摘要:

Experimental results show that angular dispersion strongly influences the self-induced frequency scanning of a multimode broad-area diode laser array coupled to a photorefractive self-pumped phase conjugate mirror. Prisms or a dispersive grating placed in the external cavity opposing the material frequency dispersion of the phase conjugateBaTiO3crystal suppress the frequency scanning and stabilize the center wavelength and the output power. We show that the dispersion of the crystal is crucial for the mechanism of the frequency scanning. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120605

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report a novel microcavity design that allows the control in wavelength of the resonant modes of a microcavity operating in the visible spectrum. We have been able to shift the modes by up to 56 nm. The device is comprised of a thin film of a fluorescent semiconducting polymer combined with an electrically switchable liquid crystal layer, which are sandwiched between the two cavity mirrors. This structure serves as a tool for further experimental studies of the properties of microcavities and also has considerable technological potential, providing, for example, an efficient wavelength converter or tunable light source. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121045

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A continuous wave (cw) optical power of 108 mW was coupled into a polarization maintaining fiber from a high power distributed feed back (DFB) laser at 1550 nm wavelength. The laser also displays excellent high temperature performance, low noise, and narrow linewidth, which makes it very attractive for broadband supertrunking applications. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121047

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A GaSb/PbSe/GaSb double heterojunction laser structure is proposed. The advantages and feasibility of fabricating such lasers are discussed. Theoretical calculations show that the threshold gain for GaSb/PbSe lasers is much smaller than for traditional PbEuSe/PbSe lasers. Electrical confinement and heat dissipation is also significantly improved. The resulting much lower threshold currents and temperature difference between the active layer and heat sink should allow GaSb/PbSe lasers to operate in continuous wave mode above room temperature. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121048

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The electro-optic properties of self-organizedIn0.4Ga0.6As/GaAsquantum dots have been studied experimentally. Single-mode ridge waveguide structures were grown by molecular beam epitaxy with self-organizedIn0.4Ga0.6As/GaAsquantum dots in the guiding region. The measured linear and quadratic electro-optic coefficients are2.58×10−11m/V and6.25×10−17 m2/V2,respectively, which are much higher than those obtained for bulk GaAs or quantum well structures. The measured transmission characteristics indicate that low-voltage amplitude modulators can be realized with quantum dot active regions. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121049

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Simple photoconductive optical detectors for 1.55 &mgr;m wavelength have been fabricated on InGaAsP grown by He-plasma assisted molecular beam epitaxy. Characterization of the photodetectors shows that their speed is determined by the free carrier trapping time, with a full width at half-maximum impulse response of approximately 6 ps. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121046

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report the observation of self-starting optical phase-conjugate oscillation in a nematic liquid-crystal cell. A theoretical model based on the continuum theory of liquid crystals and optical theory of degenerate four-wave mixing is developed to explain the observed phenomena. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121050

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report the emission properties of concentric-circle-grating, surface-emitting (CCGSE), distributed-feedback semiconductor lasers oscillating in single high-order azimuthal spatial modes. The evolution of the spatial profile of the beam emitted by such lasers with increasing excitation depends upon the spatial gain distribution and the depth of the circular waveguide grating. The polarization of the high-order spatial modes is predominantly radial. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121051

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In a15.7 GeO2⋅84.3 SiO2glass prepared by a vapor axial deposition method, optical absorptions at 4.92 and 5.08 eV were observed from 300 to 600 K. The results were then compared with electron spin resonance (ESR) measurement using the same samples. The absorption at 4.92 eV was found to increase with increasing temperature, while the optical absorption at 5.08 eV decreased with increasing temperature. These changes of optical absorption indicate that the concentration of neutral oxygen monovacancy is reduced at higher temperatures. The changes were quite reversible with the temperature. Concentration ofGe E′center, estimated from ESR, increased with increasing temperature, which is in contrast with the decrease of neutral oxygen monovacancy. The present result strongly suggests the thermal equilibrium reaction between neutral oxygen monovacancy andGe E′center. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121052

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A conic-cylindrical-cavities liquid crystal (conic CCLC) cell is developed for wide-viewing-angle displays. This conic-CCLC cell has been successfully manufactured and inquired. This display has a superwide viewing angle of over±70°in both the horizontal and vertical directions under the condition of no gray-scale inversion. The enhancement of viewing angle is believed to result from the director symmetric alignment in the conic-CCLC. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121053

出版商:AIP    

年代:1998

数据来源: AIP