摘要:

We have realized a novel wavelength division multiplexer/demultiplexer based on rib waveguides in GaInAsP/InP. The device is a strongly asymmetric codirectional coupler with periodic variation of the coupling constant and has sinc2‐type characteristics. Our devices have center wavelengths around 1.3 &mgr;m, filter half‐widths 10–15 nm, and far end isolation down to −17 dB. The structure is suited for integration into optoelectronic integrated circuits for applications in bidirectional optical communication systems.

ISSN:0003-6951    

DOI:10.1063/1.103841

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The origin of nonlinear gain suppression in InGaAsP lasers is analyzed by experiments sensitive to small gain changes. The spectral distribution of gain change is determined by measuring the intensity modulation spectra of current modulated Fabry–Perot lasers with nearly single longitudinal mode emission. The gain change spectra show a cross saturation behavior as expected for spectral hole burning with a polarization relaxation time of about 0.07 ps. They do not reveal a dominant contribution of the gain and index grating induced by the cavity standing waves.

ISSN:0003-6951    

DOI:10.1063/1.103842

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We demonstrate active mode locking and a tunable narrow spectrum under cw conditions in an extended cavity laser which uses an AlGaAs/GaAs array gain medium and an external feedback from a self‐pumped photorefractive phase conjugate mirror. The mirror ensures self‐aligned, spatially matched feedback. The mode‐locked pulses are 92 ps wide. The tuning, obtained by an intracavity grating, has a range of 70 A˚ under cw conditions.

ISSN:0003-6951    

DOI:10.1063/1.103843

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

KrF excimer laser irradiation of CdTe at fluences below the melt threshold (≤75 mJ/cm2) removes surface layers and produces reversible changes in the surface composition that depend upon the laser fluence and number of laser pulses delivered to the surface. At fluences above ∼40 mJ/cm2a Te‐rich layer is obtained. A stoichiometric composition can be restored by irradiation at reduced laser fluence. The primary desorption products are Cd and Te2, and the velocities of these species are well described by a Maxwellian distribution. The fluence‐dependent changes in CdTe surface composition are consistent with a photothermal mechanism based on the competition between formation and desorption of Te2and desorption of Cd atoms from the laser‐irradiated surface.

ISSN:0003-6951    

DOI:10.1063/1.103844

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We describe a new type of color display consisting of polymer‐dispersed droplets of chiral liquid crystal having negative dielectric anisotropy. In the field‐off state, the droplets scatter light randomly. In the field‐on state the droplets selectively reflect a bright color. Measurements of reflectivities and switching times are presented and we discuss possible applications.

ISSN:0003-6951    

DOI:10.1063/1.103845

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

At the ferroelectric phase transition in the optically sensitized ferroelectric vinylidene fluoride‐trifluoroethylene copolymers P(VDF‐TrFE) the sharp change of the dye energy level is revealed. In ferroelectric P(VDF‐TrFE) copolymer doped by indolynospiropyran the structural chromic effect is observed, which is characterized by the reversible change of the film color at the ferroelectric phase transition.

ISSN:0003-6951    

DOI:10.1063/1.103846

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Stripe geometry lasers defined by impurity‐induced layer disordering (IILD) have been fabricated utilizing a novel technology of self‐aligned Si‐Zn diffusion from which both optical and electrical confinements are obtained simultaneously. The fabrication process is considerably simpler than that for the conventional IILD lasers and the parasiticp‐njunction area in the laser structures is minimized. Typical lasers with threshold currentIth=5.2 mA and differential quantum efficiency &eegr;d=81% at room‐temperature continuous operation as well as highly uniform yield ≳80% have been obtained.

ISSN:0003-6951    

DOI:10.1063/1.103847

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Photonic integrated circuits with a virtually complete set of active and passive devices are fabricated in the GaAs/AlGaAs system by single‐step chemically assisted ion beam etching. Using this straightforward processing technique, photonic integrated circuits consisting of etched facet ridge waveguide lasers coupled to passive waveguides, beamsplitters, etched turning mirrors, and photodetectors are demonstrated. The results presented point to the promise of this technique for the fabrication of future high‐complexity photonic integrated circuits.

ISSN:0003-6951    

DOI:10.1063/1.103848

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We present a theoretical investigation of the mechanisms responsible for the recently reported efficient type I blue second‐harmonic generation in periodically segmented KTiOPO4:Rb,Tl waveguides. In these guides, grating‐assisted phase matching of second‐harmonic light between 390 and 480 nm has been achieved. 5‐mm‐long guides give output powers on the order of 1 mW at around 425 nm with fundamental powers in the 50–100 mW range. We show that such high efficiencies can be expected from strongly perturbed guides through terms representing the modulation of phase mismatch and mode size in addition to the nonlinear susceptibility and refractive index modulations.

ISSN:0003-6951    

DOI:10.1063/1.103849

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The generation of arsine from the reactions of hydrogen and elemental arsenic in a microwave plasma reactor is described. The arsenic is evaporated from a solid source upstream and carried into the microwave plasma region by a mixture of hydrogen and argon. Stable reaction products, arsine and diarsine are observed by molecular beam sampled mass spectroscopy along with partially hydrogenated species (e.g., AsH and AsH2). The effect of composition and flow rate of the argon/hydrogen carrier gas mixture on the amount of arsine generated is investigated. The arsine production reaches a maximum for an argon‐to‐hydrogen ratio of unity indicating that metastable argon species act as energy transfer intermediates in the overall reaction. The generation of arsine and diarsine from easily handled solid arsenic by this technique makes it attractive as a possible arsenic source for the growth of compound semiconductors by low‐pressure metalorganic chemical vapor deposition.<lz> <lz> <lz> <lz> <lz>

ISSN:0003-6951    

DOI:10.1063/1.104182

出版商:AIP    

年代:1990

数据来源: AIP