摘要:

We have investigated the characteristics of molecular beam epitaxial In0.53(GaxAl1−x)0.47As/InP waveguides and phase modulators in the 1.15–1.3 &mgr;m wavelength range. Loss at 1.15 &mgr;m has been measured and is ∼5 dB/cm. The measured phase shift due to the electro‐optic effect results in an electro‐optic coefficientr63∼0.6×10−12m/V. Preliminary results at 1.3 &mgr;m show that the loss is reduced and is ∼3.4 dB/cm.

ISSN:0003-6951    

DOI:10.1063/1.103045

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

High‐power operation of hydrogenated AlyGa1−yAs‐GaAs‐InxGa1−xAs ten‐stripe arrays operating at &lgr;∼1.06 &mgr;m is described. Continuous (cw) operation of arrays with uncoated facets that are stabilized in temperature at 10 °C has produced output powers as high as 375 mW/facet at 1.4 A. The optical coupling of the gain‐guided arrays is shown to be significantly different from otherwise similar arrays fabricated in the AlyGa1−yAs‐GaAs system. Limited ‘‘lifetesting’’ (168 h) of these strained layer diodes, stabilized at 50 °C and a cw output power of 100 mW/facet (200 mW total), indicates good operating stability.

ISSN:0003-6951    

DOI:10.1063/1.103194

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

LiNbO3crystals with periodically alternating ferroelectric domains have been produced using laser‐heated pedestal growth. Domain thicknesses as small as 1 &mgr;m have been achieved. This material was applied to room‐temperature, quasi‐phase‐matched frequency doubling to generate light at wavelengths as short as 407 nm, using thed33andd22nonlinear coefficients. The measured conversion efficiencies and wavelength and temperature tuning bandwidths are consistent with an effective interaction length of ≊320 &mgr;m (>230 domains). An initial test with high‐intensity focused blue beams showed that the periodically poled material exhibits no discernible photorefractive damage effect.

ISSN:0003-6951    

DOI:10.1063/1.103276

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We describe the first results of hybrid mode locking combining both active and passive mode locking of a semiconductor laser. These functions are integrated into a monolithic device with a 1.3 &mgr;m GaInAsP gain region, an active waveguide, and a saturable absorber. The devices have low threshold currents, and exhibit hysteresis in their light/current characteristics. The long integrated waveguides allow mode locking at a repetition rate of 15 GHz without the need for an external cavity. Pulse widths as short as 1.4 ps have been demonstrated using the combined effects of active and passive mode locking.

ISSN:0003-6951    

DOI:10.1063/1.103046

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Pairs of grating surface‐emitting arrays, on a single wafer but free‐running, were externally coupled with a prism. The prism acted as an optical coupler between one distributed Bragg reflector in each array. Injection locking was demonstrated by observing a dramatic increase in the lateral coherence of the far field of the prism‐coupled arrays.

ISSN:0003-6951    

DOI:10.1063/1.103047

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Data are presented on a new type of extremely quiet and sensitive GaAs/AlGaAs photodetector. The photoresponse of the device is controlled by a hole trap in a tunnel barrier. Capture of a single photoinjected hole by the trap gates the device and produces an easily measured current pulse which can be counted by a conventional pulse‐counting apparatus. There is only one detectable trap in a photoactive area of &bartil;400 &mgr;m2. However, due to electric field channeling effects the trap collects photoinjected holes with a 1% efficiency in the active region. The absence of measurable dark counts in a 25 h period at 77 K establishes a minimum detectable photon flux <0.001 photons/s at 8200 A˚.

ISSN:0003-6951    

DOI:10.1063/1.103195

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

An adiabatic polarization splitter, fabricated with silica and silicon nitride films on a silicon substrate, is demonstrated. A rejection of the unwanted polarization (cross talk) of −20 to −34 dB was achieved with single filtering and −35 to −45 dB with double filtering. The device had a 1.5 dB insertion loss and a very small wavelength dependence.

ISSN:0003-6951    

DOI:10.1063/1.103277

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The threshold current density of multiple and single quantum well lasers as a function of cavity length has been investigated. A dramatic change of the lasing wavelength and a strong increase of the threshold current density is observed for a single quantum well laser when the cavity length is reduced to ∼400 &mgr;m. In addition, discrete widely separated wavelength switching with changes up to 50 nm is achieved using an intracavity electroabsorption region.

ISSN:0003-6951    

DOI:10.1063/1.103048

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have studied InGaAs/InAsPSb double heterojunction, oxide stripe lasers grown by hydride vapor phase epitaxy. At 80 K the threshold current density is 0.4 kA/cm2, the staturated output power is about 4 mW, and the differential quantum efficiency just above threshold is 20% per facet. The output wavelength increases from 2.44 &mgr;m at 80 K to 2.52 &mgr;m at 190 K. A layer of compositionally graded InGaAs accommodates the 2% lattice mismatch between the InP substrate and the laser structure. The operating characteristics of these lasers are compared with those of InGaAs/InAsP lasers. Their improved performance results from the better electrical and optical confinement of the InAsPSb cladding layers.

ISSN:0003-6951    

DOI:10.1063/1.103049

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The effect of curvature of the liquid‐solid interface of the Czochralski silicon crystal on microdefect occurrence is examined via the crystal’s oxygen precipitation behavior. Curved interface regions were found to contain more microdefects than the flat interfaced regions. Annealing results at high and low‐high temperatures show that oxygen precipitation is dominated by heterogeneous nucleation at a high temperature (1050 °C) without a prior low‐temperature nucleation treatment. Therefore, oxygen precipitation in crystals lacking grown‐in microdefects would be retarded. When a low‐high cycle containing a low temperature near 700 °C is used, the homogeneous nucleation mechanism dominates, and the impact of grown‐in microdefects on oxygen precipitation is diminished.

ISSN:0003-6951    

DOI:10.1063/1.103050

出版商:AIP    

年代:1990

数据来源: AIP