alignment of two-lithographic methods is discussed. In Chapter 6, we provide the fabrication procedure used for the waveguides. In Chapter 7, the experimental evaluation and testing of the optical coupler is described. We present a custom test station used for angle verification and optical coupler efficiency measurement. In Chapter 8, a detailed loss analysis of the device is presented including suggestions for future reductions in loss. Conclusions and future work considerations are addressed in Chapter 9.

30 CFR 75.805 - Couplers.

Code of Federal Regulations, 2011 CFR

2011-07-01

... shall be grounded to the ground conductor in the cable. The coupler shall be constructed so that the ground check continuity conductor shall be broken first and the ground conductors shall be broken last...

A holographic waveguide based eye tracker

NASA Astrophysics Data System (ADS)

Liu, Changgeng; Pazzucconi, Beatrice; Liu, Juan; Liu, Lei; Yao, Xincheng

2018-02-01

We demonstrated the feasibility of using holographic waveguide for eye tracking. A custom-built holographic waveguide, a 20 mm x 60 mm x 3 mm flat glass substrate with integrated in- and out-couplers, was used for the prototype development. The in- and out-couplers, photopolymer films with holographic fringes, induced total internal reflection in the glass substrate. Diffractive optical elements were integrated into the in-coupler to serve as an optical collimator. The waveguide captured images of the anterior segment of the eye right in front of it and guided the images to a processing unit distant from the eye. The vector connecting the pupil center (PC) and the corneal reflex (CR) of the eye was used to compute eye position in the socket. An eye model, made of a high quality prosthetic eye, was used prototype validation. The benchtop prototype demonstrated a linear relationship between the angular eye position and the PC/CR vector over a range of 60 horizontal degrees and 30 vertical degrees at a resolution of 0.64-0.69 degrees/pixel by simple pixel count. The uncertainties of the measurements at different angular positions were within 1.2 pixels, which indicated that the prototype exhibited a high level of repeatability. These results confirmed that the holographic waveguide technology could be a feasible platform for developing a wearable eye tracker. Further development can lead to a compact, see-through eye tracker, which allows continuous monitoring of eye movement during real life tasks, and thus benefits diagnosis of oculomotor disorders.

19 CFR 24.22 - Fees for certain services.

Code of Federal Regulations, 2012 CFR

2012-04-01

... coupler to coupler and designed to operate on railroad tracks, other than a locomotive or a caboose. (2... of passengers or cargo during the repair period; (ii) Any railroad car transporting only containers...

19 CFR 24.22 - Fees for certain services.

Code of Federal Regulations, 2011 CFR

2011-04-01

... coupler to coupler and designed to operate on railroad tracks, other than a locomotive or a caboose. (2... of passengers or cargo during the repair period; (ii) Any railroad car transporting only containers...

19 CFR 24.22 - Fees for certain services.

Code of Federal Regulations, 2010 CFR

2010-04-01

... coupler to coupler and designed to operate on railroad tracks, other than a locomotive or a caboose. (2... of passengers or cargo during the repair period; (ii) Any railroad car transporting only containers...

Enhancement of coupling ratios in SOI based asymmetrical optical directional couplers

NASA Astrophysics Data System (ADS)

Pendam, Nagaraju; Vardhani, Chunduru Parvatha

2017-11-01

A novel design of slab structured asymmetrical optical directional coupler with S-bend waveguides on silicon-on-insulator (SOI) platform has been designed by using R-Soft CAD tool. Beam propagation method (BPM) is used for light propagation analysis. The simulation results of asymmetrical optical directional couplers are reported. We find that the asymmetrical directional coupler has lower coupling ratios and higher extinction ratios with waveguide parameters such as width, wavelength, waveguide spacing, and coupling length. Simulation results designate that the coupling efficiency for transverse electric (TE) and transverse magnetic (TM) modes can reach about more than 95% and extinction ratio about 6 dB when the coupling length is 6 mm for both the polarization modes and insertion loss is 17 dB with same coupling length 6 mm at central wavelength 1550 nm.

Wagon instability in long trains

NASA Astrophysics Data System (ADS)

Cole, Colin; McClanachan, Mitchell; Spiryagin, Maksym; Sun, Yan Quan

2012-01-01

Lateral force components and impacts from couplers can adversely affect wagon stability. These issues are significant in longer and heavier trains increasing the risk of wagon rollover, wheel climb, wagon body pitch, bogie pitch and wagon lift-off. Modelling of coupler angles has been added to normal longitudinal train simulation to allow comprehensive study of lateral components of coupler forces. Lateral coupler forces are then combined with centripetal inertia calculations to determine quasi-static lateral forces, quasi-static vertical forces and quasi-static bogie lateral to vertical ratio, allowing the study of stringlining, buckling and wagon rollover risks. The approach taken allows for different rolling stock lengths, overhang and coupling lengths, and allows the study of angles occurring in transitions. Wagon body and bogie pitch are also studied with enhancements added to previous modelling to allow the study of wagon lift-off.

Simplified flangeless unisex waveguide coupler assembly

DOEpatents

Michelangelo, Dimartino; Moeller, Charles P.

1993-01-01

A unisex coupler assembly is disclosed capable of providing a leak tight coupling for waveguides with axial alignment of the waveguides and rotational capability. The sealing means of the coupler assembly are not exposed to RF energy, and the coupler assembly does not require the provision of external flanges on the waveguides. In a preferred embodiment, O ring seals are not used and the coupler assembly is, therefore, bakeable at a temperature up to about 150.degree. C. The coupler assembly comprises a split collar which clamps around the waveguides and a second collar which fastens to the split collar. The split collar contains an inner annular groove. Each of the waveguides is provided with an external annular groove which receives a retaining ring. The split collar is clamped around one of the waveguides with the inner annular groove of the split collar engaging the retaining ring carried in the external annular groove in the waveguide. The second collar is then slipped over the second waveguide behind the annular groove and retaining ring therein and the second collar is coaxially secured by fastening means to the split collar to draw the respective waveguides together by coaxial force exerted by the second collar against the retaining ring on the second waveguide. A sealing ring is placed against an external sealing surface at a reduced external diameter end formed on one waveguide to sealingly engage a corresponding sealing surface on the other waveguide as the waveguides are urged toward each other.

Simplified flangeless unisex waveguide coupler assembly

DOEpatents

Michelangelo, D.; Moeller, C.P.

1993-05-04

A unisex coupler assembly is disclosed capable of providing a leak tight coupling for waveguides with axial alignment of the waveguides and rotational capability. The sealing means of the coupler assembly are not exposed to RF energy, and the coupler assembly does not require the provision of external flanges on the waveguides. In a preferred embodiment, O ring seals are not used and the coupler assembly is, therefore, bakeable at a temperature up to about 150 C. The coupler assembly comprises a split collar which clamps around the waveguides and a second collar which fastens to the split collar. The split collar contains an inner annular groove. Each of the waveguides is provided with an external annular groove which receives a retaining ring. The split collar is clamped around one of the waveguides with the inner annular groove of the split collar engaging the retaining ring carried in the external annular groove in the waveguide. The second collar is then slipped over the second waveguide behind the annular groove and retaining ring therein and the second collar is coaxially secured by fastening means to the split collar to draw the respective waveguides together by coaxial force exerted by the second collar against the retaining ring on the second waveguide. A sealing ring is placed against an external sealing surface at a reduced external diameter end formed on one waveguide to sealingly engage a corresponding sealing surface on the other waveguide as the waveguides are urged toward each other.

Simplified flangeless unisex waveguide coupler assembly

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michelangelo, D.; Moeller, C.P.

1993-05-04

A unisex coupler assembly is disclosed capable of providing a leak tight coupling for waveguides with axial alignment of the waveguides and rotational capability. The sealing means of the coupler assembly are not exposed to RF energy, and the coupler assembly does not require the provision of external flanges on the waveguides. In a preferred embodiment, O ring seals are not used and the coupler assembly is, therefore, bakeable at a temperature up to about 150 C. The coupler assembly comprises a split collar which clamps around the waveguides and a second collar which fastens to the split collar. Themore » split collar contains an inner annular groove. Each of the waveguides is provided with an external annular groove which receives a retaining ring. The split collar is clamped around one of the waveguides with the inner annular groove of the split collar engaging the retaining ring carried in the external annular groove in the waveguide. The second collar is then slipped over the second waveguide behind the annular groove and retaining ring therein and the second collar is coaxially secured by fastening means to the split collar to draw the respective waveguides together by coaxial force exerted by the second collar against the retaining ring on the second waveguide. A sealing ring is placed against an external sealing surface at a reduced external diameter end formed on one waveguide to sealingly engage a corresponding sealing surface on the other waveguide as the waveguides are urged toward each other.« less

InGaN directional coupler made with a one-step etching technique

NASA Astrophysics Data System (ADS)

Gao, Xumin; Yuan, Jialei; Yang, Yongchao; Zhang, Shuai; Shi, Zheng; Li, Xin; Wang, Yongjin

2017-06-01

We propose, fabricate and characterize an on-chip integration of light source, InGaN waveguide, directional coupler and photodiode, in which AlGaN layers are used as top and bottom optical claddings to form an InGaN waveguide for guiding the in-plane emitted light from the InGaN/GaN multiple-quantum-well light-emitting diode (MQW-LED). The difference in etch rate caused by different exposure windows leads to an etching depth discrepancy using the one-step etching technique, which forms the InGaN directional coupler with the overlapped underlying slab. Light propagation results directly confirm effective light coupling in the InGaN directional coupler, which is achieved through high-order guided modes. The InGaN waveguide couples the modulated light from the InGaN/GaN MQW-LED and transfers part of light to the coupled waveguide via the InGaN directional coupler. The in-plane InGaN/GaN MQW-photodiode absorbs the guided light by the coupled InGaN waveguide and induces the photocurrent. The on-chip InGaN photonic integration experimentally demonstrates an in-plane light communication with a data transmission of 50 Mbps.

Design and analysis of O-S-C triple band wavelength division demultiplexer using cascaded MMI couplers

NASA Astrophysics Data System (ADS)

Chack, Devendra; Kumar, V.; Raghuwanshi, Sanjeev Kumar; Singh, Dev Prakash

2017-01-01

Compact triple O-S-C band wavelength demultiplexer, which consists of series cascaded multimode interference (MMI) couplers has been carried out in this paper. The MMI coupler has been used to drop the wavelengths of 1510 nm and 1550 nm at bar port while the wavelength 1300 nm into the cross port. Then another MMI coupler has been designed to separate the wavelength 1510 nminto one port and wavelength 1550 nm into another port. The triple wavelength demultiplexer function has been performed by choosing a suitable refractive index of the guiding region and geometrical parameters such as the width and length of MMI coupler. Numerical simulation with finite difference beam propagation method (BPM) has been utilized to design and optimize the operation of the proposed triple wavelength demultiplexer. The simulation results show that insertion losses of wavelength O, S and C, bands are 1.884 dB, 1.452 dB and 2.568 dB, respectively, with isolations for each output waveguide ranging from 10 dB to 28.72 dB. The 3-dB bandwidth of insertion loss for 1300 nm, 1510 nm and 1550 nm are 80 nm, 20 nm and 10 nm, respectively.

A Tandem Coupler for Terahertz Integrated Circuits

NASA Technical Reports Server (NTRS)

Reck, Theodore J.; Deal, William; Chattopadhyay, Goutam

2013-01-01

A coplanar waveguide 3 dB quadrature coupler operating from 500 to 700 GHz is designed, fabricated and measured. On-wafer measurements demonstrate an amplitude balance of +/-2 dB and phase balance of +/-20 deg.

Compact component for integrated quantum optic processing

PubMed Central

Sahu, Partha Pratim

2015-01-01

Quantum interference is indispensable to derive integrated quantum optic technologies (1–2). For further progress in large scale integration of quantum optic circuit, we have introduced first time two mode interference (TMI) coupler as an ultra compact component. The quantum interference varying with coupling length corresponding to the coupling ratio is studied and the larger HOM dip with peak visibility ~0.963 ± 0.009 is found at half coupling length of TMI coupler. Our results also demonstrate complex quantum interference with high fabrication tolerance and quantum visibility in TMI coupler. PMID:26584759

Femtosecond laser fabrication of birefringent directional couplers as polarization beam splitters in fused silica.

PubMed

Fernandes, Luís A; Grenier, Jason R; Herman, Peter R; Aitchison, J Stewart; Marques, Paulo V S

2011-06-20

Integrated polarization beam splitters based on birefringent directional couplers are demonstrated. The devices are fabricated in bulk fused silica glass by femtosecond laser writing (300 fs, 150 nJ at 500 kHz, 522 nm). The birefringence was measured from the spectral splitting of the Bragg grating resonances associated with the vertically and horizontally polarized modes. Polarization splitting directional couplers were designed and demonstrated with 0.5 dB/cm propagation losses and -19 dB and -24 dB extinction ratios for the polarization splitting.

Bi-wavelength two dimensional chirped grating couplers for low cost WDM PON transceivers

NASA Astrophysics Data System (ADS)

Xu, Lin; Chen, Xia; Li, Chao; Tsang, Hon Ki

2011-04-01

We propose and demonstrate a bi-wavelength two dimensional (2D) waveguide grating coupler on silicon-on-insulator which has efficient coupling of optical light with two-wavelength bands independently between standard optical single mode fibers and nanophotonic waveguides. The details of design are described and the measurement results as well as system performance are experimentally characterized. The bi-wavelength grating coupler can be used as wavelength-division-multiplexing (WDM) splitter/combiner for monolithically silicon integrated transceivers, potentially meeting the low cost requirements for future WDM passive optical network (PON).

RFSQUID-Mediated Coherent Tunable Coupling Between a Superconducting Phase Qubit and a Lumped Element Resonator

DTIC Science & Technology

2010-02-02

b). We approximate the Hamiltonian of our system using the Jaynes - Cummings model in the rotating - wave approxima- tion, Ĥ = Ĥq + Ĥr + ĤI(Φx) + Ĥ...when the coupler circulating cur- rent is at the critical current. It is also worth noting that in the limit that c → 1, (Meff )max increases without ...probability is approximately 10%, we can deter- mine the circulating current in the coupler as a function of Φx. Figure 2(a) shows the measured coupler

Unidirectional complex grating assisted couplers

NASA Astrophysics Data System (ADS)

Greenberg, Maxim; Orenstein, Meir

2004-08-01

We present a novel concept which enables the realization of unidirectional and irreversible grating assisted couplers by using gain-loss modulated medium to eliminate the reversibility. Employing a matched periodic modulation of both refractive index and loss (gain) we achieve a unidirectional energy transfer between the modes of the coupler which translates to light transmission from one waveguide to another while disabling the inverse transmission. The importance of self coupling coefficients is explored as well and a feasible implementation, where the real and imaginary perturbations are implemented in different waveguides is presented.

Monolithically integrated self-rolled-up microtube-based vertical coupler for three-dimensional photonic integration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Xin; Arbabi, Ehsan; Goddard, Lynford L.

2015-07-20

We demonstrate a self-rolled-up microtube-based vertical photonic coupler monolithically integrated on top of a ridge waveguide to achieve three-dimensional (3D) photonic integration. The fabrication process is fully compatible with standard planar silicon processing technology. Strong light coupling between the vertical coupler and the ridge waveguide was observed experimentally, which may provide an alternative route for 3D heterogeneous photonic integration. The highest extinction ratio observed in the transmission spectrum passing through the ridge waveguide was 23 dB.

Analysis of the car body stability performance after coupler jack-knifing during braking

NASA Astrophysics Data System (ADS)

Guo, Lirong; Wang, Kaiyun; Chen, Zaigang; Shi, Zhiyong; Lv, Kaikai; Ji, Tiancheng

2018-06-01

This paper aims to improve car body stability performance by optimising locomotive parameters when coupler jack-knifing occurs during braking. In order to prevent car body instability behaviour caused by coupler jack-knifing, a multi-locomotive simulation model and a series of field braking tests are developed to analyse the influence of the secondary suspension and the secondary lateral stopper on the car body stability performance during braking. According to simulation and test results, increasing secondary lateral stiffness contributes to limit car body yaw angle during braking. However, it seriously affects the dynamic performance of the locomotive. For the secondary lateral stopper, its lateral stiffness and free clearance have a significant influence on improving the car body stability capacity, and have less effect on the dynamic performance of the locomotive. An optimised measure was proposed and adopted on the test locomotive. For the optimised locomotive, the lateral stiffness of secondary lateral stopper is increased to 7875 kN/m, while its free clearance is decreased to 10 mm. The optimised locomotive has excellent dynamic and safety performance. Comparing with the original locomotive, the maximum car body yaw angle and coupler rotation angle of the optimised locomotive were reduced by 59.25% and 53.19%, respectively, according to the practical application. The maximum derailment coefficient was 0.32, and the maximum wheelset lateral force was 39.5 kN. Hence, reasonable parameters of secondary lateral stopper can improve the car body stability capacity and the running safety of the heavy haul locomotive.

Monitoring well

DOEpatents

Hubbell, Joel M.; Sisson, James B.

1999-01-01

A monitoring well including a conduit defining a passageway, the conduit having a proximal and opposite, distal end; a coupler connected in fluid flowing relationship with the passageway; and a porous housing borne by the coupler and connected in fluid flowing relation thereto.

While drilling system and method

DOEpatents

Mayes, James C.; Araya, Mario A.; Thorp, Richard Edward

2007-02-20

A while drilling system and method for determining downhole parameters is provided. The system includes a retrievable while drilling tool positionable in a downhole drilling tool, a sensor chassis and at least one sensor. The while drilling tool is positionable in the downhole drilling tool and has a first communication coupler at an end thereof. The sensor chassis is supported in the drilling tool. The sensor chassis has a second communication coupler at an end thereof for operative connection with the first communication coupler. The sensor is positioned in the chassis and is adapted to measure internal and/or external parameters of the drilling tool. The sensor is operatively connected to the while drilling tool via the communication coupler for communication therebetween. The sensor may be positioned in the while drilling tool and retrievable with the drilling tool. Preferably, the system is operable in high temperature and high pressure conditions.

Design of the new couplers for C-ADS RFQ

NASA Astrophysics Data System (ADS)

Shi, Ai-Min; Sun, Lie-Peng; Zhang, Zhou-Li; Xu, Xian-Bo; Shi, Long-Bo; Li, Chen-Xing; Wang, Wen-Bin

2015-04-01

A new special coupler with a kind of bowl-shaped ceramic window for a proton linear accelerator named the Chinese Accelerator Driven System (C-ADS) at the Institute of Modern Physics (IMP) has been simulated and constructed and a continuous wave (CW) beam commissioning through a four-meter long radio frequency quadruple (RFQ) was completed by the end of July 2014. In the experiments of conditioning and beam, some problems were promoted gradually such as sparking and thermal issues. Finally, two new couplers were passed with almost 110 kW CW power and 120 kW pulsed mode, respectively. The 10 mA intensity beam experiments have now been completed, and the couplers during the operation had no thermal or electro-magnetic problems. The detailed design and results are presented in the paper. Supported by Strategic Priority Research Program of Chinese Academy of Sciences (XDA03020500)

(abstract) The Design of a Benign Fail-safe Mechanism Using a Low-melting-point Metal Alloy Coupler

NASA Technical Reports Server (NTRS)

Blomquist, Richard S.

1995-01-01

Because the alpha proton X ray spectrometer (APXS) sensor head on the Mars Pathfinder rover, Sojourner, is placed on Martian soil by the deployment mechanism (ADM), the rover would be crippled if the actuator fails when the mechanism is in its deployed position, as rover ground clearance is then reduced to zero. This paper describes the unique fail-safe mounted on the ADM, especially the use of a low-temperature-melting alloy as a coupler device. The final form of the design is a low-melting-point metal pellet coupler, made from Cerrobend, in parallel with a Negator spring pack. In its solid state, the metal rigidly connects the driver (the actuator) and the driven part (the mechanism). When commanded, a strip heater wrapped around the coupler melts the metal pellet (at 60(deg)C), allowing the driven part to turn independent of the driver. The Negator spring retracts the mechanism to its fully stowed position. This concept meets all the design criteria, and provides an added benefit. When the metal hardens the coupler once again rigidly connects the actuator and the mechanism. The concept presented here can easily be applied to other applications. Anywhere release devices are needed, low-melting-point couplers can be considered. The issues to be concerned with are thermal isolation, proper setting of the parts before actuation, and possible outgassing concerns. However, when these issues are overcome, the resulting release mechanism can promise to be the most light, simple, power conserving alternative available.

Four-Pass Coupler for Laser-Diode-Pumped Solid-State Laser

NASA Technical Reports Server (NTRS)

Coyle, Donald B.

2008-01-01

A four-pass optical coupler affords increased (in comparison with related prior two-pass optical couplers) utilization of light generated by a laser diode in side pumping of a solid-state laser slab. The original application for which this coupler was conceived involves a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal slab, which, when pumped by a row of laser diodes at a wavelength of 809 nm, lases at a wavelength of 1,064 nm. Heretofore, typically, a thin laser slab has been pumped in two passes, the second pass occurring by virtue of reflection of pump light from a highly reflective thin film on the side opposite the side through which the pump light enters. In two-pass pumping, a Nd:YAG slab having a thickness of 2 mm (which is typical) absorbs about 84 percent of the 809-nm pump light power, leaving about 16 percent of the pump light power to travel back toward the laser diodes. This unused power can cause localized heating of the laser diodes, thereby reducing their lifetimes. Moreover, if the slab is thinner than 2 mm, then even more unused power travels back toward the laser diodes. The four-pass optical coupler captures most of this unused pump light and sends it back to the laser slab for two more passes. As a result, the slab absorbs more pump light, as though it were twice as thick. The gain and laser cavity beam quality of a smaller laser slab in conjunction with this optical coupler can thus be made comparable to those of a larger two-pass-pumped laser slab.

Design and experiment of a directional coupler for X-band long pulse high power microwaves.

PubMed

Bai, Zhen; Li, Guolin; Zhang, Jun; Jin, Zhenxing

2013-03-01

Higher power and longer pulse are the trend of the development of high power microwave (HPM), and then some problems emerge in measuring the power of HPM because rf breakdown is easier to occur under the circumstance of high power (the level of gigawatt) and long pulse (about 100 ns). In order to measure the power of the dominant TM₀₁ mode of an X-band long pulse overmoded HPM source, a directional coupler with stable coupling coefficient, high directivity, and high power handling capacity in wide band is investigated numerically and experimentally. At the central frequency 9.4 GHz, the simulation results show that the coupling coefficient is -59.6 dB with the directivity of 35 dB and the power handling capacity of 2 GW. The coupling coefficient is calibrated to be accordant with the simulation results. The high power tests are performed on an X-band long pulse HPM source, whose output mode is mainly TM₀₁ mode, and the results show that the measured power and waveform of the directional coupler have a good consistency with the far-field measuring results.

Dynamic optical coupled system employing Dammann gratings

NASA Astrophysics Data System (ADS)

Di, Caihui; Zhou, Changhe; Ru, Huayi

2004-10-01

With the increasing of the number of users in optical fiber communications, fiber-to-home project has a larger market value. Then the need of dynamic optical couplers, especially of N broad-band couplers, becomes greater. Though some advanced fiber fusion techniques have been developed, they still have many shortcomings. In this paper we propose a dynamic optical coupled system employing even-numbered Dammann gratings, which have the characteristic that the phase distribution in the first half-period accurately equals to that in the second-period with π phase inversion. In our experiment, we divide a conventional even-numbered Dammann grating into two identical gratings. The system can achieve the beam splitter and combiner as the switch between them according to the relative shift between two complementary gratings. When there is no shift between the gratings, the demonstrated 1×8 dynamic optical coupler achieves good uniformity of 0.06 and insertion loss of around 10.8 dB for each channel as a splitter. When the two gratings have an accurate shift of a half-period between them, our system has a low insertion loss of 0.46 dB as a combiner at a wavelength of 1550 nm.

46 CFR 39.10-5 - Incorporation by reference-TB/ALL.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., 1 rue de Varembé, Geneva, Switzerland IEC 309-1—Plugs, Socket-Outlets and Couplers for Industrial Purposes: Part 1, General Requirements, 1979 39.20-9 IEC 309-2—Plugs, Socket-Outlets and Couplers for...

46 CFR 39.10-5 - Incorporation by reference-TB/ALL.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., 1 rue de Varembé, Geneva, Switzerland IEC 309-1—Plugs, Socket-Outlets and Couplers for Industrial Purposes: Part 1, General Requirements, 1979 39.20-9 IEC 309-2—Plugs, Socket-Outlets and Couplers for...

46 CFR 39.10-5 - Incorporation by reference-TB/ALL.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., 1 rue de Varembé, Geneva, Switzerland IEC 309-1—Plugs, Socket-Outlets and Couplers for Industrial Purposes: Part 1, General Requirements, 1979 39.20-9 IEC 309-2—Plugs, Socket-Outlets and Couplers for...

Redesign of the End Group in the 3.9 GHz LCLS-II Cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lunin, Andrei; Gonin, Ivan; Khabiboulline, Timergali

Development and production of Linac Coherent Light Source II (LCLS-II) is underway. The central part of LCLS-II is a continuous wave superconducting RF (CW SCRF) electron linac. The 3.9 GHz third harmonic cavity similar to the XFEL design will be used in LCLS-II for linearizing the longitudinal beam profile*. The initial design of the 3.9 GHz cavity developed for XFEL project has a large, 40 mm, beam pipe aperture for better higher-order mode (HOM) damping. It is resulted in dipole HOMs with frequencies nearby the operating mode, which causes difficulties with HOM coupler notch filter tuning. The CW linac operationmore » requires an extra caution in the design of the HOM coupler in order to prevent its possible overheating. In this paper we present the modified 3.9 GHz cavity End Group for meeting the LCLS-II requirements« less

Waveguide Multimode Directional Coupler for Harvesting Harmonic Power from the Output of Traveling-Wave Tube Amplifiers

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2017-01-01

This paper presents the design, fabrication, and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from dissimilar frequency band waveguides, is capable of isolating power at the 2nd harmonic frequency from the fundamental power at the output port of traveling-wave tube amplifiers. Test results from proof-of-concept demonstrations are presented for Ku/Ka-band and Ka/E-band MDCs, which demonstrate sufficient power in the 2nd harmonic for a space borne beacon source for mm-wave atmospheric propagation studies.

Waveguide Multimode Directional Coupler for Harvesting Harmonic Power from the Output of Traveling-Wave Tube Amplifiers

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2017-01-01

The paper presents the design, fabrication, and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from dissimilar frequency band waveguides, is capable of isolating power at the 2nd harmonic frequency from the fundamental power at the output port of a high power traveling-wave tube amplifier. The major advantage of the MDC is significantly lower insertion loss compared to a diplexer. The presentation slides for the paper that was approved is attached. The tracking number for the paper that was approved is TN 37015.

Deriving the real-ear SPL of audiometric data using the "coupler to dial difference" and the "real ear to coupler difference".

PubMed

Munro, K J; Davis, J

2003-04-01

The purpose of the study was to compare the measured real-ear sound pressure level (SPL) of audiometer output with the derived real-ear SPL obtained by adding the coupler to dial difference (CDD) and real-ear to coupler difference (RECD) to the audiometer dial reading. The real-ear SPL and RECD were measured in one ear of 16 normally hearing subjects using a probe-tube microphone. The CDD transform and the RECD transfer function were measured in an HA1 and an HA2 2-cc coupler using an EAR-LINK foam ear-tip or a customized earmold. The RECD transfer function was measured using the EARTone ER 3A and the Audioscan RE770 insert earphone. The procedures were very reliable with mean differences on retest of less than 1 dB. The mean difference between the measured and derived real-ear SPL was generally less than 1 dB and rarely exceeded 3 dB in any subject. The CDD measured for an individual audiometer and the RECD measured for an individual ear can be used to derive a valid estimate of real-ear SPL when it has not been possible to measure this directly.

Modeling of a Single-Notch Microfiber Coupler for High-Sensitivity and Low Detection-Limit Refractive Index Sensing.

PubMed

Zhang, Jiali; Shi, Lei; Zhu, Song; Xu, Xinbiao; Zhang, Xinliang

2016-05-11

A highly sensitive refractive index sensor with low detection limit based on an asymmetric optical microfiber coupler is proposed. It is composed of a silica optical microfiber and an As₂Se₃ optical microfiber. Due to the asymmetry of the microfiber materials, a single-notch transmission spectrum is demonstrated by the large refractive index difference between the two optical microfibers. Compared with the symmetric coupler, the bandwidth of the asymmetric structure is over one order of magnitude narrower than that of the former. Therefore, the asymmetric optical microfiber coupler based sensor can reach over one order of magnitude smaller detection limit, which is defined as the minimal detectable refractive index change caused by the surrounding analyte. With the advantage of large evanescent field, the results also show that a sensitivity of up to 3212 nm per refractive index unit with a bandwidth of 12 nm is achieved with the asymmetric optical microfiber coupler. Furthermore, a maximum sensitivity of 4549 nm per refractive index unit can be reached while the radii of the silica optical microfiber and As₂Se₃ optical microfiber are 0.5 μm and a 0.128 μm, respectively. This sensor component may have important potential for low detection-limit physical and biochemical sensing applications.

Analysis and design of arrayed waveguide gratings with MMI couplers.

PubMed

Munoz, P; Pastor, D; Capmany, J

2001-09-24

We present an extension of the AWG model and design procedure described in [1] to incorporate multimode interference, MMI, couplers. For the first time to our knowledge, a closed formula for the passing bands bandwidth and crosstalk estimation plots are derived.

Monitoring well

DOEpatents

Hubbell, J.M.; Sisson, J.B.

1999-06-29

A monitoring well is described which includes: a conduit defining a passageway, the conduit having a proximal and opposite, distal end; a coupler connected in fluid flowing relationship with the passageway; and a porous housing borne by the coupler and connected in fluid flowing relation thereto. 8 figs.

Variable frequency microwave furnace system

DOEpatents

Bible, D.W.; Lauf, R.J.

1994-06-14

A variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency microwave furnace system includes a microwave signal generator or microwave voltage-controlled oscillator for generating a low-power microwave signal for input to the microwave furnace. A first amplifier may be provided to amplify the magnitude of the signal output from the microwave signal generator or the microwave voltage-controlled oscillator. A second amplifier is provided for processing the signal output by the first amplifier. The second amplifier outputs the microwave signal input to the furnace cavity. In the preferred embodiment, the second amplifier is a traveling-wave tube (TWT). A power supply is provided for operation of the second amplifier. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. 5 figs.

Surface normal coupling to multiple-slot and cover-slotted silicon nanocrystalline waveguides and ring resonators

NASA Astrophysics Data System (ADS)

Covey, John; Chen, Ray T.

2014-03-01

Grating couplers are ideal for coupling into the tightly confined propagation modes of semiconductor waveguides. In addition, nonlinear optics has benefited from the sub-diffraction limit confinement of horizontal slot waveguides. By combining these two advancements, slot-based nonlinear optics with mode areas less than 0.02 μm2 can become as routine as twisting fiber connectors together. Surface normal fiber alignment to a chip is also highly desirable from time, cost, and manufacturing considerations. To meet these considerable design challenges, a custom genetic algorithm is created which, starting from purely random designs, creates a unique four stage grating coupler for two novel horizontal slot waveguide platforms. For horizontal multiple-slot waveguides filled with silicon nanocrystal, a theoretical fiber-towaveguide coupling efficiency of 68% is obtained. For thin silicon waveguides clad with optically active silicon nanocrystal, known as cover-slot waveguides, a theoretical fiber-to-waveguide coupling efficiency of 47% is obtained, and 1 dB and 3 dB theoretical bandwidths of 70 nm and 150 nm are obtained, respectively. Both waveguide platforms are fabricated from scratch, and their respective on-chip grating couplers are experimentally measured from a standard single mode fiber array that is mounted surface normally. The horizontal multiple-slot grating coupler achieved an experimental 60% coupling efficiency, and the horizontal cover-slot grating coupler achieved an experimental 38.7% coupling efficiency, with an extrapolated 1 dB bandwidth of 66 nm. This report demonstrates the promise of genetic algorithm-based design by reducing to practice the first large bandwidth vertical grating coupler to a novel silicon nanocrystal horizontal cover-slot waveguide.

Design of photonic phased array switches using nano electromechanical systems on silicon-on-insulator integration platform

NASA Astrophysics Data System (ADS)

Hussein, Ali Abdulsattar

This thesis presents an introduction to the design and simulation of a novel class of integrated photonic phased array switch elements. The main objective is to use nano-electromechanical (NEMS) based phase shifters of cascaded under-etched slot nanowires that are compact in size and require a small amount of power to operate them. The structure of the switch elements is organized such that it brings the phase shifting elements to the exterior sides of the photonic circuits. The transition slot couplers, used to interconnect the phase shifters, are designed to enable biasing one of the silicon beams of each phase shifter from an electrode located at the side of the phase shifter. The other silicon beam of each phase shifter is biased through the rest of the silicon structure of the switch element, which is taken as a ground. Phased array switch elements ranging from 2x2 up to 8x8 multiple-inputs/multiple-outputs (MIMO) are conveniently designed within reasonable footprints native to the current fabrication technologies. Chapter one presents the general layout of the various designs of the switch elements and demonstrates their novel features. This demonstration will show how waveguide disturbances in the interconnecting network from conventional switch elements can be avoided by adopting an innovative design. Some possible applications for the designed switch elements of different sizes and topologies are indicated throughout the chapter. Chapter two presents the design of the multimode interference (MMI) couplers used in the switch elements as splitters, combiners and waveguide crossovers. Simulation data and design methodologies for the multimode couplers of interest are detailed in this chapter. Chapter three presents the design and analysis of the NEMS-operated phase shifters. Both simulations and numerical analysis are utilized in the design of a 0°-180° capable NEMS-operated phase shifter. Additionally, the response of some of the designed photonic phased array switch elements is demonstrated in this chapter. An executive summary and conclusions sections are also included in the thesis.

Fluid powered linear piston motor with harmonic coupling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raymond, David W.

2016-09-20

A motor is disclosed that includes a module assembly including a piston that is axially cycled. The piston axial motion is coupled to torque couplers that convert the axial motion into rotary motion. The torque couplers are coupled to a rotor to rotate the rotor.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dowell, David

It is well-known that the electron beam quality required for applications such as FEL’s and ultra-fast electron diffraction can be degraded by the asymmetric fields introduced by the RF couplers of superconducting linacs. This effect is especially troublesome in the injector where the low energy beam from the gun is captured into the first high gradient accelerator section. Unfortunately modifying the established cavity design is expensive and time consuming, especially considering that only one or two sections are needed for an injector. Instead, it is important to analyze the coupler fields to understand their characteristics and help find less costlymore » solutions for their cancellation and mitigation. This paper finds the RF coupler-induced emittance for short bunches is mostly due to the transverse spatial sloping or tilt of the field, rather than the field’s time-dependence. It is shown that the distorting effects of the coupler can be canceled with a static (DC) quadrupole lens rotated about the z-axis.« less

Implementation of a diode-pumped Nd:YAG laser with quick-change output couplers for high-beam quality 1064 or 532 nm wavelength generation

NASA Astrophysics Data System (ADS)

Li, Chun-Hao; Tsai, Ming-Jong

2009-06-01

A novel diode-pumped Nd:YAG laser system that employs a fixed active laser medium and a pair of quick-change output couplers on a precision linear stage for 1064 or 532 nm wavelength generation is presented. Fixed elements include a rear mirror, an acousto-optical Q-switch, and a diode-pumped solid-state laser (DPSSL). Movable elements for 1064 nm generation include an intra-cavity aperture as a mode selection element (MSE) and an output coupler. Movable elements for 532 nm generation include an intra-cavity frequency conversion with KTP, an intra-cavity aperture as a mode selection element (MSE), and an output coupler. Under stable operating conditions, the 1064 nm configuration produced a beam propagation ratio of 1.18 whereas the 532 nm configuration produced a beam propagation ratio of 1.1, both of which used an intra-cavity MSE with an aperture of 1.2 mm and a length of 5 mm.

Tunable negative-tap photonic microwave filter based on a cladding-mode coupler and an optically injected laser of large detuning.

PubMed

Chan, Sze-Chun; Liu, Qing; Wang, Zhu; Chiang, Kin Seng

2011-06-20

A tunable negative-tap photonic microwave filter using a cladding-mode coupler together with optical injection locking of large wavelength detuning is demonstrated. Continuous and precise tunability of the filter is realized by physically sliding a pair of bare fibers inside the cladding-mode coupler. Signal inversion for the negative tap is achieved by optical injection locking of a single-mode semiconductor laser. To couple light into and out of the cladding-mode coupler, a pair of matching long-period fiber gratings is employed. The large bandwidth of the gratings requires injection locking of an exceptionally large wavelength detuning that has never been demonstrated before. Experimentally, injection locking with wavelength detuning as large as 27 nm was achieved, which corresponded to locking the 36-th side mode. Microwave filtering with a free-spectral range tunable from 88.6 MHz to 1.57 GHz and a notch depth larger than 35 dB was obtained.

High-directionality fiber-chip grating coupler with interleaved trenches and subwavelength index-matching structure.

PubMed

Benedikovic, Daniel; Alonso-Ramos, Carlos; Cheben, Pavel; Schmid, Jens H; Wang, Shurui; Xu, Dan-Xia; Lapointe, Jean; Janz, Siegfried; Halir, Robert; Ortega-Moñux, Alejandro; Wangüemert-Pérez, J Gonzalo; Molina-Fernández, Iñigo; Fédéli, Jean-Marc; Vivien, Laurent; Dado, Milan

2015-09-15

We present the first experimental demonstration of a new fiber-chip grating coupler concept that exploits the blazing effect by interleaving the standard full (220 nm) and shallow etch (70 nm) trenches in a 220 nm thick silicon layer. The high directionality is obtained by controlling the separation between the deep and shallow trenches to achieve constructive interference in the upward direction and destructive interference toward the silicon substrate. Utilizing this concept, the grating directionality can be maximized independent of the bottom oxide thickness. The coupler also includes a subwavelength-engineered index-matching region, designed to reduce the reflectivity at the interface between the injection waveguide and the grating. We report a measured fiber-chip coupling efficiency of -1.3  dB, the highest coupling efficiency achieved to date for a surface grating coupler in a 220 nm silicon-on-insulator platform fabricated in a conventional dual-etch process without high-index overlays or bottom mirrors.

Laboratory investigation of grouted coupler connection details for ABC bridge projects : [tech transfer summary].

DOT National Transportation Integrated Search

2015-08-01

Advancements and increased use of accelerated bridge construction (ABC) : often result in the use of newly developed, or modified, technologies and/or : construction techniques that are sometimes untested in this new application. : For designers and ...

Conductive surge testing of circuits and systems

NASA Technical Reports Server (NTRS)

Richman, P.

1980-01-01

Techniques are given for conductive surge testing of powered electronic equipment. The correct definitions of common and normal mode are presented. Testing requires not only spike-surge generators with a suitable range of open-circuit voltage and short-circuit current waveshapes, but also appropriate means, termed couplers, for connecting test surges to the equipment under test. Key among coupler design considerations is minimization of fail positives resulting from reduction in delivered surge energy due to the coupler. Back-filters and the lines on which they are necessary, are considered as well as ground-fault and ground potential rise. A method for monitoring delivered and resulting surge waves is mentioned.

Silicon Nitride Grating Coupler with Flexible Bandwidth Incorporating a Serially Concatenated Multimode Interference Filter

NASA Astrophysics Data System (ADS)

Kim, Woo-Ju; Lee, Hak-Soon; Lee, Sang-Shin

2012-04-01

A compact silicon nitride grating coupler with flexible bandwidth was demonstrated taking advantage of a basic grating integrated with a serially connected multistage multimode interference (MMI) filter. The spectral response could be tailored by varying the order of the MMI filter, without affecting the basic grating structure. The dependence of the spectral response of the proposed device on the order of the MMI stage was thoroughly investigated. As regards the fabricated grating coupler with a four-stage MMI filter, the observed spectral bandwidth was efficiently altered from 53 to 21 nm in the ˜1550 nm spectral band.

Modal noise in multimode optical fibers

NASA Astrophysics Data System (ADS)

Rawson, E. G.; Goodman, J. W.

1983-03-01

A changing speckle pattern exists at the output of a multimode optical fiber if the optical source is sufficiently coherent. When spatial filtration (for example, at a misaligned connector) or polarization filtration (for example, in certain access couplers) occurs in the presence of such speckle, the optical signal power fluctuates; such fluctuations are called 'modal noise'. This paper reviews modal noise theory and experiment, including the prediction and measurement of the modal noise signal-to-noise ratio in the presence of spatial filtration and constrained total guided power. It also presents new results relating to modal noise effects in fiber branching devices such as star couplers, access couplers, and power dividers.

Noise characteristics of passive components for phased array applications

NASA Technical Reports Server (NTRS)

Sonmez, M. Kemal; Trew, Robert J.

1991-01-01

The results of a comparative study on noise characteristics of basic power combining/dividing and phase shifting schemes are presented. The theoretical basics of thermal noise in a passive linear multiport are discussed. A new formalism is presented to describe the noise behavior of the passive circuits, and it is shown that the fundamental results are conveniently achieved using this description. The results of analyses concerning the noise behavior of basic power combining/dividing structures (the Wilkinson combiner, 90 deg hybrid coupler, hybrid ring coupler, and the Lange coupler) are presented. Three types of PIN-diode switch phase shifters are analyzed in terms of noise performance.

Flexible polymeric rib waveguide with self-align couplers system

PubMed Central

Huang, Cheng-Sheng; Wang, Wei-Chih

2011-01-01

The authors report a polymeric based rib waveguide with U shape self-align fiber couplers system using a simple micromolding process with SU8 as a molding material and polydimethysiloxane as a waveguide material. The material is used for its good optical transparency, low surface tension, biocompatibility, and durability. Furthermore, the material is highly formable. This unique fabrication molding technique provides a means of keeping the material and manufacturing costs to a minimum. The self-align fiber couplers system also proves a fast and simple means of light coupling. The flexible nature of the waveguide material makes this process ideal for a potential wearable optical sensor. PMID:22171151

Tissue Viscoelasticity Imaging Using Vibration and Ultrasound Coupler Gel

NASA Astrophysics Data System (ADS)

Yamakawa, Makoto; Shiina, Tsuyoshi

2012-07-01

In tissue diagnosis, both elasticity and viscosity are important indexes. Therefore, we propose a method for evaluating tissue viscoelasticity by applying vibration that is usually performed in elastography and using an ultrasound coupler gel with known viscoelasticity. In this method, we use three viscoelasticity parameters based on the coupler strain and tissue strain: the strain ratio as an elasticity parameter, and the phase difference and the normalized hysteresis loop area as viscosity parameters. In the agar phantom experiment, using these viscoelasticity parameters, we were able to estimate the viscoelasticity distribution of the phantom. In particular, the strain ratio and the phase difference were robust to strain estimation error.

Ultralow loss, high Q, four port resonant couplers for quantum optics and photonics.

PubMed

Rokhsari, H; Vahala, K J

2004-06-25

We demonstrate a low-loss, optical four port resonant coupler (add-drop geometry), using ultrahigh Q (>10(8)) toroidal microcavities. Different regimes of operation are investigated by variation of coupling between resonator and fiber taper waveguides. As a result, waveguide-to-waveguide power transfer efficiency of 93% (0.3 dB loss) and nonresonant insertion loss of 0.02% (<0.001 dB) for narrow bandwidth (57 MHz) four port couplers are achieved in this work. The combination of low-loss, fiber compatibility, and wafer-scale design would be suitable for a variety of applications ranging from quantum optics to photonic networks.

30 CFR 75.805 - Couplers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ground check continuity conductor shall be broken first and the ground conductors shall be broken last.... [Statutory Provisions] Couplers that are used with medium-voltage or high-voltage power circuits shall be of the three-phase type with a full metallic shell, except that the Secretary may permit, under such...

Reconfigurable Nano-Plasmonics Holography

DTIC Science & Technology

2013-04-01

conventional copper interconnects will no longer support increased clock speeds and the industry will enter a new regime of electronic interconnect... flotation ; 2) an in- coupler grating on one side of the beams, also in the top layer and also with the in- sulator removed beneath; 3) an out-coupler slit

33 CFR 154.106 - Incorporation by reference: Where can I get a copy of the publications incorporated by reference...

Code of Federal Regulations, 2013 CFR

2013-07-01

...) IEC 309-1—Plugs, Socket-Outlets and Couplers for Industrial Purposes: Part 1, General Requirements, 1979, IBR approved for § 154.812. (2) IEC 309-2—Plugs, Socket-Outlets and Couplers for Industrial...

Mode-routed fiber-optic add-drop filter

NASA Technical Reports Server (NTRS)

Moslehi, Behzad (Inventor); Black, Richard James (Inventor); Shaw, Herbert John (Inventor)

2000-01-01

New elements mode-converting two-mode grating and mode-filtering two-mode coupler are disclosed and used as elements in a system for communications, add-drop filtering, and strain sensing. Methods of fabrication for these new two-mode gratings and mode-filtering two-mode couplers are also disclosed.

49 CFR 238.307 - Periodic mechanical inspection of passenger cars and unpowered vehicles used in passenger trains.

Code of Federal Regulations, 2010 CFR

2010-10-01

...: (i) Emergency lighting systems required under § 238.115 are in place and operational; and (ii... type couplers (MCB contour 1904), or not more than 55/16 inches on D&E couplers; (ii) The free slack in...

Effects of Geometric Azimuthal Asymmetries of the PPM Stack on Electron Beam Characteristics

NASA Technical Reports Server (NTRS)

Kory, Carol L.

2000-01-01

The effects of geometric azimuthally asymmetric properties of a periodic permanent magnet (PPM) focusing stack on electron beam characteristics obtained using a fully three dimensional (3D) particle-in-cell (PIC) code will be presented. The simulation model, using MAFIA (Solution of MAxwell's equations by the Finite-Integration-Algorithm), incorporates 3D behavior of the beam immersed in static fields calculated directly from the exact geometry and material properties of the 3D magnetic focusing structure. The Hughes 8916H, 18-40 GHz helical TWT for the millimeter-wave power module (MMPM) was used as a prototype. Firstly, the effects of C-magnets used at the input and output of the TWT to allow for coupling of the RF signal into and out of the tube are considered. The 8916H input and output C-magnets differ because coaxial couplers are used at the input and waveguide couplers are used at the output The repositioning of the beam from its central axis due to the inclusion of the output C-magnet was found to be most significant. The modeled output C-magnet and its orientation in the Cartesian coordinate system is shown, and a two-dimensional beam profile including the output C-magnet is also shown. A table presents the shift of the beam center off the central axis relative to the average radius of the beam at the longitudinal points A, B and C designated on an enclosed figure. Secondly, the addition of shunts, or rectangular iron pieces applied manually by a skilled technician in order to improve beam transmission, is considered. The shunts are applied to the top of the tube; thus, azimuthal symmetry of the focusing stack is interrupted. Although shunts are typically added during RF focusing, they are also typically added at the input section of the tube where RF forces are minimal, making an electron optics analysis meaningful. Because several shunts are usually applied to one pole piece, the simulations have been simplified by modeling a half washer with the same radius and longitudinal length as a shunt over the entire x, positive-y half of the transverse plane. A modeled pole piece and shunt as described are shown. Lastly, in order to study the effects of magnet misalignments, a magnet in the PPM stack was arbitrarily chosen and adjusted so that its central axis was shifted both 0.7 percent and 1.0 percent of the magnet outer diameter in the positive-y direction. In practice, positioning the magnets so that their central axis is accurately aligned with the central axis of the tube is challenging. Thus, it is a strong possibility that one or more magnets will be misaligned relative to the tube central axis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halavanau, Aliaksei; Eddy, Nathan; Edstrom, Dean

Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread application in Science and Industry. Many current and planned projects employ 1.3-GHz 9-cell superconducting cavities of the TESLA design*. In the present paper we discuss the transverse-focusing properties of such a cavity and non-ideal transverse-map effects introduced by field asymmetries in the vicinity of the input and high-order-mode radiofrequency (RF) couplers**. We especially consider the case of a cavity located downstream of an RF-gun in a setup similar to the photoinjector of the Fermilab Accelerator Science and Technology (FAST) facility. Preliminary experimental measurements of the CC2more » cavity transverse matrix were carried out at the FAST facility. The results are discussed and compared with analytical and numerical simulations.« less

Applications Of A Fibre Optic TV Holography System To The Study Of Large Automotive Structures.

NASA Astrophysics Data System (ADS)

Davies, Jeremy C.; Buckberry, Clive H.

1990-04-01

Mono-mode fibre optic components, including directional couplers and piezo-electric phase control elements, have been used to construct a TV holography system. The instrument has advantages of simplicity and ruggedness of construction and, with a 40m fibre optic link to a 600m argon ion laser, has proved to be an ideal tool for studying the structural behaviour of automotive assemblies. The TV holography system is described and two examples presented of its use: analysis of the deformation of a petrol engine cylinder bore due to head bolt forces, and the vibration study of a vehicle bodyshell subjected to wheel induced inputs. Limitations in the application of the technique are identified and future work to address these shortcomings outlined.

The pulsed dye laser versus the Q-switched Nd:YAG laser in laser-induced shock-wave lithotripsy.

PubMed

Thomas, S; Pensel, J; Engelhardt, R; Meyer, W; Hofstetter, A G

1988-01-01

To date, there are two fairly well-established alternatives for laser-induced shock-wave lithotripsy in clinical practice. The Q-switched Nd:YAG laser is distinguished by the high-stone selectivity of its coupler systems. The necessity of a coupler system and its fairly small conversion rate of light energy into mechanical energy present serious drawbacks. Furthermore, the minimal outer diameter of the transmission system is 1.8 mm. The pulsed-dye laser can be used with a highly flexible and uncomplicated 200-micron fiber. However, the laser system itself is more complicated than the Q-switched Nd:YAG laser and requires a great deal of maintenance. Biological evaluation of damage caused by direct irradiation shows that both laser systems produce minor damage of different degrees. YAG laser lithotripsy with the optomechanical coupler was assessed in 31 patients with ureteral calculi. The instability and limited effectiveness of the fiber application system necessitated auxiliary lithotripsy methods in 14 cases. Dye-laser lithotripsy is currently being tested in clinical application. Further development, such as systems for blind application or electronic feedback mechanisms to limit adverse tissue effects, have yet to be optimized. Nevertheless, laser-induced shock-wave lithotripsy has the potential to become a standard procedure in the endourologic management of stone disease.

Establishment and verification of three-dimensional dynamic model for heavy-haul train-track coupled system

NASA Astrophysics Data System (ADS)

Liu, Pengfei; Zhai, Wanming; Wang, Kaiyun

2016-11-01

For the long heavy-haul train, the basic principles of the inter-vehicle interaction and train-track dynamic interaction are analysed firstly. Based on the theories of train longitudinal dynamics and vehicle-track coupled dynamics, a three-dimensional (3-D) dynamic model of the heavy-haul train-track coupled system is established through a modularised method. Specifically, this model includes the subsystems such as the train control, the vehicle, the wheel-rail relation and the line geometries. And for the calculation of the wheel-rail interaction force under the driving or braking conditions, the large creep phenomenon that may occur within the wheel-rail contact patch is considered. For the coupler and draft gear system, the coupler forces in three directions and the coupler lateral tilt angles in curves are calculated. Then, according to the characteristics of the long heavy-haul train, an efficient solving method is developed to improve the computational efficiency for such a large system. Some basic principles which should be followed in order to meet the requirement of calculation accuracy are determined. Finally, the 3-D train-track coupled model is verified by comparing the calculated results with the running test results. It is indicated that the proposed dynamic model could simulate the dynamic performance of the heavy-haul train well.

49 CFR 215.123 - Defective couplers.

Code of Federal Regulations, 2010 CFR

2010-10-01

... automatically with the adjacent car; (b) The car has a coupler that has a crack in the highly stressed junction... knuckle that is broken or cracked on the inside pulling face of the knuckle. (d) The car has a knuckle pin...) Missing; (ii) Inoperative; (iii) Bent; (iv) Cracked; or (v) Broken. ...

49 CFR 215.123 - Defective couplers.

Code of Federal Regulations, 2011 CFR

2011-10-01

... automatically with the adjacent car; (b) The car has a coupler that has a crack in the highly stressed junction... knuckle that is broken or cracked on the inside pulling face of the knuckle. (d) The car has a knuckle pin...) Missing; (ii) Inoperative; (iii) Bent; (iv) Cracked; or (v) Broken. ...

33 CFR 154.106 - Incorporation by reference: Where can I get a copy of the publications incorporated by reference...

Code of Federal Regulations, 2011 CFR

2011-07-01

...://www.iec.ch/: (1) IEC 309-1—Plugs, Socket-Outlets and Couplers for Industrial Purposes: Part 1, General Requirements, 1979, IBR approved for § 154.812. (2) IEC 309-2—Plugs, Socket-Outlets and Couplers for Industrial...

33 CFR 154.106 - Incorporation by reference: Where can I get a copy of the publications incorporated by reference...

Code of Federal Regulations, 2012 CFR

2012-07-01

...://www.iec.ch/: (1) IEC 309-1—Plugs, Socket-Outlets and Couplers for Industrial Purposes: Part 1, General Requirements, 1979, IBR approved for § 154.812. (2) IEC 309-2—Plugs, Socket-Outlets and Couplers for Industrial...

Effects of coupler height mismatch on the structural integrity of railroad tank car stub sills.

DOT National Transportation Integrated Search

2001-12-01

This project evaluated the safety implications of coupler height mismatches on the integrity of railroad tank car stub sills, through a series of static and impact tests. The test car was a loaded tank car instrumented with strain gages at critical l...

49 CFR 178.337-3 - Structural integrity.

Code of Federal Regulations, 2013 CFR

2013-10-01

... each case, the forces applied must be 0.35 times the vertical reaction at the suspension assembly... assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel) or turntable; or... reaction at the suspension assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel...

49 CFR 178.337-3 - Structural integrity.

Code of Federal Regulations, 2012 CFR

2012-10-01

... each case, the forces applied must be 0.35 times the vertical reaction at the suspension assembly... assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel) or turntable; or... reaction at the suspension assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel...

49 CFR 178.337-3 - Structural integrity.

Code of Federal Regulations, 2014 CFR

2014-10-01

... each case, the forces applied must be 0.35 times the vertical reaction at the suspension assembly... assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel) or turntable; or... reaction at the suspension assembly of a trailer; or the horizontal pivot of the upper coupler (fifth wheel...

Subwavelength engineered fiber-to-chip silicon-on-sapphire interconnects for mid-infrared applications (Conference Presentation)

NASA Astrophysics Data System (ADS)

Alonso-Ramos, Carlos; Han, Zhaohong; Le Roux, Xavier; Lin, Hongtao; Singh, Vivek; Lin, Pao Tai; Tan, Dawn; Cassan, Eric; Marris-Morini, Delphine; Vivien, Laurent; Wada, Kazumi; Hu, Juejun; Agarwal, Anuradha; Kimerling, Lionel C.

2016-05-01

The mid-Infrared wavelength range (2-20 µm), so-called fingerprint region, contains the very sharp vibrational and rotational resonances of many chemical and biological substances. Thereby, on-chip absorption-spectrometry-based sensors operating in the mid-Infrared (mid-IR) have the potential to perform high-precision, label-free, real-time detection of multiple target molecules within a single sensor, which makes them an ideal technology for the implementation of lab-on-a-chip devices. Benefiting from the great development realized in the telecom field, silicon photonics is poised to deliver ultra-compact efficient and cost-effective devices fabricated at mass scale. In addition, Si is transparent up to 8 µm wavelength, making it an ideal material for the implementation of high-performance mid-IR photonic circuits. The silicon-on-insulator (SOI) technology, typically used in telecom applications, relies on silicon dioxide as bottom insulator. Unfortunately, silicon dioxide absorbs light beyond 3.6 µm, limiting the usability range of the SOI platform for the mid-IR. Silicon-on-sapphire (SOS) has been proposed as an alternative solution that extends the operability region up to 6 µm (sapphire absorption), while providing a high-index contrast. In this context, surface grating couplers have been proved as an efficient means of injecting and extracting light from mid-IR SOS circuits that obviate the need of cleaving sapphire. However, grating couplers typically have a reduced bandwidth, compared with facet coupling solutions such as inverse or sub-wavelength tapers. This feature limits their feasibility for absorption spectroscopy applications that may require monitoring wide wavelength ranges. Interestingly, sub-wavelength engineering can be used to substantially improve grating coupler bandwidth, as demonstrated in devices operating at telecom wavelengths. Here, we report on the development of fiber-to-chip interconnects to ZrF4 optical fibers and integrated SOS circuits with 500 nm thick Si, operating around 3.8 µm wavelength. Results on facet coupling and sub-wavelength engineered grating coupler solutions in the mid-IR regime will be compared.

Using the Real-Ear-to-Coupler Difference within the American Academy of Audiology Pediatric Amplification Guideline: Protocols for Applying and Predicting Earmold RECDs.

PubMed

Moodie, Sheila; Pietrobon, Jonathan; Rall, Eileen; Lindley, George; Eiten, Leisha; Gordey, Dave; Davidson, Lisa; Moodie, K Shane; Bagatto, Marlene; Haluschak, Meredith Magathan; Folkeard, Paula; Scollie, Susan

2016-03-01

Real-ear-to-coupler difference (RECD) measurements are used for the purposes of estimating degree and configuration of hearing loss (in dB SPL ear canal) and predicting hearing aid output from coupler-based measures. Accurate measurements of hearing threshold, derivation of hearing aid fitting targets, and predictions of hearing aid output in the ear canal assume consistent matching of RECD coupling procedure (i.e., foam tip or earmold) with that used during assessment and in verification of the hearing aid fitting. When there is a mismatch between these coupling procedures, errors are introduced. The goal of this study was to quantify the systematic difference in measured RECD values obtained when using a foam tip versus an earmold with various tube lengths. Assuming that systematic errors exist, the second goal was to investigate the use of a foam tip to earmold correction for the purposes of improving fitting accuracy when mismatched RECD coupling conditions occur (e.g., foam tip at assessment, earmold at verification). Eighteen adults and 17 children (age range: 3-127 mo) participated in this study. Data were obtained using simulated ears of various volumes and earmold tubing lengths and from patients using their own earmolds. Derived RECD values based on simulated ear measurements were compared with RECD values obtained for adult and pediatric ears for foam tip and earmold coupling. Results indicate that differences between foam tip and earmold RECDs are consistent across test ears for adults and children which support the development of a correction between foam tip and earmold couplings for RECDs that can be applied across individuals. The foam tip to earmold correction values developed in this study can be used to provide improved estimations of earmold RECDs. This may support better accuracy in acoustic transforms related to transforming thresholds and/or hearing aid coupler responses to ear canal sound pressure level for the purposes of fitting behind-the-ear hearing aids. American Academy of Audiology.

Structural and dynamic analysis of an ultra short intracavity directional coupler

NASA Astrophysics Data System (ADS)

Gravé, Ilan; Griffel, Giora; Daou, Youssef; Golan, Gadi

1997-01-01

A recently proposed intracavity directional coupler is analysed. Exact analytic expressions for important parameters such as the transmission ratio, the coupling length, and the photon lifetime are given. We show that by controlling the mirror reflectivities of the cavity, it is theoretically possible to reduce the coupling length to a zero limit. The photon lifetime, which governs the dynamic properties of the structure, sets an upper frequency limit of a few hundreds of GHz, which is well over the bandwidth limitation of microwave lumped or travelling wave electrodes. This novel family of intracavity couplers has important applications in the realization of integrated optics circuits for high-speed computing, data processing, and communication.

Low-crosstalk orbital angular momentum fiber coupler design.

PubMed

Zhang, Zhishen; Gan, Jiulin; Heng, Xiaobo; Li, Muqiao; Li, Jiong; Xu, Shanhui; Yang, Zhongmin

2017-05-15

A fiber coupler for low-crosstalk orbital angular momentum mode beam splitter is proposed with the structure of two separate and parallel microfibers. By properly setting the center-to-center distance between microfibers, the crosstalk is less than -20 dB, which means that the purity of the needed OAM mode in output port is higher than 99%. For a fixed overlapping length, high coupling efficiency (>97%) is achieved in 1545-1560 nm. The operating wavelength is tuned to the whole C-band by using the thermosensitive liquid. So the designed coupler can achieve the tunable coupling ratio over the whole C-band, which is a prospective component for the further OAM fiber system.

Analytical modeling and analysis of magnetic field and torque for novel axial flux eddy current couplers with PM excitation

NASA Astrophysics Data System (ADS)

Li, Zhao; Wang, Dazhi; Zheng, Di; Yu, Linxin

2017-10-01

Rotational permanent magnet eddy current couplers are promising devices for torque and speed transmission without any mechanical contact. In this study, flux-concentration disk-type permanent magnet eddy current couplers with double conductor rotor are investigated. Given the drawback of the accurate three-dimensional finite element method, this paper proposes a mixed two-dimensional analytical modeling approach. Based on this approach, the closed-form expressions of magnetic field, eddy current, electromagnetic force and torque for such devices are obtained. Finally, a three-dimensional finite element method is employed to validate the analytical results. Besides, a prototype is manufactured and tested for the torque-speed characteristic.

Study of Linearization of Optical Polymer Modulators

DTIC Science & Technology

2004-02-01

To improve the Spur Free Dynamic Range of analog electro - optic modulators in the 10 GHz regime, techniques for improving the linearity of these...devices must be developed. This report discusses an investigation into electro - optic directional couplers that use variable coupling in polymer-based

SOI ring resonators with controllable MMI coupler sections

NASA Astrophysics Data System (ADS)

Hu, Youfang; Gardes, Frédéric Y.; Mashanovich, Goran Z.; Reed, Graham T.

2011-01-01

A ring resonator using a single 2×2 MMI as the coupler section has the distinct advantages of low sensitivity to fabrication error, temperature, wavelength and polarisation. However, the coupling coefficient of the 2×2 MMI coupler is fixed; hence, the performance of this type of device is limited, e.g. transmission spectrum with high extinction ratio is difficult to achieve. We have designed and simulated ring resonators with coupler sections consisting of two 2×2 MMIs and phase shifters, so that the coupling efficiency can be varied from 0% to 100% with relative ease. For a single ring resonator, the transmission spectrum can be controlled to achieve an extinction ratio of >20dB and a spectral bandwidth of <1nm. For a multiple ring filter, the transmission spectrum can be controlled to achieve an extinction ratio of >30dB and a bandwidth of <1nm in addition, a flat-top transmission spectrum is also achievable. The whole device has a footprint of approximately 200μm by 100μm.

Strip gratings on dielectric substrates as output couplers for submillimeter lasers

NASA Astrophysics Data System (ADS)

Veron, D.; Whitbourn, L. B.

1986-03-01

This paper describes the use and advantages of metallic strip gratings on dielectric substrates as output couplers for both optically pumped and discharge-excited submillimeter lasers. Formulas are presented for the calculation of transmittance and loss of such couplers, taking account of loss in the strip grating as well as loss and multiple reflections in the substrate. Included are expressions for the phase shifts on reflection and transmission by an arbitrary lossy grid on a plane boundary between two dielectrics, according to a transmission-line model that is applicable for wavelengths in both dielectrics longer than the grid period. In relation to these phase shifts, attention is drawn to an important sign convention. The theory is shown to agree well with measured transmittance of a typical device between 500 and 1600 GHz as well as spot measurements at 891 (337-micron HCN laser), 1540, and 1578 GHz (195- and 190-micron DCN laser). Finally, the theory is used to design a low loss coupler for the low gain 119-micron line of discharge excited H2O.

RF Couplers for Normal-Conducting Photoinjector of High-Power CW FEL

NASA Astrophysics Data System (ADS)

Kurennoy, Sergey; Schrage, Dale; Wood, Richard; Schultheiss, Tom; Rathke, John; Young, Lloyd

2004-05-01

A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be build for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by "dog-bone" irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

Power-ratio tunable dual-wavelength laser using linearly variable Fabry-Perot filter as output coupler.

PubMed

Wang, Xiaozhong; Wang, Zhongfa; Bu, Yikun; Chen, Lujian; Cai, Guoxiong; Huang, Wencai; Cai, Zhiping; Chen, Nan

2016-02-01

For a linearly variable Fabry-Perot filter, the peak transmission wavelengths change linearly with the transverse position shift of the substrate. Such a Fabry-Perot filter is designed and fabricated and used as an output coupler of a c-cut Nd:YVO₄ laser experimentally in this paper to obtain a 1062 and 1083 nm dual-wavelength laser. The peak transmission wavelengths are gradually shifted from 1040.8 to 1070.8 nm. The peak transmission wavelength of the Fabry-Perot filter used as the output coupler for the dual-wavelength laser is 1068 nm and resides between 1062 and 1083 nm, which makes the transmissions of the desired dual wavelengths change in opposite slopes with the transverse shift of the filter. Consequently, powers of the two wavelengths change in opposite directions. A branch power, oppositely tunable 1062 and 1083 nm dual-wavelength laser is successfully demonstrated. Design principles of the linear variable Fabry-Perot filter used as an output coupler are discussed. Advantages of the method are summarized.

L-shaped fiber-chip grating couplers with high directionality and low reflectivity fabricated with deep-UV lithography.

PubMed

Benedikovic, Daniel; Alonso-Ramos, Carlos; Pérez-Galacho, Diego; Guerber, Sylvain; Vakarin, Vladyslav; Marcaud, Guillaume; Le Roux, Xavier; Cassan, Eric; Marris-Morini, Delphine; Cheben, Pavel; Boeuf, Frédéric; Baudot, Charles; Vivien, Laurent

2017-09-01

Grating couplers enable position-friendly interfacing of silicon chips by optical fibers. The conventional coupler designs call upon comparatively complex architectures to afford efficient light coupling to sub-micron silicon-on-insulator (SOI) waveguides. Conversely, the blazing effect in double-etched gratings provides high coupling efficiency with reduced fabrication intricacy. In this Letter, we demonstrate for the first time, to the best of our knowledge, the realization of an ultra-directional L-shaped grating coupler, seamlessly fabricated by using 193 nm deep-ultraviolet (deep-UV) lithography. We also include a subwavelength index engineered waveguide-to-grating transition that provides an eight-fold reduction of the grating reflectivity, down to 1% (-20  dB). A measured coupling efficiency of -2.7  dB (54%) is achieved, with a bandwidth of 62 nm. These results open promising prospects for the implementation of efficient, robust, and cost-effective coupling interfaces for sub-micrometric SOI waveguides, as desired for large-volume applications in silicon photonics.

Ultra-wideband high-speed Mach-Zehnder switch based on hybrid plasmonic waveguides.

PubMed

Janjan, Babak; Fathi, Davood; Miri, Mehdi; Ghaffari-Miab, Mohsen

2017-02-20

In this paper, the distinctive dispersion characteristic of hybrid plasmonic waveguides is exploited for designing ultra-wideband directional couplers. It is shown that by using optimized geometrical dimensions for hybrid plasmonic waveguides, nearly wavelength-independent directional couplers can be achieved. These broadband directional couplers are then used to design Mach-Zehnder-interferometer-based switches. Our simulation results show the ultra-wide bandwidth of ∼260  nm for the proposed hybrid plasmonic-waveguide-based switch. Further investigation of the proposed Mach-Zehnder switch confirms that because of the strong light confinement in the hybrid plasmonic waveguide structure, the switching time, power consumption, and overall footprint of the device can be significantly improved compared to silicon-ridge-waveguide-based Mach-Zehnder switches. For the Mach-Zehnder switch designed by using the optimized directional coupler, the switching time is found to be less than one picosecond, while the power consumption, V_πL_π figure of merit, and active length of the device are ∼61  fJ/bit, 85  V×μm, and 30 μm, respectively.

An ultra-compact and low loss passive beam-forming network integrated on chip with off chip linear array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lepkowski, Stefan Mark

2015-05-01

The work here presents a review of beam forming architectures. As an example, the author presents an 8x8 Butler Matrix passive beam forming network including the schematic, design/modeling, operation, and simulated results. The limiting factor in traditional beam formers has been the large size dictated by transmission line based couplers. By replacing these couplers with transformer-based couplers, the matrix size is reduced substantially allowing for on chip compact integration. In the example presented, the core area, including the antenna crossover, measures 0.82mm×0.39mm (0.48% the size of a branch line coupler at the same frequency). The simulated beam forming achieves amore » peak PNR of 17.1 dB and 15dB from 57 to 63GHz. At the 60GHz center frequency the average insertion loss is simulated to be 3.26dB. The 8x8 Butler Matrix feeds into an 8-element antenna array to show the array patterns with single beam and adjacent beam isolation.« less

Optical clock distribution in supercomputers using polyimide-based waveguides

NASA Astrophysics Data System (ADS)

Bihari, Bipin; Gan, Jianhua; Wu, Linghui; Liu, Yujie; Tang, Suning; Chen, Ray T.

1999-04-01

Guided-wave optics is a promising way to deliver high-speed clock-signal in supercomputer with minimized clock-skew. Si- CMOS compatible polymer-based waveguides for optoelectronic interconnects and packaging have been fabricated and characterized. A 1-to-48 fanout optoelectronic interconnection layer (OIL) structure based on Ultradel 9120/9020 for the high-speed massive clock signal distribution for a Cray T-90 supercomputer board has been constructed. The OIL employs multimode polymeric channel waveguides in conjunction with surface-normal waveguide output coupler and 1-to-2 splitters. Surface-normal couplers can couple the optical clock signals into and out from the H-tree polyimide waveguides surface-normally, which facilitates the integration of photodetectors to convert optical-signal to electrical-signal. A 45-degree surface- normal couplers has been integrated at each output end. The measured output coupling efficiency is nearly 100 percent. The output profile from 45-degree surface-normal coupler were calculated using Fresnel approximation. the theoretical result is in good agreement with experimental result. A total insertion loss of 7.98 dB at 850 nm was measured experimentally.

Semiconductor Nonlinear Waveguide Devices and Integrated-Mirror Etalons

NASA Astrophysics Data System (ADS)

Chuang, Chih-Li.

This dissertation investigates different III-V semiconductor devices for applications in nonlinear photonics. These include passive and active nonlinear directional couplers, current-controlled optical phase shifter, and integrated -mirror etalons. A novel method to find the propagation constants of an optical waveguide is introduced. The same method is applied, with minor modifications, to find the coupling length of a directional coupler. The method presented provides a tool for the design of optical waveguide devices. The design, fabrication, and performance of a nonlinear directional coupler are presented. This device uses light intensity to control the direction of light coming out. This is achieved through photo-generated-carriers mechanism in the picosecond regime and through the optical Stark effect in the femtosecond regime. A two-transverse -dimensions beam-propagation computation is used to model the switching behavior in the nonlinear directional coupler. It is found that, by considering the pulse degradation effect, the computation agrees well with experiments. The possibility of operating a nonlinear directional coupler with gain is investigated. It is concluded that by injecting current into the nonlinear directional coupler does not provide the advantages hoped for and the modelling using 2-D beam -propagation methods verifies that. Using current injection to change the refractive index of a waveguide, an optical phase shifter is constructed. This device has the merit of delivering large phase shift with almost no intensity modulation. A phase shift as large as 3pi is produced in a waveguide 400 μm in length. Finally, a new structure, grown by the molecular beam epitaxy machine, is described. The structure consists of two quarter-wave stacks and a spacer layer to form an integrated-mirror etalon. The theory, design principles, spectral analyses are discussed with design examples to clarify the ideas. Emphasis is given to the vertical-cavity surface-emitting laser constructed from this structure. Here we demonstrated the cw operation of the VCSEL at room temperature.

Fabrication et caracterisation d'hybrides optiques tout-fibre

NASA Astrophysics Data System (ADS)

Madore, Wendy Julie

In this thesis, we present the fabrication and characterization of optical hybrids made of all fibre 3 × 3 and 4 × 4 couplers. The three-fibre components are made with a triangular cross section, while the four-fibre components are made with a square cross section. All of these couplers have to exhibit equipartition of output amplitudes and specific relative phases of the output signals to be referred to as optical hybrids. These two types of couplers are first modelled to determine the appropriate set of experimental parameters to make hybrids out of them. The prototypes are made in standard telecommunication fibres and then characterized to quantify the performances in transmission and in phase. The objectives of this work is first to model the behaviour and physical properties of 3×3 and 4 × 4 couplers to make sure they can meet the requirements of optical hybrids with an appropriate set of fabrication parameters. The next step is to make prototypes of these 3×3 and 4 × 4 couplers and test their behaviour to check how they fulfill the requirements of optical hybrids. The experimental set-up selected is based on the fusion-tapering technique to make optical fibre components. The heat source is a micro-torch fuelled with a gas mix including propane and oxygen. This type of set-up gives the required freedom to adjust experimental parameters to suit both 3×3 and 4×4 couplers. The versatility of the set-up is also an advantage towards a repeatable and stable process to fuse and taper the different structures. The fabricated triangular-shape couplers have a total transmission of 85 % (-0,7 dB), the crossing is typically located around 1 550 nm with a transmission of around 33 % (-4 dB) per branch. In addition, the relative phases between the output signals are 120±9°. The fabricated square-shape couplers have a total transmission of 89 % (-0,5 dB) with a crossing around 1 550 nm and a transmission around 25 % (-6 dB) per branch. The relative phases between the output signals are 90±3°. As standard telecommunications fibres are used to make the couplers, the prototypes are compatible with all standard fibered set-ups and benches. The properties of optical hybrids are very interesting in coherent detection, where an unambiguous phase measurement is desired. For instance, some standard telecommunication systems use phase-shift keying (PSK), which means information is encoded in the phase of the electromagnetic wave. An all-optical decoding of signal is possible using optical hybrids. Another application is in biomedical imaging with techniques such as optical coherence tomography (OCT), or to a more general extend, profilometry systems. In state-of-the-art techniques, a conventional interferometer combined with Fourier analysis only gives absolute value of the phase. Therefore, the achievable imaging depth in the sample is decreased by a factor 2. Using optical hybrids would simply allow that unambiguous phase measurement, giving the sign and value of the phase at the same time.

49 CFR 229.61 - Draft system.

Code of Federal Regulations, 2011 CFR

2011-10-01

... D&E couplers. (2) A crack or break in the side wall or pin bearing bosses outside of the shaded... or draft gears that exceeds one-half inches. (5) A broken or cracked coupler carrier. (6) A broken or cracked yoke. (7) A broken draft gear. (b) A device shall be provided under the lower end of all drawbar...

49 CFR 229.61 - Draft system.

Code of Federal Regulations, 2010 CFR

2010-10-01

... D&E couplers. (2) A crack or break in the side wall or pin bearing bosses outside of the shaded... or draft gears that exceeds one-half inches. (5) A broken or cracked coupler carrier. (6) A broken or cracked yoke. (7) A broken draft gear. (b) A device shall be provided under the lower end of all drawbar...

Variable-energy drift-tube linear accelerator

DOEpatents

Swenson, Donald A.; Boyd, Jr., Thomas J.; Potter, James M.; Stovall, James E.

1984-01-01

A linear accelerator system includes a plurality of post-coupled drift-tubes wherein each post coupler is bistably positionable to either of two positions which result in different field distributions. With binary control over a plurality of post couplers, a significant accumlative effect in the resulting field distribution is achieved yielding a variable-energy drift-tube linear accelerator.

Variable-energy drift-tube linear accelerator

DOEpatents

Swenson, D.A.; Boyd, T.J. Jr.; Potter, J.M.; Stovall, J.E.

A linear accelerator system includes a plurality of post-coupled drift-tubes wherein each post coupler is bistably positionable to either of two positions which result in different field distributions. With binary control over a plurality of post couplers, a significant accumlative effect in the resulting field distribution is achieved yielding a variable-energy drift-tube linear accelerator.

Rf capacitively-coupled electrodeless light source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manos, Dennis M.; Diggs, Jessie; Ametepe, Joseph D.

2000-01-01

An rf capacitively-coupled electrodeless light source is provided. The light source comprises a hollow, elongated chamber and at least one center conductor disposed within the hollow, elongated chamber. A portion of each center conductor extends beyond the hollow, elongated chamber. At least one gas capable of forming an electronically excited molecular state is contained within each center conductor. An electrical coupler is positioned concentric to the hollow, elongated chamber and the electrical coupler surrounds the portion of each center conductor that extends beyond the hollow, elongated chamber. A rf-power supply is positioned in an operable relationship to the electrical couplermore » and an impedance matching network is positioned in an operable relationship to the rf power supply and the electrical coupler.« less

Experimental study of a VBG-based Tm : YLF slab laser at different output coupler parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, X M; Ding, Y; Dai, T Y

2015-04-30

The performance of a Tm : YLF slab laser is studied at different output coupler parameters. Use is made of a 20-mm-long a-cut slab crystal doped with 2.5 at. % thulium ions. With a volume Bragg grating and a Fabry – Perot etalon, the selected output wavelength of this Tm : YLF slab laser is 1908 nm. For the optimised output coupler with a transmission of 20% and a radius of curvature of 300 mm, the output power exceeds 74.1 W and the slope efficiency with respect to the absorbed pump power reaches 48.4%. In addition, the beam quality ofmore » the Tm : YLF slab laser is improved. (lasers)« less

A Ratiometric Wavelength Measurement Based on a Silicon-on-Insulator Directional Coupler Integrated Device

PubMed Central

Wang, Pengfei; Hatta, Agus Muhamad; Zhao, Haoyu; Zheng, Jie; Farrell, Gerald; Brambilla, Gilberto

2015-01-01

A ratiometric wavelength measurement based on a Silicon-on-Insulator (SOI) integrated device is proposed and designed, which consists of directional couplers acting as two edge filters with opposite spectral responses. The optimal separation distance between two parallel silicon waveguides and the interaction length of the directional coupler are designed to meet the desired spectral response by using local supermodes. The wavelength discrimination ability of the designed ratiometric structure is demonstrated by a beam propagation method numerically and then is verified experimentally. The experimental results have shown a general agreement with the theoretical models. The ratiometric wavelength system demonstrates a resolution of better than 50 pm at a wavelength around 1550 nm with ease of assembly and calibration. PMID:26343668

Design and fabrication of three-dimensional polymer mode multiplexer based on asymmetric waveguide couplers

NASA Astrophysics Data System (ADS)

He, Guobing; Gao, Yang; Xu, Yan; Ji, Lanting; Sun, Xiaoqiang; Wang, Xibin; Yi, Yunji; Chen, Changming; Wang, Fei; Zhang, Daming; Wu, Yuanda

2018-05-01

A polymer mode multiplexer based on asymmetric couplers is theoretically designed and experimentally demonstrated. The proposed X-junction coupler is formed by waveguides overlapped with different crossing angles in the vertical direction. A beam propagation method is adopted to optimize the dimensional parameters of the mode multiplexer to convert LP01 mode of two lower waveguides to LP11a and LP21a mode of the upper waveguide. The ultraviolet lithography and wet chemical etching are used in the fabrication process. A conversion ratio over 98% for both LP11a and LP21a mode in the wavelength range from 1530 to 1570 nm are experimentally demonstrated. This mode multiplexer has potential in broadband mode-division multiplexing transmission systems.

Multistability and switching in oppositely-directed saturated coupler

NASA Astrophysics Data System (ADS)

Nithyanandan, K.; Shafeeque Ali, A. K.; Porsezian, K.; Nishad, M. P. M.; Tchofo Dinda, P.; Grelu, Ph.

2018-06-01

We investigate theoretically the optical multistability that takes place in a two-core oppositely-directed saturated coupler (ODSC) having negative index material (NIM) channel. The dynamics are studied using the Lagrangian variational method, and analytical solutions are constructed with Jacobi elliptic functions. The ODSC exhibits a bandgap as a consequence of the effective feedback mechanism due to the opposite directionality of the phase velocity and the Poynting vector in the NIM channel. Depending on the strength of the nonlinear saturation, the system admits multiple stable states. Considering the additional degrees of design freedom with respect to conventional nonlinear couplers, the ODSC could become an attractive choice for all-optical switching. The existence of multiple transmission resonance windows could also facilitate the realization of gap solitons.

Three-dimensional ideal theta(1)/theta(2) angular transformer and its uses in fiber optics.

PubMed

Ning, X

1988-10-01

A 3-D ideal theta(1)/theta(2) angular transformer in nonimaging optics is introduced. The axially symmetric transformer, combining a portion of a hyperbolic concentrator with two lenses, transforms an input limited Lambertian over an angle theta(1) to an output limited Lambertian over an angle theta(2) without losing throughput. This is the first known transformer with such ideal properties. Results of computer simulations of a transformer with planospherical lenses are presented. Because of its ideal angular transforming property, the transformer offers an excellent solution for power launching and fiber-fiber coupling in optical fiber systems. In principle, the theoretical maximum coupling efficiency based on radiance conservation can be achieved with this transformer. Several conceptual designs of source-fiber and fiber-fiber couplers using the transformer are given.

Suspended mid-infrared fiber-to-chip grating couplers for SiGe waveguides

NASA Astrophysics Data System (ADS)

Favreau, Julien; Durantin, Cédric; Fédéli, Jean-Marc; Boutami, Salim; Duan, Guang-Hua

2016-03-01

Silicon photonics has taken great importance owing to the applications in optical communications, ranging from short reach to long haul. Originally dedicated to telecom wavelengths, silicon photonics is heading toward circuits handling with a broader spectrum, especially in the short and mid-infrared (MIR) range. This trend is due to potential applications in chemical sensing, spectroscopy and defense in the 2-10 μm range. We previously reported the development of a MIR photonic platform based on buried SiGe/Si waveguide with propagation losses between 1 and 2 dB/cm. However the low index contrast of the platform makes the design of efficient grating couplers very challenging. In order to achieve a high fiber-to-chip efficiency, we propose a novel grating coupler structure, in which the grating is locally suspended in air. The grating has been designed with a FDTD software. To achieve high efficiency, suspended structure thicknesses have been jointly optimized with the grating parameters, namely the fill factor, the period and the grating etch depth. Using the Efficient Global Optimization (EGO) method we obtained a configuration where the fiber-to-waveguide efficiency is above 57 %. Moreover the optical transition between the suspended and the buried SiGe waveguide has been carefully designed by using an Eigenmode Expansion software. Transition efficiency as high as 86 % is achieved.

A Comprehensive Investigation and Coupler Design for Higher-Order Modes in the BNL Energy Recovery Linear Accelerator

NASA Astrophysics Data System (ADS)

Marques, Carlos

A next generation Energy Recovery Linac (ERL) is under development in the Collider-Accelerator Department at Brookhaven National Laboratory (BNL). This ERL uses a superconducting radio frequency (SFR) cavity to produce an electric field gradient ideal to accelerate charged particles. As with many accelerators, higher-order modes (HOMs) can be induced by a beam of charged particles traversing the linear accelerator cavity. The excitation of these modes can result in problematic single and multi-bunch effects and also produce undesirable heat loads to the cryogenic system. Understanding HOM prevalence and structure inside the accelerator cavity is crucial for devising a procedure for extracting HOM power and promoting excellent beam quality. In this work, a method was created to identify and characterize HOMs using a perturbation technique on a copper (Cu) cavity prototype of the BNL3 linac and a double lambda/4 crab cavity. Both analyses and correlation between simulated and measured results are shown. A coaxial to dual-ridge waveguide HOM coupler was designed, constructed and implemented to extract power from HOMs simultaneously making an evanescent fundamental mode for the BNL3 cavity. A full description of the design is given along with a simulated analysis of its performance. Comparison between previous HOM coupler designs as well as correspondence between simulation and measurement is also given.

Variable frequency microwave furnace system

DOEpatents

Bible, Don W.; Lauf, Robert J.

1994-01-01

A variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34) for testing or other selected applications. The variable frequency microwave furnace system (10) includes a microwave signal generator (12) or microwave voltage-controlled oscillator (14) for generating a low-power microwave signal for input to the microwave furnace. A first amplifier (18) may be provided to amplify the magnitude of the signal output from the microwave signal generator (12) or the microwave voltage-controlled oscillator (14). A second amplifier (20) is provided for processing the signal output by the first amplifier (18). The second amplifier (20) outputs the microwave signal input to the furnace cavity (34). In the preferred embodiment, the second amplifier (20) is a traveling-wave tube (TWT). A power supply (22) is provided for operation of the second amplifier (20). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Development of the ITER ICH Transmission Line and Matching System

NASA Astrophysics Data System (ADS)

Rasmussen, D. A.; Goulding, R. H.; Pesavento, P. V.; Peters, B.; Swain, D. W.; Fredd, E. H.; Hosea, J.; Greenough, N.

2011-10-01

The ITER Ion Cyclotron Heating (ICH) System is designed to couple 20 MW of heating power for ion and electron heating. Prototype components for the ITER Ion Cyclotron Heating (ICH) transmission line and matching system are being designed and tested. The ICH transmission lines are pressurized 300 mm diameter coaxial lines with water-cooled aluminum outer conductor and gas-cooled and water-cooled copper inner conductor. Each ICH transmission line is designed to handle 40-55 MHz power at up to 6 MW/line. A total of 8 lines split to 16 antenna inputs on two ICH antennas. Industrial suppliers have designed coaxial transmission line and matching components and prototypes will be manufactured. The prototype components will be qualified on a test stand operating at the full power and pulse length needed for ITER. The matching system must accommodated dynamic changes in the plasma loading due to ELMS and the L to H-mode transition. Passive ELM tolerance will be performed using hybrid couplers and loads, which can absorb the transient reflected power. The system is also designed to compensate for the mutual inductances of the antenna current straps to limit the peak voltages on the antenna array elements.

Neutron position-sensitive scintillation detector

DOEpatents

Strauss, Michael G.; Brenner, Raul

1984-01-01

A device is provided for mapping one- and two-dimensional distributions of neutron-positions in a scintillation detector. The device consists of a lithium glass scintillator coupled by an air gap and a light coupler to an array of photomultipliers. The air gap concentrates light flashes from the scintillator, whereas the light coupler disperses this concentrated light to a predetermined fraction of the photomultiplier tube array.

Design of microwave antenna system on planar Yagi-Uda elements and microstrip coupler

NASA Astrophysics Data System (ADS)

Petrovnin, K. V.; Latypov, R. R.

2017-11-01

Paper presents results of calculation, electromagnetic modelling and measurements of manufactured antenna system on planar Yagi-Uda elements and microstrip coupler. System has summary and subtract modes. Center frequency of system is 1532 MHz with 96 MHz bandwidth. Gain of system is 8 dB in main lobe direction (in-phase mode) and 5 dB (antiphase mode).

Interferometer using a 3 × 3 coupler and Faraday mirrors

NASA Astrophysics Data System (ADS)

Breguet, J.; Gisin, N.

1995-06-01

A new interferometric setup using a 3 \\times 3 coupler and two Faraday mirrors is presented. It has the advantages of being built only with passive components, of freedom from the polarization fading problem, and of operation with a LED. It is well suited for sensing time-dependent signals and does not depend on reciprocal or nonreciprocal constant perturbations.

Quantum Statistical Properties of the Codirectional Kerr Nonlinear Coupler in Terms of su (2 ) Lie Group in Interaction with a Two-level Atom

NASA Astrophysics Data System (ADS)

Abdalla, M. Sebawe; Khalil, E. M.; Obada, A. S.-F.

2017-08-01

The problem of the codirectional Kerr coupler has been considered several times from different point of view. In the present paper we introduce the interaction between a two-level atom and the codirectional Kerr nonlinear coupler in terms of su (2 ) Lie algebra. Under certain conditions we have adjusted the Kerr coupler and consequently we have managed to handle the problem. The wave function is obtained by using the evolution operator where the Heisnberg equation of motion is invoked to get the constants of the motion. We note that the Kerr parameter χ as well as the quantum number j plays the role of controlling the atomic inversion behavior. Also the maximum entanglement occurs after a short period of time when χ = 0. On the other hand for the entropy and the variance squeezing we observe that there is exchange between the quadrature variances. Furthermore, the variation in the quantum number j as well as in the parameter χ leads to increase or decrease in the number of fluctuations. Finally we examined the second order correlation function where classical and nonclassical phenomena are observed.

High bandwidth all-optical 3×3 switch based on multimode interference structures

NASA Astrophysics Data System (ADS)

Le, Duy-Tien; Truong, Cao-Dung; Le, Trung-Thanh

2017-03-01

A high bandwidth all-optical 3×3 switch based on general interference multimode interference (GI-MMI) structure is proposed in this study. Two 3×3 multimode interference couplers are cascaded to realize an all-optical switch operating at both wavelengths of 1550 nm and 1310 nm. Two nonlinear directional couplers at two outer-arms of the structure are used as all-optical phase shifters to achieve all switching states and to control the switching states. Analytical expressions for switching operation using the transfer matrix method are presented. The beam propagation method (BPM) is used to design and optimize the whole structure. The optimal design of the all-optical phase shifters and 3×3 MMI couplers are carried out to reduce the switching power and loss.

A Novel Ku-Band/Ka-Band and Ka-Band/E-Band Multimode Waveguide Couplers for Power Measurement of Traveling-Wave Tube Amplifier Harmonic Frequencies

NASA Technical Reports Server (NTRS)

Wintucky, Edwin G.; Simons, Rainee N.

2015-01-01

This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler, fabricated from two dissimilar frequency band waveguides, is capable of isolating power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT) amplifier. Test results from proof-of-concept demonstrations are presented for a Ku-band/Ka-band MDC and a Ka-band/E-band MDC. In addition to power measurements at harmonic frequencies, a potential application of the MDC is in the design of a satellite borne beacon source for atmospheric propagation studies at millimeter-wave (mm-wave) frequencies (Ka-band and E-band).

Directional multimode coupler for planar magnonics: Side-coupled magnetic stripes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A.; Kotel'nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009

We experimentally demonstrate spin waves coupling in two laterally adjacent magnetic stripes. By the means of Brillouin light scattering spectroscopy, we show that the coupling efficiency depends both on the magnonic waveguides' geometry and the characteristics of spin-wave modes. In particular, the lateral confinement of coupled yttrium-iron-garnet stripes enables the possibility of control over the spin-wave propagation characteristics. Numerical simulations (in time domain and frequency domain) reveal the nature of intermodal coupling between two magnonic stripes. The proposed topology of multimode magnonic coupler can be utilized as a building block for fabrication of integrated parallel functional and logic devices suchmore » as the frequency selective directional coupler or tunable splitter, enabling a number of potential applications for planar magnonics.« less

On the photonic implementation of universal quantum gates, bell states preparation circuit and quantum LDPC encoders and decoders based on directional couplers and HNLF.

PubMed

Djordjevic, Ivan B

2010-04-12

The Bell states preparation circuit is a basic circuit required in quantum teleportation. We describe how to implement it in all-fiber technology. The basic building blocks for its implementation are directional couplers and highly nonlinear optical fiber (HNLF). Because the quantum information processing is based on delicate superposition states, it is sensitive to quantum errors. In order to enable fault-tolerant quantum computing the use of quantum error correction is unavoidable. We show how to implement in all-fiber technology encoders and decoders for sparse-graph quantum codes, and provide an illustrative example to demonstrate this implementation. We also show that arbitrary set of universal quantum gates can be implemented based on directional couplers and HNLFs.

Terahertz master-oscillator power-amplifier quantum cascade laser with a grating coupler of extremely low reflectivity.

PubMed

Zhu, Huan; Zhu, Haiqing; Wang, Fangfang; Chang, Gaolei; Yu, Chenren; Yan, Quan; Chen, Jianxin; Li, Lianhe; Davies, A Giles; Linfield, Edmund H; Tang, Zhou; Chen, Pingping; Lu, Wei; Xu, Gangyi; He, Li

2018-01-22

A terahertz master-oscillation power-amplifier quantum cascade laser (THz-MOPA-QCL) is demonstrated where a grating coupler is employed to efficiently extract the THz radiation. By maximizing the group velocity and eliminating the scattering of THz wave in the grating coupler, the residue reflectivity is reduced down to the order of 10 -3 . A buried DFB grating and a tapered preamplifier are proposed to improve the seed power and to reduce the gain saturation, respectively. The THz-MOPA-QCL exhibits single-mode emission, a single-lobed beam with a narrow divergence angle of 18° × 16°, and a pulsed output power of 136 mW at 20 K, which is 36 times that of a second-order DFB laser from the same material.

Optical device fabrication using femtosecond laser processing with glass-hologram

NASA Astrophysics Data System (ADS)

Suzuki, Jun'ichi; Arima, Yasunori; Tanaka, Shuhei

2011-03-01

Using femtosecond laser processing with glass-hologram, fabrication of 1cm-long straight waveguide and X-coupler is reported in this paper. We design and fabricate 4-level glass-hologram which generates 1cm-long straight line intensity. We fabricate 1cm-long waveguides inside fused silica at one shot exposure with the glass-hologram. We investigate the waveguide performance of near field pattern and propagation loss at wavelength of 1550nm. The near field pattern is almost circular shape. The propagation loss at 1550nm is estimated to be < 1.0 dB/cm. As an example of an optical device consisting of straight waveguides, we fabricate X-coupler or 2x2 coupler using straight line waveguides, and observe the output power ratio depending on crossing angle.

Surface acoustic waves voltage controlled directional coupler

NASA Astrophysics Data System (ADS)

Golan, G.; Griffel, G.; Yanilov, E.; Ruschin, S.; Seidman, A.; Croitoru, N.

1988-10-01

An important condition for the development of surface wave integrated-acoustic devices is the ability to guide and control the propagation of the acoustic energy. This can be implemented by deposition of metallic "loading" channels on an anisotropic piezoelectric substrate. Deposition of such two parallel channels causes an effective coupling of acoustic energy from one channel to the other. A basic requirement for this coupling effect is the existence of the two basic modes: a symmetrical and a nonsymmetrical one. A mode map that shows the number of sustained modes as a function of the device parameters (i.e., channel width; distance between channels; material velocity; and acoustical exciting frequency) is presented. This kind of map can help significantly in the design process of such a device. In this paper we devise an advanced acoustical "Y" coupler with the ability to control its effective coupling by an externally applied voltage, thereby causing modulation of the output intensities of the signals.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Read, Michael; Ives, Robert Lawrence; Marsden, David

The Phase II program developed an internal RF coupler that transforms the whispering gallery RF mode produced in gyrotron cavities to an HE11 waveguide mode propagating in corrugated waveguide. This power is extracted from the vacuum using a broadband, chemical vapor deposited (CVD) diamond, Brewster angle window capable of transmitting more than 1.5 MW CW of RF power over a broad range of frequencies. This coupling system eliminates the Mirror Optical Units now required to externally couple Gaussian output power into corrugated waveguide, significantly reducing system cost and increasing efficiency. The program simulated the performance using a broad range ofmore » advanced computer codes to optimize the design. Both a direct coupler and Brewster angle window were built and tested at low and high power. Test results confirmed the performance of both devices and demonstrated they are capable of achieving the required performance for scientific, defense, industrial, and medical applications.« less

Optical Measurement of Mass Flow of a Two-Phase Fluid

NASA Technical Reports Server (NTRS)

Wiley, John; Pedersen, Kevin; Koman, Valentin; Gregory, Don

2008-01-01

An optoelectronic system utilizes wavelength-dependent scattering of light for measuring the density and mass flow of a two-phase fluid in a pipe. The apparatus was invented for original use in measuring the mass flow of a two-phase cryogenic fluid (e.g., liquid hydrogen containing bubbles of hydrogen gas), but underlying principles of operation can readily be adapted to non-cryogenic two-phase fluids. The system (see figure) includes a laser module, which contains two or more laser diodes, each operating at a different wavelength. The laser module also contains beam splitters that combine the beams at the various wavelengths so as to produce two output beams, each containing all of the wavelengths. One of the multiwavelength output beams is sent, via a multimode fiberoptic cable, to a transmitting optical coupler. The other multiwavelength output beam is sent, via another multimode fiber-optic cable, to a reference detector module, wherein fiber-optic splitters split the light into several multiwavelength beams, each going to a photodiode having a spectral response that is known and that differs from the spectral responses of the other photodiodes. The outputs of these photodiodes are digitized and fed to a processor, which executes an algorithm that utilizes the known spectral responses to convert the photodiode outputs to obtain reference laser-power levels for the various wavelengths. The transmitting optical coupler is mounted in (and sealed to) a hole in the pipe and is oriented at a slant with respect to the axis of the pipe. The transmitting optical coupler contains a collimating lens and a cylindrical lens that form the light emerging from the end of the fiber-optic cable into a fan-shaped beam in a meridional plane of the pipe. Receiving optical couplers similar to the transmitting optical couplers are mounted in the same meridional plane at various longitudinal positions on the opposite side of the pipe, approximately facing the transmitting optical coupler along the same slant. Light collected by each receiving optical coupler is sent, via a multimode fiber-optic cable, to a detector module similar to the reference detector module. The outputs of the photodiodes in each detector module are digitized and processed, similarly to those of the reference detector module, to obtain indications of the amounts of light of each wavelength scattered to the corresponding receiving position. The value for each wavelength at each position is also normalized to the reference laser-power level for that wavelength. From these normalized values, the density and the mass flow rate of the fluid are estimated.

Fiber-optics couple arthroscope to TV

NASA Technical Reports Server (NTRS)

Franke, J. M.; Rhodes, D. B.

1981-01-01

Convenient, hand-held coupler images output of arthroscope onto coherent fiber bundle. Arthroscope allows surgeons to examine internal organs through any small opening in body. Coupler is also used for engine inspection, instrument repair, and around-corner visual inspection. Image from arthroscope travels along flexible bundle and appears at other cable end where it is recollimated by lens. Image is read from lens or projected on color TV camera.

Polarization preserving single mode fiber optic coupler

NASA Technical Reports Server (NTRS)

Nelson, M. D.; Goss, W. C.

1982-01-01

A technique is described for fabrication of etched single mode fiber optical waveguide couplers which preserve the polarization state to within 0.0001. The coupling ratio is tunable over a broad range (0-9 percent) during fabrication. Back-coupling is less than 0.001, insertion loss is less than 1.5 dB, and coupling ratio thermal coefficient is about 1 percent per degree C.

Integrated-optical directional coupler biosensor

NASA Astrophysics Data System (ADS)

Luff, B. J.; Harris, R. D.; Wilkinson, J. S.; Wilson, R.; Schiffrin, D. J.

1996-04-01

We present measurements of biomolecular binding reactions, using a new type of integrated-optical biosensor based on a planar directional coupler structure. The device is fabricated by Ag+ - Na+ ion exchange in glass, and definition of the sensing region is achieved by use of transparent fluoropolymer isolation layers formed by thermal evaporation. The suitability of the sensor for application to the detection of environmental pollutants is considered.

Dynamic System Coupler Program (DYSCO 4.1). Volume 1. Theoretical Manual

DTIC Science & Technology

1989-01-01

present analysis is as follows: 1. Triplet X, Y, Z represents an inertia frame, R. The R system coordinates are the rotor shaft axes when there is...small perturbation analysis . 2.5 3-D MODAL STRUCTURE - CFM3 A three-dimensional structure is represented as a linear combination of orth­ ogonal modes...Include rotor blade damage modeling, Elgen analysis development, general time history solution development, frequency domain solution development

Development and performance of a new version of the OASIS coupler, OASIS3-MCT_3.0

NASA Astrophysics Data System (ADS)

Craig, Anthony; Valcke, Sophie; Coquart, Laure

2017-09-01

OASIS is coupling software developed primarily for use in the climate community. It provides the ability to couple different models with low implementation and performance overhead. OASIS3-MCT is the latest version of OASIS. It includes several improvements compared to OASIS3, including elimination of a separate hub coupler process, parallelization of the coupling communication and run-time grid interpolation, and the ability to easily reuse mapping weight files. OASIS3-MCT_3.0 is the latest release and includes the ability to couple between components running sequentially on the same set of tasks as well as to couple within a single component between different grids or decompositions such as physics, dynamics, and I/O. OASIS3-MCT has been tested with different configurations on up to 32 000 processes, with components running on high-resolution grids with up to 1.5 million grid cells, and with over 10 000 2-D coupling fields. Several new features will be available in OASIS3-MCT_4.0, and some of those are also described.

Sensitivity of a three-mirror cavity to thermal and nonlinear lensing: Gaussian-beam analysis.

PubMed

Anctil, G; McCarthy, N; Piché, M

2000-12-20

We consider a compact three-mirror cavity consisting of a flat output coupler, a curved folding mirror, and an active medium with one facet cut at the Brewster angle and the other facet coated for unit reflectivity. We examine the sensitivity to thermal lensing and to self-focusing in the active medium of the Gaussian beam that is circulating in that cavity. We use a simple thin-lens model; the astigmatism of the beam that is circulating in the cavity and the nonlinear coupling between the field distributions along the two orthogonal axes are taken into account. We find configurations in which beam ellipticity is compensated for at either end of the cavity in the presence of thermal lensing. We have derived an analytical criterion that predicts the sensitivity of the beam size to nonlinear lensing. The ability of the cavity to favor self-mode locking is found to be sensitive to the strength of thermal lensing. In the absence of thermal lensing, cavities operated as telescopic systems (C = 0) or self-imaging systems (B = 0) are most appropriate for achieving self-mode locking, with nonlinear mode selection accomplished through saturation of the spatially varying laser gain. We identify conditions for which self-mode locking can be produced by variable-reflectivity output couplers with either maximum or minimum reflectivity at the center of the coupler. We use our model to estimate the nonlinear gain produced in laser cavities equipped with such output couplers. We identify a cavity configuration for which nonlinear lensing can simultaneously produce mode locking and correction of beam ellipticity at the output coupler.

Sensitivity of a Three-Mirror Cavity to Thermal and Nonlinear Lensing: Gaussian-Beam Analysis

NASA Astrophysics Data System (ADS)

Anctil, Geneviève; McCarthy, Nathalie; Piché, Michel

2000-12-01

We consider a compact three-mirror cavity consisting of a flat output coupler, a curved folding mirror, and an active medium with one facet cut at the Brewster angle and the other facet coated for unit reflectivity. We examine the sensitivity to thermal lensing and to self-focusing in the active medium of the Gaussian beam that is circulating in that cavity. We use a simple thin-lens model; the astigmatism of the beam that is circulating in the cavity and the nonlinear coupling between the field distributions along the two orthogonal axes are taken into account. We find configurations in which beam ellipticity is compensated for at either end of the cavity in the presence of thermal lensing. We have derived an analytical criterion that predicts the sensitivity of the beam size to nonlinear lensing. The ability of the cavity to favor self-mode locking is found to be sensitive to the strength of thermal lensing. In the absence of thermal lensing, cavities operated as telescopic systems ( C 0 ) or self-imaging systems ( B 0 ) are most appropriate for achieving self-mode locking, with nonlinear mode selection accomplished through saturation of the spatially varying laser gain. We identify conditions for which self-mode locking can be produced by variable-reflectivity output couplers with either maximum or minimum reflectivity at the center of the coupler. We use our model to estimate the nonlinear gain produced in laser cavities equipped with such output couplers. We identify a cavity configuration for which nonlinear lensing can simultaneously produce mode locking and correction of beam ellipticity at the output coupler.

Novel mono-static arrangement of the ASDEX Upgrade high field side reflectometers compatible with electron cyclotron resonance heating stray radiation.

PubMed

Silva, A; Varela, P; Meneses, L; Manso, M

2012-10-01

The ASDEX Upgrade frequency modulated continuous wave broadband reflectometer system uses a mono-static antenna configuration with in-vessel hog-horns and 3 dB directional couplers. The operation of the new electron cyclotron resonance heating (ECRH) launcher and the start of collective Thomson scattering experiments caused several events where the fragile dummy loads inside the high field side directional couplers were damaged, due to excessive power resulting from the ECRH stray fields. In this paper, we present a non-conventional application of the existing three-port directional coupler that hardens the system to the ECRH stray fields and at the same time generates the necessary reference signal. Electromagnetic simulations and laboratory tests were performed to validate the proposed solution and are compared with the in-vessel calibration tests.

Multi-band Microwave Antennas and Devices based on Generalized Negative-Refractive-Index Transmission Lines

NASA Astrophysics Data System (ADS)

Ryan, Colan Graeme Matthew

Focused on the quad-band generalized negative-refractive-index transmission line (G-NRI-TL), this thesis presents a variety of novel printed G-NRI-TL multi-band microwave device and antenna prototypes. A dual-band coupled-line coupler, an all-pass G-NRI-TL bridged-T circuit, a dual-band metamaterial leaky-wave antenna, and a multi-band G-NRI-TL resonant antenna are all new developments resulting from this research. In addition, to continue the theme of multi-band components, negative-refractive-index transmission lines are used to create a dual-band circularly polarized transparent patch antenna and a two-element wideband decoupled meander antenna system. High coupling over two independently-specified frequency bands is the hallmark of the G-NRI-TL coupler: it is 0.35lambda0 long but achieves approximately -3 dB coupling over both bands with a maximum insertion loss of 1 dB. This represents greater design flexibility than conventional coupled-line couplers and less loss than subsequent G-NRI-TL couplers. The single-ended bridged-T G-NRI-TL offers a metamaterial unit cell with an all-pass magnitude response up to 8 GHz, while still preserving the quad-band phase response of the original circuit. It is shown how the all-pass response leads to wider bandwidths and improved matching in quad-band inverters, power dividers, and hybrid couplers. The dual-band metamaterial leaky-wave antenna presented here was the first to be reported in the literature, and it allows broadside radiation at both 2 GHz and 6 GHz without experiencing the broadside stopband common to conventional periodic antennas. Likewise, the G-NRI-TL resonant antenna is the first reported instance of such a device, achieving quad-band operation between 2.5 GHz and 5.6 GHz, with a minimum radiation efficiency of 80%. Negative-refractive-index transmission line loading is applied to two devices: an NRI-TL meander antenna achieves a measured 52% impedance bandwidth, while a square patch antenna incorporates NRI-TL elements to achieve circular polarization at 2.3 GHz and 2.7 GHz, with radiation efficiencies of 70% and 78%, respectively. Optical transparency of 50% is then realized by cutting a grid through the antenna and substrate, making the device suitable for direct integration with solar panels. Therefore, this research provides several proof-of-concept devices to highlight the flexibility and multi-band properties of the G-NRI-TL which extend the capabilities of microwave transceiver systems.

Universal Linear Optics: An implementation of Boson Sampling on a Fully Reconfigurable Circuit

NASA Astrophysics Data System (ADS)

Harrold, Christopher; Carolan, Jacques; Sparrow, Chris; Russell, Nicholas J.; Silverstone, Joshua W.; Marshall, Graham D.; Thompson, Mark G.; Matthews, Jonathan C. F.; O'Brien, Jeremy L.; Laing, Anthony; Martín-López, Enrique; Shadbolt, Peter J.; Matsuda, Nobuyuki; Oguma, Manabu; Itoh, Mikitaka; Hashimoto, Toshikazu

Linear optics has paved the way for fundamental tests in quantum mechanics and has gone on to enable a broad range of quantum information processing applications for quantum technologies. We demonstrate an integrated photonics processor that is universal for linear optics. The device is a silica-on-silicon planar waveguide circuit (PLC) comprising a cascade of 15 Mach Zehnder interferometers, with 30 directional couplers and 30 tunable thermo-optic phase shifters which are electrically interfaced for the arbitrary setting of a phase. We input ensembles of up to six photons, and monitor the output with a 12-single-photon detector system. The calibrated device is capable of implementing any linear optical protocol. This enables the implementation of new quantum information processing tasks in seconds, which would have previously taken months to realise. We demonstrate 100 instances of the boson sampling problem with verification tests, and six-dimensional complex Hadamards. Also Imperial College London.

Optical signal processing of spatially distributed sensor data in smart structures

NASA Technical Reports Server (NTRS)

Bennett, K. D.; Claus, R. O.; Murphy, K. A.; Goette, A. M.

1989-01-01

Smart structures which contain dense two- or three-dimensional arrays of attached or embedded sensor elements inherently require signal multiplexing and processing capabilities to permit good spatial data resolution as well as the adequately short calculation times demanded by real time active feedback actuator drive circuitry. This paper reports the implementation of an in-line optical signal processor and its application in a structural sensing system which incorporates multiple discrete optical fiber sensor elements. The signal processor consists of an array of optical fiber couplers having tailored s-parameters and arranged to allow gray code amplitude scaling of sensor inputs. The use of this signal processor in systems designed to indicate the location of distributed strain and damage in composite materials, as well as to quantitatively characterize that damage, is described. Extension of similar signal processing methods to more complicated smart materials and structures applications are discussed.

Plasma Switch for High-Power Active Pulse Compressor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirshfield, Jay L.

2013-11-04

Results are presented from experiments carried out at the Naval Research Laboratory X-band magnicon facility on a two-channel X-band active RF pulse compressor that employed plasma switches. Experimental evidence is shown to validate the basic goals of the project, which include: simultaneous firing of plasma switches in both channels of the RF circuit, operation of quasi-optical 3-dB hybrid directional coupler coherent superposition of RF compressed pulses from both channels, and operation of the X-band magnicon directly in the RF pulse compressor. For incident 1.2 ?s pulses in the range 0.63 ? 1.35 MW, compressed pulses of peak powers 5.7 ?more » 11.3 MW were obtained, corresponding to peak power gain ratios of 8.3 ? 9.3. Insufficient bakeout and conditioning of the high-power RF circuit prevented experiments from being conducted at higher RF input power levels.« less

Slot silicon-gallium nitride waveguide in MMI structures based 1x8 wavelength demultiplexer

NASA Astrophysics Data System (ADS)

Ben Zaken, Bar Baruch; Zanzury, Tal; Malka, Dror

2017-06-01

We propose a novel 8-channel wavelength multimode interference (MMI) demultiplexer in slot waveguide structures that operated at 1530 nm, 1535 nm, 1540 nm, 1545 nm, 1550 nm, 1555 nm, 1560 nm and 1565 nm wavelengths. Gallium nitride (GaN) surrounded by silicon (Si) was founded as suitable materials for the slot-waveguide structures. The proposed device was designed by seven 1x2 MMI couplers, fourteen S-band and one input taper. Numerical investigations were carried out on the geometrical parameters by using a full vectorial-beam propagation method (FVBPM). Simulation results show that the proposed device can transmit 8-channel that works in the whole C-band (1530- 1565 nm) with low crosstalk ((-19.97)-(-13.77) dB) and bandwidth (1.8-3.6 nm). Thus, the device can be very useful in optical networking systems that work on dense wavelength division multiplexing (DWDM) technology.

Generalized fiber Fourier optics.

PubMed

Cincotti, Gabriella

2011-06-15

A twofold generalization of the optical schemes that perform the discrete Fourier transform (DFT) is given: new passive planar architectures are presented where the 2 × 2 3 dB couplers are replaced by M × M hybrids, reducing the number of required connections and phase shifters. Furthermore, the planar implementation of the discrete fractional Fourier transform (DFrFT) is also described, with a waveguide grating router (WGR) configuration and a properly modified slab coupler.

Communication adapter for use with a drilling component

DOEpatents

Hall, David R [Provo, UT; Pixton, David S [Lehi, UT; Hall,; Jr,; Tracy, H [Provo, UT; Bradford, Kline [Orem, UT; Rawle, Michael [Springville, UT

2007-04-03

A communication adapter is disclosed that provides for removable attachment to a drilling component when the drilling component is not actively drilling and for communication with an integrated transmission system in the drilling component. The communication adapter comprises a data transmission coupler that facilitates communication between the drilling component and the adapter, a mechanical coupler that facilitates removable attachment of the adapter to the drilling component, and a data interface.

Low-cost integrated-optic fiber couplers

NASA Astrophysics Data System (ADS)

Sheem, Sang K.; Zhang, Feng; Choi, Jong-Ho; Lee, Yong-Woo; Low, Sarah; Lu, Shih-Yau

1997-04-01

In an effort to lower the cost of fiber optic couplers, integrated optic channel waveguide circuits are made of a UV-curable polymer using a molding technique, and then a novel fiber-to-channel connecting approach is employed in which UV light radiating from an optical fiber core cures the polymer in the channel, thus accomplishing a 'touchdown' of the core-extension waveguide onto the walls of the channel waveguide.

49 CFR Appendix A to Part 179 - Procedures for Tank-Head Puncture-Resistance Test

Code of Federal Regulations, 2013 CFR

2013-10-01

...” car. c. At least two separate tests must be conducted with the coupler on the vertical centerline of the ram car. One test must be conducted with the coupler at a height of 53.3 cm (21 inches), plus-or... height at 79 cm (31 inches), plus-or-minus 2.5 cm (1 inch), above the top of the sill. If the combined...

Magnetic Shielding Design for Coupler of Wireless Electric Vehicle Charging Using Finite Element Analysis

NASA Astrophysics Data System (ADS)

Zhao, W. N.; Yang, X. J.; Yao, C.; Ma, D. G.; Tang, H. J.

2017-10-01

Inductive power transfer (IPT) is a practical and preferable method for wireless electric vehicle (EV) charging which proved to be safe, convenient and reliable. Due to the air gap between the magnetic coupler, the magnetic field coupling decreases and the magnetic leakage increases significantly compared to traditional transformer, and this may lead to the magnetic flux density around the coupler more than the safety limit for human. So magnetic shielding should be adding to the winding made from litz wire to enhance the magnetic field coupling effect in the working area and reduce magnetic field strength in non-working area. Magnetic shielding can be achieved by adding high-permeability material or high-conductivity material. For high-permeability material its magnetic reluctance is much lower than the surrounding air medium so most of the magnetic line goes through the high-permeability material rather than surrounding air. For high-conductivity material the eddy current in the material can produce reverse magnetic field to achieve magnetic shielding. This paper studies the effect of the two types of shielding material on coupler for wireless EV charging and designs combination shielding made from high-permeability material and high-conductivity material. The investigation of the paper is done with the help of finite element analysis.

Design of the 1.5 MW, 30-96 MHz ultra-wideband 3 dB high power hybrid coupler for Ion Cyclotron Resonance Frequency (ICRF) heating in fusion grade reactor.

PubMed

Yadav, Rana Pratap; Kumar, Sunil; Kulkarni, S V

2016-01-01

Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. In designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper.

Inductive coupler for downhole components and method for making same

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Briscoe, Michael A.; Sneddon, Cameron; Fox, Joe

2006-05-09

The present invention includes a method of making an inductive coupler for downhole components. The method includes providing an annular housing, preferably made of steel, the housing having a recess. A conductor, preferably an insulated wire, is also provided along with a plurality of generally U-shaped magnetically conducting, electrically insulating (MCEI) segments. Preferably, the MCEI segments comprise ferrite. An assembly is formed by placing the plurality of MCEI segments within the recess in the annular housing. The segments are aligned to form a generally circular trough. A first portion of the conductor is placed within the circular trough. This assembly is consolidated with a meltable polymer which fills spaces between the segments, annular housing and the first portion of the conductor. The invention also includes an inductive coupler including an annular housing having a recess defined by a bottom portion and two opposing side wall portions. At least one side wall portion includes a lip extending toward but not reaching the other side wall portion. A plurality of generally U-shaped MCEI segments, preferably comprised of ferrite, are disposed in the recess and aligned so as to form a circular trough. The coupler further includes a conductor disposed within the circular trough and a polymer filling spaces between the segments, the annular housing and the conductor.

Pseudo-circulator implemented as a multimode fiber coupler

NASA Astrophysics Data System (ADS)

Bulota, F.; Bélanger, P.; Leduc, M.; Boudoux, C.; Godbout, N.

2016-03-01

We present a linear all-fiber device exhibiting the functionality of a circulator, albeit for multimode fibers. We define a pseudo-circulator as a linear three-port component that transfers most of a multimode light signal from Port 1 to Port 2, and from Port 2 to Port 3. Unlike a traditional circulator which depends on a nonlinear phenomenon to achieve a non-reciprocal behavior, our device is a linear component that seemingly breaks the principle of reciprocity by exploiting the variations of etendue of the multimode fibers in the coupler. The pseudo-circulator is implemented as a 2x2 asymmetric multimode fiber coupler, fabricated using the fusion-tapering technique. The coupler is asymmetric in its transverse fused section. The two multimode fibers differ in area, thus favoring the transfer of light from the smaller to the bigger fiber. The desired difference of area is obtained by tapering one of the fiber before the fusion process. Using this technique, we have successfully fabricated a pseudo-circulator surpassing in efficiency a 50/50 beam-splitter. In all the visible and near-IR spectrum, the transmission ratio exceeds 77% from Port 1 to Port 2, and 80% from Port 2 to Port 3. The excess loss is less than 0.5 dB, regardless of the entry port.

Design of the 1.5 MW, 30-96 MHz ultra-wideband 3 dB high power hybrid coupler for Ion Cyclotron Resonance Frequency (ICRF) heating in fusion grade reactor

NASA Astrophysics Data System (ADS)

Yadav, Rana Pratap; Kumar, Sunil; Kulkarni, S. V.

2016-01-01

Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. In designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper.

Integrated Optics Achromatic Nuller for Stellar Interferometry

NASA Technical Reports Server (NTRS)

Ksendzov, Alexander

2012-01-01

This innovation will replace a beam combiner, a phase shifter, and a mode conditioner, thus simplifying the system design and alignment, and saving weight and space in future missions. This nuller is a dielectric-waveguide-based, four-port asymmetric coupler. Its nulling performance is based on the mode-sorting property of adiabatic asymmetric couplers that are intrinsically achromatic. This nuller has been designed, and its performance modeled, in the 6.5-micrometer to 9.25-micrometer spectral interval (36% bandwidth). The calculated suppression of starlight for this 15-cm-long device is 10(exp -5) or better through the whole bandwidth. This is enough to satisfy requirements of a flagship exoplanet-characterization mission. Nulling interferometry is an approach to starlight suppression that will allow the detection and spectral characterization of Earth-like exoplanets. Nulling interferometers separate the light originating from a dim planet from the bright starlight by placing the star at the bottom of a deep, destructive interference fringe, where the starlight is effectively cancelled, or nulled, thus allowing the faint off-axis light to be much more easily seen. This process is referred to as nulling of the starlight. Achromatic nulling technology is a critical component that provides the starlight suppression in interferometer-based observatories. Previously considered space-based interferometers are aimed at approximately 6-to-20-micrometer spectral range. While containing the spectral features of many gases that are considered to be signatures of life, it also offers better planet-to-star brightness ratio than shorter wavelengths. In the Integrated Optics Achromatic Nuller (IOAN) device, the two beams from the interferometer's collecting telescopes pass through the same focusing optic and are incident on the input of the nuller.

Double-pump-pass singly resonant optical parametric oscillator for efficient generation of infrared light at 2300 nm based on PPMgSLT

NASA Astrophysics Data System (ADS)

Lee, Seungmin; Rhee, Bum Ku

2015-02-01

The pump laser was a cw-diode-pumped, acousto-optically Q-switched Nd:YAG laser. The laser had a pulse width of ~85 ns when operating at 10 kHz repetition rates. For infrared output of 2300 nm, we used 35-mm-long PPMgSLT which has a grating period of 32.7 μm for the first-order quasi-phase matching, resulting in the signal wavelength of 1980 nm at the crystal temperature of 76.5oC. Our optical parametric oscillator (OPO) was of a simple linear extra-cavity structure, formed by two flat dichroic mirrors with a separation of ~45 mm. The input coupling mirror had a high transmission of 98% for the pump, high reflectance of 98% at the signal and idler wavelengths, whereas the output coupler had a high reflectance of 98% at the pump wavelength. Hence, the OPO can be considered as singly resonant with double-pass pumping. In order to find an optimum reflectance for the efficient generation of infrared radiation of 2300 nm, we used the three different output mirrors whose reflectivity are ranging from 90% to 38% at the signal wavelength. We measured the signal and idler power as a function of the pumping power of Nd:YAG laser for three different output couplers. A maximum extraction efficiency with an optimum reflectance of output mirror was 27% for the idler, corresponding to 5.6 W of average output power. The fluctuations in the idler root-mean-square output power were measured to be below 1.5%. Our result is comparable with the recent one based on PPLN even with a simple cavity.

High-Speed Isolation Board for Flight Hardware Testing

NASA Technical Reports Server (NTRS)

Yamamoto, Clifford K.; Goodpasture, Richard L.

2011-01-01

There is a need to provide a portable and cost-effective galvanic isolation between ground support equipment and flight hardware such that any unforeseen voltage differential between ground and power supplies is eliminated. An interface board was designed for use between the ground support equipment and the flight hardware that electrically isolates all input and output signals and faithfully reproduces them on each side of the interface. It utilizes highly integrated multi-channel isolating devices to minimize size and reduce assembly time. This single-board solution provides appropriate connector hardware and breakout of required flight signals to individual connectors as needed for various ground support equipment. The board utilizes multi-channel integrated circuits that contain transformer coupling, thereby allowing input and output signals to be isolated from one another while still providing high-fidelity reproduction of the signal up to 90 MHz. The board also takes in a single-voltage power supply input from the ground support equipment and in turn provides a transformer-derived isolated voltage supply to power the portion of the circuitry that is electrically connected to the flight hardware. Prior designs used expensive opto-isolated couplers that were required for each signal to isolate and were time-consuming to assemble. In addition, these earlier designs were bulky and required a 2U rack-mount enclosure. The new design is smaller than a piece of 8.5 11-in. (.22 28-mm) paper and can be easily hand-carried where needed. The flight hardware in question is based on a lineage of existing software-defined radios (SDRs) that utilize a common interface connector with many similar input-output signals present. There are currently four to five variations of this SDR, and more upcoming versions are planned based on the more recent design.

Spacecraft IF switch matrix for wideband service applications in 30/20 GHz communications satellite systems: Proof-of-concept model, executive summary

NASA Technical Reports Server (NTRS)

Ho, P. T.; Coban, E.; Pelose, J.

1983-01-01

The design and development of a unique coupler crossbar 20 x 20 microwave switch matrix are described. The test results of the proof of concept model that meets the requirements for a high speed satellite switched, time division multiple access (SS-TDMA) system are presented.

All silicon waveguide spherical microcavity coupler device.

PubMed

Xifré-Pérez, E; Domenech, J D; Fenollosa, R; Muñoz, P; Capmany, J; Meseguer, F

2011-02-14

A coupler based on silicon spherical microcavities coupled to silicon waveguides for telecom wavelengths is presented. The light scattered by the microcavity is detected and analyzed as a function of the wavelength. The transmittance signal through the waveguide is strongly attenuated (up to 25 dB) at wavelengths corresponding to the Mie resonances of the microcavity. The coupling between the microcavity and the waveguide is experimentally demonstrated and theoretically modeled with the help of FDTD calculations.

New Methods for Rotation Sensing by Using a Two-Coupler Fiber-Optic Ring Resonator

NASA Astrophysics Data System (ADS)

Seraji, Faramarz E.

1993-04-01

This paper presents a theoretical analysis of new methods for rotation sensing by using a two-coupler type fiber-optic ring resonator. It is shown that in the proposed methods a resonance spike can be generated whose amplitude gives a direct measure of the rotation rates. The approaches are simple and have a major advantage of not using a closed-loop to control the operating points for resonance.

Extending The Calibration In The Underwater Sound Reference Division (USRD) Reciprocity Coupler To Incorporate Phase

DTIC Science & Technology

2016-09-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS EXTENDING THE CALIBRATION IN THE UNDERWATER SOUND REFERENCE DIVISION (USRD) RECIPROCITY COUPLER...AND DATES COVERED Master’s Thesis 08-01-2014 to 08-21-2016 4. TITLE AND SUBTITLE EXTENDING THE CALIBRATION IN THE UNDERWATER SOUND REFERENCE DIVISION...SPONSORING / MONITORING AGENCY REPORT NUMBER 11. SUPPLEMENTARY NOTES The views expressed in this document are those of the author and do not reflect

DIRECTIONAL COUPLERS

DOEpatents

Nigg, D.J.

1961-12-01

A directional coupler of small size is designed. Stripline conductors of non-rectilinear configuration, and separated from each other by a thin dielectric spacer. cross each other at least at two locations at right angles, thus providing practically pure capacitive coupling which substantially eliminates undesirable inductive coupling. The conductors are sandwiched between a pair of ground planes. The coupling factor is dependent only on the thickness and dielectric constant of the dielectric spacer at the point of conductor crossover. (AEC)

Method and device for remotely monitoring an area using a low peak power optical pump

DOEpatents

Woodruff, Steven D.; Mcintyre, Dustin L.; Jain, Jinesh C.

2014-07-22

A method and device for remotely monitoring an area using a low peak power optical pump comprising one or more pumping sources, one or more lasers; and an optical response analyzer. Each pumping source creates a pumping energy. The lasers each comprise a high reflectivity mirror, a laser media, an output coupler, and an output lens. Each laser media is made of a material that emits a lasing power when exposed to pumping energy. Each laser media is optically connected to and positioned between a corresponding high reflectivity mirror and output coupler along a pumping axis. Each output coupler is optically connected to a corresponding output lens along the pumping axis. The high reflectivity mirror of each laser is optically connected to an optical pumping source from the one or more optical pumping sources via an optical connection comprising one or more first optical fibers.

Polarization entangled cluster state generation in a lithium niobate chip

NASA Astrophysics Data System (ADS)

Szep, Attila; Kim, Richard; Shin, Eunsung; Fanto, Michael L.; Osman, Joseph; Alsing, Paul M.

2016-10-01

We present a design of a quantum information processing C-phase (Controlled-phase) gate applicable for generating cluster states that has a form of integrated photonic circuits assembled with cascaded directional couplers on a Ti in-diffused Lithium Niobate (Ti-LN) platform where directional couplers as the integrated optical analogue of bulk beam splitters are used as fundamental building blocks. Based on experimentally optimized fabrication parameters of Ti-LN optical waveguides operating at an 810nm wavelength, an integrated Ti-LN quantum C-phase gate is designed and simulated. Our proposed C-phase gate consists of three tunable directional couplers cascaded together with having different weighted switching ratios for providing a tool of routing vertically- and horizontally-polarized photons independently. Its operation mechanism relies on selectively controlling the optical coupling of orthogonally polarized modes via the change in the index of refraction, and its operation is confirmed by the BPM simulation.

Compact broadband polarization beam splitter using a symmetric directional coupler with sinusoidal bends.

PubMed

Zhang, Fan; Yun, Han; Wang, Yun; Lu, Zeqin; Chrostowski, Lukas; Jaeger, Nicolas A F

2017-01-15

We design and demonstrate a compact broadband polarization beam splitter (PBS) using a symmetric directional coupler with sinusoidal bends on a silicon-on-insulator platform. The sinusoidal bends in our PBS suppress the power exchange between two parallel symmetric strip waveguides for the transverse-electric (TE) mode, while allowing for the maximum power transfer to the adjacent waveguide for the transverse-magnetic (TM) mode. Our PBS has a nominal coupler length of 8.55 μm, and it has an average extinction ratio (ER) of 12.0 dB for the TE mode, an average ER of 20.1 dB for the TM mode, an average polarization isolation (PI) of 20.6 dB for the through port, and an average PI of 11.5 dB for the cross port, all over a bandwidth of 100 nm.

Monitoring well

DOEpatents

Hubbell, Joel M.; Sisson, James B.

2002-01-01

The present invention relates to a monitoring well which includes an enclosure defining a cavity and a water reservoir enclosed within the cavity and wherein the reservoir has an inlet and an outlet. The monitoring well further includes a porous housing borne by the enclosure and which defines a fluid chamber which is oriented in fluid communication with the outlet of the reservoir, and wherein the porous housing is positioned in an earthen soil location below-grade. A geophysical monitoring device is provided and mounted in sensing relation relative to the fluid chamber of the porous housing; and a coupler is selectively moveable relative to the outlet of reservoir to couple the porous housing and water reservoir in fluid communication. An actuator is coupled in force transmitting relation relative to the coupler to selectively position the coupler in a location to allow fluid communication between the reservoir and the fluid chamber defined by the porous housing.

Silicon nitride tri-layer vertical Y-junction and 3D couplers with arbitrary splitting ratio for photonic integrated circuits.

PubMed

Shang, Kuanping; Pathak, Shibnath; Liu, Guangyao; Feng, Shaoqi; Li, Siwei; Lai, Weicheng; Yoo, S J B

2017-05-01

We designed and demonstrated a tri-layer Si₃N₄/SiO₂ photonic integrated circuit capable of vertical interlayer coupling with arbitrary splitting ratios. Based on this multilayer photonic integrated circuit platform with each layer thicknesses of 150 nm, 50 nm, and 150 nm, we designed and simulated the vertical Y-junctions and 3D couplers with arbitrary power splitting ratios between 1:10 and 10:1 and with negligible(< -50 dB) reflection. Based on the design, we fabricated and demonstrated tri-layer vertical Y-junctions with the splitting ratios of 1:1 and 3:2 with excess optical losses of 0.230 dB. Further, we fabricated and demonstrated the 1 × 3 3D couplers with the splitting ratio of 1:1:4 for symmetric structures and variable splitting ratio for asymmetric structures.

Portable waveguide display system with a large field of view by integrating freeform elements and volume holograms.

PubMed

Han, Jian; Liu, Juan; Yao, Xincheng; Wang, Yongtian

2015-02-09

A compact waveguide display system integrating freeform elements and volume holograms is presented here for the first time. The use of freeform elements can broaden the field of view, which limits the applications of a holographic waveguide. An optimized system can achieve a diagonal field of view of 45° when the thickness of the waveguide planar is 3mm. Freeform-elements in-coupler and the volume holograms out-coupler were designed in detail in our study, and the influence of grating configurations on diffraction efficiency was analyzed thoroughly. The off-axis aberrations were well compensated by the in-coupler and the diffraction efficiency of the optimized waveguide display system could reach 87.57%. With integrated design, stability and reliability of this monochromatic display system were achieved and the alignment of the system was easily controlled by the record of the volume holograms, which makes mass production possible.

Portable waveguide display system with a large field of view by integrating freeform elements and volume holograms

PubMed Central

Han, Jian; Liu, Juan; Yao, Xincheng; Wang, Yongtian

2015-01-01

A compact waveguide display system integrating freeform elements and volume holograms is presented here for the first time. The use of freeform elements can broaden the field of view, which limits the applications of a holographic waveguide. An optimized system can achieve a diagonal field of view of 45° when the thickness of the waveguide planar is 3mm. Freeform-elements in-coupler and the volume holograms out-coupler were designed in detail in our study, and the influence of grating configurations on diffraction efficiency was analyzed thoroughly. The off-axis aberrations were well compensated by the in-coupler and the diffraction efficiency of the optimized waveguide display system could reach 87.57%. With integrated design, stability and reliability of this monochromatic display system were achieved and the alignment of the system was easily controlled by the record of the volume holograms, which makes mass production possible. PMID:25836207

Optical single sideband millimeter-wave signal generation and transmission using 120° hybrid coupler

NASA Astrophysics Data System (ADS)

Zheng, Zhiwei; Peng, Miao; Zhou, Hui; Chen, Ming; Jiang, Leyong; Tan, Li; Dai, Xiaoyu; Xiang, Yuanjiang

2018-03-01

We propose a novel 60 GHz optical single sideband (OSSB) millimeter-wave (mm-wave) signal generation scheme using 120° hybrid coupler based on external integrated Mach-Zehnder modulator (MZM). The proposed scheme shows that the bit error ratio (BER) performance is improved by suppressing the +2nd-order sideband. Meanwhile, the transmission distance is extended as only the optical +1st-order sideband is modulated by using 5 Gbit/s baseband signal while the carrier is blank, owing to the elimination of walk-off effect suffered from fiber dispersion. The simulation results demonstrated that the eye diagrams of the generated 60 GHz OSSB signal keep open and clear after 100 km standard single-mode fiber (SSMF). In addition, the proposed scheme can achieve 2 dB receiver sensitivity improvements than the conventional 90° hybrid coupler when transmitted over 100 km SSMF at a BER of 10-9.

Traveling-Wave Tube Amplifier Second Harmonic as Millimeter-Wave Beacon Source for Atmospheric Propagation Studies

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

The design and test results of a novel waveguide multimode directional coupler for a CW millimeter-wave satellite beacon source are presented. The coupler separates the second harmonic power from the fundamental output power of a traveling-wave tube amplifier. A potential application of the beacon source is for investigating the atmospheric effects on Q-band (37 to 42 GHz) and VW-band (71 to 76 GHz) satellite-to-ground signals.

Compact wavelength-insensitive fabrication-tolerant silicon-on-insulator beam splitter.

PubMed

Rasigade, Gilles; Le Roux, Xavier; Marris-Morini, Delphine; Cassan, Eric; Vivien, Laurent

2010-11-01

A star coupler-based beam splitter for rib waveguides is reported. A design method is presented and applied in the case of silicon-on-insulator rib waveguides. Experimental results are in good agreement with simulations. Excess loss lower than 1 dB is experimentally obtained for star coupler lengths from 0.5 to 1 μm. Output balance is better than 1 dB, which is the measurement accuracy, and broadband transmission is obtained over 90 nm.

Assembly for facilitating inservice inspection of a reactor coolant pump rotor

DOEpatents

Veronesi, Luciano

1990-01-01

A reactor coolant pump has an outer casing with an internal cavity holding a coolant and a rotor rotatably mounted in the cavity within the coolant. An assembly for permitting inservice inspection of the pump rotor without first draining the coolant from the casing cavity is attached to an end of the pump. A cylindrical bore is defined through the casing in axial alignment with an end of pump rotor and opening into the internal cavity. An extension attached on the rotor end and rotatable therewith has a cylindrical coupler member extending into the bore. An outer end of the coupler member has an element configured to receive a tool for performance of inservice rotor inspection. A hollow cylindrical member is disposed in the bore and surrounds the coupler member. The cylindrical member is slidably movable relative to the coupler member along the bore between a retracted position wherein the cylindrical member is stored for normal pump operation and an extended position wherein the cylindrical member is extended for permitting inservice rotor inspection. A cover member is detachably and sealably attached to the casing across the bore for closing the bore and retaining the cylindrical member at its retracted position for normal pump operation. Upon detachment of the cover member, the cylindrical member can be extended to permit inservice rotor inspection.

A NEW CONCEPT FOR HIGH POWER RF COUPLING BETWEEN WAVEGUIDES AND RESONANT RF CAVITIES

DOE PAGES

Xu, Chen; Ben-Zvi, Ilan; Wang, Haipeng; ...

2017-01-01

Microwave engineering of high average-power (hundreds of kilowatts) devices often involves a transition from a waveguide to a device, typically a resonant cavity. This is a basic operation, which finds use in various application areas of significance to science and industry. At relatively low frequencies, L-band and below, it is convenient, sometimes essential, to couple the power between the waveguide and the cavity through a coaxial antenna, forming a power coupler. Power flow to the cavity in the fundamental mode leads to a Fundamental Power Coupler (FPC). High-order mode power generated in the cavity by a particle beam leads tomore » a high-order mode power damper. Coupling a cryogenic device, such as a superconducting cavity to a room temperature power source (or damp) leads to additional constraints and challenges. We propose a new approach to this problem, wherein the coax line element is operated in a TE11 mode rather than the conventional TEM mode. We will show that this method leads to a significant increase in the power handling capability of the coupler as well as a few other advantages. As a result, we describe the mode converter from the waveguide to the TE11 coax line, outline the characteristics and performance limits of the coupler and provide a detailed worked out example in the challenging area of coupling to a superconducting accelerator cavity.« less

Design of the 1.5 MW, 30-96 MHz ultra-wideband 3 dB high power hybrid coupler for Ion Cyclotron Resonance Frequency (ICRF) heating in fusion grade reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yadav, Rana Pratap, E-mail: ranayadav97@gmail.com; Kumar, Sunil; Kulkarni, S. V.

2016-01-15

Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. Inmore » designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper.« less

A NEW CONCEPT FOR HIGH POWER RF COUPLING BETWEEN WAVEGUIDES AND RESONANT RF CAVITIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Chen; Ben-Zvi, Ilan; Wang, Haipeng

Microwave engineering of high average-power (hundreds of kilowatts) devices often involves a transition from a waveguide to a device, typically a resonant cavity. This is a basic operation, which finds use in various application areas of significance to science and industry. At relatively low frequencies, L-band and below, it is convenient, sometimes essential, to couple the power between the waveguide and the cavity through a coaxial antenna, forming a power coupler. Power flow to the cavity in the fundamental mode leads to a Fundamental Power Coupler (FPC). High-order mode power generated in the cavity by a particle beam leads tomore » a high-order mode power damper. Coupling a cryogenic device, such as a superconducting cavity to a room temperature power source (or damp) leads to additional constraints and challenges. We propose a new approach to this problem, wherein the coax line element is operated in a TE11 mode rather than the conventional TEM mode. We will show that this method leads to a significant increase in the power handling capability of the coupler as well as a few other advantages. As a result, we describe the mode converter from the waveguide to the TE11 coax line, outline the characteristics and performance limits of the coupler and provide a detailed worked out example in the challenging area of coupling to a superconducting accelerator cavity.« less

CEBAF Upgrade Cryomodule Component Testing in the Horizontal Test Bed (HTB)

DOE Office of Scientific and Technical Information (OSTI.GOV)

I.E. Campisi; B. Carpenter; G.K. Davis

2001-06-01

The planned upgrade of the CEBAF electron accelerator includes the development of an improved cryomodule. Several components differ substantially from the original CEBAF cryomodule; these include: the new 7-cell, 1.5 GHz cavities with integral helium vessel, a new, backlash-free cavity tuner, the waveguide coupler with its room-temperature ceramic window, and the HOM damping filters. In order to test the design features and performance of the new components, a horizontal cryostat (Horizontal Test Bed) has been constructed which allows testing with a turn around time of less than three weeks. This cryostat provides the environment for testing one or two cavities,more » with associated auxiliary components, in a condition similar to that of a real cryomodule. A series of tests has been performed on a prototype 7-cell cavity and the above-mentioned systems. In this paper the results of the tests on the cryostat, on the cavity performance, on its coupler, on the tuner characteristics, and on the microphonics behavior will be reported.« less

Resonance Frequency Tuning of a Double Ring Resonator in GaInAsP/InP: Experiment and Simulation

NASA Astrophysics Data System (ADS)

Rabus, Dominik Gerhard; Hamacher, Michael; Heidrich, Helmut

2002-02-01

A racetrack shaped double ring resonator (DRR) filter is demonstrated with radii of 200 μm. The double ring resonator contains two -3 dB multimode interference (MMI) couplers for I/O coupling and a -13 dB codirectional coupler in between the rings. A free spectral range of 50 GHz has been realized. A simulation model has been developed to describe the DRR. As fabrication tolerances do not allow the realization of two identical rings with required nm-circumference accuracy in the resonator, a frequency alignment of the resonator is indispensable. The resonance frequency tuning is performed thermally using platinum resistors which have been placed on top of the waveguides in both rings. An on-off ratio increase has been achieved of more than 3 dB, resulting in a total on-off ratio larger than 18 dB. The frequency alignment is inevitable in the case of multiple coupled micro ring resonators.

Enhanced vibrational spectroscopy, intracellular refractive indexing for label-free biosensing and bioimaging by multiband plasmonic-antenna array.

PubMed

Chen, Cheng-Kuang; Chang, Ming-Hsuan; Wu, Hsieh-Ting; Lee, Yao-Chang; Yen, Ta-Jen

2014-10-15

In this study, we report a multiband plasmonic-antenna array that bridges optical biosensing and intracellular bioimaging without requiring a labeling process or coupler. First, a compact plasmonic-antenna array is designed exhibiting a bandwidth of several octaves for use in both multi-band plasmonic resonance-enhanced vibrational spectroscopy and refractive index probing. Second, a single-element plasmonic antenna can be used as a multifunctional sensing pixel that enables mapping the distribution of targets in thin films and biological specimens by enhancing the signals of vibrational signatures and sensing the refractive index contrast. Finally, using the fabricated plasmonic-antenna array yielded reliable intracellular observation was demonstrated from the vibrational signatures and intracellular refractive index contrast requiring neither labeling nor a coupler. These unique features enable the plasmonic-antenna array to function in a label-free manner, facilitating bio-sensing and imaging development. Copyright © 2014 Elsevier B.V. All rights reserved.

Etched beam splitters in InP/InGaAsP.

PubMed

Norberg, Erik J; Parker, John S; Nicholes, Steven C; Kim, Byungchae; Krishnamachari, Uppiliappan; Coldren, Larry A

2011-01-17

An etched beam splitter (EBS) photonic coupler based on frustrated total internal reflection (FTIR) is designed, fabricated and characterized in the InP/InGaAsP material system. The EBS offers an ultra compact footprint (8x11 μm) and a complete range of bar/cross coupling ratio designs. A novel pre-etching process is developed to achieve sufficient depth of the etched coupling gaps. Fabricated EBS couplers demonstrate insertion loss between 1 and 2.6 dB with transmission (cross-coupling) ≤ 10%. The results show excellent agreement with 3D finite-difference time-domain (FDTD) modeling. The coupling of EBS has weak wavelength dependence in the C-band, making it suitable for wavelength division multiplexing (WDM) or other wide bandwidth applications. Finally, the EBS is integrated with active semiconductor optical amplifier (SOA) and phase-modulator components; using a flattened ring resonator structure, a channelizing filter tunable in both amplitude and center frequency is demonstrated, as well as an EBS coupled ring laser.

SSC San Diego Biennial Review 2003. Vol 2: Communication and Information Systems

DTIC Science & Technology

2003-01-01

University, Department of Electrical and Computer Engineering) Michael Jablecki (Science and Technology Corporation) Stochastic Unified Multiple...wearable computers and cellular phones. The technology-transfer process involved a coalition of government and industrial partners, each providing...the design and fabrication of the coupler. SSC San Diego developed a computer -controlled fused fiber fabrication station to achieve the required

OBLIMAP 2.0: a fast climate model-ice sheet model coupler including online embeddable mapping routines

NASA Astrophysics Data System (ADS)

Reerink, Thomas J.; van de Berg, Willem Jan; van de Wal, Roderik S. W.

2016-11-01

This paper accompanies the second OBLIMAP open-source release. The package is developed to map climate fields between a general circulation model (GCM) and an ice sheet model (ISM) in both directions by using optimal aligned oblique projections, which minimize distortions. The curvature of the surfaces of the GCM and ISM grid differ, both grids may be irregularly spaced and the ratio of the grids is allowed to differ largely. OBLIMAP's stand-alone version is able to map data sets that differ in various aspects on the same ISM grid. Each grid may either coincide with the surface of a sphere, an ellipsoid or a flat plane, while the grid types might differ. Re-projection of, for example, ISM data sets is also facilitated. This is demonstrated by relevant applications concerning the major ice caps. As the stand-alone version also applies to the reverse mapping direction, it can be used as an offline coupler. Furthermore, OBLIMAP 2.0 is an embeddable GCM-ISM coupler, suited for high-frequency online coupled experiments. A new fast scan method is presented for structured grids as an alternative for the former time-consuming grid search strategy, realising a performance gain of several orders of magnitude and enabling the mapping of high-resolution data sets with a much larger number of grid nodes. Further, a highly flexible masked mapping option is added. The limitation of the fast scan method with respect to unstructured and adaptive grids is discussed together with a possible future parallel Message Passing Interface (MPI) implementation.

Efficient On-chip Optical Microresonator for Optical Comb Generation: Design and Fabrication

NASA Astrophysics Data System (ADS)

Han, Kyunghun

An optical frequency comb is a series of equally spaced frequency components. It has gained much attention since Nobel physics prize was awarded John L. Hall and Theodor W. Hansch for their contribution to the optical frequency comb technique in 2005. The optical frequency comb has been extensively studied because of its precision as a tool for spectroscopy, and is now widely used in bio- and chemical sensors, optical clocks, mode-locked dark pulse generation, soliton generation, and optical communication. Recently, thanks to the developments in nanotechnology, the optical frequency comb generation is made possible at a chip-scale level with microresonators. However, because the threshold power of the optical frequency comb generation is beyond the capability of the on-chip laser source, efficient microresonator is required. Here, we demonstrate an ultra-compact and highly efficient strip-slot direct mode coupler, aiming to achieve slotted silicon microresonator cladded with nonlinear polymer Poly-DDMEBT in SOI platform. As an application of the strip-slot direct mode coupling, a double slot fiber-to-chip edge coupler is demonstrated showing 2 dB insertion loss reduction compared to the conventional single tip edge coupler. For silicon nitride platform, we investigated evanescent wave coupling of microresonator, focusing on bus waveguide geometry optimization. The optimized waveguide width offers an efficient excitation of a fundamental mode in the resonator waveguide. This investigation can benefit low threshold comb generation by enhancing the extinction ratio. We experimentally demonstrated the high Q-factor micro-ring resonator with intrinsic Q of 12.6 million as well as the single FSR comb generation with 63 mW.

Deepening Insights of Charge Transfer and Photophysics in a Novel Donor-Acceptor Cocrystal for Waveguide Couplers and Photonic Logic Computation.

PubMed

Zhu, Weigang; Zhu, Lingyun; Zou, Ye; Wu, Yishi; Zhen, Yonggang; Dong, Huanli; Fu, Hongbing; Wei, Zhixiang; Shi, Qiang; Hu, Wenping

2016-07-01

The charge transfer and photophysics in a new light-emitting cocrystal with ribbon-like morphology are revealed in-depth. These cocrystals can serve as an efficient 1D optical waveguide, and the cocrystal waveguide couplers fabricated by a probe-assisted crystal-moving technique exhibit interfacial white emission and can function as basic photonic logic gates, showing potential for future integrated photonics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Monolithically integrated fiber-to-the-home diplexers and triplexers using a bilevel etched 2 x 2 optical coupler.

PubMed

Zhang, Li; Wang, Lei; He, Jian-Jun

2009-09-01

A novel design of monolithically integrated diplexers and triplexers for fiber-to-the-home applications is presented. A bilevel etched asymmetrical 2 x 2 optical coupler is analyzed for efficient couplings of both upstream and downstream signals. The design of the diplexer is extended to a triplexer by adding an etched diffraction grating as an additional downstream demultiplexing element. The total size of the integrated diplexer and triplexer is smaller than 500 microm x 500 microm.

Organic membrane photonic integrated circuits (OMPICs).

PubMed

Amemiya, Tomohiro; Kanazawa, Toru; Hiratani, Takuo; Inoue, Daisuke; Gu, Zhichen; Yamasaki, Satoshi; Urakami, Tatsuhiro; Arai, Shigehisa

2017-08-07

We propose the concept of organic membrane photonic integrated circuits (OMPICs), which incorporate various functions needed for optical signal processing into a flexible organic membrane. We describe the structure of several devices used within the proposed OMPICs (e.g., transmission lines, I/O couplers, phase shifters, photodetectors, modulators), and theoretically investigate their characteristics. We then present a method of fabricating the photonic devices monolithically in an organic membrane and demonstrate the operation of transmission lines and I/O couplers, the most basic elements of OMPICs.

Multi-directional emission and detection of spin waves propagating in yttrium iron garnet with wavelengths down to about 100 nm

NASA Astrophysics Data System (ADS)

Maendl, Stefan; Grundler, Dirk

2018-05-01

We performed broadband spin-wave spectroscopy on 200 nm thick yttrium iron garnet containing arrays of partially embedded magnetic nanodisks. Using integrated coplanar waveguides (CPWs), we studied the excitation and transmission of spin waves depending on the presence of nanomagnet arrays of different lateral extensions. By means of the grating coupler effect, we excited spin waves propagating in multiple lateral directions with wavelengths down to 111 nm. They exhibited group velocities of up to 1 km/s. Detection of such short-wavelength spin waves was possible only in symmetrically designed emitter/detector configurations, not with a bare CPW. We report spin waves propagating between grating couplers under oblique angles exhibiting a wave vector component parallel to the CPW. The effective propagation distance amounted to about 80 μm. Such transmission signals were not addressed before and substantiate the versatility of the grating coupler effect for implementing nanomagnonic circuits.

Ultrathin Optical Panel And A Method Of Making An Ultrathin Optical Panel.

DOEpatents

Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

2005-02-15

An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated with a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

Ultrathin Optical Panel And A Method Of Making An Ultrathin Optical Panel.

DOEpatents

Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

2005-05-17

An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated with a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

Ultrathin optical panel and a method of making an ultrathin optical panel

DOEpatents

Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

2003-02-11

An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated with a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

Ultrathin optical panel and a method of making an ultrathin optical panel

DOEpatents

Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

2001-10-09

An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated with a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

Ultrathin optical panel and a method of making an ultrathin optical panel

DOEpatents

Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

2002-01-01

An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated With a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

BERLinPro Booster Cavity Design, Fabrication and Test Plans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burrill, Andrew; Anders, W; Frahm, A.

2014-12-01

The bERLinPro project, a 100 mA, 50 MeV superconducting RF (SRF) Energy Recovery Linac (ERL) is under construction at Helmholtz-Zentrum Berlin for the purpose of studying the technical challenges and physics of operating a high current, c.w., 1.3 GHz ERL. This machine will utilize three unique SRF cryomodules for the injector, booster and linac module respectively. The booster cryomodule will contain three 2-cell SRF cavities, based on the original design by Cornell University, and will be equipped with twin 115 kW RF power couplers in order to provide the appropriate acceleration to the high current electron beam. This paper willmore » review the status of the fabrication of the 4 booster cavities that have been built for this project by Jefferson Laboratory and look at the challenges presented by the incorporation of fundamental power couplers capable of delivering 115 kW. The test plan for the cavities and couplers will be given along with a brief overview of the cryomodule design.« less

Femtosecond laser inscription of asymmetric directional couplers for in-fiber optical taps and fiber cladding photonics.

PubMed

Grenier, Jason R; Fernandes, Luís A; Herman, Peter R

2015-06-29

Precise alignment of femtosecond laser tracks in standard single mode optical fiber is shown to enable controllable optical tapping of the fiber core waveguide light with fiber cladding photonic circuits. Asymmetric directional couplers are presented with tunable coupling ratios up to 62% and bandwidths up to 300 nm at telecommunication wavelengths. Real-time fiber monitoring during laser writing permitted a means of controlling the coupler length to compensate for micron-scale alignment errors and to facilitate tailored design of coupling ratio, spectral bandwidth and polarization properties. Laser induced waveguide birefringence was harnessed for polarization dependent coupling that led to the formation of in-fiber polarization-selective taps with 32 dB extinction ratio. This technology enables the interconnection of light propagating in pre-existing waveguides with laser-formed devices, thereby opening a new practical direction for the three-dimensional integration of optical devices in the cladding of optical fibers and planar lightwave circuits.

Optical sensor of magnetic fields

DOEpatents

Butler, M.A.; Martin, S.J.

1986-03-25

An optical magnetic field strength sensor for measuring the field strength of a magnetic field comprising a dilute magnetic semi-conductor probe having first and second ends, longitudinally positioned in the magnetic field for providing Faraday polarization rotation of light passing therethrough relative to the strength of the magnetic field. Light provided by a remote light source is propagated through an optical fiber coupler and a single optical fiber strand between the probe and the light source for providing a light path therebetween. A polarizer and an apparatus for rotating the polarization of the light is provided in the light path and a reflector is carried by the second end of the probe for reflecting the light back through the probe and thence through the polarizer to the optical coupler. A photo detector apparatus is operably connected to the optical coupler for detecting and measuring the intensity of the reflected light and comparing same to the light source intensity whereby the magnetic field strength may be calculated.

Optimized optical devices for edge-coupling-enabled silicon photonics platform

NASA Astrophysics Data System (ADS)

Png, Ching Eng; Ang, Thomas Y. L.; Ong, Jun Rong; Lim, Soon Thor; Sahin, Ezgi; Chen, G. F. R.; Tan, D. T. H.; Guo, Tina X.; Wang, Hong

2018-02-01

We present a library of high-performance passive and active silicon photonic devices at the C-band that is specifically designed and optimized for edge-coupling-enabled silicon photonics platform. These devices meet the broadband (100 nm), low-loss (< 2dB per device), high speed (>= 25 Gb/s), and polarization diversity requirements (TE and TM polarization extinction ratio <= 25 dB) for optical communication applications. Ultra-low loss edge couplers, broadband directional couplers, high-extinction ratio polarization beam splitters (PBSs), and high-speed modulators are some of the devices within our library. In particular, we have designed and fabricated inverse taper fiber-to-waveguide edge couplers of tip widths ranging from 120 nm to 200 nm, and we obtained a low coupling loss of 1.80+/-0.28 dB for 160 nm tip width. To achieve polarization diversity operation for inverse tapers, we have experimentally realized different designs of polarization beam splitters (PBS). Our optimized PBS has a measured extinction ratio of <= 25 dB for both the quasiTE modes, and quasi-TM modes. Additionally, a broadband (100 nm) directional coupler with a 50/50 power splitting ratio was experimentally realized on a small footprint of 20×3 μm2 . Last but not least, high-speed silicon modulators with a range of carrier doping concentrations and offset of the PN junction can be used to optimise the modulation efficiency, and insertion losses for operation at 25 GHz.

Multi-access fiber optic data bus using FDM/FSK

NASA Technical Reports Server (NTRS)

Zanger, H.

1984-01-01

The major thrust was to develop a T coupler with very low (0.1 0.2dB) in-line loss. This is essential to any multiaccess bus structure where the word multi implies fifteen or more nodes on the bus, and it is tacitly assumed to be a passive bus. (Reliability considerations tend to exclude the use of active nodes - repeater nodes.)

Interferometric fiber-optic temperature sensor with spiral polarization couplers

NASA Astrophysics Data System (ADS)

Cortés, R.; Khomenko, A. V.; Starodumov, A. N.; Arzate, N.; Zenteno, L. A.

1998-09-01

A fiber optic temperature sensor, for which the changes in modal birefringence of a short section of a long birefringent fiber are monitored remotely, is described. It employs a white light interferometer, which is formed by two concatenated spiral polarization mode couplers. A new method for white light interferometer output signal processing is described which provides a high accuracy absolute temperature measurement even in discontinuous operation of the sensor. Experimental results are presented for temperature measurements over a 100°C range with resolution of 3×10 -3 °C.

Modal analysis and cut-off conditions of multichannel surface-acoustic-waveguide structures.

PubMed

Griffel, G; Golan, G; Ruschin, S; Seidman, A; Croitoru, N

1988-01-01

Multichannel guides for surface acoustic waves can improve the efficiency of SAW (surface acoustic-wave) devices significantly. Focusing, steering, and modulating the propagating acoustical modes can be achieved similarly to optical waveguided devices. A general formulation is presented for the analysis of the lateral waveguiding properties of Rayleigh modes in surfaces loaded with deposited strips of different materials. General expressions are obtained for the number of modes and cutoff conditions in these structures. As examples of applications, a simple directional coupler and an electrically controlled coupler are proposed.

Coaxial cable Bragg grating assisted microwave coupler.

PubMed

Huang, Jie; Wei, Tao; Fan, Jun; Xiao, Hai

2014-01-01

This paper reports a microwave coupler based on two parallel coaxial cable Bragg gratings fabricated by drilling U-grooves across the cables at periodic distance along the cable direction. Electromagnetic field couplings between two cables were observed at discrete frequencies through both near and far ends detections. The coupling frequency and strength can be precisely controlled by varying the grating period and length. The coupling bandwidth may also be controlled through specific grating design. The device physics was also described through transfer matrix which matched well with the experimental results.

Infrasonic Stethoscope for Monitoring Physiological Processes

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J. (Inventor); Shams, Qamar A. (Inventor); Dimarcantonio, Albert L. (Inventor)

2018-01-01

An infrasonic stethoscope for monitoring physiological processes of a patient includes a microphone capable of detecting acoustic signals in the audible frequency bandwidth and in the infrasonic bandwidth (0.03 to 1000 Hertz), a body coupler attached to the body at a first opening in the microphone, a flexible tube attached to the body at a second opening in the microphone, and an earpiece attached to the flexible tube. The body coupler is capable of engagement with a patient to transmit sounds from the person, to the microphone and then to the earpiece.

Infrasonic Stethoscope for Monitoring Physiological Processes

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J. (Inventor); Shams, Qamar A. (Inventor); Dimarcantonio, Albert L. (Inventor)

2016-01-01

An infrasonic stethoscope for monitoring physiological processes of a patient includes a microphone capable of detecting acoustic signals in the audible frequency bandwidth and in the infrasonic bandwidth (0.03 to 1000 Hertz), a body coupler attached to the body at a first opening in the microphone, a flexible tube attached to the body at a second opening in the microphone, and an earpiece attached to the flexible tube. The body coupler is capable of engagement with a patient to transmit sounds from the person, to the microphone and then to the earpiece.

OPTICAL FIBRES AND FIBREOPTIC SENSORS: Fibreoptic distributed temperature sensor with spectral filtration by directional fibre couplers

NASA Astrophysics Data System (ADS)

Kuznetsov, A. G.; Babin, Sergei A.; Shelemba, Ivan S.

2009-11-01

We demonstrate a Raman-based all-fibre temperature sensor utilising a pulsed erbium fibre laser. The sensor is made of a standard single-mode telecom fibre, SMF-28, and includes a number of directional couplers as band-pass filters. The temperature profile along a 7-km fibreoptic line is measured with an accuracy of 2oC and a spatial resolution of 10 m. In data processing, we take into account the difference in attenuation between the spectral components of the backscatter signal.

A facetless regrowth-free single mode laser based on MMI couplers

NASA Astrophysics Data System (ADS)

Caro, Ludovic; Kelly, Niall P.; Dernaika, Mohamad; Shayesteh, Maryam; Morrissey, Padraic E.; Alexander, Justin K.; Peters, Frank H.

2017-09-01

This paper presents a facetless, tunable laser operating near 1575 nm, as well as a theoretical model predicting spectral features of the laser. The lasers were fabricated without regrowth or advanced lithography techniques, and are based on MMI couplers and etched facets. Coarse vernier tuning was achieved over a range of 25 nm, while fine, thermal tuning was also demonstrated over a range of 1.5 nm. SMSR values of 25 dB and higher were observed, with a measured laser linewidth of 600 kHz.

Characterization of Anisotropic Leaky Mode Modulators for Holovideo

PubMed Central

Gneiting, Scott; Kimball, Jacob; Henrie, Andrew; McLaughlin, Stephen; DeGraw, Taylor; Smalley, Daniel

2016-01-01

Holovideo displays are based on light-bending spatial light modulators. One such spatial light modulator is the anisotropic leaky mode modulator. This modulator is particularly well suited for holographic video experimentation as it is relatively simple and inexpensive to fabricate1-3. Some additional advantages of leaky mode devices include: large aggregate bandwidth, polarization separation of signal light from noise, large angular deflection and frequency control of color1. In order to realize these advantages, it is necessary to be able to adequately characterize these devices as their operation is strongly dependent on waveguide and transducer parameters4. To characterize the modulators, the authors use a commercial prism coupler as well as a custom characterization apparatus to identify guided modes, calculate waveguide thickness and finally to map the device's frequency input and angular output of leaky mode modulators. This work gives a detailed description of the measurement and characterization of leaky mode modulators suitable for full-color holographic video. PMID:27023115

Discriminator Stabilized Superconductor/Ferroelectric Thin Film Local Oscillator

NASA Technical Reports Server (NTRS)

Romanofsky, Robert R. (Inventor); Miranda, Felix A. (Inventor)

2000-01-01

A tunable local oscillator with a tunable circuit that includes a resonator and a transistor as an active element for oscillation. Tuning of the circuit is achieved with an externally applied dc bias across coupled lines on the resonator. Preferably the resonator is a high temperature superconductor microstrip ring resonator with integral coupled lines formed over a thin film ferroelectric material. A directional coupler samples the output of the oscillator which is fed into a diplexer for determining whether the oscillator is performing at a desired frequency. The high-pass and lowpass outputs of the diplexer are connected to diodes respectively for inputting the sampled signals into a differential operational amplifier. The amplifier compares the sampled signals and emits an output signal if there is a difference between the resonant and crossover frequencies. Based on the sampled signal, a bias supplied to the ring resonator is either increased or decreased for raising or lowering the resonant frequency by decreasing or increasing, respectively, the dielectric constant of the ferroelectric.

Neural networks within multi-core optic fibers

PubMed Central

Cohen, Eyal; Malka, Dror; Shemer, Amir; Shahmoon, Asaf; Zalevsky, Zeev; London, Michael

2016-01-01

Hardware implementation of artificial neural networks facilitates real-time parallel processing of massive data sets. Optical neural networks offer low-volume 3D connectivity together with large bandwidth and minimal heat production in contrast to electronic implementation. Here, we present a conceptual design for in-fiber optical neural networks. Neurons and synapses are realized as individual silica cores in a multi-core fiber. Optical signals are transferred transversely between cores by means of optical coupling. Pump driven amplification in erbium-doped cores mimics synaptic interactions. We simulated three-layered feed-forward neural networks and explored their capabilities. Simulations suggest that networks can differentiate between given inputs depending on specific configurations of amplification; this implies classification and learning capabilities. Finally, we tested experimentally our basic neuronal elements using fibers, couplers, and amplifiers, and demonstrated that this configuration implements a neuron-like function. Therefore, devices similar to our proposed multi-core fiber could potentially serve as building blocks for future large-scale small-volume optical artificial neural networks. PMID:27383911

Neural networks within multi-core optic fibers.

PubMed

Cohen, Eyal; Malka, Dror; Shemer, Amir; Shahmoon, Asaf; Zalevsky, Zeev; London, Michael

2016-07-07

Hardware implementation of artificial neural networks facilitates real-time parallel processing of massive data sets. Optical neural networks offer low-volume 3D connectivity together with large bandwidth and minimal heat production in contrast to electronic implementation. Here, we present a conceptual design for in-fiber optical neural networks. Neurons and synapses are realized as individual silica cores in a multi-core fiber. Optical signals are transferred transversely between cores by means of optical coupling. Pump driven amplification in erbium-doped cores mimics synaptic interactions. We simulated three-layered feed-forward neural networks and explored their capabilities. Simulations suggest that networks can differentiate between given inputs depending on specific configurations of amplification; this implies classification and learning capabilities. Finally, we tested experimentally our basic neuronal elements using fibers, couplers, and amplifiers, and demonstrated that this configuration implements a neuron-like function. Therefore, devices similar to our proposed multi-core fiber could potentially serve as building blocks for future large-scale small-volume optical artificial neural networks.

Analysis of hybrid dielectric-plasmonic slot waveguide structures with 3D Fourier Modal Methods

NASA Astrophysics Data System (ADS)

Ctyroky, J.; Kwiecien, P.; Richter, I.

2013-03-01

Recently, plasmonic waveguides have been intensively studied as promising basic building blocks for the construction of extremely compact photonic devices with subwavelength characteristic dimensions. A number of different types of plasmonic waveguide structures have been recently proposed, theoretically analyzed, and their properties experimentally verified. The fundamental trade-off in the design of plasmonic waveguides for potential application in information technologies lies in the contradiction between their mode field confinement and propagation loss: the higher confinement, the higher loss, and vice versa. Various definitions of figures of merit of plasmonic waveguides have been also introduced for the characterization of their properties with a single quantity. In this contribution, we theoretically analyze one specific type of a plasmonic waveguide - the hybrid dielectric-loaded plasmonic waveguide, or - as we call it in this paper - the hybrid dielectric-plasmonic slot waveguide, which exhibits very strong field confinement combined with acceptable losses allowing their application in some integrated plasmonic devices. In contrast to the structures analyzed previously, our structure makes use of a single low-index dielectric only. We first define the effective area of this waveguide type, and using waveguide parameters close to the optimum we analyze several waveguide devices as directional couplers, multimode interference couplers (MMI), and the Mach-Zehnder interferometer based on the MMI couplers. For the full-vector 3D analysis of these structures, we use modelling tools developed in-house on the basis of the Fourier Modal Method (FMM). Our results thus serve to a dual purpose: they confirm that (i) these structures represent promising building blocks of plasmonic devices, and (ii) our FMM codes are capable of efficient 3D vector modelling of plasmonic waveguide devices.

Tutorial: Integrated-photonic switching structures

NASA Astrophysics Data System (ADS)

Soref, Richard

2018-02-01

Recent developments in waveguided 2 × 2 and N × M photonic switches are reviewed, including both broadband and narrowband resonant devices for the Si, InP, and AlN platforms. Practical actuation of switches by electro-optical and thermo-optical techniques is discussed. Present datacom-and-computing applications are reviewed, and potential applications are proposed for chip-scale photonic and optoelectronic integrated switching networks. Potential is found in the reconfigurable, programmable "mesh" switches that enable a promising group of applications in new areas beyond those in data centers and cloud servers. Many important matrix switches use gated semiconductor optical amplifiers. The family of broadband, directional-coupler 2 × 2 switches featuring two or three side-coupled waveguides deserves future experimentation, including devices that employ phase-change materials. The newer 2 × 2 resonant switches include standing-wave resonators, different from the micro-ring traveling-wave resonators. The resonant devices comprise nanobeam interferometers, complex-Bragg interferometers, and asymmetric contra-directional couplers. Although the fast, resonant devices offer ultralow switching energy, ˜1 fJ/bit, they have limitations. They require several trade-offs when deployed, but they do have practical application.

Design of a compact and integrated TM-rotated/TE-through polarization beam splitter for silicon-based slot waveguides.

PubMed

Xu, Yin; Xiao, Jinbiao

2016-01-20

A compact and integrated TM-rotated/TE-through polarization beam splitter for silicon-based slot waveguides is proposed and characterized. For the input TM mode, it is first transferred into the cross strip waveguide using a tapered directional coupler (DC), and then efficiently rotated to the corresponding TE mode using an L-shaped bending polarization rotator (PR). Finally, the TE mode for slot waveguide at the output end is obtained with the help of a strip-to-slot mode converter. By contrast, for the input TE mode, it almost passes through the slot waveguide directly and outputs at the bar end with nearly neglected coupling due to a large mode mismatch. Moreover, an additional S-bend connecting the tapered DC and bending PR is used to enhance the performance. Results show that a total device length of 19.6 μm is achieved, where the crosstalk (CT) and polarization conversion loss are, respectively -26.09 and 0.54 dB, for the TM mode, and the CT and insertion loss are, respectively, -22.21 and 0.41 dB, for the TE mode, both at 1.55 μm. The optical bandwidth is approximately 50 nm with a CT<-20  dB. In addition, fabrication tolerances and field evolution are also presented.

Extrinsic fiber optic displacement sensors and displacement sensing systems

DOEpatents

Murphy, K.A.; Gunther, M.F.; Vengsarkar, A.M.; Claus, R.O.

1994-04-05

An extrinsic Fizeau fiber optic sensor comprises a single-mode fiber, used as an input/output fiber, and a multimode fiber, used purely as a reflector, to form an air gap within a silica tube that acts as a Fizeau cavity. The Fresnel reflection from the glass/air interface at the front of the air gap (reference reflection) and the reflection from the air/glass interface at the far end of the air gap (sensing reflection) interfere in the input/output fiber. The two fibers are allowed to move in the silica tube, and changes in the air gap length cause changes in the phase difference between the reference reflection and the sensing reflection. This phase difference is observed as changes in intensity of the light monitored at the output arm of a fused biconical tapered coupler. The extrinsic Fizeau fiber optic sensor behaves identically whether it is surface mounted or embedded, which is unique to the extrinsic sensor in contrast to intrinsic Fabry-Perot sensors. The sensor may be modified to provide a quadrature phase shift extrinsic Fizeau fiber optic sensor for the detection of both the amplitude and the relative polarity of dynamically varying strain. The quadrature light signals may be generated by either mechanical or optical means. A plurality of the extrinsic sensors may connected in cascade and multiplexed to allow monitoring by a single analyzer. 14 figures.

Extrinsic fiber optic displacement sensors and displacement sensing systems

DOEpatents

Murphy, Kent A.; Gunther, Michael F.; Vengsarkar, Ashish M.; Claus, Richard O.

1994-01-01

An extrinsic Fizeau fiber optic sensor comprises a single-mode fiber, used as an input/output fiber, and a multimode fiber, used purely as a reflector, to form an air gap within a silica tube that acts as a Fizeau cavity. The Fresnel reflection from the glass/air interface at the front of the air gap (reference reflection) and the reflection from the air/glass interface at the far end of the air gap (sensing reflection) interfere in the input/output fiber. The two fibers are allowed to move in the silica tube, and changes in the air gap length cause changes in the phase difference between the reference reflection and the sensing reflection. This phase difference is observed as changes in intensity of the light monitored at the output arm of a fused biconical tapered coupler. The extrinsic Fizeau fiber optic sensor behaves identically whether it is surface mounted or embedded, which is unique to the extrinsic sensor in contrast to intrinsic Fabry-Perot sensors. The sensor may be modified to provide a quadrature phase shift extrinsic Fizeau fiber optic sensor for the detection of both the amplitude and the relative polarity of dynamically varying strain. The quadrature light signals may be generated by either mechanical or optical means. A plurality of the extrinsic sensors may connected in cascade and multiplexed to allow monitoring by a single analyzer.

Experiments and theory for a Tm:Ho:YAG laser end pumped by a Cr:GSAG laser

NASA Technical Reports Server (NTRS)

Kim, Kyong H.; Choi, Young S.; Hess, Robert V.; Blair, Clayton H.; Brockman, Philip; Barnes, Norman P.

1991-01-01

A Cr:GSAG-laser-pumped Tm:Ho:YAG laser has been fabricated and tested. A maximum output energy of 14 mJ with a slope efficiency of 33.6 percent was obtained using a 98-percent reflective output coupler. A comprehensive rate equation model has been developed to describe laser performance. Details of the experimental measurements and model are presented.

Broadband W-band Rapid Frequency Sweep Considerations for Fourier Transform EPR.

PubMed

Strangeway, Robert A; Hyde, James S; Camenisch, Theodore G; Sidabras, Jason W; Mett, Richard R; Anderson, James R; Ratke, Joseph J; Subczynski, Witold K

2017-12-01

A multi-arm W-band (94 GHz) electron paramagnetic resonance spectrometer that incorporates a loop-gap resonator with high bandwidth is described. A goal of the instrumental development is detection of free induction decay following rapid sweep of the microwave frequency across the spectrum of a nitroxide radical at physiological temperature, which is expected to lead to a capability for Fourier transform electron paramagnetic resonance. Progress toward this goal is a theme of the paper. Because of the low Q-value of the loop-gap resonator, it was found necessary to develop a new type of automatic frequency control, which is described in an appendix. Path-length equalization, which is accomplished at the intermediate frequency of 59 GHz, is analyzed. A directional coupler is favored for separation of incident and reflected power between the bridge and the loop-gap resonator. Microwave leakage of this coupler is analyzed. An oversize waveguide with hyperbolic-cosine tapers couples the bridge to the loop-gap resonator, which results in reduced microwave power and signal loss. Benchmark sensitivity data are provided. The most extensive application of the instrument to date has been the measurement of T 1 values using pulse saturation recovery. An overview of that work is provided.

Comparison of lung sound transducers using a bioacoustic transducer testing system.

PubMed

Kraman, Steve S; Wodicka, George R; Pressler, Gary A; Pasterkamp, Hans

2006-08-01

Sensors used for lung sound research are generally designed by the investigators or adapted from devices used in related fields. Their relative characteristics have never been defined. We employed an artificial chest wall with a viscoelastic surface and a white noise signal generator as a stable source of sound to compare the frequency response and pulse waveform reproduction of a selection of devices used for lung sound research. We used spectral estimation techniques to determine frequency response and cross-correlation of pulses to determine pulse shape fidelity. The sensors evaluated were the Siemens EMT 25 C accelerometer (Siemens); PPG 201 accelerometer (PPG); Sony ECM-T150 electret condenser microphone with air coupler (air coupler; with cylindrical air chambers of 5-, 10-, and 15-mm diameter and conical air chamber of 10-mm diameter); Littman classic stethoscope head (Littman) connected to an electret condenser microphone; and the Andries Tek (Andries) electronic stethoscope. We found that the size and shape of the air coupler chamber to have no important effect on the detected sound. The Siemens, air coupler, and Littman performed similarly with relatively flat frequency responses from 200 to 1,200 Hz. The PPG had the broadest frequency response, with useful sensitivity extending to 4,000 Hz. The Andries' frequency response was the poorest above 1,000 Hz. Accuracy in reproducing pulses roughly corresponded with the high-frequency sensitivity of the sensors. We conclude that there are important differences among commonly used lung sound sensors that have to be defined to allow the comparison of data from different laboratories.

Investigation of Grating-Assisted Trimodal Interferometer Biosensors Based on a Polymer Platform.

PubMed

Liang, Yuxin; Zhao, Mingshan; Wu, Zhenlin; Morthier, Geert

2018-05-10

A grating-assisted trimodal interferometer biosensor is proposed and numerically analyzed. A long period grating coupler, for adjusting the power between the fundamental mode and the second higher order mode, is investigated, and is shown to act as a conventional directional coupler for adjusting the power between the two arms. The trimodal interferometer can achieve maximal fringe visibility when the powers of the two modes are adjusted to the same value by the grating coupler, which means that a better limit of detection can be expected. In addition, the second higher order mode typically has a larger evanescent tail than the first higher order mode in bimodal interferometers, resulting in a higher sensitivity of the trimodal interferometer. The influence of fabrication tolerances on the performance of the designed interferometer is also investigated. The power difference between the two modes shows inertia to the fill factor of the grating, but high sensitivity to the modulation depth. Finally, a 2050 2π/RIU (refractive index unit) sensitivity and 43 dB extinction ratio of the output power are achieved.

Wideband tunable wavelength-selective coupling in asymmetric side-polished fiber coupler with dispersive interlayer.

PubMed

Chen, Nan-Kuang; Lee, Cheng-Ling; Chi, Sien

2007-12-24

We demonstrate tunable highly wavelength-selective filter based on a 2 x 2 asymmetric side-polished fiber coupler with dispersive interlayer in one of the coupling arms. The asymmetric fiber coupler is made of two side-polished fibers using identical single-mode fibers and one of the polished fibers is further chemically etched at the central evanescent coupling region to gain closer to the core. An optical liquid with different dispersion characteristics than that of silica fiber is used to fill up the etched hollow and therefore the propagation constant for the polished fiber with dispersive liquid becomes more dispersive and crosses with that of another untreated polished fiber. The location of the cross point and the cross angle between two propagation constant curves determine the coupling wavelength and coupling bandwidth as well as channel wavelength separation, respectively. The coupling wavelength can be tuned at least wider than 84 nm (1.326-1.410 microm) under index variation of 0.004 and with coupling ratios of higher than 30 dB.

High speed ultra-broadband amplitude modulators with ultrahigh extinction >65 dB.

PubMed

Liu, S; Cai, H; DeRose, C T; Davids, P; Pomerene, A; Starbuck, A L; Trotter, D C; Camacho, R; Urayama, J; Lentine, A

2017-05-15

We experimentally demonstrate ultrahigh extinction ratio (>65 dB) amplitude modulators (AMs) that can be electrically tuned to operate across a broad spectral range of 160 nm from 1480 - 1640 nm and 95 nm from 1280 - 1375 nm. Our on-chip AMs employ one extra coupler compared with conventional Mach-Zehnder interferometers (MZI), thus form a cascaded MZI (CMZI) structure. Either directional or adiabatic couplers are used to compose the CMZI AMs and experimental comparisons are made between these two different structures. We investigate the performance of CMZI AMs under extreme conditions such as using 95:5 split ratio couplers and unbalanced waveguide losses. Electro-optic phase shifters are also integrated in the CMZI AMs for high-speed operation. Finally, we investigate the output optical phase when the amplitude is modulated, which provides us valuable information when both amplitude and phase are to be controlled. Our demonstration not only paves the road to applications such as quantum information processing that requires high extinction ratio AMs but also significantly alleviates the tight fabrication tolerance needed for large-scale integrated photonics.

Compact cantilever couplers for low-loss fiber coupling to silicon photonic integrated circuits.

PubMed

Wood, Michael; Sun, Peng; Reano, Ronald M

2012-01-02

We demonstrate coupling from tapered optical fibers to 450 nm by 250 nm silicon strip waveguides using compact cantilever couplers. The couplers consist of silicon inverse width tapers embedded within silicon dioxide cantilevers. Finite difference time domain simulations are used to design the length of the silicon inverse width taper to as short as 6.5 μm for a cantilever width of 2 μm. Modeling of various strip waveguide taper profiles shows reduced coupling losses for a quadratic taper profile. Infrared measurements of fabricated devices demonstrate average coupling losses of 0.62 dB per connection for the quasi-TE mode and 0.50 dB per connection for the quasi-TM mode across the optical telecommunications C band. In the wavelength range from 1477 nm to 1580 nm, coupling losses for both polarizations are less than 1 dB per connection. The compact, broadband, and low-loss coupling scheme enables direct access to photonic integrated circuits on an entire chip surface without the need for dicing or cleaving the chip.

Rapid assessment of mid-infrared refractive index anisotropy using a prism coupler: chemical vapor deposited ZnS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiao, Hong; Lipschultz, Kristen A.; Anheier, Norman C.

2012-04-01

A state-of-the-art mid-infrared prism coupler was used to study the refractive index properties of forward-looking-infrared (FLIR) grade zinc sulfide samples prepared with unique planar grain orientations and locations with respect to the CVD growth axis. This study was motivated by prior photoluminescence and x-ray diffraction measurements that suggested refractive index may vary according to grain orientation. Measurements were conducted to provide optical dispersion and thermal index (dn/dT) data at discrete laser wavelengths between 0.633 and 10.591 {mu}m at two temperature set points (30 C and 90 C). Refractive index measurements between samples exhibited an average standard deviation comparable to themore » uncertainty of the prism coupler measurement (0.0004 refractive index units), suggesting that the variation in refractive index as a function of planar grain orientation and CVD deposition time is negligible, and should have no impact on subsequent optical designs. Measured dispersion data at mid-infrared wavelengths was found to agree well with prior published measurements.« less

Superconducting Prototype Cavities for the Spallation Neutron Source (SNS) Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

G. Ciovati; P. Kneisel; K. Davis

2002-06-01

The Spallation Neutron Source project includes a superconducting linac section in the energy range from 186 MeV to 1000 MeV operating at a frequency of 805 MHz at 2.1 K. For this energy range two types of cavities are needed with geometrical Beta-values of Beta=0.61 and Beta=0.81. An aggressive cavity prototyping program is being pursued at JLab, which calls for fabricating and testing of four Beta=0.61 cavities and two Beta=0.81 cavities. Both types consist of six cells made from high purity niobium and feature one HOM coupler of the TESLA type on each beam pipe and a port for amore » high power coaxial input coupler. Three of the four Beta=0.61 cavities will be used for a cryomodule test in early 2002. At this time, four medium beta cavities and one high beta cavity have been completed and tested at JLab. In addition, the three medium beta cavities for the prototype cryomodule have been equipped with the integrated Ti-Helium vessel, successfully retested and will be assembled into a cavity string. Results from the cryo-module test should be available by the time of the conference. The tests on the Beta=0.61 cavity and the Beta=0.81 cavity exceeded the design values for gradient and Q - value: E{sub acc} =10.1 MV/m and Q = 5 x 10{sup 9} at 2.1K for Beta=0.61 and E{sub acc} = 12.3 MV/m and Q=5 x 10{sup 9} at 2.1K for Beta = 0.81. The medium beta cavities reached gradients between E{sub acc} = 15 MV/m and 21 MV/m. This paper will describe the test results obtained with the various cavities, some aspects of the HOM damping at cryogenic temperatures, results from microphonics and Lorentz force detuning tests and the cavity string assembly at the time of this workshop.« less

Coupling Ideality of Integrated Planar High-Q Microresonators

NASA Astrophysics Data System (ADS)

Pfeiffer, Martin H. P.; Liu, Junqiu; Geiselmann, Michael; Kippenberg, Tobias J.

2017-02-01

Chip-scale optical microresonators with integrated planar optical waveguides are useful building blocks for linear, nonlinear, and quantum-optical photonic devices alike. Loss reduction through improving fabrication processes results in several integrated microresonator platforms attaining quality (Q ) factors of several millions. Beyond the improvement of the quality factor, the ability to operate the microresonator with high coupling ideality in the overcoupled regime is of central importance. In this regime, the dominant source of loss constitutes the coupling to a single desired output channel, which is particularly important not only for quantum-optical applications such as the generation of squeezed light and correlated photon pairs but also for linear and nonlinear photonics. However, to date, the coupling ideality in integrated photonic microresonators is not well understood, in particular, design-dependent losses and their impact on the regime of high ideality. Here we investigate design-dependent parasitic losses described by the coupling ideality of the commonly employed microresonator design consisting of a microring-resonator waveguide side coupled to a straight bus waveguide, a system which is not properly described by the conventional input-output theory of open systems due to the presence of higher-order modes. By systematic characterization of multimode high-Q silicon nitride microresonator devices, we show that this design can suffer from low coupling ideality. By performing 3D simulations, we identify the coupling to higher-order bus waveguide modes as the dominant origin of parasitic losses which lead to the low coupling ideality. Using suitably designed bus waveguides, parasitic losses are mitigated with a nearly unity ideality and strong overcoupling (i.e., a ratio of external coupling to internal resonator loss rate >9 ) are demonstrated. Moreover, we find that different resonator modes can exchange power through the coupler, which, therefore, constitutes a mechanism that induces modal coupling, a phenomenon known to distort resonator dispersion properties. Our results demonstrate the potential for significant performance improvements of integrated planar microresonators for applications in quantum optics and nonlinear photonics achievable by optimized coupler designs.

All-optical LAN architectures based on arrayed waveguide grating multiplexers

NASA Astrophysics Data System (ADS)

Woesner, Hagen

1998-10-01

The paper presents optical LAN topologies which are made possible using an Arrayed Waveguide Grating Multiplexer (AWGM) instead of a passive star coupler to interconnect stations in an all-optical LAN. Due to the collision-free nature of an AWGM it offers the n-fold bandwidth compared to the star coupler. Virtual ring topologies appear (one ring on each wavelength) if the number of stations attached to the AWGM is a prime number. A method to construct larger networks using Cayley graphs is shown. An access protocol to avoid collisions on the proposed network is outlined.

Circuit Methods for VLF Antenna Couplers. [for use in Loran or Omega receiver systems

NASA Technical Reports Server (NTRS)

Burhans, R. W.

1977-01-01

The limitations of different E-field antenna coupler or preamplifier circuits are presented. All circuits were evaluated using actual Loran or Omega signals. Electric field whip or wire antennas are the simplest types which can be used for reception of VLF signals in the 10 to 100 kHz range. JFET or MOSFET transistors provide impedance transformation and some voltage gain in simple circuits where the power for operating the preamplifier uses the same coaxial cable that feeds the signal back to the receiver. The circuit techniques provide useful alternative methods for Loran-Omega receiver system designers.

Dry coupling for whole-body small-animal photoacoustic computed tomography

NASA Astrophysics Data System (ADS)

Yeh, Chenghung; Li, Lei; Zhu, Liren; Xia, Jun; Li, Chiye; Chen, Wanyi; Garcia-Uribe, Alejandro; Maslov, Konstantin I.; Wang, Lihong V.

2017-04-01

We have enhanced photoacoustic computed tomography with dry acoustic coupling that eliminates water immersion anxiety and wrinkling of the animal and facilitates incorporating complementary modalities and procedures. The dry acoustic coupler is made of a tubular elastic membrane enclosed by a closed transparent water tank. The tubular membrane ensures water-free contact with the animal, and the closed water tank allows pressurization for animal stabilization. The dry coupler was tested using a whole-body small-animal ring-shaped photoacoustic computed tomography system. Dry coupling was found to provide image quality comparable to that of conventional water coupling.

The physics of transverse mode instability-induced nonlinear phase distortions in large area optical fiber amplifiers and their mitigation with applications in scaling of pulsed and continuous wave high-energy lasers

DTIC Science & Technology

2016-12-13

plate and novel all-fiber fused coupler. Such work has laid the platform to demonstrate the mitigation of thermal mode instability through vortex beam...at IIT Madras to experimentally validate the above results as well as to explore the generation of vortex modes through a spiral phase plate and...modes through spiral phase plates and novel all-fiber fused couplers. We have demonstrated the excitation of a vortex mode with charge 1 through a

Design and characterization of Ge passive waveguide components on Ge-on-insulator wafer for mid-infrared photonics

NASA Astrophysics Data System (ADS)

Kang, Jian; Takagi, Shinichi; Takenaka, Mitsuru

2018-04-01

We present the design methodology for Ge passive components including single-mode waveguide, grating couplers, multimode interferometer (MMI) couplers, and micro-ring resonators on the Ge-on-insulator wafer at a 1.95 µm wavelength. Characterizations of the fabricated Ge passive devices reveal a good consistence between the experimental and simulation results. By using the Ge micro-ring device, we also reveal that the thermo-optic coefficient in the Ge strip waveguide is 5.74 × 10-4/°C, which is much greater than that in Si.

Microwave coupler and method

DOEpatents

Holcombe, C.E.

1984-11-29

The present invention is directed to a microwave coupler for enhancing the heating or metallurgical treatment of materials within a cold-wall, rapidly heated cavity as provided by a microwave furnace. The coupling material of the present invention is an alpha-rhombohedral-boron-derivative-structure material such as boron carbide or boron silicide which can be appropriately positioned as a susceptor within the furnace to heat other material or be in powder particulate form so that composites and structures of boron carbide such as cutting tools, grinding wheels and the like can be rapidly and efficiently formed within microwave furnaces.

Microwave coupler and method

DOEpatents

Holcombe, Cressie E.

1985-01-01

The present invention is directed to a microwave coupler for enhancing the heating or metallurgical treatment of materials within a cold-wall, rapidly heated cavity as provided by a microwave furnace. The coupling material of the present invention is an alpha-rhombohedral-boron-derivative-structure material such as boron carbide or boron silicide which can be appropriately positioned as a susceptor within the furnace to heat other material or be in powder particulate form so that composites and structures of boron carbide such as cutting tools, grinding wheels and the like can be rapidly and efficiently formed within microwave furnaces.

Theoretical study of nanophotonic directional couplers comprising near-field-coupled metal nanoparticles.

PubMed

Holmström, Petter; Yuan, Jun; Qiu, Min; Thylén, Lars; Bratkovsky, Alexander M

2011-04-11

The properties of integrated-photonics directional couplers composed of near-field-coupled arrays of metal nanoparticles are analyzed theoretically. It is found that it is possible to generate very compact, submicron length, high field-confinement and functionality devices with very low switch energies. The analysis is carried out for a hypothetical lossless silver to demonstrate the potential of this type of circuits for applications in telecom and interconnects. Employing losses of real silver, standalone devices with the above properties are still feasible in optimized metal nanoparticle structures. © 2011 Optical Society of America

Analysis of dual coupler nested coupled cavities.

PubMed

Adib, George A; Sabry, Yasser M; Khalil, Diaa

2017-12-01

Coupled ring resonators are now forming the basic building blocks in several optical systems serving different applications. In many of these applications, a small full width at half maximum is required, along with a large free spectral range. In this work, a configuration of passive coupled cavities constituting dual coupler nested cavities is proposed. A theoretical study of the configuration is presented allowing us to obtain analytical expressions of its different spectral characteristics. The transfer function of the configuration is also used to generate design curves while comparing these results with analytical expressions. Finally, the configuration is compared with other coupled cavity configurations.

Harsh Environment Silicon Carbide Sensor Technology for Geothermal Instrumentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pisano, Albert P.

2013-04-26

This project utilizes Silicon Carbide (SiC) materials platform to fabricate advanced sensors to be used as high-temperature downhole instrumentation for the DOE’s Geothermal Technologies Program on Enhanced Geothermal Systems. The scope of the proposed research is to 1) develop a SiC pressure sensor that can operate in harsh supercritical conditions, 2) develop a SiC temperature sensor that can operate in harsh supercritical conditions, 3) develop a bonding process for adhering SiC sensor die to well casing couplers, and 4) perform experimental exposure testing of sensor materials and the sensor devices.

Development of Ultra-Low Noise, High Performance III-V Quantum Well Infrared Photodetectors (QWIPs) for Focal Plane Array Staring Image Sensor Systems

DTIC Science & Technology

1993-08-01

Development of Ultra-Low Noise , High Performance III-V Quantum Well Infrared Photodetectors ( QWIPs ) for Focal Plane Array Staring Image Sensor Systems...using a 2-D square mesh grating coupler to achieve maximum responsivity for an InGaAs SBTM QWIP , and (iv) performed noise characterization on four...different types of Ir-V QWIPs and identified their noise sources. Detailed results and accomplishments are discussed in this report. 1 SJ •aTEtcRMrtlS

Users' manual for computer program for three-dimensional analysis of coupler-cavity traveling wave tubes

NASA Technical Reports Server (NTRS)

Omalley, T. A.

1984-01-01

The use of the coupled cavity traveling wave tube for space communications has led to an increased interest in improving the efficiency of the basic interaction process in these devices through velocity resynchronization and other methods. A flexible, three dimensional, axially symmetric, large signal computer program was developed for use on the IBM 370 time sharing system. A users' manual for this program is included.

Multi-Gigabit Fiber Optic Wide Area Network Development.

DTIC Science & Technology

1991-07-01

to propagate, no modal dispersion can occur. In multimode fiber , a parabolic index profile across the core is often used so that mode travel times are...In the fiber plant, such as connectors, splices couplers, splitters, switches, tunable filters , wavelength division multiplexers and demultiplexers...losses are much higher, at around 0.5 dB, and are usually avoided in long-haul systems. 30 Some fiber plant components have a filtering effect on the

Assessment of Fiber Chromatic Dispersion Based on Elimination of Second-Order Harmonics in Optical OFDM Single Sideband Modulation Using Mach Zehnder Modulator

NASA Astrophysics Data System (ADS)

Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.

2016-07-01

This work addresses the analytical and numerical investigations of the transmission performance of an optical Single Sideband (SSB) modulation technique generated by a Mach Zehnder Modulator (MZM) with a 90° and 120° hybrid coupler. It takes into account the problem of chromatic dispersion in single mode fibers in Passive Optical Networks (PON), which severely degrades the performance of the system. Considering the transmission length of the fiber, the SSB modulation generated by maintaining a phase shift of π/2 between the two electrodes of the MZM provides better receiver sensitivity. However, the power of higher-order harmonics generated due to the nonlinearity of the MZM is directly proportional to the modulation index, making the SSB look like a quasi-double sideband (DSB) and causing power fading due to chromatic dispersion. To eliminate one of the second-order harmonics, the SSB signal based on an MZM with a 120° hybrid coupler is simulated. An analytical model of conventional SSB using 90° and 120° hybrid couplers is established. The latter suppresses unwanted (upper/lower) first-order and second-order (lower/upper) sidebands. For the analysis, a varying quadrature amplitude modulation (QAM) Orthogonal Frequency Division Multiplexing (OFDM) signal with a data rate of 5 Gb/s is upconverted using both of the SSB techniques and is transmitted over a distance of 75 km in Single Mode Fiber (SMF). The simulation results show that the SSB with 120° hybrid coupler proves to be more immune to chromatic dispersion as compared to the conventional SSB technique. This is in tandem with the theoretical analysis presented in the article.

The PRISM project

NASA Astrophysics Data System (ADS)

Guilyardi, E.

2003-04-01

The European Union's PRISM infrastructure project (PRogram for Integrated earth System Modelling) aims at designing a flexible environment to easily assemble and run Earth System Models (http://prism.enes.org). Europe's widely distributed modelling expertise is both a strength and a challenge. Recognizing this, the PRISM project aims at developing an efficient shared modelling software infrastructure for climate scientists, providing them with an opportunity for greater focus on scientific issues, including the necessary scientific diversity (models and approaches). The proposed PRISM system includes 1) the use - or definition - and promotion of scientific and technical standards to increase component modularity, 2) an end-to-end software environment (coupler, user interface, diagnostics) to launch, monitor and analyze complex Earth System Models built around the existing and future community models, 3) testing and quality standards to ensure HPC performance on a variety of platforms and 4) community wide inputs and requirements capture in all stages of system specifications and design through user/developers meetings, workshops and thematic schools. This science driven project, led by 22 institutes* and started December 1st 2001, benefits from a unique gathering of scientific and technical expertise. More than 30 models (both global and regional) have expressed interest to be part of the PRISM system and 6 types of components have been identified: atmosphere, atmosphere chemistry, land surface, ocean, sea ice and ocean biochemistry. Progress and overall architecture design will be presented. * MPI-Met (Coordinator), KNMI (co-coordinator), MPI-M&D, Met Office, University of Reading, IPSL, Meteo-France, CERFACS, DMI, SMHI, NERSC, ETH Zurich, INGV, MPI-BGC, PIK, ECMWF, UCL-ASTR, NEC, FECIT, SGI, SUN, CCRLE

New data acquisition system for beam loss monitor used in J-PARC main ring

NASA Astrophysics Data System (ADS)

Satou, K.; Toyama, T.; Kamikubota, N.; Yoshida, S.; Matsushita, J.; Wakita, T.; Sugiyama, M.; Morino, T.

2018-04-01

A new data acquisition system has been developed continually as a part of the development of a new beam loss monitor (BLM) system for the J-PARC main ring. This development includes a newly designed front-end isolation amp that uses photo-couplers and a VME-based new analog-to-digital converter (ADC) system. Compared to the old amp, the new amp has a 10 times higher conversion impedance for the input current to the output voltage; this value is 1 M Ω. Moreover, the bandwidth was improved to from DC to 50 kHz, which is about two orders of magnitude greater than the previously used bandwidth. The theoretical estimations made in this study roughly agree with the frequency response obtained for the new system. The new ADC system uses an on-board field-programmable gate array chip for signal processing. By replacing the firmware of this chip, changes pertaining to future accelerator upgrade plans may be introduced into the new ADC system; in addition, the ADC system can be used in other applications. The sampling speed of the system is 1 MS/s, and it exhibits a 95 dBc spurious-free dynamic range and 16.5 effective number of bits. The obtained waveform and integrated charge data are compared with two reference levels in the ADC system. If the data exceeds the reference level, the system generates an alarm to dump the beams. By using the new data acquisition system, it was proved that the new BLM system shows a wide dynamic range of 160 dB. In this study, the details of the new data acquisition system are described.

Development of pre pre-driver amplifier stage for generator of SST-1 ICRH system

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Sinh Makwana, Azad; Srinivas, Y. S. S.; Kulkarni, S. V.; ICRH-RF Group

2010-02-01

The Ion Cyclotron Resonance Heating (ICRH) system for SST1 consists mainly of the cwrf power generator to deliver 1.5MW for 1000sec duration at the frequencies 22.8, 24.3 and 45.6±1MHz, the transmission line and the antenna. This is planned to develop a independent and dedicated cwrf generator that consists of a oscillator, buffer, rf switch, modulator, rf attenuator, directional coupler, three stage solid state low power amplifier and four stage triode & tetrode based high power amplifier with specific performance at 45.6±1MHz including frequencies 22.8 and 24.3±1MHz. The pre pre-driver high power amplifier stage is fabricated about triode 3CX3000A7. The tube has sufficient margin in terms of plate dissipation and grid dissipation that makes it suitable to withstand momentarily load mismatch and to upgrade the source in terms of output power later. This indigenously developed amplifier is integrated inside a radiation resistant rack with all required biasing power supplies, cooling blower, controls, monitors and interlocks for manual or remote control operation. This grounded grid mode amplifier will be operated at plate with 3.8KV/ 800mA in class AB for 1.8KW cwrf output power rating. The input circuit is broadband and the output circuit is tunable with slide variable inductor and a vacuum variable capacitor in the frequency range of 22.8 to 45.6MHz. It is designed for a gain of about 12dB, fabrication completed and undergoing cwrf power testing. This paper presents specifications, design criteria, circuit used, operating parameters, tests conducted and the results obtained.

Determining the refractive index and thickness of thin films from prism coupler measurements

NASA Technical Reports Server (NTRS)

Kirsch, S. T.

1981-01-01

A simple method of determining thin film parameters from mode indices measured using a prism coupler is described. The problem is reduced to doing two least squares straight line fits through measured mode indices vs effective mode number. The slope and y intercept of the line are simply related to the thickness and refractive index of film, respectively. The approach takes into account the correlation between as well as the uncertainty in the individual measurements from all sources of error to give precise error tolerances on the best fit values. Due to the precision of the tolerances, anisotropic films can be identified and characterized.

KSC-08pd3085

NASA Image and Video Library

2008-10-09

CAPE CANAVERAL, FIa. -- In the Space Station Processing Facility at NASA's Kennedy Space Center in Florida, an overhead crane lifts the flexible hose rotary coupler. The coupler will be moved to the Lightweight Multi-Purpose Experiment Support Structure Carrier for installation. The carrier will be installed in space shuttle Endeavour for the STS-126 mission to the International Space Station. The 15-day flight will deliver equipment and supplies to the space station in preparation for expansion from a three- to six-person resident crew aboard the complex. The mission also will include four spacewalks to service the station’s Solar Alpha Rotary Joints. Photo credit: NASA/Jim Grossmann

KSC-08pd3084

NASA Image and Video Library

2008-10-09

CAPE CANAVERAL, FIa. -- In the Space Station Processing Facility at NASA's Kennedy Space Center in Florida, workers keep close watch as an overhead crane lifts the flexible hose rotary coupler. The coupler will be moved to the Lightweight Multi-Purpose Experiment Support Structure Carrier for installation. The carrier will be installed in space shuttle Endeavour for the STS-126 mission to the International Space Station. The 15-day flight will deliver equipment and supplies to the space station in preparation for expansion from a three- to six-person resident crew aboard the complex. The mission also will include four spacewalks to service the station’s Solar Alpha Rotary Joints. Photo credit: NASA/Jim Grossmann

Spatial mode filters realized with multimode interference couplers

NASA Astrophysics Data System (ADS)

Leuthold, J.; Hess, R.; Eckner, J.; Besse, P. A.; Melchior, H.

1996-06-01

Spatial mode filters based on multimode interference couplers (MMI's) that offer the possibility of splitting off antisymmetric from symmetric modes are presented, and realizations of these filters in InGaAsP / InP are demonstrated. Measured suppression of the antisymmetric first-order modes at the output for the symmetric mode is better than 18 dB. Such MMI's are useful for monolithically integrating mode filters with all-optical devices, which are controlled through an antisymmetric first-order mode. The filtering out of optical control signals is necessary for cascading all-optical devices. Another application is the improvement of on-off ratios in optical switches.

Generation of vacuum ultraviolet radiation by intracavity high-harmonic generation toward state detection of single trapped ions

NASA Astrophysics Data System (ADS)

Wakui, Kentaro; Hayasaka, Kazuhiro; Ido, Tetsuya

2014-12-01

Vacuum ultraviolet (VUV) radiation around 159 nm is obtained toward direct excitation of a single trapped ion. An efficient fluoride-based VUV output coupler is employed for intracavity high-harmonic generation of a Ti:S oscillator. Using this coupler, where we measured its reflectance to be about 90 %, an average power reaching 6.4 W is coupled out from a modest fundamental power of 650 mW. When a single comb component out of 1.9 10 teeth is resonant to the atomic transition, 100s of fluorescence photons per second will be detectable under a realistic condition.

Liquid droplet sensing using twisted optical fiber couplers fabricated by hydrofluoric acid flow etching

NASA Astrophysics Data System (ADS)

Son, Gyeongho; Jung, Youngho; Yu, Kyoungsik

2017-04-01

We report a directional-coupler-based refractive index sensor and its cost-effective fabrication method using hydrofluoric acid droplet wet-etching and surface-tension-driven liquid flows. The proposed fiber sensor consists of a pair of twisted tapered optical fibers with low excess losses. The fiber cores in the etched microfiber region are exposed to the surrounding medium for efficient interaction with the guided light. We observe that the etching-based low-loss fiber-optic sensors can measure the water droplet volume by detecting the refractive index changes of the surrounding medium around the etched fiber core region.

Microwave time delays for the dual L-C-band feed system

NASA Technical Reports Server (NTRS)

Chen, J.

1989-01-01

A new dual-frequency feed system at Goldstone is designed to receive the Phobos spacecraft signal at L-band (1668 + or - 40 MHz) and transmit to the spacecraft at C-band (5008.75 + or - 5.00 MHz) simultaneously. Hence, calculations of the time delay from the C-band range calibration coupler to the phase center of the L-C dual feed and back to the L-band range calibration coupler are required to correct the range measurements. Time delays of the elements in the dual-frequency feed system are obtained mostly from computer calculations and partly from experimental measurements. The method used and results obtained are described.

TM grating coupler on low-loss LPCVD based Si3N4 waveguide platform

NASA Astrophysics Data System (ADS)

Dabos, G.; Manolis, A.; Giesecke, A. L.; Porschatis, C.; Chmielak, B.; Wahlbrink, T.; Pleros, N.; Tsiokos, D.

2017-12-01

We demonstrate, for the first time to our knowledge, a fully etched TM grating coupler for low-loss Low-Pressure-Chemical-Vapor-Deposition (LPCVD) based silicon nitride platform with a coupling loss of 6.5 dB at 1541 nm and a 1 dB bandwidth of 55 nm, addressing applications where TM polarization is a pre-requisite. The proposed GC and the 360 nm × 800 nm strip based Si3N4 waveguides have been fabricated by optical projection lithography using an i-line stepper tool enabling low-cost and mass manufacturing of photonic-integrated-circuits.

Wideband Communications Equipment, Ground Radio Communication, Space Comm Systems Equipment. 304X0/X4/X6. Appendix B - EF/A and Job Inventory Items by Equipment

DTIC Science & Technology

1990-05-01

L0341 K ISOLATE MALFUNCTIONS TO DIRECTIONAL COUPLERS - 6 L0436 A REMOVE OR REPLACE TWTS - 6 M0443 A ALIGN DELAY EQUALIZER COMPONENTS - 6 M0447 A ALIGN...CONTROLS - 6 L0390 A PERFORM OPERATIONAL TESTS ON RECEIVER TRANSMITTER CONTROLS - 6 LO0O1 A PERFORM PHIS ON TWT SHF TRANSMITTERS - 6 L0410 A REMOVE OR...REPLACE DIRECTIONAL COUPLERS - 6 L0420 A REMOVE OR REPLACE LINE VOLTAGE REGULATORS - 6 L0435 A REMOVE OR REPLACE TWT SHF TRANSMITTERS - 6 L0436 A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zanotto, Simone; Melloni, Andrea

By hybrid integration of plasmonic and dielectric waveguide concepts, it is shown that nearly perfect coherent absorption can be achieved in a co-propagating coupler geometry. First, the operating principle of the proposed device is detailed in the context of a more general 2 × 2 lossy coupler formalism. Then, it is shown how to tune the device in a wide region of possible working points, its broadband operation, and the tolerance to fabrication uncertainties. Finally, a complete picture of the electromagnetic modes inside the hybrid structure is analyzed, shining light onto the potentials which the proposed device holds in viewmore » of classical and quantum signal processing, nonlinear optics, polarization control, and sensing.« less

STS-119 EVA 3 GAT S1 Truss Flex Hose Rotary Coupler (FHRC) P-Clamp Release

NASA Image and Video Library

2009-03-23

S119-E-007110 (23 March 2009) --- Astronaut Joseph Acaba, STS-119 mission specialist, participates in the mission's third scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the six-hour, 27-minute spacewalk, Acaba and Richard Arnold (out of frame), mission specialist, helped robotic arm operators relocate the Crew Equipment Translation Aid (CETA) cart from the Port 1 to Starboard 1 truss segment, installed a new coupler on the CETA cart, lubricated snares on the "B" end of the space station's robotic arm and performed a few "get ahead" tasks.

STS-119 EVA 3 GAT S1 Truss Flex Hose Rotary Coupler (FHRC) P-Clamp Release

NASA Image and Video Library

2009-03-23

S119-E-007119 (23 March 2009) --- Astronaut Joseph Acaba, STS-119 mission specialist, participates in the mission's third scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the six-hour, 27-minute spacewalk, Acaba and Richard Arnold (out of frame), mission specialist, helped robotic arm operators relocate the Crew Equipment Translation Aid (CETA) cart from the Port 1 to Starboard 1 truss segment, installed a new coupler on the CETA cart, lubricated snares on the "B" end of the space station's robotic arm and performed a few "get ahead" tasks.

Integrated Fiber-Optic Coupler.

DTIC Science & Technology

1987-04-01

p. 563, 1984. 1 .T.H. W. n h= n , G.M. Metze, B.- Y . Tuu ,J.C.C. Far., "A a s double-heterostructure diode lasers fabricated on a monolithic GaAs/Si...INII RAitI) R HR ( OLIlIR HR t( N ,% NOS( I D108 I R IOst\\1 tN( LASS~l1 D R 87 mm mhhh z V. 0 0- z C ,, Technical Document 1086 April 1987 Integrated...Cmeed".~) n Interated Fiber-Optic Coupler 12 PERSONAL AU1HOS) P.L Pruaal, E.R. Foesuim 139 TYPE OF RE[POR 3b, IME COVERED4 DATE OF REPORT (’r. 4#e ow S

Use of a reflective semiconductor optical amplifier and dual-ring architecture design to produce a stable multi-wavelength fiber laser

NASA Astrophysics Data System (ADS)

Yeh, Chien-Hung; Chow, Chi-Wai; Lu, Shao-Sheng

2014-05-01

In this work, we propose and demonstrate a multi-wavelength laser source produced by utilizing a C-band reflective semiconductor optical amplifier (RSOA) with a dual-ring fiber cavity. Here, the laser cavity consists of an RSOA, a 1 × 2 optical coupler, a 2 × 2 optical coupler and a polarization controller. As a result, thirteen to eighteen wavelengths around the L band could be generated simultaneously when the bias current of the C-band RSOA was driven at 30-70 mA. In addition, the output stabilities of the power and wavelength are also discussed.

Optical-fiber-to-waveguide coupling using carbon-dioxide-laser-induced long-period fiber gratings.

PubMed

Bachim, Brent L; Ogunsola, Oluwafemi O; Gaylord, Thomas K

2005-08-15

Optical fibers are expected to play a role in chip-level and board-level optical interconnects because of limitations on the bandwidth and level of integration of electrical interconnects. Therefore, methods are needed to couple optical fibers directly to waveguides on chips and on boards. We demonstrate optical-fiber-to-waveguide coupling using carbon-dioxide laser-induced long-period fiber gratings (LPFGs). Such gratings can be written in standard fiber and offer wavelength multiplexing-demultiplexing performance. The coupler fabrication process and the characterization apparatus are presented. The operation and the wavelength response of a LPFG-based optical-fiber-to-waveguide directional coupler are demonstrated.

A macrochip interconnection network enabled by silicon nanophotonic devices.

PubMed

Zheng, Xuezhe; Cunningham, John E; Koka, Pranay; Schwetman, Herb; Lexau, Jon; Ho, Ron; Shubin, Ivan; Krishnamoorthy, Ashok V; Yao, Jin; Mekis, Attila; Pinguet, Thierry

2010-03-01

We present an advanced wavelength-division multiplexing point-to-point network enabled by silicon nanophotonic devices. This network offers strictly non-blocking all-to-all connectivity while maximizing bisection bandwidth, making it ideal for multi-core and multi-processor interconnections. We introduce one of the key components, the nanophotonic grating coupler, and discuss, for the first time, how this device can be useful for practical implementations of the wavelength-division multiplexing network using optical proximity communications. Finite difference time-domain simulation of the nanophotonic grating coupler device indicates that it can be made compact (20 microm x 50 microm), low loss (3.8 dB), and broadband (100 nm). These couplers require subwavelength material modulation at the nanoscale to achieve the desired functionality. We show that optical proximity communication provides unmatched optical I/O bandwidth density to electrical chips, which enables the application of wavelength-division multiplexing point-to-point network in macrochip with unprecedented bandwidth-density. The envisioned physical implementation is discussed. The benefits of such an interconnect network include a 5-6x improvement in latency when compared to a purely electronic implementation. Performance analysis shows that the wavelength-division multiplexing point-to-point network offers better overall performance over other optical network architectures.

Fiber-optic couplers as displacement sensors

NASA Astrophysics Data System (ADS)

Baruch, Martin C.; Gerdt, David W.; Adkins, Charles M.

2003-04-01

We introduce the novel concept of using a fiber-optic coupler as a versatile displacement sensor. Comparatively long fiber-optic couplers, with a coupling region of approximately 10 mm, are manufactured using standard communication SM fiber and placed in a looped-back configuration. The result is a displacement sensor, which is robust and highly sensitive over a wide dynamic range. This displacement sensor resolves 1-2 μm over distances of 1-1.5 mm and is characterized by the essential absence of a 'spring constant' plaguing other strain gauge-type sensors. Consequently, it is possible to couple to extremely weak vibrations, such as the skin displacement affected by arterial heart beat pulsations. Used as a wrist-worn heartbeat monitor, the fidelity of the arterial pulse signal has been shown to be so high that it is possible to not only determine heartbeat and breathing rates, but to implement a new single-point blood pressure measurement scheme which does not squeeze the arm. In an application as a floor vibration sensor for the non-intrusive monitoring of independently living elderly, the sensor has been shown to resolve the distinct vibration spectra of different persons and different events.

Performance improvement of optical fiber coupler with electric heating versus gas heating.

PubMed

Shuai, Cijun; Gao, Chengde; Nie, Yi; Peng, Shuping

2010-08-20

Gas heating has been widely used in the process of fused biconical tapering. However, as the instability and asymmetric flame temperature of gas heating exist, the performance of the optical devices fabricated by this method was affected. To overcome the problems resulting from gas combustion, an electric heater is designed and manufactured using a metal-ceramic (MoSi(2)) as a heating material. Our experimental data show that the fused-taper machine with an electric heater has improved the performance of optical devices by increasing the consistency of the extinction ratio, excess loss, and the splitting ratio over that of the previous gas heating mode. Microcrystallizations and microcracks were observed at the fused region of the polarization-maintaining (PM) fiber coupler and at the taper region with scanning electron microscopy and atomic force microscopy respectively. The distribution of the microcrystallizations and microcracks are nonuniform along the fiber with gas heating, while their distribution is rather uniform with electric heating. These findings show that the novel optical fiber coupler with an electric heater has improved the performance of optical fiber devices by affecting the consistency of the optical parameters and micromorphology of the surface of PM fiber.

Fused-fiber-based 3-dB mode insensitive power splitters for few-mode optical fiber networks

NASA Astrophysics Data System (ADS)

Ren, Fang; Huang, Xiaoshan; Wang, Jianping

2017-11-01

We propose a 3-dB mode insensitive power splitter (MIPS) capable of broadcasting and combining optical signals. It is fabricated with two identical few-mode fibers (FMFs) by a heating and pulling technique. The mode-dependent power transfer characteristic as a function of pulling length is investigated. For exploiting its application, we experimentally demonstrate both FMF-based transmissive and reflective star couplers consisting of multiple 3-dB mode insensitive power splitters, which perform broadcasting and routing signals in few-mode optical fiber networks such as mode-division multiplexing (MDM) local area networks using star topology. For experimental demonstration, optical on-off keying signals at 10 Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. Measured bit error ratio results show reasonable power penalties. It is found that a reflective star coupler in MDM networks can reduce half of the total amount of required fibers comparing to that of a transmissive star coupler. This MIPS is more efficient, more reliable, more flexible, and more cost-effective for future expansion and application in few-mode optical fiber networks.

On the overriding issue of train front end collision in rail vehicle dynamics

NASA Astrophysics Data System (ADS)

Yang, Chao; Li, Qiang; Xiao, Shoune; Wang, Xi

2018-04-01

A three-dimensional dynamic model of crashed vehicles coupled with moving tracks is developed to research the dynamic behaviour of the train front end collision on tangent tracks. The three-dimensional dynamic model consists of a crashed vehicle model, moving track models, a simple wheel-rail contact model, a velocity-based coupler model and the model of energy absorption and anti-climbing devices. The vector method dealing with the nonlinear wheel-rail geometry is put forward in the paper. The developed model is applicable in the scope that central collisions occur on tangent tracks at low speeds. The examples of the vehicle impacting with a rigid wall and the train front end collision are carried out to obtain the dynamic responses of vehicles. The overriding issue is studied on the basis of the wheel rise in train collisions. The results show that the second bogie of the first colliding vehicle possesses the maximal wheel rise. The wheel rise increases with the increase of vehicles. However, the number of vehicles has tiny influence on the overriding in train collisions at low speeds. On the contrary, the impact speed has significant influence on the overriding in train collisions. The wheel rise increases rapidly if the impact speed is close to the critical speed of overriding. The large wheel rise is principally generated by the great coupler force related to the rigid impact in the axial direction.

Real-ear-to-coupler difference predictions as a function of age for two coupling procedures.

PubMed

Bagatto, Marlene P; Scollie, Susan D; Seewald, Richard C; Moodie, K Shane; Hoover, Brenda M

2002-09-01

The predicted real-ear-to-coupler difference (RECD) values currently used in pediatric hearing instrument prescription methods are based on 12-month age range categories and were derived from measures using standard acoustic immittance probe tips. Consequently, the purpose of this study was to develop normative RECD predicted values for foam/acoustic immittance tips and custom earmolds across the age continuum. To this end, RECD data were collected on 392 infants and children (141 with acoustic immittance tips, 251 with earmolds) to develop normative regression equations for use in deriving continuous age predictions of RECDs for foam/acoustic immittance tips and earmolds. Owing to the substantial between-subject variability observed in the data, the predictive equations of RECDs by age (in months) resulted in only gross estimates of RECD values (i.e., within +/- 4.4 dB for 95% of acoustic immittance tip measures; within +/- 5.4 dB in 95% of measures with custom earmolds) across frequency. Thus, it is concluded that the estimates derived from this study should not be used to replace the more precise individual RECD measurements. Relative to previously available normative RECD values for infants and young children, however, the estimates derived through this study provide somewhat more accurate predicted values for use under those circumstances for which individual RECD measurements cannot be made.

Electro-Optic Modulator Based on Organic Planar Waveguide Integrated with Prism Coupler

NASA Technical Reports Server (NTRS)

Sarkisov, Sergey S.

2002-01-01

The objectives of the project, as they were formulated in the proposal, are the following: (1) Design and development of novel electro-optic modulator using single crystalline film of highly efficient electro-optic organic material integrated with prism coupler; (2) Experimental characterization of the figures-of-merit of the modulator. It is expected to perform with an extinction ratio of 10 dB at a driving signal of 5 V; (3) Conclusions on feasibility of the modulator as an element of data communication systems of future generations. The accomplishments of the project are the following: (1) The design of the electro-optic modulator based on a single crystalline film of organic material NPP has been explored; (2) The evaluation of the figures-of-merit of the electro-optic modulator has been performed; (3) Based on the results of characterization of the figures-of-merit, the conclusion was made that the modulator based on a thin film of NPP is feasible and has a great potential of being used in optic communication with a modulation bandwidth of up to 100 GHz and a driving voltage of the order of 3 to 5 V.

A first approach to the distortion analysis of nonlinear analog circuits utilizing X-parameters

NASA Astrophysics Data System (ADS)

Weber, H.; Widemann, C.; Mathis, W.

2013-07-01

In this contribution a first approach to the distortion analysis of nonlinear 2-port-networks with X-parameters1 is presented. The X-parameters introduced by Verspecht and Root (2006) offer the possibility to describe nonlinear microwave 2-port-networks under large signal conditions. On the basis of X-parameter measurements with a nonlinear network analyzer (NVNA) behavioral models can be extracted for the networks. These models can be used to consider the nonlinear behavior during the design process of microwave circuits. The idea of the present work is to extract the behavioral models in order to describe the influence of interfering signals on the output behavior of the nonlinear circuits. Hereby, a simulator is used instead of a NVNA to extract the X-parameters. Assuming that the interfering signals are relatively small compared to the nominal input signal, the output signal can be described as a superposition of the effects of each input signal. In order to determine the functional correlation between the scattering variables, a polynomial dependency is assumed. The required datasets for the approximation of the describing functions are simulated by a directional coupler model in Cadence Design Framework. The polynomial coefficients are obtained by a least-square method. The resulting describing functions can be used to predict the system's behavior under certain conditions as well as the effects of the interfering signal on the output signal. 1 X-parameter is a registered trademark of Agilent Technologies, Inc.

805 MHz Beta = 0.47 Elliptical Accelerating Structure R & D

DOE Office of Scientific and Technical Information (OSTI.GOV)

S. Bricker; C. Compton; W. Hartung

2008-09-22

A 6-cell 805 MHz superconducting cavity for acceleration in the velocity range of about 0.4 to 0.53 times the speed of light was designed. After single-cell prototyping, three 6-cell niobium cavities were fabricated. In vertical RF tests of the 6-cell cavities, the measured quality factors (Q{sub 0}) were between 7 {center_dot} 10{sup 9} and 1.4 {center_dot} 10{sup 10} at the design field (accelerating gradient of 8 to 10 MV/m). A rectangular cryomodule was designed to house 4 cavities per cryomodule. The 4-cavity cryomodule could be used for acceleration of ions in a linear accelerator, with focusing elements between the cryomodules.more » A prototype cryomodule was fabricated to test 2 cavities under realistic operating conditions. Two of the 6-cell cavities were equipped with helium tanks, tuners, and input coupler and installed into the cryomodule. The prototype cryomodule was used to verify alignment, electromagnetic performance, frequency tuning, cryogenic performance, low-level RF control, and control of microphonics.« less

Numerical analysis of a 3D optical sensor based on single mode fiber to multimode interference graphene design

NASA Astrophysics Data System (ADS)

Mutter, Kussay N.; Jafri, Zubir M.; Tan, Kok Chooi

2016-04-01

In this paper, the simulation and design of a waveguide for water turbidity sensing are presented. The structure of the proposed sensor uses a 2x2 array of multimode interference (MMI) coupler based on micro graphene waveguide for high sensitivity. The beam propagation method (BPM) are used to efficiently design the sensor structure. The structure is consist of an array of two by two elements of sensors. Each element has three sections of single mode for field input tapered to MMI as the main core sensor without cladding which is graphene based material, and then a single mode fiber as an output. In this configuration MMI responses to any change in the environment. We validate and present the results by implementing the design on a set of sucrose solution and showing how these samples lead to a sensitivity change in the sensor based on the MMI structures. Overall results, the 3D design has a feasible and effective sensing by drawing topographical distribution of suspended particles in the water.

A Compliant Four-bar Linkage Mechanism that Makes the Fingers of a Prosthetic Hand More Impact Resistant

PubMed Central

Choi, Kyung Yun; Akhtar, Aadeel; Bretl, Timothy

2017-01-01

Repeated mechanical failure due to accidental impact is one of the main reasons why people with upper-limb amputations abandon commercially-available prosthetic hands. To address this problem, we present the design and evaluation of a compliant four-bar linkage mechanism that makes the fingers of a prosthetic hand more impact resistant. Our design replaces both the rigid input and coupler links with a monolithic compliant bone, and replaces the follower link with three layers of pre-stressed spring steel. This design behaves like a conventional four-bar linkage but adds lateral compliance and eliminates a pin joint, which is a main site of failure on impact. Results from free-end and fixed-end impact tests show that, compared to those made with a conventional four-bar linkage, fingers made with our design absorb up to 11% more energy on impact with no mechanical failure. We also show the integration of these fingers in a prosthetic hand that is low-cost, light-weight, and easy to assemble, and that has grasping performance comparable to commercially-available hands. PMID:29527386

Variable frequency microwave furnace system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bible, D.W.; Lauf, R.J.

1994-06-14

A variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency microwave furnace system includes a microwave signal generator or microwave voltage-controlled oscillator for generating a low-power microwave signal for input to the microwave furnace. A first amplifier may be provided to amplify the magnitude of the signal output from the microwave signal generator or the microwave voltage-controlled oscillator. A second amplifier is provided for processing the signal output by the first amplifier. The second amplifier outputs the microwave signal inputmore » to the furnace cavity. In the preferred embodiment, the second amplifier is a traveling-wave tube (TWT). A power supply is provided for operation of the second amplifier. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. 5 figs.« less

X-ray beam transfer between hollow fibers for long-distance transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Yoshihito, E-mail: tanaka@sci.u-hyogo.ac.jp; Matsushita, Ryuki; Shiraishi, Ryutaro

2016-07-27

Fiber optics for controlling the x-ray beam trajectory has been examined at the synchrotron facility of SPring-8. Up to now, we have achieved beam deflection by several tens of milli-radian and axis shift of around 75 mm with a 1.5 m-long flexible hollow glass capillary. The achievable beam deflecting angle, axis shift, and timing delay are, in principle, proportional to the length, the square of length and the cube of length, respectively. Thus, for further applications, requiring larger beam shift and pulse delay, longer fibers are indispensable. In order to achieve long-distance transport using the fiber, we thus examined themore » connection transferring x-rays between fibers in an experimental hutch. The acceptance angle at the input end and the throughput efficiency of the second fiber is consistent with the consideration of the output beam divergence of the first fiber. The enhancement of the transfer efficiency is also discussed for the cases of a closer joint and the use of a refractive lens as a coupler.« less

Coordination of cell death and the cell cycle: linking proliferation to death through private and communal couplers.

PubMed

Abrams, John M; White, Michael A

2004-12-01

In development and in the adult, complex signaling pathways operate within and between cells to coordinate proliferation and cell death. These networks can be viewed as coupling devices that link engines driving the cell cycle and the initiation of apoptosis. We propose three simple frameworks for modeling the effects of proliferative drive on apoptotic propensity. This perspective offers a potentially useful foundation for predicting group behaviors of cells in normal and pathological settings.

Development of a superconducting claw-pole linear test-rig

NASA Astrophysics Data System (ADS)

Radyjowski, Patryk; Keysan, Ozan; Burchell, Joseph; Mueller, Markus

2016-04-01

Superconducting generators can help to reduce the cost of energy for large offshore wind turbines, where the size and mass of the generator have a direct effect on the installation cost. However, existing superconducting generators are not as reliable as the alternative technologies. In this paper, a linear test prototype for a novel superconducting claw-pole topology, which has a stationary superconducting coil that eliminates the cryocooler coupler will be presented. The issues related to mechanical, electromagnetic and thermal aspects of the prototype will be presented.

Multiplexed Energy Coupler for Rotating Equipment

NASA Technical Reports Server (NTRS)

Zhao, Xiaoliang

2011-01-01

A multiplexing antenna assembly can efficiently couple AC signal/energy into, or out of, rotating equipment. The unit only passes AC energy while blocking DC energy. Concentric tubes that are sliced into multiple pieces are assembled together so that, when a piece from an outer tube aligns well with an inner tube piece, efficient energy coupling is achieved through a capacitive scheme. With N outer pieces and M inner pieces, an effective N x M combination can be achieved in a multiplexed manner. The energy coupler is non-contact, which is useful if isolation from rotating and stationary parts is required. Additionally, the innovation can operate in high temperatures. Applications include rotating structure sensing, non-contact energy transmission, etc.

KSC-08pd3083

NASA Image and Video Library

2008-10-09

CAPE CANAVERAL, FIa. -- In the Space Station Processing Facility at NASA's Kennedy Space Center in Florida, workers attach an overhead crane to the flexible hose rotary coupler. After attachment, the crane will lift and move the coupler to the Lightweight Multi-Purpose Experiment Support Structure Carrier for installation. The carrier will be installed in space shuttle Endeavour for the STS-126 mission to the International Space Station. The 15-day flight will deliver equipment and supplies to the space station in preparation for expansion from a three- to six-person resident crew aboard the complex. The mission also will include four spacewalks to service the station’s Solar Alpha Rotary Joints. Photo credit: NASA/Jim Grossmann