bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Picosecond Cryo-Sampler Using Electro-Optic Techniques*
Authors: Dykaar D.R. , Hsiang T.Y. , Mourou G.A.
Published: February 2023

Previously we reported on a picosecond electro-optic sampling system used to characterize superconducting Josephson devices.1 A block diagram is shown in Figure 1. The sampler was driven by a colliding-pulse mode-locked laser which produced two 120 fs FWHM pulses at 100 MHz. One pulse was used to generate an electrical signal of adjustable height and width, via a photoconductive switch. This signal was used to excite the test device placed in the cryogenic environment. The resultant electrical transient was then sampled with the second optical pulse using a birefringent lithium tantalate crystal. By changing the relative delay between the optical excitation and sampling pulses, the temporal development of the electrical transient was recorded using conventional slow speed electronics. The limitations on system response were found to be due to the long cables required to move signals into, and out of, the cryogenic environment.
Characterization of TEGFETs and MESFETs Using the Electro-Optic Sampling Technique
Authors: Meyer K.E. , Dykaar D.R. , Mourou G.A.
Published: February 2023

It has been demonstrated that the electro-optic sampling technique can be used to characterize electrical signals with rise times as short as .46 ps.1 In this report we show the application of this sampling technique to the measurement of the transient response of GaAs TEGFETs and MESFETs.
Two-dimensional E-Field Mapping with Subpicosecond Resolution
Authors: Meyer K.E. , Mourou G.A.
Published: February 2023

With the development of very high speed GaAs devices such as heterojunction bipolar transistors, GaAs MESFETs, TEGFETs and MODFETs, with response well into the picosecond regime, comes the need for new instrumentation to directly characterize these ultrafast devices. Requirements of such instrumentation include good spatial resolution, i.e., a few micrometers, a temporal response of few ps, and minimum interference with the circuit being tested.
An InGaAsP 1.55 μm Mode-Locked Laser With a Single-Mode Fiber Output
Authors: Eisenstein G. , Korotky S.K. , Tucker R.S. , Koren U. , Jopson R.M. , Stulz L.W. , Veselka J.J. , Hall K.L.
Published: February 2023

Active mode-locking of semiconductor lasers1 is a useful technique for the generation of short, high peak-power optical pulses. For communication purposes, these pulse trains may subsequently be encoded by a modulator, which can either be integrated with the mode-locked laser2 or external and coupled to it using an optical fiber3. The external cavity of mode-locked lasers can take various forms1. In all reported schemes however, the output is from a cleaved laser chip facet. Coupling to an output fiber consequently incurrs a coupling loss of 3-5dB. In this paper we describe the first mode-locked 1.55 μm InGaAsP-optical -fiber composite-cavity laser with a single-mode fiber output. The laser output is coupled to a fiber of the same type as used for the cavity with a coupling loss of less than 0.5dB.
Monte Carlo Investigation of Hot Carriers Generated by Subpicosecond Laser Pulses in Schottky Barrier Diodes*
Authors: Osman M.A. , Ravaioli U. , Ferry D.K.
Published: February 2023

The self-consistent Ensemble Monte Carlo (E.M.C.) method is used to study the dynamics of carriers generated by subpicosecond laser pulses in a Silicon n+/n/metal submicron Schottky diode. The E.M.C. model for the Schottky diode is the same presented in [1]. In this model the Poisson’s equation is solved using an accurate collocation method [2], which gives a very precise solution for the electric field E on the ohmic contact boundary. This allows us to determine the current injected through the ohmic contact using the relation J=n+μOE(0), where μO is the low field mobility in an n+ contact region. This is justified if the width of the n+ region is at least a few Debye lengths, so that we can consider the carriers at the ohmic contact boundary to be in equilibrium with the lattice. In this way we can model the depletion of carriers and fully account for the non charge neutral behavior of the Schottky barrier diode, keeping track of the carriers exiting the device and allocating the ones which are not reinjected on the metal side.
Time-Resolved Photoluminescence of GaAs/AlxGa1−xAs Quantum Well Structures Grown by Metal-Organic Chemical Vapor Deposition
Authors: Fouquet J.E. , Siegman A.E. , Burnham R.D. , Paoli T.L.
Published: February 2023

Previous studies of time-resolved photoluminescence from GaAs/Al
x
Ga1−
x
As quantum well structures have examined material grown by molecular beam epitaxy. The large differences in behavior seen by different groups suggests a strong dependence of carrier dynamics on material. Until now, time-resolved photoluminescence from GaAs/Al
x
Ga1−
x
As quantum wells grown by metal-organic chemical vapor deposition (MOCVD) has not been extensively studied. We report data taken at temperatures from 16K to 300K and over a wide range of excitation densities on MOCVD quantum well structures. These structures were grown in a reactor which routinely produces high quality laser material, and exhibit high photoluminescence efficiency at room temperature.
High-Speed Phenomena in GaAs Multiple-Quantum-Wells
Authors: Mysyrowicz A. , Hulin D. , Migus A. , Antonetti A. , Gibbs H. M. , Peyghambarian N. , Morkoc H.
Published: February 2023

Type I quantum-well structures are promising candidates as active devices in fast optoelectronics. Because of the forced confinement of electrons and holes in the same layer, pronounced excitonic structures are observed up to room temperature, even in materials with small bulk exciton binding energy. Optically induced changes of such excitonic structures lead to the large and very rapid nonlinearities required in device applications. We describe here some of the underlying physical processes. The discussion is restricted to the case of GaAs quantum wells, with the accent put on those effects affecting the lowest (heavy-hole) exciton resonance on a picosecond or subpicosecond time-scale.
Dynamics of Below-Gap Photoexcitation in GaAs Quantum Wells
Authors: Zucker J.E. , VonLehmen A. , Chemla D.S. , Heritage J.P.
Published: February 2023

We have identified several physical processes by which below-gap photons can modify excitonic absorption in GaAs quantum wells.1-3 These different phenomena can be distinguished by their temporal response times, which range from tens of nanoseconds to less than one picosecond. Our experiments also show that the relative contributions of these mechanisms to below-gap optical modulation of exciton absorption depend strongly on temperature as well as on the wavelength of the below-gap modulating beam. The size of the modulation indicates that a new class of absorptive and dispersive devices for optical signal processing is possible in which signals propagate in the transparent region of the crystal and experience negligible attenuation. In order to successfully interpret and calculate the magnitude of these exciting new effects, we show that it is necessary to take into account the special properties of two-dimensional excitons in semiconductor quantum wells.
Optical Modulation above 20 GHz using a Waveguide Electrooptic Switch
Authors: Korotky S.K. , Eisenstein G. , Tucker R.S. , Veselka J.J. , Raybon G.
Published: February 2023

Optical modulators operating from below 1GHz to the millimeter wave regime are of interest for many applications including wideband fiber communication using microwave subcarrier modulation. External laser modulation offers the flexibility of optimizing the optical transmitter for high modulation bandwidths and high optical power output, while maintaining excellent spectral purity, as has been demonstrated in multi-gigabit/sec digital fiber communication. Electrooptic modulators, based on single-mode titanium indiffused lithium niobate (Ti.LiNbO3) optical waveguides, with 3 dB electrical bandwidths of approximately 16 GHz have been demonstrated and directly evaluated to about 18 GHz. [1] The extension of these results to higher frequencies has been hindered by stringent device design requirements and a lack of sufficiently high-speed detection systems.
Femtosecond Nonequilibrium Electronic Heat Transport in Thin Gold Films
Authors: Brorson S. D. , Fujimoto J. G. , Ippen E. P.
Published: February 2023

With the advent of femtosecond lasers has come the promise of directly measuring ultrafast electron transport effects in technologically important materials. Using a front pump/back probe1 measurement of transient reflectivity changes, we have observed ultrafast electronic heat transport through thin films of gold. For film thicknesses of 500 - 2000 Å, we find thermal transport occurs on a time scale of 40 - 200 fs. In this regime, the transport of heat seems to be governed by electronic motion, since lattice heat diffusion times are much slower.
Microwave and Millimeter-Wave Resonant Tunneling Diodes
Authors: Gerhard Sollner T. C. L. , Brown Elliott R. , Goodhue W. D.
Published: February 2023

Resonant tunneling through double-barrier heterostructures has attracted increasing interest recently, largely because of the fast charge transport1 it provides. In addition, the negative differential resistance regions which exist in the current-voltage (I-V) curve (peak-to-valley ratios of 3.5:1 at room temperature2-4 and nearly 10:1 at 77 K have been measured) suggest that high-speed devices based on the peculiarities of the I-V curve should be possible. For example, the negative differential resistance region is capable of providing the gain necessary for high-frequency oscillations5. In our laboratory we have been attempting to increase the frequency and power of these oscillators6, and others have worked toward a better understanding of the equivalent circuit of the device7 and the underlying processes responsible for the frequency response8-10.
High-Speed Optical Logic Using GaAs
Authors: Gibbs H. M. , Peyghambarian N. , Lee Y. H. , Jewell J.L. , Migus A. , Antonetti A. , Hulin D. , Mysyrowicz A.
Published: February 2023

The status of bulk-GaAs etalons and their application to high-speed optical logic will be summarized. Several characteristics are of particular importance: time to make a logic decision ("switch-on time"), time required for the device to recover and be ready to make the next decision (recovery time), energy required per logic decision (switching energy), ability to switch the next device (cascadability) or perhaps several devices (fanout), etc.
Progress and Challenges in HEMT LSI Technology
Authors: Abe Masayuki , Mimura Takashi , Kondo Kazuo , Kobayashi Masaaki
Published: February 2023

Six years have now passed since the announcement in 1980 of the High Electron Mobility Transistor (HEMT)1), and HEMT technology has certainly opened the door to new possibilities for ultra-high-speed LSI/VLSI applications2). Due to the supermobility GaAs/AlGaAs heterojunction structure, the HEMT is especially attractive for low-temperature operations at liquid nitrogen temperature. For LSI level complexity, HEMT technology has made it possible to develop a 1.5 kgate gate array with an 8 x 8 bit parallel multiplier3)for logic circuits, and 4 kbit static RAM for memory circuits.4)
High Speed, High Repetition Rate, High Voltage Photoconductive Switching
Authors: Donaldson William R.
Published: February 2023

We describe a method of producing robust silicon photconductive switches. These switches are used in high power applications where it is necessary to switch high voltages on the picosecond time scale. They have the advantage that they are activated by the bulk absorption of light in a semiconductor.1 Thus avalanching and transit time effects normally associated with high voltage switches are absent. As a result the switches have no jitter with respect to the optical pulse and very little heating due to the joule energy deposited in the switch as they turn on.2 These qualities make these switches desirable in applications which require parallelism or low thermal energy deposited in the switch. However, photoconductive switches cannot be used in practical applications until they can be proven reliable.
Picosecond Optoelectronic Switches Using Composite Electronic Materials
Authors: Chauchard E.A. , Lee Chi H. , Diadiuk V. , Turner G.W.
Published: February 2023

Since the discovery of picosecond photoconductivity, optoelectronic switches made from a variety of materials have been studied [1]. A great number of applications have already been recognized and many new techniques depend on the availability of ultrafast (picosecond) devices. The two switches using composite electronic materials studied in this work are Fe-doped InGaAs grown on InP substrates and GaAs on a silicon-on-sapphire (SOS) substrate. The semi-insulating character of the Fe:InGaAs epilayer makes it very attractive for fabrication of integrated devices such as PIN photodetectors and FETs [2]. This material also exhibits a very high mobility (10000 cm2/Vs) and a photosensitivity extending up to 1.65 pm. The GaAs on SOS is of interest for the monolithic integration of GaAs and silicon devices where, for example, a GaAs FET could be integrated on a silicon wafer. This process takes advantage of the mature Si technology and the availability of low cost, high quality silicon wafers [3]. There is also interest for SOS as substrate because it provides better isolation and it is transparent. The interface silicon-sapphire exhibits a high density of defects, allowing faster devices to be fabricated. In our experiment, the sapphire substrate was used for mechanical strength. Whatever the material, the fabrication of a switch by deposition of metallic electrodes makes it possible to determine the switch characteristics and possible applications as well as to test the material optical properties.
Generation and Forming of Ultrashort High Voltage Pulses
Authors: Sayadian Hrayr A. , Feng S. T. , Goldhar J. , Lee Chi H.
Published: February 2023

High voltage pulse forming techniques, utilizing spark gaps, is a mature field. However, problems associated with synchronizing spark gap switching, in the picosecond regime, limit its application. A new approach, developed over the past few years, is to use laser controlled photoconductive switches in generating ultrashort high voltage pulses.1 The use of photoconductive switches achieves picosecond synchronization and very long lifetimes. Furthermore such switches can be readily incorporated into various types of pulse generating and forming structures. We report here on an investigation of the performance of various types of high voltage generating structures with photoconductive switches. These include Blumleins (with multiple switches), Marx banks, stacked lines and L.C. generators in coaxial, microstrip and coplanar geometries. High voltage pulses with picosecond rise and fall times were generated and monitored using Pockels cells monolithically integrated with the pulse forming structures. Using dc charged voltage multiplication circuits, up to 5 kv was generated in nanosecond pulses. Also, 5 kv of peak to peak RF single cycle pulses were generated using a similar multiplication circuit. This type of RF pulses have important applications in high resolution radar systems.2
Optical Detection of Resonant Tunneling of Electrons in Quantum Wells
Authors: Livescu G. , Fox A M. , Sizer T. , Knox W.H. , Miller D.A.B.
Published: February 2023

The investigation of vertical transport in superlattices (SL's) and multiple quantum wells (MQW’s) has recently attracted much attention. Intense research was focused on basic quantum effects such as Bloch transport of electrons and holes in minibands,1 coherent and incoherent, resonant, sequential and Zener tunneling2 in double barriers,3,4 SL’s and MQW’s of GaAs/AlAs,5,6 GaAs/AlGaAs,7 and InGaAs/InP.2,8 In addition to the academic interest, the understanding of the mechanisms of escape from and travel through quantum wells is vital for the recently developed and constantly growing family of electro-optical devices using semiconductor quantum wells. Most of them are based on the quantum-confined Stark effect (QCSE), and they include bistable selfelectro-optic effect devices (SEED’s), tunable detectors, electro-absorption modulators and optical logic elements.9 The basic unit of all of these is an epitaxially grown p-i-n diode, with the quantum well layers in the intrinsic region. By reverse biasing the diode, an electrical field is applied on the quantum wells, controlling its optical absorption spectrum. Since operating wavelengths are close to the excitonic absorption peaks, photoexcited charge is created in the quantum wells and is transported to the electrodes. The mechanisms by which this transport occurs are ultimately responsible for the intrinsic maximum speed or operating intensity of these devices.
Picosecond Lasing Dynamics in Quantum-Well Lasers and Its Dependence on the Number of Quantum Wells
Authors: Arakawa Y. , Sogawa T. , Tanaka M. , Sakaki H.
Published: February 2023

Investigation of physics of ultra-fast phenomena in semiconductor lasers is important for high-speed modulation and short pulse generation. It has been recently demonstrated that quantum well (QW) lasers have the advantage to generate shorter light pulses, since the differential gain is enhanced by a factor of four compared to conventional double-hetero structure lasers [1]. In fact, an extremely narrow light pulse (<1.3psec) was successfully observed in a quantum well laser [2]. This is the shortest pulse so far achieved in the semiconductor lasers without external cavity. However, effects of QW structure-parameters, such as thickness and the number of QWs, on the picosecond pulse dynamics have not been discussed sufficiently. In this paper, we investigate short pulse generation in QW lasers with emphasis on dependence of pulse form on the QW structures. The results demonstrate that the pulse duration strongly depends on the QW structures: The QW laser having a smaller number of QWs generates broader light pulses, which results from in both reduced differential gain and higher quasi-Fermi-energy level of electrons E
Fc
.
Timing Jitter of Colliding Pulse Mode-Locked Lasers
Authors: Harvey G. T. , Heutmaker M. S. , Smith P. R. , Valdmanis J. A. , Nuss M. C.
Published: February 2023

The colliding pulse modelocked (CPM) laser is an attractive source of subpicosecond pulses for electro-optic sampling, but the time resolution of electro-optic sampling also depends on the timing jitter of the optical pulse train. We find that the jitter of the CPM running alone (the absolute jitter) is about 5 ps at 100 MHz, while the jitter between the CPM and a phase-locked RF synthesizer (the relative jitter) is about 1.8 ps.
Application of Frequency-Domain Techniques for Tuning Pulsed Lasers
Authors: Swartz J. C. , De Lucia F. C. , Guenther B. D.
Published: February 2023

We demonstrate an alternative technique to the use of an autocorrelator for accurately tuning pulsed lasers. This technique is based upon the use of frequency domain information in place of the time domain information to obtain the optimum modelocked condition.
Coplanar Vacuum Photodiode for Measurement of Short-Wavelength Picosecond Pulses
Authors: Bokor J. , Johnson A. M. , Simpson W. M. , Storz R. H. , Smith P. R.
Published: February 2023

We have fabricated a vacuum photodiode in a coplanar stripline geometry. This device is capable of high quantum efficiency and picosecond response time. It may be particularly useful for diagnostics of picosecond soft X-rays from laser produced plasmas.
Photoconductive and Photovoltaic Picosecond Pulse Generation Using Synthetic Diamond Film
Authors: Feng S. T. , Goldhar J. , Lee Chi H.
Published: February 2023

Photovoltaic and photoconductive electrical pulse generation was investigated in a composite switching device using thin diamond film. Fast response under high fields was observed with picosecond laser pulses.
Beryllium-Bombarded In0.53Ga0.47As and InP Photoconductors with High Responsivity and Picosecond Resolution
Authors: Loepfe R. , Schaelin A. , Melchior H.
Published: February 2023

Small size In0.53Ga0.47As and Fe:InP photoconduc­tors with optimized Be3+-ion implantation reach response speeds of 2ps to 4ps, while maintaining responsivities of 0.006A/W and 0.02 A/W. The high speed of these devices is due to the Be-bombardement related introduction of recombination centers. The responsivity is inverse proportional to the speed of response and proportional to the mobility. This mobility appears to be dominated by bombardement related neutral impurity scattering.
Use of Tandem Photoconductive Switches for Measuring Picosecond Turn-On Delay of Laser Diodes
Authors: Blixt P. , Adomaitis E. , Krotkus A.
Published: February 2023

A tandem photoconductive switch, producing up to 75 V pulses with 15 ps rise and fall times, were used to characterize a laser diode.
Beams of Terahertz Electromagnetic Pulses
Authors: Fattinger Ch. , Grischkowsky D.
Published: February 2023

The generation of diffraction limited beams of single-cycle 0.5 terahertz electromagnetic pulses is described. The beams, centimeters in diameter, have a frequency independent divergence of only 15 mrad and have been propagated distances up to 350 cm. The very high collection efficiency of the optical system used for the generation and the detection of these beams provides exceptionally clean and sensitive reception of the transmitted signal. A spectral characterization of water vapor in the intervening ambient air is also presented.
Optical Phonon-Assisted Tunneling in Double Quantum-Well Structures
Authors: Oberli D. Y. , Shah Jagdeep , Damen T. C. , Kopf R. F. , Kuo J. M. , Henry J. E.
Published: February 2023

Using subpicosecond time-resolved luminescence spectroscopy, we have investigated tunneling of electrons in a double quantum well structure. The sample is a p-i-n diode, which contains two GaAs quantum wells of different thicknesses separated by a 55 Å Al0.65Ga0.35As barrier layer. We observe a large increase of the tunneling rates when the two lowest energy subbands of the coupled wells are separated by more than an optical phonon energy. These results demonstrate that phonon-assisted tunneling play a significant role in this structure and in the carrier transport of related multiple quantum well structures.
Silicon FETs at 0.1-μm Gate Length
Authors: Sai-Halasz G. A.
Published: February 2023

Results are being presented from a work aimed at demonstrating the feasibility of silicon FET technology in the 0.1μm gate length regime. Self-aligned, n-channel polysilicon gated MOSFETs were designed for operation at 77°K, with reduced power-supply levels. Noteworthy results of the exercise were: observing clear manifestation of velocity overshoot which resulted in extrinsic transconductance of over 940μS/μm at 0.07μm gate-length, measuring 13ps delay per stage in 0.1 μm gate length ring oscillators, with simulations showing potential for below 5ps performance.
Electron-Hole Effects on the Velocity Overshoot in Photoconductive Switches
Authors: Joshi R. , Chamoun S. , Grondin R. O.
Published: February 2023

The role of the electron-hole interaction on the transient velocity of photoexcited carriers in bulk GaAs is investigated using a bipolar Ensemble Monte Carlo approach. The dependence of the intervalley transfer on the photoexcitation energy, intensity and operating temperature is also discussed. The results show that under appropriate conditions, the electron-hole interaction can enhance the velocity overshoot. Some recent experimental observations can also be better explained by including this interaction. Influence of the non-equilibrium phonons remains negligible even at low temperatures.
Picosecond Superconductive Electronics
Authors: Van Duzer T.
Published: February 2023

Materials developments during the past several years will facilitate the realization of promises of picosecond electronics with superconductive devices. An increasing number of groups around the world have developed the capability of making all refractory integrated circuits based on the Nb-NbOxNb Josephson tunnel junction, which has the I-V characteristic shown in Fig. 1a. These devices have excellent and controllable electrical characteristics and are stable both in terms of shelf life and in thermal cycling. Circuits with tens of thousands of logic gates have been made and have shown remarkable electrical performance. It should be borne in mind that in complex electronic circuits with gates that switch with speeds of several picoseconds, the terminal data rates are on the nanosecond scale except in special pipelined situations, such as a shift register. It should also be kept in mind that parasitics limit switch speeds. While the niobium Josephson junctions has a theoretical limiting switching speed of 0.22 ps, the junction capacitance limits the speeds realized to date to slightly more than 1 ps.
High-Frequency Analog Signal Processing With High-Temperature Superconductors*
Authors: Lyons W. Gregory
Published: February 2023

The low conductor loss of superconducting materials makes it possible to build passive microwave devices that cannot be built with normal metal conductors. For example, compact transversal filters in the form of tapped delay lines can be fabricated from superconducting niobium to operate with multi-gigahetz signal processing bandwidths [1,2]. Recent advances in the growth of thin films of the high-temperature superconductor (HTS) Y-Ba-Cu-O [3,4] have made possible the demonstration of a variety of passive microwave devices. This includes long delay lines [5], tapped delay line filters [6], and narrow-band microstrip bandpass filters using edge-coupled resonators [5]. The most notable of these demonstations has been the operation of a 2.6-GHz bandwidth stripline chirp filter with 12 ns of total delay and a Y-Ba-Cu-O patterned line length of 0.7 m. The HTS microwave components crucial to this development were long delay lines with more than 10 ns of delay, impedance transformers, and backward-wave couplers. Microstrip, coplanar, and stripline geometries were all examined during the course of this development. The stripline configuration selected for the chirp filter was developed using microwave CAD routines and superconducting niobium prototypes.
Modeling of An Electro-Optically Probed Photoconductive Switching Experiment
Authors: Connolly K.M. , Grondin R.O. , El-Ghazaly S.M. , Joshi R.P.
Published: February 2023

Photoconductive switching and electro-optic sampling provide a basis for generating and measuring electrical waveforms with subpicosecond risetimes [1]. The simplest structure, shown in Fig. 1, consists of a photoconductive switch and coplanar microstrip fabricated on a GaAs substrate. The switch is turned on by illuminating the gap with a laser pulse to generate electron-hole pairs. The electrons and holes then move according to the fields created by the bias voltage applied to one side of the gap, and induce a propagating wave on the microstrip structure.
Improvement of the Minimum Detectability of Electro-Optic Sampling by Using a Structurally New Probe
Authors: Aoshima Shinichiro , Takahashi Hironori , Hirano Isuke , Tsuchiya Yutaka
Published: February 2023

For practical applications, such as the measurement of high speed electrical waveforms at internal nodes in integrated circuits, we proposed, for the first time in 19891), Electro-Optic (E-0) sampling using a longitudinal probe and laser diode (LD) pulses. The longitudinal probe measures electric field just above the conductor and is free from crosstalk problems occurring in transverse probing. The laser diode is compact, inexpensive, reliable and easy to handle. Moreover, the laser pulses can be easily synchronized with the clock signals for the Device Under Test (DUT).
Recent Advances in Ultra-Fast High Electron Mobility Transistor Technology
Authors: Nguyen Loi D.
Published: February 2023

Recent advances in material growth and fabrication process have made possible the realization of a new class of ultra-fast High Electron Mobility Transistors (HEMTs) in the AlInAs/GalnAs material system (lattice-matched to InP). In the last three (3) years alone, through improvements in materials and shrinking of gate length, the speed of state-of-the-art AlInAs/GalnAs HEMTs has been increased at an astounding rate: from 80 GHz in 1987 to 250 GHz as of today [1-4].
Low-Temperature Epitaxially-Grown GaAs as a High-Speed Photoconductor for Terahertz Spectroscopy
Authors: Chwalek J.M. , Whitaker J.F. , Mourou G.A.
Published: February 2023

Photoconductive elements have been employed to generate and detect ultrafast electrical signals in many areas of optical electronics.[1,2] One outstanding application of these structures, when they are fabricated on substrates with rapid recombination times, is as transmitting and receiving antennas that can be used for millimeter-wave and submillimeter-wave spectroscopy. Experiments which characterize a terahertz radiation system using dipole-like antennas have been carried out,[3] and the system has been applied to the spectroscopy of dielectrics [4] and, in one case, n- and p-doped silicon.[5]
Propagation of 100 GHz bandwidth electrical pulses on a microstrip line with buried silicide groundplane
Authors: Roskos Hartmut , Nuss Martin C. , Goossen Keith W. , Kisker David W. , Tell Ben , White Alice E. , Short Ken T. , Jacobson Dale C. , Poate John M.
Published: February 2023

Microstrip transmission lines consisting of a narrow center line and an extended groundplane are the most commonly used device interconnections in millimeter-wave integrated circuits. Typically, the ground plane of a microstrip line is located on the backside of the roughly 500 µm thick semiconductor wafer that carries the circuit elements. For frequencies above 10 GHz, this simple scheme can lead to a limitation of the useful bandwidth of ultra-high-speed electronic circuits because dispersion can significantly distort the electrical pulses propagating on the microstrip interconnect [Goossen, 1989]. Recently, it has been proposed to use buried silicide layers as groundplanes for microstrip lines in silicon based circuits [Goossen, 1990]; the resulting reduction in the separation of the center conductor and the ground plane should push the onset of the dispersion to frequencies above the range of interest. For a separation of 10 pm the dispersion should be negligible for frequencies up to 500 GHz. Here, we test this concept by studying the propagation of 100 GHz bandwidth electrical pulses on microstrip lines that have been fabricated on silicon wafers with buried and with conventionally formed groundplanes.
Carrier Sweep-Out from Quantum Wells in an Electric Field
Authors: Fox A.M. , Miller D.A.B. , Livescu G. , Cunningham J.E. , Jan W.Y.
Published: February 2023

The physics of carrier escape from quantum wells in an electric field is important for improving the quantum well electroabsorptive devices such as the Self Electrooptic Effect Device (SEED) [1]. The carrier lifetime is important not only because it puts a lower limit on the switching time [2], but also because it affects other properties such as the electroabsorption and the exciton saturation intensity [3]. This latter point in fact proves to be very significant for SEED systems, because these systems tend to run at intensity levels much greater than that required to switch a single device. (Sufficient energy must be passed to the next device in the system to switch it after allowing for the system losses.) At these high power levels, the exciton absorption saturates, which puts an upper limit on the intensity which can be used. We have recently shown how the saturation intensity is strongly affected by the design of the quantum well structure, most likely because of the changes in carrier sweep-out times which accompanied the change in design [3].
Coherent Oscillations of a Wavepacket in a Semiconductor Double Quantum Well Structure
Authors: Leo Karl , Shah Jagdeep , Göbel Ernst O. , Damen T.C. , Schmitt–Rink Stefan , Schäfer Wilfried , Köhler Klaus
Published: February 2023

Advances in the growth of ultrathin semiconductor layers have allowed to realize structures showing novel physical effects and device applications. One of the most exciting developments was the ability to grow heterostructures with barrier layers thin enough that tunneling becomes important. One particular structure which has recently found much interest is an asymmetric double quantum well structure (a-DQW), which is related to double well potentials important in many other fields of physics.[1] Figure 1 depicts schematically an a-DQW structure: Out of resonance (left), the electronic wavefunctions are localized in the respective well; at resonance (right), the levels anticross, and the wavefunctions are delocalized over both wells. If one excites resonantly the WW with a short pulse having a spectrum which covers transitions to both electronic levels, a wavepacket localized in the WW is created.
Terahertz absorption between split subbands in coupled quantum wells
Authors: Roskos Hartmut , Nuss Martin C. , Shah Jagdeep , Tell Ben , Cunningham Jack
Published: February 2023

Two quantum systems with energy levels in resonance with each other experience a splitting of these levels when the wavefunctions of the systems overlap. In semiconductor structures consisting of pairs of closely spaced quantum wells the wavefunction overlap of charge carriers in the wells leads to a novel kind of intersubband transition. To date, this transition has been studied by interband absorption and luminescence and, most recently, by four-wave-mixing experiments [Leo, 1990]. Here, we report of the first direct absorption measurements of the split-subband transition in coupled quantum wells.
Quantum Transport of an Electron Wavepacket across a Heterostructure Discontinuity – Applications in the GaAs/AlGaAs Heterostructure
Authors: Sankaran Vasu , Singh Jasprit
Published: February 2023

Theoretical techniques used to study time dependent electron transport in heterostructures use one or more of the following approximations: i) In Monte Carlo methods the electron is described as a point particle whose transport properties (such as effective mass, scattering rates, etc.) change abruptly when it moves across a boundary. As the electron moves across a boundary, the role of central cell symmetries (i.e., Γ, X, L character) is suppressed; ii) In time dependent quantum description, once again the electron wavepacket is assumed to abruptly see different material properties across a discontinuity. Moreover, the quantum description usually employs a one band effective mass equation that implicitly assumes that the character of the Bloch function is not significantly altered across the regions. The first approach is valid for heterostructures where electrons travel ≈ 1000 Å in each region and where the valley order is not altered across the heterostructure. The second approach is required in heterostructures of dimension ≈ 50 Å where the effects of quantum confinement are important, but where the central cell symmetry is again unchanged across the heterostructure.
Organic Materials for Nonlinear Optics
Authors: Small R. D. , Sohn J. E. , Singer K. D. , Kuzyk M. G.
Published: February 2023

Numerous investigations into the nonlinear optical properties of certain organic and polymeric materials have shown that these materials possess the largest observed optical nonlinearities.[1] [2] [3] [4]For implementation of all-optical and electro-optical communications and data processing systems, materials possessing large optical nonlinearities are required. Applications employing guided wave structures require materials that also are suitable for waveguiding and integration.
Optical Amplification in Switching Networks
Authors: Thylén L , Granestrand P , Djupsjöbacka A
Published: February 2023

We report experimental results involving BER-measurements at 990 Mb/s for a Ti:LiNbO3, integrated optics device cascaded with a semiconductor laser amplifier.
Deterministic and Statistic Circuit Assignement Architectures for Optical Switching Systems
Authors: de Bosio A. , De Bernardi C. , Melindo F.
Published: February 2023

The size of an optical switching network based on 2×2 optical switching elements, is limited by a series of factors: the relatively small phisical size of the substrate (no more than 100×75 mm for LiNbO3), the phisical size, loss and crosstalk of the switching element, the loss introduced by the fiber-substrate coupling and the large radii (more than 1 cm) imposed to the waveguide to keep bend loss around few hundredths of dB/degree.
A Monolithically Integrated Optical Gate 2x2 Matrix Switch Using GaAs/AlGaAs Multiple Quantum Well Structure
Authors: Ajisawa A. , Fujiwara M. , Shimizu J. , Sugimoto M. , Uchida M. , Ohta Y. , Asakawa K.
Published: February 2023

A small size matrix switch is desired for constructing large scale optical switching systems. An optical gate matrix switch which consists of optical splitters, combiners and gates has advantages of its simple construction and ability of non-blocking and point-to-multipoint connections. So far this kind of switch (1) was hybrid and it seemed difficult to interconnect optical gates with optical circuits.
Silicon Carrier-Enhanced Electrooptical Guided-Wave Switch
Authors: Lorenzo J.P. , Soref R.A.
Published: February 2023

Experimental results on an all-silicon 1.3 µm 2 × 2 optical switch are presented in this paper. Waveguiding of 1.3 µm light has been shown to be feasible in silicon with little attenuation expected for doping concentrations below 1017cm−3. (1) This and other state-of-the-art developments(2) has led to the monolithic opto-electronic device under study in this work. A schematic view of the integrated device structure is shown in figure 1. The active region is integrated at the crossing intersection of two raised rib channel waveguides. Each device chip consists of three individual bi directional 2×2 devices with different crossing angles and rib widths. The chip is polished in a special mounting jig to delineate the ridge waveguide ends. Electrooptical interactions are induced by actively altering the refractive index profile under a metallurgical p+/n junction at the waveguide intersection region shown in figure 2. An index decrease in this region is created with injected carriers.(1) Refractive index change near the junction is estimated to be 1.5 × 10−3 for 1018cm−3 free holes.(3)
Overview of Switching Needs for 1990-2000+
Authors: Nussbaum E.
Published: February 2023

Research and development underway 30 years ago brought about today’s world of stored program controlled digital switching. The confluence of three key elements was the trigger for this new era in switching--the transistor, the basic concepts of stored program controlled computing, and the techniques of digital communication in the form of PCM. Today, roughly one quarter of the world’s 400 million telephone lines are served by central offices deploying most of these technologies. Though stored program gave these switches considerable new flexibility for customer features and allowed great strides in automation and simplification of maintenance and operations, the new technology was primarily deployed as a one-for-one cost reduction element for its electromechanical predecessors in the existing network--effectively a replacement vehicle between existing mainframes.
Novel Optically Bistable Optoelectronic Device for Infrared Signal Processing
Authors: MacKenzie H. A. , Iltaif A. , Hughes J. I. L. , Hunter J. J. , Ronaldson D.
Published: February 2023

We report a new optically bistable opto-electronic (OBOE) InSb device which, while retaining all-optical switching capability can also be switched (ON and OFF) electrically. A photo-conductive monitoring system is utilised to give readout of the logic state. Applications of OBOE arrays for image processing are discussed. The latest performance data for the switch time (150 ns) and switching power (500 μW) of fully optimised InSb bistable devices are reported.
Optical Flip–Flop Operation of a Bistable Laser Diode Using Single-Wavelength Light Signals
Authors: Odagawa T. , Yamakoshi S.
Published: February 2023

Optical flip-flop operation of a bistable laser diode has been demonstrated using single­wavelength light signals which have different pulse intensity or pulse width.
Transverse Modes, Waveguide Dispersion, and 30-ps Recovery in Submicrometer GaAs–AlAs Microresonators
Authors: Jewell J. L. , McCall S. L. , Scherer A. , Houh H. H. , Whitaker N. A. , Gossard A. C. , English J. H.
Published: February 2023

We have studied room-temperature optical gating of ~5 ps pulses in GaAs/AlAs microresonators with diameters ranging from <0.5 μm to 1.5 μm by using a high-refractive-index lens system having a numerical aperture of 1.3. The larger devices show well-defined transverse modes and waveguide dispersion having fair agreement with calculations. The former effect causes decreased modulation of the probe beam. The smallest-diameter devices (<0.5 μm) show higher modulation, fully recover in <30 ps, and have their peak transmission wavelengths shifted by >500 Å compared to a large ~ 10 μm region.
Switching in an Optical Interconnect Environment
Authors: Goodman Joseph W.
Published: February 2023

The special circumstances associated with the optical interconnect problem are outlined, and the differences between this type of problem and the long distance communication problem are reviewed. The drive power required of an interconnect is one parameter that influences the choice of technology used. Optical interconnects can compete favorably with electrical interconnects in those problems where a terminating impedance would be required as part of the electrical solution. Several switch architectures that can be used are briefly reviewed. The proper degree of parallelism to be used in an optical interconnect is considered from the point of view of minimizing cost, and the impact of switch cost on the optimum solution is explored.
Spatial Extension of Multistage Interconnection Networks
Authors: Giglmayr Josef
Published: February 2023

The extension of common multistage interconnection networks (MINs) to three-dimensional (3D)-MINs causes various problems for their definition and analysis. Some of them and their relations to photonic switching and optical computing are addressed throughout this paper. In particular, three questions are discussed: 1) The appropriate interconnection pattern, 2) the number of stages, and 3) the size of the switching modules.
Effect of Absorber Position in Bistable InGaAsP Lasers
Authors: Öhlander Ulf , Sahlen Olof
Published: February 2023

Threshold current, hysteresis width, luminescence wavelength and carrier redistribution depend strongly on whether the middle-section or end-facet-section is used as the absorber in a bistable laser.
Small-Size, Low-Cross-Talk GaAs–AlGaAs Electro-Optic Directional Coupler Switches with Alternating Δβ for Long-Wavelength Matrix Switches
Authors: Komatsu K. , Sugimoto M. , Ajisawa A. , Suzuki A.
Published: February 2023

Small size ( 2mm-long ) GaAs/AlGaAs directional couplers, with crosstalk as low as -16 dB at λ=1.3μm without a requirement for precise device dimensions control, have been achieved by using alternating Δβ technique.
Self-Routing Optical Switch Using Ring Topology
Authors: Su S. F. , Koai K. T.
Published: February 2023

A self-routing optical switch using ring topology is proposed. This switch self-routes multiple optical packets simultaneously to their destination ports. The incoming and outgoing data streams are serial, but all internal transfers are parallel. It can easily adapt to changing service, traffic and control requirements and effectively exploit new optical components without changing the basic switch architectures. The switch can be used for central office switching or for remote unit switching.
Optical Technology Applications to Fast Packet Switching
Authors: Cinato P. , de Bosio A.
Published: February 2023

After introducing Fast Packet Switching (FPS) technique, the paper presents a near future scenario characterized by a relevant utilization of wideband services based on packetized information exchange, and analyzes a possible application of FPS technique to photonic switching. An electro-optical Fast Packet Switching node model is proposed and the main optical switching fabric requirements are defined, considering its insertion in the wide-band public telecommunication network.
High-Speed Hitless Switching Using Ti:LiNbO3
Authors: Erickson J. R. , Huisman R. F. , Nordin R. A. , Veach R. S. , Major K. D.
Published: February 2023

In designing switching systems with Ti:LiNbO3, one faces a dichotomy: couplers may be long with low voltage requirements and fast switching speed, or they may be short with higher integration but slower switching speed.
All-Optical Signal Routing Using Bistable Interferometers
Authors: Buller G. S. , Smith S. D. , Walker A. C.
Published: February 2023

An examination of the potential applications of bistable interferometers to signal routing is presented. Device contrast, switch networks and wavelength routing are discussed.
Demonstration of a Self-Clocked Optical Time-Slot Interchanger
Authors: Perrier Philippe A. , Prucnal Paul R. , Chbat Michel W.
Published: February 2023

A novel time-division photonic switch architecture is demonstrated. In the proposed configuration, an optimized number of fiber-optic delay-lines are used as optical memories; the rearrangement of the time slots is performed passively, thus eliminating the need for an active reading gate; and the switch operates asynchronously.
Time and Wavelength Division in a Photonic Switching Network
Authors: Whitehead Nigel , Parsons Nick
Published: February 2023

A photonic switching systems experiment is described which exploits space, wavelength and time division techniques under development within the European RACE programme.
Semiconductor based switches within the RACE photonic switching program
Authors: Erman M.
Published: February 2023

Photonic switching options for various applications including ATM switching, high speed LANs, optical cross-connects, etc, are currently investigated within the european project RACE OSCAR (Optical Switching Components and Application Research). InP based Photonic Integrated Circuits have been identified as key devices.
Picosecond On-Off Switching Using a Pair of Picosecond-On/Nanosecond-Off GaAs Etalons
Authors: Lowry C. W. , Gibbs H. M. , Pon R. M. , Khitrova G.
Published: February 2023

Semiconductor nonlinear Fabry-Perot etalons are promising devices for performing optical logic and switching operations in systems in which operational speed, throughput and interconnectivity are critical. An important characteristic of a logic or switching device is the number of operations it can perform in a given time. This figure is limited by both the device turn-on time (≃1 ps for GaAs nonlinear etalons1) and the turn-off time.
GEO-Modules and All-Optical Time Slot Interchangers
Authors: Soccolich C.E. , Islam M.N. , Sauer J.R.
Published: February 2023

A Generalized Exclusive-OR (GEO) module is a boolean and connectivity complete logical representation of soliton dragging logic gates [1,2]. All-Optical designs using GEO-modules can lead to minimal component implementation of many important functions because the GEO-module logic is closely tied to the physics of the fiber gates. We use two or three GEO-modules to design NOR-gates, routing switches, and two versions of a time slot interchanger.