摘要:

Aging tests of InGaAsP/InP V‐grooved substrate buried heterostructure lasers have performed. The cw threshold current of these lasers is around 20 mA at 25 °C. The laser are tested at 10, 50, and 70 °C with a constant optical power of 5 mW/facet and are still operating at over 5000 h with only a slight increase in the driving current. The far‐field pattern and lasing spectrum do not change appreciably during aging, and self‐pulsation is not observed after aging.

ISSN:0003-6951    

DOI:10.1063/1.93616

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Stimulated spin‐flip Raman scattering has been observed in the semimagnetic semiconductor Cd1−xMnxSe.gvalues as large as 170 were observed, allowing the spin‐flip frequency to be tuned by 20 meV with magnetic fields belowB= 30 kG. A threshold intensity of less than 1 MW/cm2was found. This threshold varies rapidly with pump wavelength, and peaks near the donor‐bound exciton energy. The tunability and gain coefficient are comparable to those in narrow‐gap semiconductors, such as InSb and (Hg,Cd)Te, under nonresonant conditions. Laser action is achieved for longitudinal pumping.

ISSN:0003-6951    

DOI:10.1063/1.93617

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Using a combination of antireflection coating and proton implantation techniques, GaAlAs double‐heterostructure lasers are fabricated to operate in superradiant mode. Light output, in excess of seven milliwatts, is obtained with spectral half‐power widths of 15–20 nm. This implies extremely short coherence lengths of less than 50 &mgr;m. Such a short coherence length light source should be very useful for many applications in fiber sensors and fiber optic communications. In particular, it has produced marked reduction (better than 15 dB) of coherent Rayleigh backscattering noise in a single‐mode fiber. Since the laser operates in superradiant mode, the output light is only partially polarized, another unique characteristic that is important for fiber gyroscopes. The typical light output angle of 30°×50° also provides easy coupling into fibers. Coupling efficiencies of 80% into multimode fiber and over 20% into single‐mode fiber have been achieved.

ISSN:0003-6951    

DOI:10.1063/1.93618

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Four‐wave mixing experiments are used to study the variation of the third‐order susceptibility &khgr;(3), with frequency difference &Dgr;&ohgr; and laser intensityIin low carrier concentration HgCdTe crystals. At small &Dgr;&ohgr;, &khgr;(3)is caused by nonparabolicity of free electrons generated by two‐photon absorption, with &khgr;(3)scaling as &Dgr;&ohgr;−1andI2/3. The &Dgr;&ohgr; variation of &khgr;(3)indicates that the electron thermalization time is longer than 8 ps. At large &Dgr;&ohgr;, &khgr;(3)≃3×10−8esu is mainly due to bound electrons.

ISSN:0003-6951    

DOI:10.1063/1.93619

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Employing the principle of a phase‐locked loop (PLL) we have synchronized the frequency and phase of two CO2lasers. The laser acting as voltage controlled oscillator is tuned both by electro‐optic and piezoelectric means. A cooled photodiode serves as the phase detector. The main loop parameters, natural frequency &ohgr;nand damping factor &zgr;, have been measured. The small phase jitter in the error signal obtained will allow application of such an optical PLL in homodyne receivers at 10 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.93620

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The optical absorption coefficient of silicon has been measured at the HeNe near‐infrared line (&lgr; = 1.152 &mgr;m) from room temperature to 1140 K. The results are compared with the previous less extensive data in the literature, and with the formulation given by Macfarlaneetal. [Phys. Rev. 111, 1245 (1958)]. It is found that the absorption is described very well by phonon‐assisted indirect transitions across an energy gap having the temperature dependence described by Thurmond.

ISSN:0003-6951    

DOI:10.1063/1.93621

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The frequency of an AlGaAs diode laser has been stabilized to the center frequency of the optogalvanic signal corresponding to the 4s′01–4p12(Racah notation) transition of Ar I at 8408.2094 A˚. The first derivative curve of the line was used as the error signal to be fed back to the operating current source of the diode laser. Fluctuation of the laser frequency was within 200 kHz for several hours.

ISSN:0003-6951    

DOI:10.1063/1.93622

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A photoconducting sampling gate which is triggered by a picosecond optical pulse and has an aperture of approximately 12 ps has been used to measure accurately the response of a high‐speed, solid‐state photodiode. The sample gate, which is made from a radiation‐damaged semiconductor, is demonstrated to have better speed, lower noise level, negligible jitter, and fewer reflections than conventional sampling oscilloscopes. In addition, it can be used over a wide temperature range by direct mounting in a variable temperature cryostat.

ISSN:0003-6951    

DOI:10.1063/1.93612

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Long life (≳106shots), sealed operation of a repetitively pulsed (4 pps), compact (5‐cm3active volume), transversely excited atmosphere (TEA) CO2laser has been achieved using an efficient corona‐type preionization and traces of tripropylamine (TPA) as gas additive. The use of TPA has enabled extended operation with a maximum output peak power of about 350 kW.

ISSN:0003-6951    

DOI:10.1063/1.93613

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A new technique for the study of surfaces is described, whereby materials with different optical properties may be identified from characteristic responses, and which may be developed to give measurements of the optical properties. The technique is similar to one already used in acoustic microscopy.

ISSN:0003-6951    

DOI:10.1063/1.93614

出版商:AIP    

年代:1982

数据来源: AIP