摘要:

Optical modulation with a bandwidth of about 3 GHz centered at 5.75 GHz was observed in a thin film of[BiLu]3Fe5O12using the magneto-optical interaction. A microstrip transducer was placed in contact with the film and TM polarized optical guided modes were excited beneath and parallel to the transducer. The TM→TE mode conversion was measured as a function of the angle between an in-plane field, of up to 100 Oe, and the optical beam. The bandwidth of the modulation was limited by the microwave components used in the external circuit. The experiments qualitatively agree with a simple model that describes a modulation of the optical beam by a nonresonant precession of the magnetization about an equilibrium. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119487

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The stability of a diode pumped Nd:YAG laser with intracavity KTP in an L-shaped cavity is studied. The mirror which connects the two cavity arms is a dielectric which also acts as a partial polarizer. This design provides a high level of stability for the total output power, despite the instability of the separate modes: separate modes are chaotic with large amplitude noise while the total output displays reduced noise below 1&percent; rms. A model based on the Jones matrices is studied numerically. It shows antiphase and clustering, in excellent qualitative agreement with the experimental data. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119488

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A microscopic analysis of experimental GaInP quantum well gain spectra is presented for a wide range of excitation. A consistent treatment of carrier collision effects, at the level of quantum kinetic theory in the Markovian limit, is found to be necessary for agreement with experiment. ©1997 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.119489

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Analysis is presented to calculate the eigenmode of a Fabry–Perot microcavity containing an optically thin dielectric aperture. The treatment yields the eigenmode field distribution, frequency, and threshold susceptibility. It is also suggested that self-focusing phenomena in large area vertical-cavity surface-emitting lasers can arise due to aperture formation by the complex susceptibility of a quantum well active region. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119490

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

High pressure discharges are the basis of small high intensity light sources. In this work, we demonstrate the formation of high pressure discharges, in cavities formed by applying micromachining and integrated circuit techniques to quartz substrates. Cavities containing varying amounts of mercury and argon were fabricated to obtain high pressure discharges. A high pressure mercury discharge was formed in the electrodeless cavities by exciting them with a microwave source, operating at 2.45 GHz and in the electroded cavities by applying a dc voltage. The contraction of the discharge into a high pressure arc was observed. A broad emission spectrum due to self-absorption and collisions between excited atoms and normal atoms, typical of high pressure mercury discharges, was measured. The light output and efficacy increased with increasing pressure. The measured voltage was used to estimate the pressure within the electroded cavities, which is as high as 127 atm for one of the two cavities discussed in this work. Efficacies over 40 lumens per watt were obtained for the electrodeless cavities and over 50lm/W for the electroded cavities. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120412

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have examined the absolute yield of keV x-rays emitted from gaseous plasmas created by the intense irradiation of large Xe clusters. We find that>10 &mgr;Jof x rays with photon energies above 1 keV are produced from clustering Xe gas targets when heated by 250 mJ, 2 ps laser pulses at an intensity of∼1017 W/cm2.The yields show strong laser intensity dependence and variation with Xe cluster size. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119491

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A new method of apertureless near-field optical microscopy that combines laterally differential detection with close-proximity detection has been developed. The laterally differential detection allows the light scattered from the probe apex to be distinguished from the background light. The close-proximity detection is done using a microfabricated photosensitive cantilever; it is thought to be a form of heterodyne detection, which provides a high signal level. This method makes it possible to detect the light scattered from the probe apex, which depends on the coupling between the probe apex dipole and the sample feature dipole. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119492

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

High power, 0.81-&mgr;m-emitting, semiconductor diode lasers are used as pump sources for Nd:YAG solid-state lasers. Devices (1-mm-long) consisting of aInGaAsP/In0.5(Ga0.9Al0.1)0.5P/In0.5(Ga0.5Al0.5)0.5Plaser structure provide a threshold-current density,Jth,of290 A/cm2and a relatively high threshold-current characteristic temperature,T0(140 K). Uncoated diode lasers (1.2-mm-long) have a maximum continuous wave output power of 5 W (both facets) at 20 °C. The internal power density at catastrophic optical mirror damage (COMD),P¯COMD,is determined to be9.1 MW/cm2;that is, 1.8 times that for GaAs-active layer, Al-free, uncoated devices. Coated, InGaAsP-active devices are expected to haveP¯COMD=18 MW/cm2,more than twice theP¯COMDof AlGaAs-active, 0.81-&mgr;m-emitting devices with the same emitting aperture. Therefore, 0.81-&mgr;m-emitting, InGaAsP-active diode lasers should operate reliably at powers at least twice those of AlGaAs-based devices with the same contact-stripe geometry. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119528

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Visible/near-IR-range radiation hardening of a pair of low-OH/low-Cl silica-core optical fibers has been accomplished by &ggr;-ray preirradiation at 27 C to a dose of 13 MGy(Si) at a dose rate of 1 Gy(Si)/s in the dark. Reirradiation under identical conditions three months later demonstrated a 25-fold decrease in the initially induced intensities of the prominent radiation-induced bands centered near 660 and 760 nm and comparable decreases in weaker bands at longer and shorter wavelengths. Spectral changes observed in the wavelength regime 400–1000 nm upon quenching the irradiated fibers to 77 K have revealed the likely copresence, even at room temperature, of a previously reported “low temperature infrared absorption” which peaks near 1600 nm. Based on this insight, induced losses at 1550 nm have been extrapolated from the present data. It is argued that self-trapped holes are most likely responsible for most of the metastable induced absorption bands in the range∼400–2000 nm.©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119493

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A new coupled-cavity resonant photodetector structure is studied to provide a flat-topped passband with steep skirts in the photoresponse. The idea is to add a low-loss cavity that is optically coupled to the absorptive cavity via an intermediate mirror. Experimental reflection spectra confirm this coupling effect. Modeling for an InGaAs/GaAs/AlGaAs design reveals that this new coupled-cavity structure will be able to show a 22 dB channel rejection ratio even when the optical channel spacing is as narrow as 2 nm. In addition, the design and processing tolerances for cavity-mode adjustment are also addressed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119523

出版商:AIP    

年代:1997

数据来源: AIP