Abstract-A buried crescent InGaAsP-InP laser with two active layers was fabricated to study the temperature behavior of the doublecarrier-confinement structure. An anomalously high-characteristic temperature To was measured and an optical switching behavior was observed. A model analysis and numerical calculation using a rate equation approach explained qualitatively very well the experimental results. It was revealed that not only the Auger recombination in this special double-active-layer configuration, but that the temperature dependent leakage current, which leads to uniform carrier distribution in both active regions, is essential to increase To.
We consider optimization of phase functions of computer generated holograms used in conjunction with ordinary optical elements to reduce the aberrations of monocromatic optical systems. We develop matrix methods that are useful in first -order design of holographic optical systems, and in analysis and optimization of these systems for narrow laser beams, for which geometrical optics is not applicable. We also report experiences on optimization of phase functions by geometrical ray tracing with the aid of damped least squares algorithm. Design examples contain various telescope systems, in which the holographic secondary elements correct aberrations induced by the glass primary.
We consider the fabrication of high-quality interferogram-type diffractive optical elements with conventional photolithographic techniques and compare the results with those achievable with electron-beam lithography. The fringes associated with the phase transfer function of the binary phase holographic interferogram are approximated with rectangles, which can be realized at submicron accuracy using a pattern generator and step-and-repeat camera. The effects of the rectangle quantization are analyzed both numerically and experimentally with the aid of diffraction patterns produced by simple focusing elements. Both resolution and diffraction efficiency of the best holograms approach their theoretical values.
A tandem combination of a uniform gain broad-area semiconductor laser and a (lateral) periodic gain section displays a stable, near-diffraction-limited single-lobed far-field pattern. The GaAs/GaAlAs quantum well lasers display a high degree of coherence across 60-μm-wide apertures provided that the broad-area section is sufficiently long.
A buried crescent InGaAsP/InP laser with a double active layer was fabricated. The laser showed very high characteristic temperature T0 and highly nonlinear light versus current characteristics. A theoretical model using a rate equation approach showed good agreement with the experimental results.
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