摘要:

We have applied laser‐induced fluorescence diagnostics to expanding recombining barium plasmas produced by laser ablation. For relatively modest ablation laser energy fluences (∼102–103W cm−2), we have measured neutral barium leading edge density gradients of 1012–0.5×1013cm−3 cm−1and cloud expansion velocities of ∼106cm s−1, consistent with recent results of ablation studies in copper [R. J. von Gutfeld and D. W. Dreyfus, Appl. Phys. Lett.54, 1212 (1989)].

ISSN:0003-6951    

DOI:10.1063/1.103124

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Heterobarrier blocking structure InGaAlP visible light laser diodes employing a thin active layer (0.04 &mgr;m) and asymmetry coatings have been fabricated. The high light‐output power operation with this heterobarrier blocking structure was investigated. The light‐output power versus cw current curve was linear up to 43 mW and a maximum light output power of 51 mW was obtained. A high‐power operation such as 20 mW was maintained at 40 °C. Stable oscillation in the fundamental transverse mode was obtained up to 30 mW. These results show that this heterobarrier blocking structure supplies a sufficient current confinement effect even under a high‐light output power operation.

ISSN:0003-6951    

DOI:10.1063/1.103125

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Data are presented showing limited layer disordering (or intermixing) of S‐diffused Se‐doped or C‐doped AlxGa1−xAs‐GaAs superlattices. The S diffusion is characterized via secondary‐ion mass spectroscopy, shallow angle beveled cross sections, and absorption measurements. Limited intermixing of column‐III‐site atoms (Al&rlarr2;Ga) as well as minimal displacement of the column‐V‐site acceptor C is observed. The S diffusion depth is much greater than that of the layer disordering, the magnitude of which is similar to that of native‐defect vacancy‐assisted disordering (vacancyVIII).

ISSN:0003-6951    

DOI:10.1063/1.103126

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Some liquid‐crystal device applications favor a thin‐film polarizer adjacent to the liquid. Wire grid type polarizing metal films fabricated by oblique evaporation can provide liquid‐crystal alignment layers. The alignment of a nematic liquid crystal on a polarizing metal film is reported.

ISSN:0003-6951    

DOI:10.1063/1.103127

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new phase matching technique is described which is based on phase mismatch balancing in crystal or waveguide segments that are short compared to their respective coherence lengths. The technique is demonstrated experimentally in a mixed bulk crystal/waveguide structure in KTiOPO4, resulting in a second‐harmonic generation conversion efficiency of 15%/W/cm2at 1.064 &mgr;m, close to the theoretical maximum. We show that this technique can significantly broaden processing latitude for fabricating practical nonlinear optical waveguide devices.

ISSN:0003-6951    

DOI:10.1063/1.103128

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Holographic recording on a real‐time basis of two‐dimensional images in an iron‐doped lithium niobate fiber with a 200 &mgr;m diameter and 3 mm length is demonstrated for the first time. The erasure time constant as a function of readout beam power, the diffraction efficiency as a function of incident reference angle, and the results of angular‐multiple recording of two images are shown. These results suggest that the LN fiber could replace bulk materials for holographic recordings in optical parallel processing.

ISSN:0003-6951    

DOI:10.1063/1.103129

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Highly efficient ridge waveguide pseudomorphic single quantum well lasers, emitting at 980 nm, have been fabricated from an In0.2Ga0.8As/GaAs/AlGaAs graded‐index separate confinement heterostructure grown by molecular beam epitaxy. The lateral index guiding provided by the ridge reduces the anomalously large lateral loss of optical power found in gain‐guided structures, thereby reducing the internal loss by more than 50%. The low threshold current (7.6 mA) and high differential quantum efficiency (79%) obtained under continuous operation as well as the transparency of the GaAs substrate to the emitted radiation render these lasers attractive for GaAs‐based optoelectronic integration.

ISSN:0003-6951    

DOI:10.1063/1.103106

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A simple reflection technique for measuring the electro‐optic coefficient of nonlinear optical polymeric films is described. The technique is based on the polarization rotation of a laser beam due to the electro‐optic effect. It requires no waveguiding and can be used to measure polymeric films during, as well as after, the electrical poling process. The results are in excellent agreement with those obtained from the more conventional but much more time consuming waveguiding method.

ISSN:0003-6951    

DOI:10.1063/1.103107

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A novel ‘‘vertical impedance matching’’ approach is demonstrated to improve absorption in evanescently coupled, integrated waveguide/photodiodes by 500% over conventional structures. Our devices exhibit both high absorption at short length (90% at 190 &mgr;m) and efficient fiber butt coupling (42%) at 1.3–1.55 &mgr;m wavelengths. Unusual transient phenomena are observed in such impedance‐matched devices and discussed theoretically.

ISSN:0003-6951    

DOI:10.1063/1.103084

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have studied ultrafast gain dynamics in InGaAsP optical amplifiers by means of pump‐probe and cross‐correlation measurements using 180 fs optical pulses. The data show strong gain nonlinearities due to nonequilibrium carrier distributions and differ significantly from those observed in AlGaAs amplifiers.

ISSN:0003-6951    

DOI:10.1063/1.103085

出版商:AIP    

年代:1990

数据来源: AIP