摘要:

A new dual‐wavelength, resonant‐cavity photodiode is described. It has previously been shown that the resonant‐cavity structure can achieve high quantum efficiencies in a relatively narrow spectral region with thin absorbing regions. In this letter, a dual wavelength mirror is incorporated into the cavity to achieve operation in two wavelength regions. Peak external quantum efficiencies greater than 50% were demonstrated at 730 and 910 nm. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114004

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A new midinfrared (&lgr;∼4.5 &mgr;m) intersubband quantum cascade laser based on a vertical transition is reported. A superlattice graded gap region was incorporated in the design to provide strong electron confinement in the upper state using a Bragg reflector. Pulsed operation at 100 K is reported with a threshold current density ofJth=3 kA/cm2and a measured slope efficiency of 300 mW/A. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114005

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present results on devices fabricated in a waveguide system utilizing a voltage tunable quantum well cladding layer. A (GaAs/AlGaAs) beam steering device produced an angular shift of 2.4° under an applied voltage of 20 V. It is shown numerically that electro‐optic modulators fabricated in such a material configuration can have simultaneously improved contrast ratios and insertion losses if the ratio of light propagating in the cladding and in the core regions can be controlled. A proof of concept device is demonstrated in which an electric field is used to change the distribution of light propagating in the waveguide. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114006

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have studied the redistribution of the electrons between the tunnel‐coupled ground levels in double quantum wells (DQWs), caused by the resonant infrared (IR) excitation on the next level and relaxation of the photoexcited electrons due to spontaneous emission of the optical phonons. The condition for the inversion of the electron populations in the tunnel‐coupled pair of ground states is presented as a function of the DQWs parameters. Negative absorption coefficient of the submillimeter radiation under intensive (2–4 kW/cm2) IR pumping and commonly realized parameters of DQWs is of order 20–50 cm−1. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114007

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A laser diode pumped ring resonator was built with a new organic second‐order nonlinear optical crystal, 8‐(4’‐acetylphenyl)‐1,4‐dioxa‐8‐azaspiro[4.5] decane. Ultraprecision diamond polishing was used for the crystal and optically flat surfaces and roughnesses of less than &lgr;/10 were achieved. The surfaces were dip coated with a perfluorinated polymer thin film to suppress surface reflection loss. Under resonant conditions, fundamental power was enhanced and a blue second‐harmonic emission with wavelength of 405.5 nm was observed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114008

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Pump‐probe experiments in semiconductor amplifiers are analyzed theoretically. On the basis of Maxwell–Semiconductor–Bloch equations it is shown that the probe signal exhibits dominant oscillatory interference‐like structures. These structures are superimposed on the pump and probe intensity dependent features. The calculations are qualitatively similar to experimental results. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114009

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The experimental study of a two‐stage scheme in which the same intense relativistic electron beam (0.6 MV, 3 kA, 70 ns) first produces powerful radiation (100 MW) at 3.0 cm and then the radiation is used as a pump wave for a free‐electron laser interaction at 3.0 mm is described. The results of the experiment and nonlinear theory are discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114010

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A monolithically integrated array of InGaAs/AlGaAs flared amplifiers driven by a single DBR laser through a power splitter network and individually addressed phase modulators is described. Phase adjustment of ≳2&pgr; per element by free‐carrier effects is verified by monitoring the interference pattern of all four emitters, and typically requires <15 mA of current to obtain a 2&pgr; phase shift. Phase matching is achieved among all four diffraction‐limited emitters at a pulsed output power of ≳5 W, and, combined with the proper external lensing, could therefore result in an ultranarrow, single‐lobed far‐field pattern whose width is determined by the extended aperture of the array. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114011

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Starting from a set of equations derived from a microscope theory we show that the familiar nonlinear gain of the forma/(1+I/Is) introduced in semiconductor laser rate equations phenomenologically should be replaced by a more general form ofa/(1+I/Is)b. The new scaling exponentbdepends on the relaxation constant &ggr;Tthat describes the rate of heat dissipation from plasma to the lattice due to carrier‐phonon scattering. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114012

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The cathodoluminescence (CL) of erbium and oxygen coimplanted GaN (GaN:Er:O) and sapphire (sapphire:Er:O) was studied as a function of temperature. Following annealing, the 1.54 &mgr;m intra‐4f‐shell emission line was observed in the temperature range of 6–380 K. As the temperature increased from 6 K to room temperature, the integrated intensity of the infrared peak decreased by less than 5% for GaN:Er:O, while it decreased by 18% for sapphire:Er:O. The observation of minimal thermal quenching by CL suggests that Er and O doped GaN is a promising material for electrically pumped room‐temperature optical devices emitting at 1.54 &mgr;m. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114013

出版商:AIP    

年代:1995

数据来源: AIP