摘要:

We demonstrate the continuous alteration of the exciton‐polariton mode splitting in semiconductor microcavities, through the change of the exciton oscillator strength induced by quantum confined Stark effect (QCSE). This is clear evidence of the direct influence of the oscillator strength on the mode splitting. A wide range variation, from 0 to 2 nm, of the splitting is obtained by the tuning of the cavity resonance based on the in‐plane dispersion of the photon mode as well as the tuning of exciton energy by QCSE. The influence of the field‐induced exciton line broadening on the mode splitting is also observed for the applied electric field as high as 90 kV/cm. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116059

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The longer‐wavelength quantum well in an AlGaAs/GaAs asymmetric dual quantum well laser structure was selectively removed by localized intermixing. High Si doping on each side of the longer‐wavelength well caused intermixing during an anneal under a SiNxcap, while leaving the other nearby well intact. During an anneal under an exposed GaAs surface layer, both quantum wells remained intact. By patterning the surface with alternating SiNxand exposed GaAs, the longer‐wavelength quantum well was selectively intermixed. Integrated broad area lasers were fabricated with threshold current density and external quantum efficiency of 260 A/cm2and 30%/facet at a wavelength of 751 nm in capped regions and 195 A/cm2, 32%/facet at 824 nm in the uncapped regions. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116060

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Experimental data are presented, which demonstrates an optical limiter based on a large birefringence which is optically induced in bacteriorhodopsin. The induced birefringence is observed to be a function of incident intensity, but saturates at a value of about 0.454 W/cm2. A measured value of &Dgr;nof 6.6×10−4at a wavelength of 514 nm is reported. The observed birefringence is found to be in good agreement with a proposed model. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116061

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A photodiode has been constructed from lightly boron doped, Si supported, thin film chemically vapor deposited (CVD) diamond which shows over five orders of magnitude discrimination between deep UV (≤220 nm) and visible light. A thin (10 nm) gold Schottky barrier with an associated Ti–Ag–Au ohmic contact was used to create a rectifying device with low (≤2 pA) dark currents when reversed biased. This structure showed a sharp cut off in photoresponse at 220 nm, the band gap energy of diamond. Conversely, a photoconductive device fabricated from similar (nominally undoped) material gave a broader UV photoresponse and displayed high dark currents; the superior performance of the diode structure on fine grain material is discussed. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116062

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

This letter reports an organic crystal that can generate a second‐harmonic beam under type II noncritical phase‐matching conditions. The cleavage plane of a 4‐(isopropylcarbamoyl)nitrobenzene (PCNB) crystal was found by theoretical calculation to have a type II noncritical phase‐matched incident surface. This enables the PCNB crystal to convert Ti:sapphire laser light (930 nm) into 465 nm blue light with high conversion efficiency (1%/W at 5.5 mm path length). ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116063

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The determination of gain properties in group III nitride quantum wells is complicated by the incomplete knowledge of band structure properties, and the need for a consistent treatment of many‐body Coulomb effects. This letter describes an approach that involves a first‐principles band structure calculation, the results of which are incorporated into a microscopic laser theory where many‐body Coulomb effects are treated in a consistent manner. Using this approach, we investigate quantum well structures composed of alloys of GaN, AlN, and InN, in particular, GaN–AlInN, which has high confinement potentials in both strained and unstrained configurations. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116064

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

An infrared optical field effect transistor has been developed using a thin film of lead titanate (PbTiO3) deposited on an/p+Si substrate by rf sputtering, in which the drain conductance changes in proportion to the infrared light power. A fast response with a rise time of 2.3 &mgr;s has been obtained that is about 150% faster than the other types of thermal infrared optical field effect transistor. The developed infrared sensor is a bulk channel field effect transistor structure, that possesses higher mobility. Thus, faster speed can be obtained. In addition, the sensor has been prepared on a Si substrate, which offers the potential to develop Si‐based infrared optical‐electric integrated circuits. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116065

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

z‐cut lithium niobate optical modulator devices were ac (Vp‐p=20 V) operated at 130 °C with an accumulated dc bias voltage of 4 and 8 V. A consequent dc drift phenomenon was larger for the 8 V bias application. After the operation, inversed domains were found along the Mach–Zehnder waveguides, particularly on the waveguide placed under the hot electrode. The results suggested that the device operation at higher voltage and temperature led to an accelerated dc drift and a fatiguelike deterioration of the lithium niobate material. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116066

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Colloidal suspensions of InP quantum dots (diameters 25 and 35 A˚) show steplike absorption spectra which are blue‐shifted by about 1 eV with respect to bulk material. Time resolved femtosecond spectroscopy at room temperature identifies the first quantum confined state. The nonlinear bleaching signal rises within 300 fs and persists longer than 200 ps. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116067

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The probe‐surface interaction underlying the ‘‘shear‐force’’ distance control commonly used in near‐field microscopy has been studied in detail by measuring dither resonance profiles and approach curves in vacuum and liquid helium. Simulations based on a nonlinear oscillator model considering the probe geometry, its elastic properties, adiabatic short‐range probe‐surface contact, and the surface tilt angle, are in excellent agreement with the experiments. We prove conclusively that a nonlinear bending force mechanism with parametric mode conversion is responsible for the observed phenomena. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116068

出版商:AIP    

年代:1996

数据来源: AIP