摘要:

We demonstrate experimentally that a phase‐sensitive optical parametric amplifier used to amplify the incoming optical signal on a lossy photodiode improves the noise figure of detection. At high parametric gains this noise figure tends to 0 dB corresponding to a detection quantum efficiency approaching 100%. This result contrasts with the performance of preamplification by a classical laserlike amplifier in which the noise figure tends to 3 dB giving a saturation of the detection quantum efficiency at 50%. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114201

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Ultrafast infrared laser pulses at 10.6 &mgr;m as short as 600±200 fs have been produced using optical semiconductor switching. This is achieved by using GaAs damaged with a 180 keV H+dose of 1×1016cm−2as an optical–optical switch. Cross‐correlation measurements are used to obtain the pulse shapes. We find that the generated infrared reflectivity pulse widths are proportional to the H+ion dose to the power −0.4. This allows a precise control over the generated pulse durations. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114036

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A simple theory based on a nonlinear differential equation derived from Kukhtarev’s materials equations and the coupled mode analysis of wave equation is developed to describe the spatial subharmonics in the photorefractive moving gratings. The optimum detuning frequency ofK/2 spatial subharmonic resonance is calculated and compared with experimental data. It is found that our simple theory describes the experimental data very well. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114037

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Experimental studies on the formation of single‐domain layers in a multidomainz‐cut LiNbO3crystal plate by proton exchange followed by quick heat treatment were performed. It was found that the direction of the spontaneous polarization in the single‐domain layer points to the inside of the plate. To explain this phenomenon, an internal electric field model was proposed which is related to the proton concentration gradient. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114038

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the results of Tm3+doped Ba–Y–Yb–F thin film planar waveguides in glassy form, which produced red, green, blue, and ultraviolet upconverted luminescence when pumped by infrared radiation at &lgr;=960 nm. The films of nominal composition BaYYbF8doped with 1% Tm have been deposited with both thermal and e‐beam evaporation techniques on substrates of fused silica, Si, and GaAs. Planar waveguiding was demonstrated for the films deposited on fused silica. Optimal deposition conditions with respect to the ability of the films to produce upconverted luminescence and low propagation loss are discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114039

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The operation of an all‐optical switch in a rare‐earth doped channel waveguide is described. The switching mechanism is based on an optically induced intramodal energy exchange, driven by a resonantly enhanced nonlinearity of a Nd3+ion. Switching times around 410 &mgr;s at a repetition rate of 1 kHz was demonstrated. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114040

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have shown that the spectral properties of an asymmetric Fabry–Pe´rot e´talon, with a multiple quantum well cavity, are very sensitive to dispersion in the refractive index. We also show that this effect can be used to measure the dispersion around the exciton absorption features in the GaAs/Al0.35Ga0.65As multiple quantum well. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114041

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Atomic layer epitaxy has been employed to fabricate white light emitting ZnS:Pr and SrS:Pr thin film electroluminescent devices. Electrical and optical properties of these devices have been characterized and compared. It is found that SrS:Pr devices are significantly brighter and more efficient than ZnS:Pr devices. The effect of ZnS buffer layers on the electrical characteristics of the SrS electroluminescent devices is discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114042

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Tip surfaces ofn‐type Si field emitter arrays (FEAs) have been anodized to obtainn‐type porous layers on the top surfaces of the Si emitters. The gate voltage required for emission could be lowered by tip anodization and the emission current was enhanced by a factor of up to 10. Fowler–Nordheim plots for the FEAs before and after tip anodization revealed that the work function of the tip could be decreased and the field conversion factor could be increased by the process. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.114043

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Change in the distribution state of Mn2+before and after annealing was examined by electron spin resonance (ESR) in order to elucidate the electroluminescence properties of Mn‐doped ZnS modified by Cu. Formation of Mn2+ion pairs and clusters, as determined from the hyperfine structure of ESR profiles, was revealed to be dominant for concentration quenching. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114044

出版商:AIP    

年代:1995

数据来源: AIP