bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast Multiple Quantum Well Absorber for Mode Locking of Semiconductor Lasers
Authors: Silberberg Y. , Smith P. W. , Miller D. A. B. , Tell B. , Gossard A. C. , Wiegmann W.
Published: February 2023

Passive mode locking of a semiconductor laser using GaAs/GaAlAs multiple quantum well (MOW) material as a saturable absorber has been reported recently.(1) The MQW material exhibits clear and easily-saturable room-temperature exciton absorption resonances. The mode locked laser produces a train of pulses as short as 1.6 psec. Such lasers are potentially important sources for future high-capacity optical communications systems.
Measurements of the Temperature and Intensity Dependence of Transient Photoconductivity in InP:Fe*
Authors: Kania D. R. , Bartlett R. J. , Hammond R. B. , Smith D. L.
Published: February 2023

Recent applications of photoconductors as radiation detectors1 has increased interest in a deeper understanding of the operation of these devices and the physical processes affecting their operation. Specifically, a more complete understanding of transient recombination of photoproduced carriers in intrinsic semiconductors is required. Here, we report our measurements of the temperature and photon intensity dependence of transient photoconductivity in InP:Fe photoconductors.
Hertzian Dipole Measurements with InP and InGaAs Photoconductors
Authors: Downey P. M. , Karin J. R.
Published: February 2023

Research in the use of radiation damaged semiconductors[1] as picosecond photoconducting pulse generator, and sampling gates has led to the identification of material systems where subpicosecond[2] free carrier relaxation times along with reasonably high free carrier mobilities and material dark resistivities can be realized. However, on such small time scales these optoelectronic autocorrelation measurements are limited by the speed of response of the microstrip circuits used[3]. A recently described measurement scheme[4] overcomes such circuit limitations to the response speed by utilizing picosecond photoconductors as radiating and receiving dipole antennas. In such Hertzian dipole experiments no transmission line structures are used to couple the electrical pulse generator to the sampling gate; instead, the picosecond electromagnetic pulse from the pulse generator is radiated freely through a bulk dielectric medium to the receiving photoconductor, which acts as a picosecond sampling gate. This results in a high pass coupling scheme, as opposed to the low pass transfer characteristics of microstrip interconnections.
Modeling of Picosecond-Pulse Propagation in Silicon Integrated-Circuits
Authors: Goossen K. W. , Hammond R. B.
Published: February 2023

We have made theoretical time-domain analyses of the dispersion and loss of both square-wave and exponential pulses on microstrip transmission line interconnections on silicon integrated-circuit substrates. Geometric dispersion and conductor linewidth, as well as losses from conductor resistance, conductor skin effect, and substrate conductance are considered over the frequency range from 100 MHz to 100 GHz. Results show the enormous significance of the substrate losses, and demonstrate the need for substrate resistivities >10 Ω-cm for high performance circuits. The results also show the effects of geometric dispersion for frequencies above 10 GHz (which increase with decreasing linewidth), the transition from the high-frequency quasi-TEM regime to the "slow-wave" regime, and the unimportance of conductor skin-effect losses for frequencies up to 100 GHz. Qualitatively similar phenomena are seen for Al, W, and WSi2 lines. The differences in resistivity of these materials do not significantly alter their pulse propagation properties. Surprisingly, however, slow-wave velocity is increased for either increasing conductor resistivity, decreasing conductor linewidth, or both. Poly-Si, with its significantly greater loss, shows qualitatively different frequency-dependent behavior. High phase velocity and high loss can coexist in poly-Si lines.
Optoelectronic Modulation of Millimeter-Waves in a Silicon-on-Sapphire Waveguide
Authors: Lee Chi. H. , Yurek Aileen M. , Li M. G. , Chauchard E. , Fischers R.
Published: February 2023

Optically controlled millimeter-wave devices such as IMPATT(1) and TRAPATT(2) diode have been reported. Millimeter-wave phase shifter utilizing an electronically injected electron-hole plasma in a semiconductor waveguide has also been demonstrated.(3) None of these devices, however, can operate at high speed. In our laboratory, we have developed a family of optoelectronic devices at the millimeter-wave spectral region which have picosecond speed capability.(4,5) For example, the gating of millimeter-wave pulse with vasriable pulse duration ranging from a few nanoseconds to subnanoseconds has been reported. When the device is operated as a phase shifter, the phase shift as large as 1500°/cm has been observed.(5) In these previous studies, we have found that, in general, the carrier diffusion will cause large loss and less phase shift for the millimeter-waves. In this work, we will report on the performance of dielectric waveguide made of silicon-on-sapphire (SOS). It is expected that the optically induced electron-hole plasma will be confined in a thin layer of epitaxially grown silicon and thus a high density but thin thickness plasma layer may be maintained, resulting in a small dynamic insertion loss.
Observation of Modulation Speed Enhancement and Phase Noise Reduction by Detuned Loading in a Coupled-Cavity Semiconductor Laser
Authors: Vahala Kerry , Paslaski Joel , Yariv Amnon , Lau Kam , Chaim Nadav Bar
Published: February 2023

An understanding of the modulation dynamics and phase noise properties of semiconductor lasers will be essential in certain applications of these devices. In this regard two important quantities are the relaxation oscillation frequency ωR which sets the useful direct modulation bandwidth of the device [1], and the field spectrum linewidth Δω which gives a direct measure of phase noise in single mode operation [2,3], in another paper two of us proposed a new method for control of the above properties [4]. This method, referred to as "detuned loading," was shown in that paper to simultaneously cause enhancement of modulation speed and reduction of phase noise (linewidth). In general, the method involves the introduction of a frequency dependent loss mechanism in the spectral proximity of the lasing frequency and relies upon the unique physics involved in lasing action in a semiconductor (a detuned gain spectrum leading to amplitude-phase coupling in the lasing field [2,3]). In this paper we present the first experimental observations of the detuned loading effect in semiconductor lasers. Specifically, we have observed enhancement of the modulation response with simultaneous reduction of linewidth resulting from application and control of detuned loading.
Hot Electron Diffusion in Superlattices
Authors: Ho J. , Grondin R. O.
Published: February 2023

Hot electron diffusion in a lateral surface superlattice (LSSL) is studied by the Monte Carlo technique. The LSSL is a surface oriented, two-dimensional superlattice made from GaAlAs and GaAs. Reich et al [1] have previously developed a Monte Carlo model of hot electron transport in a LSSL. They found that the structure should exhibit a negative differential mobility due to the onset of Bloch oscillations. This negative differential mobility may make this structure useful as a millimeter-wave negative resistance oscillator. To properly model its application as such an oscillator one needs to know the value of the electron diffusion coefficient as a function of field. We have used the Reich model and estimated values of the diffusion coefficient by Monte Carlo techniques.
Picosecond Carrier Transport in GaAs Quantum Wells
Authors: Shah Jagdeep , Hopfel R. A.
Published: February 2023

We review three recent experiments in which we have used picosecond optical techniques to investigate quantities relevant to high field transport in semiconductors. We will discuss (1) measurement of the drift velocity of minority carriers in GaAs quantum wells by a time-of-flight technique, (2) a simultaneous measurement of the luminescence spectra which allows us to measure the carrier distribution function and investigate the energy exchange rate between electrons and holes and (3) an optical imaging experiment which demonstrates the existence of negative absolute mobility for the minority carrier in modulation-doped quantum wells. The momentum scattering rate between electrons and holes is determined form this experiment.
Radar and EW Applications of Multi-Gigahertz Optical Components and Systems
Authors: Taylor Henry F.
Published: February 2023

Recent advances in wideband components for use in optical fiber systems have been very impressive. Laser diodes have shown 3dB modulation bandwidths near 20 GHz at room temperature,1,2 and external modulators with similar high-frequency performance have been reported.3 Bandwidths as high as 100 GHz have been achieved in semiconductor photodiodes.4 Performance of these components at such high frequencies opens a new realm of possibilities for the use of optics in military systems. These include not only signal transmission over optical fibers, but also signal generation, signal processing, and optical control of microwave devices. Coverage spanning the 0 – 18 GHz range, where most radar and electronic warfare (EW) systems operate, is now possible. Some of these techniques can also be applied in the millimeter wave frequency range (> 30 GHz), which is receiving increased emphasis for military applications.
Picosecond Response of an Optically Controlled Millimeter Wave Phase Shifter
Authors: Tzuang C.-K. C. , Miller D. , Wang T.-H. , Itoh T. , Neikirk D. P. , Williams P. , Downer M.
Published: February 2023

The introduction of electro-optic sampling techniques now allows the study of very high speed pulse propagation on planar transmission lines. In the frequency domain, recent work on microstrip and coplanar waveguides (CPW) on semiconductor substrates has shown the existence of slow-wave phenomena [1][2]. Since these phenomena are frequency dependent, strong dispersive effects on picosecond pulses would be expected. For a lossless substrate, a spectral domain technique has been used to calculate pulse dispersion for a coplanar waveguide (CPW) and coplanar strips [3], and for a particular geometry and lossy layer both mode matching and finite element techniques have been used to predict pulse behavior in microstrip and CPW [4]. In a typical structure exhibiting strong slow wave effects there are three distinct layers in the substrate: first, a thin, lossless spacer layer immediately below the CPW; second, a somewhat thicker lossy (i.e. doped) layer; and third, a very thick lossless layer. The slow-wave phenomenon (and corresponding variation in effective dielectric constant) occurs as a result of the different interactions of the electric and magnetic fields of the propagating wave with the lossy layer below the CPW. The complex effective dielectric constant of the guide is a function of the conductivity of the lossy layer, the separation of the CPW from this layer, the transmission line dimensions, and the frequency. For frequency domain applications, we have recently proposed a new method to control the slow wave factor in these structures by replacing the doped lossy layer with an (CW) optically generating electron-hole plasma layer in the semiconductor substrate [5]. The device could then serve as a phase-shifter, controlled by varying the optical excitation level, and thus the conductivity of the lossy layer. In this paper we discuss the the effects of the lossy layer on picosecond pulse dispersion.
Electron Device Probing in the Femtosecond Time Scale
Authors: Mourou Gerard A.
Published: February 2023

The advent of ultrashort pulses used in conjunction with the electro-optic effect has made possible the temporal analysis of electrical phenomena on the picosecond time scale. On this time scale nonequilibrium transport such as velocity overshoot and ballistic effects as well as resonant quantum mechanical tunneling can take place. These effects will govern the operation of the next generation of electronic three-terminal devices. Using ultrafast techniques such as electro-optic samping it is possible to directly monitor these effects.
Silicon Pulse Sharpening Diodes - Switching Kilovolts in 10's of Picoseconds+
Authors: Pocha M. D. , Wiedwald J. D. , Dease C. G. , Contreras M. M.
Published: February 2023

Silicon pulse sharpening diodes were first described by Grekhov et al. [1] in the USSR. Grekhov's work described generation of several kilovolt pulses with rise times in the order of 200 ps. We have been studying these diodes for applications requiring fast, high voltage, low jitter, electrically triggered pulses. The fastest rise times we have observed to date are approximately 70 ps for 1-2 KV pulses. Theoretical calculations using a numerical simulation of the operation of theses devices indicates that rise times shorter than 30 ps should be achieved with optimally designed structures.
Characteristics, Packaging and Physics of Ultra High Speed Diode Lasers and Detectors
Authors: Bowers J. E. , Burrus C. A.
Published: February 2023

Recently high speed, high power semiconductor lasers with impulse responses of 13 ps, peak powers of tens of milliwatts, and modulation capabilities to 40 GHz have been demonstrated. These small, efficient sources are useful for fiber optic communications, microwave signal transmission for instrument, satellite and military applications, and they can serve as convenient benchtop sources for physics experiments and optical device characterization.
InP/GaInAs/InP PIN Photodiode with FWHM < 18 ps
Authors: Wang S.Y. , Carey K.W. , Kolner B.H.
Published: February 2023

High speed optical detectors in the 1.3-1.55 μm wavelength range are required for a new generation of microwave-optical instruments to characterize high data rate systems, microwave transmission via lightwave, and other applications requiring true replication of the modulation signal. Front-side illuminated photodiodes have an advantage over back-side illuminated devices in simplicity of packaging. In addition, the transit time of the photocarriers is determined by electrons rather than by holes as for backside illuminated devices fabricated on n-type substrates. The speed of response of the double heterostructure photodiode is wavelength independent since photocarriers can only be generated in the i-layer which is fully depleted. For single heterostructure backside illuminated photodiodes with p-GaInAs, the speed response degrades as the wavelength increases since photocarriers can be generated in the low field p-layer resulting in carrier diffussion. For high speed operation of the device, the i-layer thickness is selected such that the device is transit time limited and is of the order of one absorption length. However one potential obstacle exists that could degrade the speed of a front-side illuminated device, and that is the trapping of holes at the discontinuity in the valance band between the InP and GalnAs. The effect of hole trapping was not evident in the results of Susa et al[1] which utilized a separate absorption and multiplication (SAM) structure for a front-side illuminated avalanche photodiode. This suggests that the quality of interface could play a dominant role in the transit time at heterojunction interfaces.
Picosecond Optical Autocorrelation Experiments on Fast Photodetectors
Authors: Carruthers T. F. , Weller J. F.
Published: February 2023

The nonlinear component of the photoresponse of many optoelectronic devices can be used to determine their response speeds. The technique is of value because measurements are performed upon a single device rather than upon two interconnected devices. Transmission line problems, including bandwidth limitations and spurious signals due to reflections and radiated transients, are therefore avoided, and intrinsic response time measurements are possible on devices that cannot be paired with a high-speed photodetector in a large-bandwidth circuit.
Direct Subpicosecond Measurement of Carrier Mobility of Photoexcited Electrons in GaAs
Authors: Nuss M.C. , Auston D.H.
Published: February 2023

The dynamics of hot photoexcited or injected carriers in semiconductors has been studied extensively with picosecond and femtosecond optical pulses[1]. On a subpicosecond time scale, both absorption saturation[2] and photoluminescence techniques[3] were employed to trace the relaxation of the initial nonequilibrium distribution of carriers after their injection. These techniques have in common, that they probe the carrier distribution in the bands, but not the actual time dependent transport properties like mobility or drift velocity. These in turn are the important parameters for high speed devices like hot electron transistors. On the other hand, electron transport in semiconductors has been investigated by microwave conductivity measurements and microwave time-of-flight techniques. However, the time resolution of the existing microwave sources is not high enough to observe transient transport phenomena on a picosecond or even femtosecond time scale.
Monte Carlo Investigation of Hot Photoexcited Electron Relaxation in GaAs*
Authors: Osman M. A. , Kann M. J. , Ferry D. K. , Lugli P.
Published: February 2023

Recently, several authers [1-3] have investigated the dynamics of electron-hole plasma generated by picosecond and sub-picosecond laser pulses in GaAs. In one of these experiments El 3 the electron-LO phonon dynamics was directly observed at 77 K by means of a pump-probe Raman scattering experiment using a 600 fs, 588nm laser pulse. They observed an increase in the LO phonon population at 2 ps, which was attributed to the phonons emitted during the cascade of electrons to edge of the band. We have investigated the cooling of carriers excited by a 588nm laser pulse using ensemble Monte Carlo approach. The model takes into account the carrier-carrier and carrier-phonon interactions using a band model which consists of three nonparabolic valleys for the conduction band and two parabolic valance bands. Since the excitation levels used in the above experiment were less or equal to 1017 cm–3 and the holes were neglected in their theoretical model, we have investigated first a simple model, where only carrier-phonon interactions were active and the presence of the heavy holes was considered, to account for the energy gained by the holes.
Ballistic Transport and Hot Electron Spectroscopy in Tunnelling Hot Electron Transfer Amplifier (Theta)
Authors: Heiblum M.
Published: February 2023

An important aspect of obtaining the fastest electronic devices is minimizing the transit time of charge carriers from input to output. The shortest times can be achieved by having the carriers move at the highest velocity allowed by the band structure of the solid crystal. In present high speed devices collisions redirect and slow down the moving carriers. To avoid this electron scattering, transit regions have to be short enough to make collisions less probable. Such "ballistic transport" of fast carriers (hot carriers) moving at their maximum possible velocity, should in principle allow the fastest device operation.
Resonant Tunneling Electron Spectroscopy
Authors: Capasso F. , Sen S. , Cho A. Y. , Hutchinson A. L.
Published: February 2023

In this paper we demonstrate a new electron spectroscopy technique based on resonant tunneling. The key difference compared to conventional hot electron spectroscopy1 is the use of a resonant tunneling double barrier in the collector of the structure (Fig. 1). The advantage of this new feature is that it allows one to obtain information on the electron momentum distribution n(p⊥) (or energy distribution n(E⊥)) perpendicular to the layers directly from the measured resonant tunneling collector current, without requiring the use of derivative techniques. Figure 1 illustrates the band diagrams of two structures for resonant tunneling electron spectroscopy. The first one (Fig. 1a), realized by us in the present experiment, consists of a reverse biased pn heterojunction and can be used to investigate hot minority carrier transport. Incident light is strongly absorbed in the wide-gap p+ layer. Photo-generated minority carrier electrons diffuse to an adjacent low-gap layer. Upon entering this region electrons are ballistically accelerated by the abrupt potential step and gain a kinetic energy ≅ ΔEc. Collisions in the low gap layer tend to randomize the injected, nearly mono-energetic distribution, making it "hot".
Laser Pulsed E-Beam System for High Speed I.C. Testing
Authors: May Paul , Halbout Jean-Marc , Chiu George
Published: February 2023

Electron probe techniques for the high speed testing of Integrated Circuits have considerably higher spatial resolution compared to optical techniques but have tended to suffer from poorer temporal resolution. In this presentation we describe a novel type of instrument that combines the advantages of conventional SEM voltage contrast techniques(1) (including a spatial resolution better than 0.1μm and beam steerability) with an order of magnitude improvement in temporal resolution.
A New 10 μm Infrared Detector Using Intersubband Absorption in Resonant Tunneling GaAlAs Superlattices
Authors: Levine B. F. , Choi K. K. , Bethea C. G. , Walker J. , Malik R. J.
Published: February 2023

The fabrication of 10 μm infrared detectors from III-V materials would allow advantageous use of their highly developed growth and processing technologies, as compared with II-VI compounds.1-2 Furthermore, device parameters (e.g. bandgap, operating temperature, bandwidth and speed) can be tailored in ways that are difficult to do with either II-VI’s or extrinsic Si detectors. We report here the first demonstration of a novel high speed infrared detector based on intersubband absorption and sequential resonant tunneling in doped GaAs/Al
x
Ga1-
x
As quantum well superlattices. We achieved a responsivity of 0.52 A/W at λ = 10.8 μm, an advantageous narrow bandwidth response Δλ/λ ≃ 10%, and estimate the speed to be ≈ 45 psec. From our experiments we have determined that the mean free path of the photogenerated hot electrons through the superlattice is 2500 Å.
A Non-Contact Picosecond Prober for Integrated Circuit Testing
Authors: Valdmanis J.A. , Pei S.S.
Published: February 2023

Electro-optic sampling has been used extensively for the charaterization of picosecond electronic devices such as photodetectors, transistors, and diodes [1,2]. For the large part, these studies have been with discrete devices coupled to specialized electro-optic modulators in a hybrid electrode geometry. However, there is great interest in being able to probe internal points on integrated circuits. Recently, a specialized embodiment of electro-optic sampling [3] was developed to exploit the electro-optic properties of GaAs and perform sampling directly in the substrate of GaAs integrated circuits. Any internal point of the circuit could be accessed and individual devices could be monitored in their working environment. However, GaAs is the only commonly used electronic material that is also electro-optic. The substrate technique also requires that both surfaces of the integrated circuit be optically polished and that the sampling laser beam has a photon energy below the band gap of the substrate material. One would ideally like a non-perturbative means of probing with high temporal and spatial resolution that is generally applicable to circuits fabricated on any type of substrate.
Energy Variations in Optical Pulses from Gain-Switched AlGaAs Diode Lasers
Authors: Hawkins R. T. , Goll J. H. , Anheier N. A.
Published: February 2023

One method for producing optical pulses as short as <20 ps FWHM with a diode laser is by gain switching. For such a laser, gain switching is readily achieved by applying an electrical (for ward bias) pulse excitation to the diode. The average duration of the resulting optical pulses depend on the detailed shape of the electrical drive pulse and the dynamic response of the laser diode (in its package) to that drive pulse. Streak camera measurements1-2 have demonstrated that significant temporal substructure is present on the optical pulse, with subpulses of duration below 10 ps. This substructure changes dramatically from pulse to pulse. Previously reported work on gain switching of laser diodes has been almost exclusively confined to minimizing the time-averaged optical pulse duration, spectral width, and time-bandwidth product. An important additional consideration for ultrafast electro-optical sampling applications is the energy contained in the optical pulse, which should ideally be large and constant to minimize both shot noise and averaging time in the optical detection system. Little work has been done heretofore to quantify the variation in energy of diode laser optical pulses. We present here the results of a series of measurements of this energy variance in pulses produced by gain switching commercially avail able gain guided double heterostructure AlGaAs laser diodes.
Characteristics of Shielded Microstrip Lines on GaAs-Si at Millimeter-Wave Frequencies
Authors: Aksun M.I. , Morkoc H.
Published: February 2023

The advantages of GaAs on Si technology have stimulated a great deal of interest [1], [2]. Although Si was studied extensively as the substrate material for microwave monolithic integration because of its high thermal conductivity, well-established technology, mechanical strength, and availability in larger diameter [3]-[5], it lacks millimeter-wave three terminal devices which is now afforded with GaAs on Si [6]. Dielectric losses in GaAs on Si, however, must be small in order for this composite technology to be practical. We have thus undertaken a theoretical study of the shielded microstrip lines on GaAs on Si up to 100 GHz for various parameters in Si and GaAs.
A 10Gb/s-100km Optical Fiber Transmission Experiment Using a High Speed MQW DFB-LD and A Back-Illuminated InGaAs-APD
Authors: Fujita S. , Kitamura M. , Torikai T. , Henmi N. , Yamada H. , Suzaki T. , Takano I. , Komatsu K. , Shikada M.
Published: February 2023

Several high-speed, long-span optical fiber transmission experiments have been reported up to 10Gb/s to explore the feasibility for future ultra high speed trunk line systems.1-3 These experiments indicated that the system suffered insufficient device frequency response, LD wavelength chirping and low receiver sensitivity to realize a high speed, long span transmission. We have confirmed feasibility of 10Gb/s optical transmissions using a high speed and low chirping MQW DFB-LD and a high quantum efficiency back-illuminated InGaAs-APD. Improved characteristics in frequency response, chirping and quantum efficiency made it possible to transmit 10Gb/s signal over 100km.
Ultra-High Bandwidth Detachable Optoelectronic Probes
Authors: Scheuermann M. , Sprik R. , Halbout J.-M. , Moskowitz P. A. , Ketchen M.
Published: February 2023

Ultra-high bandwidth detachable optoelectronic sampling probes have been fabricated and characterized. Electrical pulses having a correlation FWHM of 3.5 picoseconds can propagate across the probe contacts. The bandwidth of these probes is greater than 200 GHz. Pulses have been launched from a probe to a short transmission line and detected with a second probe. A single probe configuration has been used to characterize the optical response of a GaAs photodetector.
Comparison of Electro-Optic and Photoconductive Sampling Using a 28-GHz Monolothic Amplifier
Authors: Chauchard E. , Treacy G. , Webb K. , Lee Chi H. , Hung H.-L. A. , Huang H. C. , Polak-Dingels P.
Published: February 2023

The performance of a 28-GHz monolithic amplifier is evaluated using electro-optic sampling, photo-conductive sampling and network analyzer. The advantages and limitations of each technique are discussed.
Spread-Spectrum-Integrated Optic Modulators
Authors: Dolfi David W.
Published: February 2023

Integrated optic modulators have been developed which incorporate spread spectrum concepts in their design in order to achieve high bandwidths. We review their operating principles, limitations, and applications.
Electro-Optical Synthesis of Picosecond Optical Pulses
Authors: Kobayashi Tetsuro , Morimoto Akihiro
Published: February 2023

We demonstrate three new electrooptical pulse synthesizing methods to generate arbitrarily shaped optical pulses in the picosecond range from cw lasers using an electrooptic modulator or a deflector. They utilize (1) separation, control, and composition of each sideband component of the phase-modulated light using two gratings and a spatial filter, (2) selection of produced sidebands using an FP filter, and (3) control of near-field pattern of an elctrooptically deflected beam using a spatial filter and composition using a grating or a slit. Using these methods picosecond pulses at 9.4-75GHz repetition frequency have been generated.
Interdigitated Metal–Semiconductor–Metal Detectors
Authors: Rogers D. L.
Published: February 2023

The Interdigitated-Metal-Semiconductor-Metal (IMSM) detector has recently become one of the more popular detectors for optoelectronic integration. The factors affecting the performance of this type of detector are reviewed particularly in the context of low noise amplification circuitry.
Picosecond Optoelectronic Integrated Antennas for Broadband Dielectric Measurements
Authors: Pastol Y. , Arjavalingam G. , Halbout J.-M. , Kopcsay G. V.
Published: February 2023

The picosecond transient electromagnetic radiation from optoelectronically pulsed integrated antennas is used for broadband coherent microwave spectroscopy experiments in the 10-130 GHz frequency range. The apparatus is first characterized using microwave filters of predictable behavior. Measurements of the frequency-dependent absorption coefficient and refractive index of representative materials are also presented.
Ultrafast Optical Switching through Virtual Charge Polarization in dc-Biased Quantum-Well Structures
Authors: Yamanishi Masamichi
Published: February 2023

An extremely fast modulation of optical properties based on internal field screening due to virtual charge polarization in a dc-biased or built-in asymmetric quantum well structure is discussed with description of relevant optical nonlinearities caused by the virtual charge polarization. A possible device characteristic for electro-static ultrafast switch of quantum interference current through the virtual charge polarization is briefly described, as an application of this modulation scheme to ultrahigh speed optoelectronic devices.
Time-Resolved Observation of Luminescence from a Charge-Transfer State in Double Quantum Wells
Authors: Norris T. B. , Vodjdani N. , Vinter B. , Weisbuch C. , Mourou G. A.
Published: February 2023

We have directly observed the buildup of a charge-transfer state in double quantum well structures due to electron and hole tunneling in opposite directions.
New Equivalent-Circuit Model for Resonant Tunneling Diodes
Authors: Brown E. R. , Parker C. D. , Sollner T. C. L. G. , Huang C. I. , Stutz C. E.
Published: February 2023

It is shown that a "quantum-well inductance" can account for the effect of quasibound-state lifetime on the speed of resonant-tunneling diodes. This is demonstrated theoretically using a linear-response analysis of the conduction current through a double-barrier diode. The inductance is then incorporated into a new equivalent circuit that is used to predict the oscillation characteristics of a diode designed to make the quasibound-state lifetime longer than any other speed-limiting time constant in the device.
GaAs MESFET and HBT Technology in Picosecond Electronics
Authors: Asai Kazuyoshi , Ishibashi Tadao
Published: February 2023

Ultra-high-speed signal processing with a bit rate of over 10 Gbit/s will soon be available in GaAs MES-FET and HBT integrated circuits. Such remarkable progress in the device performances is based on the scaling down for MESFET and near ballistic transportation for HBT. Propagation delay times of inverters have been reduced to 6.7 ps/gate and 1.9 ps/gate, and maximum toggle frequencies of flip-flop circuits have reached 31.4 GHz and 22.15 GHz, respectively. Wide-band amplifiers with a band width of about 10 GHz have also been obtained. This paper reviews recent progress in the speed performance of these devices.
Intersubband Relaxation of Electrons in AlxGa1−xAs/GaAs Quantum Wells During Photoexcitation
Authors: Goodnick Stephen M. , Lugli Paolo
Published: February 2023

Using an ensemble Monte Carlo simulation of coupled electrons and nonequilibrium slab mode polar optical phonons in single and multiple quantum well systems, we have studied the relaxation of photoexcited carriers in ultra-fast optical intersubband relaxation experiments. Here we study intersubband relaxation in three different types of systems: i) wide wells in which the intersubband separation is less than the optical phonon energy, ii) narrow wells in modulation doped multi-quantum well structures, and iii) coupled asymmetric quantum wells. Simulated results using self-consistent envelope functions in the quantum well system show the importance of nonequilibrium hot phonons and self-consistency in explaining the experimental results from time resolved Raman, intersubband absorption, and photoluminescence spectroscopy.
Characterization of terahertz optoelectronic behavior of GaAs epilayers containing arsenic precipitates
Authors: Warren A.C. , Katzenellenbogen N. , Grischkowsky D. , Woodall J.M. , Melloch M.R. , Otsuka N.
Published: February 2023

Using GaAs epilayers with arsenic precipitates (GaAs:As)[1] as the photoconductive material in a complete, broad-band optoelectronic teraHz beam system[2], we have generated and detected freely-propagating, subpsec electromagnetic pulses. Our results indicate that the photoconductive response of the GaAs:As consists of an ultrafast, subpsec turn on time followed by a turn off time of several picoseconds. Both the transmitter's and receiver's performances are dominated by the leading edge (turn on time), with the receiver working effectively in an "integrating mode." The ultrafast turn on is indistinguishable from that of epi-GaAs and indicates a GaAs matrix that is essentially free of point defects. The short "effective" carrier lifetime of several psec is consistent with capture by the embedded, closely-spaced (about 20 nm) arsenic precipitates. This behavior is contrasted with that of materials containing a uniform distribution of recombination centers, such as implanted silicon-on-sapphire or un-annealed, low-temperature GaAs.
Impulse Generation and Frequency Multiplication Using Soliton Effects in Monolithic GaAs Circuits
Authors: Case Michael , Carman Eric , Kamegawa Masayuki , Giboney Kirk , Yu Ruai , Abe Kathryn , Rodwell M.J.W. , Franklin Jeff
Published: February 2023

Picosecond duration, large-amplitude electrical impulses have broad applications: as strobe generators for sampling and switching circuits, as high-order harmonic generators, and as stimulus signals in high speed electrical measurements. Broadband harmonic multipliers are also very useful as medium-power sources in millimeter-wave systems.
Femtosecond Refractive and Absorptive Nonlinearities Due to Real Carriers in GaAs
Authors: Gong T. , Mertz P. , Fauchet P. M.
Published: February 2023

The carrier dynamics in GaAs following injection with femtosecond pulses above the band gap has been a topic of interest for several years.1−5 Information on carrier scattering and thermalization has been obtained and recent Monte Carlo simulations have achieved some success at explaining these induced absorption measurements.6,7 In the present work, we report the first femtosecond spectroscopic measurements of both the real part and the imaginary part of the carrier-induced nonlinear refractive index of GaAs. Our results are useful for the design of ultrafast devices using these optical nonlinearities and bring new knowledge on hot-carrier many-body effects. We focus on instantaneous band gap renormalization and plasma screening of electron-hole interactions in the 850-920-nm region, and on the short-lived resonance in the 580-750-nm region.
Picosecond Radiation-Induced Current Transients In Digital GaAs Mesfets
Authors: McMorrow Dale , Campbell Arthur B. , Knudson Alvin R.
Published: February 2023

Single event upsets (SEUs) are transient errors that occur when energetic particles interact with sensitive areas of digital integrated circuit (IC) memories and logic. SEUs pose a serious reliability problem for space-based digital systems because of the large flux of energetic ions in cosmic rays and the Earth’s radiation belts. While a large amount of effort has been devoted to measurements of the time-integrated charge produced by the passage of an energetic ion (charge collection),1 it previously had not been possible to temporally resolve the dynamical evolution of the transients. Such information is essential for a complete understanding of SEU phenomena in complex ICs.
Numerical Simulations of an Actively Q-Switched Semiconductor Laser
Authors: Jonsson Björn , Eng Sverre T.
Published: February 2023

As the structures of optoelectronic devices become more and more complicated, a detailed understanding of the operating characteristics has to be obtained by computer simulation. In new devices with explicit longitudinal variations in the geometry former assumptions that photons and carriers are uniformly distributed has to be modified. Examples of such devices are multisegment lasers [1], lasers for active Q-switching [2], and semiconductor lasers with asymmetric mirror reflectivities [3]. The goal for this work has been to develop a computer model which is applicable to a large variety of longitudinally nonuniform optoelectronic devices with general cross-sectional geometries. Here this model is applied to the problem of a Q-switched GaAs/AlGaAs laser.
High-Capacity Lightwave Transmission: Ultra-High Speed or Wavelength Multiplexing
Authors: Li Tingye
Published: February 2023

The potential total transmission bandwidth of current single-mode optical fibers in the low-loss wavelength regions near 1.3 µm and 1.55 µm approaches 50 THz. In order to explore this enormous capacity for the transmission and distribution of future broadband services, the lightwave research community has been pushing the frontiers of high-speed technology to data rates well beyond 10 Gb/s. Long-distance transmission of wavelength-multiplexed channels that run at multi-gigabit-per-second rates have been demonstrated recently using erbium-doped fiber amplifiers as analog (non-regenerative) repeater amplifiers. As fiber dispersion may become the limiting factor that sets the bit-rate-distance product of a long regenerative repeater span containing optical amplifiers, both optical and electronic means for equalizing the effects of fiber dispersion, as well as soliton techniques, are being investigated for operation at multi-gigabit-per-second rates. Thus advances in device technologies and in transmission techniques not only provide enhancements in system performance, but also offer alternatives in system implementation.
Ultrafast Graded Double Heterostructure p-i-n Photodiode
Authors: Wey Y. G. , Giboney K. , Crawford D. L. , Bowers J. E. , Rodwell M. J. , Silvestre P. , Hafich M. J. , Robinson G. Y.
Published: February 2023

Efficient high bandwidth photodetectors are of great interest for use in optical communication, as well as in ultrafast measurement techniques. The shortest electrical pulses have been generated from photoconductors, although the quantum efficiency of the sub 10 ps devices has been too low for use in analog or digital transmission experiments. Bandwidths as large as 110 GHz1 were obtained in GaAs Schottky barrier photodiodes. The shortest measured impulse response was reported by Wang et al.2 who measured a photoresponse pulsewidth of 8.8 ps (of which 5.4 ps was attributed to the photodetector). In the long wavelength InGaAs/InP material system, p-i-n diodes have been reported with bandwidths in excess of 58 GHz3,4. Recently, Crawford et al.5 reported the lowest measured impulse response of InGaAs/InP p-i-n photodiodes of 16 ps. In this case, the photodiode response was limited by the measurement system. We have since incorporated a graded double heterostructure into our device structures to minimize carrier diffusion and trapping effects. In this paper, we will present measurements on these photodiodes which have the shortest measured impulse response of any p-i-n or Schottky photodiode yet reported.
Femtosecond Pulses of THz Radiation: Physics and Applications
Authors: Grischkowsky D. , Katzenellenbogen N.
Published: February 2023

A high-brightness pulsed THz beam system has been recently developed (1). This optoelectronic system is based on repetitive, fsec optical excitation of a Hertzian dipole antenna (1,2) embedded in a charged coplanar transmission line structure. The resulting synchronous bursts of radiation are collimated by a THz optical system into a diffraction-limited beam and focused onto a similar receiver. The THz system has exceptionally tight coupling between the transmitter and receiver, while the excellent focusing properties preserve the ultrafast time dependence of the source. Transmitted waveforms have been measured with subpsec resolution and with signal-to-noise ratios of more than 10,000:1.
100-GHz Electrooptic S-Parameter Characterization of High Electron Mobility Transistors
Authors: Frankel M.Y. , Whitaker J.F. , Mourou G.A. , Valdmanis J.A. , Smith P.M.
Published: February 2023

Progress in modem semiconductor device research has advanced response frequencies above 400 GHz.1 Such performance exceeds the conventional, purely electronic test instrumentation bandwidth, with the major limitations being imposed by the connectors and waveguides that are required for signal coupling to the device under test (DUT). This lack of convenient and accurate high-bandwidth device characterization methods imposes a serious obstacle to progress in semiconductor device development and utilization.
Photon-Assisted Resonant Tunneling Through a GaAs/AlGaAs Multiple Quantum Well Structure
Authors: Jonsson Bjorn , Andersson Ingemar , Larsson Anders , Andersson Thorwald , Westin Johan
Published: February 2023

The use of bandgap engineering techniques to tailor the perpendicular transport characteristics of layered semiconductor structures has resulted in a variety of new phenomena and devices concepts [1]. In particular the coherent interaction of electron waves reflected at interfaces gives rise to resonant tunneling effects which filter electrons of certain energy through the structure. A structure specifically designed for electron energy filtering is the variably spaced superlattice energy filter (VSSEF) in which the quantized states in adjacent quantum wells become aligned under appropriate bias conditions [2].
Gain collapse in the photon transport transistor (PTT) above lasing threshold.
Authors: Chu A. , Gigase Y. , Van Zeghbroeck B.
Published: February 2023

We measured the differential current gain (dIC/dIB) of the photon transport transistor (PTT) below and above threshold, and compared the result to a theoretical model. The device structure is shown in Fig. 1. It consists of a laser diode on top of a photodiode, with very tight optical coupling between the two devices. The laser is a GaAs/AlGaAs single quantum well ridge-GRINSCH structure. The photodiode is a GaAs/AlGaAs N-i-p diode with a 3 micron thick absorption region. Fabrication details of the device can be found in reference [1].
Room Temperature Excitonic Nonlinear Absorption in GaAs/AlGaAs Multiple Quantum Well Structures Grown By Metalorganic Chemical Vapor Deposition (MOCVD)*
Authors: Lee H. C. , Hariz A. , Dapkus P. D. , Kost A. , Kawase M. , Garmire E.
Published: February 2023

Room temperature excitonic nonlinear absorption in multiple quantum wells (MQW) has great potential for making low-power high-speed optical switching devices. The required ultrathin multilayers have been grown by both molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). Efficient, narrow-linewidth luminescence and low-threshold laser operation have been achieved in MQW's with both techniques. However, virtually all of the reported work to date dealing with nonlinear optical properties has employed MBE-grown materials [1], [2], [3]. The implementation of arrays of photonic switches in optical computing and processing systems will require large area devices with uniformity that exceeds the capability of current technology. The potential advantages of MOCVD for large area, multiple wafer growth of these complex structures provides motivation to explore this technique for their fabrication. In this paper, the growth by MOCVD of GaAs/AlGaAs MQW structures that exhibit narrow-line, room temperature excitonic absorption are reported. We further describe the linear and nonlinear optical properties of these structures and discuss the implications of this work for the construction of large area arrays of switches.
A Hard-Limiting Opto-Electronic Logic Device
Authors: Wheatley P. , Whitehead M. , Bradley P. J. , Parry G. , Midwinter J.E. , Mistry P. , Pate M.A. , Roberts J.S.
Published: February 2023

We report the first demonstration of a novel non-resonant opto-electronic device suitable for optical logic, but which is not bistable. The operation of the device is based on the principle of a current driven multiple quantum well electro-absorption modulator which was first established in the 'self-linearized modulator’ (1). By including electronic gain in the device and exploiting the limiting response of the device outside the self-linearising region, the device can be used as a logic gate with high optical gain and outputs which are 'hard limited’. The device, although it is not all-optical, does overcome many of the serious shortcomings of optical bistables device which have been outlined in ref.2.
Nonlinear Optical Logic Etalon at Todays Fiber Communication Wavelengths
Authors: Tai K. , Jewell J. L. , Tsang W. T.
Published: February 2023

In0.53Ga0.47As lattice matched to InP has been used extensively as the material for lightwave sources and detectors for optical communication. Here, we report the first use of InGaAs/InP multiple quantum wells (MQW) in the form of a nonlinear optical Fabry-Perot etalon for all-optical logic operations [1]. The MQW sample consists of 100 periods of alternating undoped thin layers of InGaAs (100 Å) and InP (150 Å) grown by chemical beam epitaxy [2] on InP substrate.
Optical Threshold Mechanism Using Fiber Coupled Phase Conjugate Mirror
Authors: Yahalom Ram , Agranat Aharon , Yariv Amnon
Published: February 2023

The recent development of optical implementations of various data processing procedures created a demand for a sensitive all optical threshold device.(1) We henceforth present a possible mechanism for such a device, based on the coupling of mutually incoherent light beams by means of the fiber coupled phase conjugate mirror (FCPCM).(2,3)
Computational Properties of Nonlinear Optical Devices
Authors: Prise Michael E. , Streibl Norbert , Downs Maralene M.
Published: February 2023

To design an optical digital computer it is essential to have a cascadable logic gate with a fanin and fanout of at least two. For a complete logical coverage it is necessary to have either a NAND or a NOR gate or have an AND and an OR gate and use dual rail logic to perform a spatial inversion. To built a general purpose computer without a ridiculous number of gates we must have loops in the system. That is the data must flow through the same gates more than once. This means one gate must be able to drive any other identical ones.