S. Ritchie

The weighted index method: a new technique for analyzing planar optical waveguides

A method of analyzing optical waveguides called the weighted-index technique is presented. It is particularly appropriate for planar geometries with abrupt refractive index profiles, such as semiconductor waveguides. The method is an extension of the simple effective-index and transverse-resonance methods and has a strong physical foundation. The weighted-index method is shown to give more accurate results and be valid for a wider range of structures. Although it is more complicated than the effective-index method, it can be implemented on the smallest of personal computers. >

Optimum overlap of electric and optical fields in semiconductor waveguide devices

The effect of an applied field on the propagation constant of a mode in a semiconductor slab waveguide is examined theoretically. A figure of merit defined as the change of propagation constant with voltage is related to the relative widths of the electrical and optical fields. It is shown that the figure of merit is maximized when the region over which the electric field is applied is minimized, rather than when the two fields have similar profiles. The constraint of electrical breakdown is also discussed with respect to the maximum change in propagation constant.

Whole‐sample and localized induced‐absorption optical bistability in GaAlAs waveguides

Induced‐absorption optical bistability has been studied in GaAlAs heterostructure rib and slab waveguides. Both whole‐sample and localized switching have been observed within the same device. The localized switch, which occurs on the time scale of a few microseconds and at an input power of 10–20 mW, has been induced using a laser‐diode source.

Interference filters using indium phosphide‐based epitaxial layers grown by metalorganic vapor phase epitaxy

Bandpass interference filters with center wavelengths between 1.3 and 1.7 μm have been made with InGaAsP/InP epitaxial layers grown by metalorganic vapor phase epitaxy. The transmission spectra measured exhibit a full width half maximum of 7 nm with peak rejections up to 20 dB and are in good agreement with the results obtained from theoretical modeling of the 81‐layer single half‐wave Fabry–Perot structure used. This indicates very good control of the composition and thickness of the layers grown, which is confirmed by transmission electron microscopy of the structure.

High Reliability Planar InGaAs/InP Photodiodes Made With High Yield by Atmospheric Pressure MOVPE

A high-yield process for making planar InGaAs/InP photodiodes based on metal-organic vapour phase epitaxy (MOVPE) growth at atmospheric pressure has been developed. The process results in very good uniformity and yield and gives high-performance devices of excellent reliability, with a random failure rate of less than 0.3 FITs at 20°C. This reliability performance is easily able to meet the stringent requirements for detectors in submarine systems.