摘要:

A simple and versatile frequency stabilization of a 612 nm He‐Ne laser in a transverse magnetic field by the beat frequency stabilization method has been presented. The characteristic magnetic field was 250 G and the width of the single‐mode region was approximately 220 MHz. The obtained frequency stability (&Dgr;f/f ) was 5×10−9over a 1 h period.

ISSN:0003-6951    

DOI:10.1063/1.104101

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The routing ability of waveguideS‐bend structures patterned by SiO2impurity induced layer disordering of a single GaAs quantum well graded barrier laser structure is investigated. For a raised‐cosine bend with 100 &mgr;m offset guides, the measured transition length for 3 dB loss was less than 300 &mgr;m for near single mode guides of 1 &mgr;m width. In addition, vacancy‐induced disordering of the native quantum well region is investigated and is shown to increase the band gap to a point where the material is low loss for radiation generated by the laser. The 3 dB length for these blue shifted cores actually decreased to about 230 &mgr;m, a fact attributed to reduced mode conversion.

ISSN:0003-6951    

DOI:10.1063/1.103431

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have produced a nonabsorbing surface‐normal optical modulator operating at 1.06 &mgr;m (e.g., for a high‐power Nd‐YAG pump laser) which has a relative transmission change of 16% for −1 to 1 voltage swing. The structure is a GaAs‐AlAs dielectric mirror with alternatingn‐ andp‐type &dgr; doping at each interface. Doping selective contacts are made to the sample so that an applied voltage appears equally across each period of the device, yielding a strong field which changes the index of the GaAs and hence shifts the mirror.

ISSN:0003-6951    

DOI:10.1063/1.103432

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We study the growth dynamics of photosensitive fiber gratings assuming a local bleaching model, and demonstrate that sustained grating growth is possible. Good agreement with our experimental results is obtained after including fiber heating effects.

ISSN:0003-6951    

DOI:10.1063/1.103433

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Gain and spectral response of heterojunction phototransistors (HPTs) having a thin (0.1 &mgr;m) InGaAs strained absorbing layer in the collector has been investigated. Low dark current ∼ 5 pA (1×10−8A/cm2) and large optical gain as high as 500 were observed. A resonant cavity composed of an AlAs/GaAs buried mirror structure (reflectivityR=0.9) and the epilayer surface (R=0.3) was used to enhance the otherwise small quantum efficiency &eegr; (at InGaAs absorption wavelength). For a 1000 A˚ absorbing layer an improvement of &eegr; from 6.7 to 43% (6.4‐fold) was demonstrated, in agreement with calculations, through the spectral analysis of the HPTs with and without resonant cavities.

ISSN:0003-6951    

DOI:10.1063/1.103410

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The strain generated electric field in a ⟨111⟩ oriented misfit superlattice provides a suitable bias for generating optically induced femtosecond electromagnetic radiation. We have measured the electromagnetic radiation from GaSb/AlSb strained‐layer superlattices and GaSb thin films; extremely fast electromagnetic pulses from ⟨111⟩ oriented superlattices have been observed. Because the quantum well structure in the superlattice samples limits the pulse duration of the transient photocurrent, it is possible to generate electromagnetic radiation having a pulse duration comparable with the photocarrier transit time across the quantum well.

ISSN:0003-6951    

DOI:10.1063/1.103411

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Direct frequency‐modulated operation of ridge‐guided linear grating‐surface‐emitting laser arrays is reported. Simultaneous far‐field and spectral measurements of these devices at 1 GHz modulation rates show that both single longitudinal mode and single spatial mode operation are maintained.

ISSN:0003-6951    

DOI:10.1063/1.103412

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the generation of short optical pulses from novel monolithic colliding‐pulse mode‐locked quantum well lasers. Transform‐limited pulses with durations of 1.4 ps at a repetition rate of 32.6 GHz have been achieved, with nearly 100% intensity modulation depth and a peak optical power of 10 mW. This is the shortest transform‐limited pulse directly generated from monolithic mode‐locked lasers (time‐bandwidth product =0.3).

ISSN:0003-6951    

DOI:10.1063/1.103413

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Optical emission properties in remote plasma deposition of SiNxfrom an N2electron cyclotron resonance microwave plasma and SiH4have been investigated over a pressure range of 0.002–0.3 Torr. The deposition process divides into three pressure regions. Forp≳0.1 Torr, film deposition results from gas phase reactions between active nitrogen and SiH4. Forp<0.02 Torr SiH4travels back to the plasma and deposition results from radical species created in the N2/SiH4mixture. At intermediate pressures deposition was negligible because neither process could substantially break down SiH4.

ISSN:0003-6951    

DOI:10.1063/1.104259

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Periodic surface structures have been observed on organic polymers when photoablated using low coherence excimer lasers. Both unpolarized and linearly polarized radiation at 248 and 308 nm produce well ordered, micron‐scale structures over dimensions greatly exceeding the coherence area of the laser at the surface. Surface scattered wave effects appear to explain these structures.

ISSN:0003-6951    

DOI:10.1063/1.103414

出版商:AIP    

年代:1990

数据来源: AIP