摘要:

The effect of (NH4)2Sxtreatment of the facet of InGaAs/AlGaAs ridge waveguide (RW) laser diodes on the nonradiative current and catastrophic optical damage (COD) level is reported. Using the power–voltage–current (P–V–I) characteristics of the electroluminescence at low injection levels, changes in the density of surface states at the laser facets are described. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115822

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A fixing process of photorefractive holograms is reported. The process is based on the formation of an ionic space charge which becomes mobile at the phase transition temperature. A fixed grating was formed in paraelectric potassium lithium niobate tantalate by a 4 K cooldown toTc, and a warmup back to the paraelectric phase. The diffraction efficiency of the fixed grating was 66% of the original photorefractive space charge grating. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115823

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We present a propagation model for the dynamics of antiguided flared amplifiers. This model takes into account diffraction, carrier diffusion, spatial hole burning, carrier‐induced antiguiding, and spontaneous emission. Numerical results demonstrate that flared antiguides are significantly less susceptible to noise induced filamentation than broad area devices. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115824

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A new form of optical spectroscopy is demonstrated whereby the local scattering from the interaction between a nanometer size probe tip and a sample is measured as a function of wavelength. We show images of viruses and molecules at molecular spatial resolution and demonstrate how the image contrast varies with wavelength. To first approximation, the contrast as a function of wavelength varies in the same way as the local polarizability of the sample ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115825

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Phase matching for the third‐harmonic generation (THG) of rutile single crystal (110) at 1.9 &mgr;m has been investigated. THG with a visible red light (633 nm) was clearly observed, indicating that TiO2(rutile) is one of the most promising third‐order nonlinear optical materials. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115826

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The feasibility of a photopumped infrared vertical‐cavity surface‐emitting laser (VCSEL) based on CdHgTe alloys is demonstrated. The structure of the VCSEL consists of a 16.5‐period Cd0.4Hg0.6Te/Cd0.75Hg0.25Te bottom Bragg reflector and a 3&lgr;/4 thick Cd0.75Hg0.25Te cavity, containing a 100‐nm‐thick well, grown by molecular beam epitaxy. The top mirror is a 7‐period YF3/ZnS dielectric stack. The cavity quality factor isQ=350. This heterostructure VCSEL operates at 3.06 &mgr;m with a measured power density threshold of 45 kW/cm2at 10 K. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115827

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Coherent THz‐wave generation is demonstrated utilizing a grating coupler fabricated on the surface of a LiNbO3crystal pumped by a Q‐switched Nd:YAG laser. Wide tunability, sharp directivity, and high efficiency were achieved. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115828

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report details of lasing transitions based on self‐localized barrier state electrons in InGaAs/InGaAsP multiple quantum well lasers. We study the mechanisms responsible for the switching between conventional lasing transitions at 1460 nm and a self‐induced transition at 1360 nm. Carrier effects and current heating contribute both on a time scale of a few ns with the current heating dominating. Carrier effects are separable from the thermal effects when 100 ps wide electrical drive pulses are used. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115829

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

With a view to making highly efficient light shutters, the object of this study is to know the best structure of the liquid crystal polymer composite yielding a high extinction ratio. The main feature of this letter shows that experimental results are consistent with anomalous diffraction approach. For our demonstration, we made polymer dispersed liquid crystal (PDLC) cells having different droplet radius (a), ranging from 0.5 to 1 &mgr;m. In addition, a strong wavelength sensitivity with these radii is measured in the visible region. Beyond one micron, droplets yield higher transmission as regards both the wavelength and the optical anisotropy of the liquid crystal. These results bring forward that the most efficient PDLC films must follow the optimization relation:a(&Dgr;n)/&lgr;=0.3, where &lgr; is the wavelength and &Dgr;nthe liquid crystal anisotropy. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115830

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Laser‐induced desorption on a nanometer scale using scanning near‐field optical microscopy (SNOM) is demonstrated. Pulsed laser‐induced desorption of anthracene with completely metallized SNOM fiber tips resulted in a lateral resolution of 70 nm. This became possible due to the use of chemically etched tips with a taper region smaller than 200 &mgr;m and cone angles varying from 6 to 30 degrees. These tips are further useful for optical imaging with a very high optical transmission coefficient (up to 10−3), achieving a lateral resolution of 80 nm. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115831

出版商:AIP    

年代:1996

数据来源: AIP