A photoluminescence study of an (AlGa)As-GaAs quantum-well-wire array directly grown by molecular-beam epitaxy on a tilted substrate is described. strong anisotropy was observed in the ratio electron-light-hole-exciton peak intensity to electron-heavy-hole-exciton intensity. theory incorporating optical selection rule for two-dimensional quantum confinement found agree very well with measured data. These results constitute first evidence artificial wire structures having cross-sectional...

A tunneling escape rate 1/${\mathrm{\ensuremath{\tau}}}_{\mathrm{T}}$ of electrons from a single quantum well through thin barriers was successfully determined by measurement and analysis the lifetime ${\mathrm{\ensuremath{\tau}}}_{\mathrm{e}}$ generated in 6.2-nm GaAs wells picosecond laser pulse. The measured found to decrease systematically as AlAs barrier thickness ${\mathrm{L}}_{\mathrm{B}}$ reduced. for ${\mathrm{L}}_{\mathrm{B}}$4 nm agree very with...

A resonant tunneling diode having AlAs/GaAs/AlAs double barrier structure is designed to enhance the current component and suppress excess which believed dominate transport at high temperatures. Based on this design, a with optimized parameters prepared by careful molecular beam epitaxial growth, in dopant incorporation into well layer interface asperities are minimized. The diodes thus fabricated were found exhibit differential negative resistance room temperature for first time.

A ridge quantum wire structure has been successfully fabricated on a patterned (001) GaAs substrate by first growing (111)B facet with very sharp and then depositing thin well its top. Electron microscope study shown that the effective lateral width of 17–18 nm is formed at Photoluminescence cathodoluminescence measurements indicate one luminescence lines comes from region blue shift (∼60 meV) agrees confined energy calculated for observed structure.

The dependence of current components on GaAs well widths is studied in AlAs/GaAs/AlAs double barrier diode structures having AlAs barriers 8 atomic layers. It shown for the first time that density JRT resonant varies from 8×102 to 1.6×104 A cm−2 by choice width 9 5 nm accordance with theoretical calculations. Furthermore, one these diodes shows excellent current-voltage characteristics at room temperature a peak valley ratio 3, highest value ever reported.

Research into optical modulators has made remarkable progress in recent years. This paper discusses the possibility of applying high extinction ratio modulator to a high-stability and high-frequency (over 100 GHz) reference signal generator. High-frequency signals are generated by highly stable two-tone generator, which is used for high-rate communication astronomical application. One method generate two producing them from pair laser sources using an phase-locked loop feed back control;...

We describe the use of two-photon absorption in submicron silicon wire waveguides for all-optical switching by cross-absorption modulation. Optical pulses 3.2 ps were successfully converted from high power pump to low continuous-wave signal with a fast recovery time. High speed operation was based on induced optical non-degenerate inside waveguides.

Periodic Al composition modulations have been observed to occur spontaneously during molecular beam epitaxy of AlGaAs on vicinal (100) substrates. The formation the spontaneous modulation requires (a) migration-enhanced deposition and (b) one monolayer Ga atoms per cycle, hence, denomination coherent tilted superlattice (C-TSL). Cross-sectional transmission electron microscopy clearly shows that C-TSL has periodicity surface steps. We also show Al-rich regions form at bottom steps before As...

We used a strain compensation technique to fabricate highly stacked InAs quantum-dot (QD) structures on InP(311)B substrates. 60 layers of QDs without degrading the crystal quality and produced structure with total QD density 4.73×1012∕cm2. then fabricated broad area laser diode 30-layer stack using conventional photolithography. The showed ground state lasing at 1.58μm threshold current 162mA. achievement is due increase in density, which result technique.

The resonant tunneling current is studied in AlAs/GaAs/AlAs double barrier heterostructures which the widths L B are precisely controlled to be exactly 5, 8 and 11 atomic monolayers. It demonstrated for first time that density of these diodes can from 5×10 2 Acm -2 1.2×10 4 by choice , accordance with theoretical calculations. Furthermore, I – V characteristics devices shown excellent peak-to-valley ratios 2.3 at room temperature 10 80 K, highest values ever reported.

We propose a new class of an electromagnetic-held probing scheme for microwave planar circuit diagnosis. The measurement principle is based on the electrooptic/magnetooptic effects crystals glued at optical fiber facets. have combined concept those fiber-edge probes with fiber-optic RF spectrum analyzing system containing continuous-wave semiconductor laser source, fast photodetector, and analyzer to realize highly sensitive equipment local impedance. Electromagnetic-field intensity...

Mechanisms of molecular beam epitaxy have been investigated for GaAs and AlAs by growing analyzing the shapes facet structures consisting an (001) top surface two (111)B side surfaces. It is found that all Ga flux on three planes incorporated into film, but growth rates depend strongly As are mainly determined diffusion ad-atoms between planes. In contrast, Al to be almost negligible, irrespective flux. By shape facet, length, λ, a estimated about 1 μm at 580 °C, while 0.02 μm. On (111)B, λ...

We review the basic linear and nonlinear properties of silicon-on-insulator photonic wire waveguides their application to nanophotonic circuits. give an overview performance issues circuit elements such as couplers intersections achievements in wavelength-selective elements, well applications wires resonators for high-speed signal processing.

The crystallographic selectivity of molecular beam epitaxial growth GaAs on mesas consisting a (001) surface and (111)B facets is studied systematically. It was found that the rate can be drastically reduced to ∼1/30 by reduction As flux facets. This enhanced results from intersurface migration, strongly indicates feasibility forming microheterostructures needed for fabrication edge quantum wires (001)-(111)B mesas.

High-efficiency generation of the third harmonic 1.55 µm light is observed in a periodically poled MgO-doped LiNbO3 disk resonator. The second simultaneously generated. blue-green emission arises from cascaded parametric processes second-harmonic and sum-frequency by whispering gallery modes. An external conversion efficiency 1.5%/W2 obtained.

This Letter reports on picosecond pulse generation at a repetition of 10 GHz by using single-stage electro-optic LiNbO(3) Mach-Zehnder modulator, stressing the simplicity its setup. It is analytically and experimentally proved that dual-arm modulation with in-phase sinusoidal signals having slightly different amplitudes generated highly coherent optical comb great spectral flatness parabolic phase relationship in spectrum. The was Fourier synthesized shaped into an ultrashort train bandpass...

In this paper, Brillouin gain performances of tellurite fiber are investigated for photonics applications. We demonstrate stimulated amplification and lasing the simulated performance slow light generation in a single-mode fiber. A 29 dB is achieved 100-m with pump power 10 mW at 1550 nm. peak value coefficients 1.6989 X <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> m/W measured on base characteristics. An all-fiber laser maximum...

We report on our study the nonlinear photodetection (NL-PD) scheme, which we have proposed and demonstrated as an extremely simple configuration for optoelectronic millimeter-wave (MM-wave) mixing. The topics described in this paper are follows: (1) advantageous optical MM-wave link architectures employing NL-PD techniques; (2) operation principle of NL-PD; (3) detailed characterization mixer properties a waveguide p-i-n photodiode; (4) experimental demonstration performance analog digital...

Electron transport in AlxGa1−xAs-GaAs-AlxGa1−xAs double barrier tunneling structures is studied as a function of Al content x the for case where thickness 11 atomic layers and that GaAs well layer 7 nm. It shown density JRT resonant current varies systematically from 7.0×102 to 3.5×104 A cm−2 varied 1.0 0.43. These data are found be quantitatively explained by theoretical calculation, which band discontinuity at Γ valley taken height. This result indicates electron through structure...

Tunneling processes of two-dimensional electrons between two quantum wells (QW's) and those from one QW to unconfined three-dimensional states outside through another are investigated in various double-QW structures by time-resolved photoluminescence (PL) measurements. Electric fields ${\mathit{F}}_{\mathit{z}}$ across the applied realize on- off-resonance conditions, electron lifetime time-integrated PL intensity measured as functions field ${\mathit{F}}_{\mathit{z}}$. The experiment has...

We report on 100 x pixel live electrooptic imaging (LEI), which is real-time of electrical signals a microwave circuit. The circuit's electric near-fields can be depicted in real time display screen at video frame rates as high 30 frames/s. This system based photonics technology are applied to an crystal plate and sensing light beam modulated there. frequency modulation down-converted by using photonic heterodyne large-scale parallelism, the spatial pattern detected with high-speed image...

By combining a Mach-Zehnder-modulator-based flat comb generator (MZ-FCG) with dispersion-flattened dispersion-decreasing fiber, femtosecond pulses have been generated from cw light. Near-Fourier-transform-limit picosecond the MZ-FCG were compressed into order by pulse compression. Our system enables flexible tuning of repetition rate and width, because those depend on driving signal MZ-FCG. Pulse trains 200 fs width continuously stably without mode hopping, range 5 to 17 GHz. consists...

Transport of two-dimensional electrons in a novel double-quantum-well (DQW) field-effect transistor was systematically studied with emphasis on the effect resonant interaction. By introducing ionized impurities appropriately into one QWs, wave-function-dependent scattering process sensitively controlled by gate voltage Vg. A prominent valley structure observed channel conductance −Vg characteristics at resonance peak-to-valley ratio 3 4.2 K. This nonlinear characteristic is caused...