B. I. Miller

Polarization rotation in asymmetric periodic loaded rib waveguides

A new mechanism for polarization rotation in rib waveguides is suggested and demonstrated in InP waveguides. The polarization rotation is achieved by loading a rib waveguide in a periodic asymmetric way. Complete TE↔TM conversion, with only 2–3 dB excess loss, is obtained in a 3.7‐mm‐long InP loaded waveguide. Strong polarization rotation (80%), in shorter devices (0.3 mm long), is also demonstrated.

Spectral Response and Efficiency Relations in Semiconductor Liquid Junction Solar Cells

States due to imperfections at or near surfaces of semiconductors in liquid junction solar cells can be identified by changes in the photoresponse spectra under short-circuit current conditions. These effects become dominant features in two-beam experiments with an intense pumping (laser) source and a weak modulated probing beam. The presence of these states can be correlated with drastic decreases in short-circuit currents, open-circuit voltages, fill factors, and maximum power conversion efficiencies of the cells. Elimination of the damaged surface regions by suitable etching allows AM2 solar conversion efficiencies of 1.3 and 7.2%, respectively, in the cells n-CdS/0.1F Na/sub 2/S--0.02F S-0.1F NaOH/C and n-CdSe/1F Na/sub 2/S--1F S-1F NaOH/C.

Effects of Cations on the Performance of the Photoanode in the n ‐ GaAs | K 2Se ‐ K 2Se2 ‐ KOH | C Semiconductor Liquid Junction Solar Cell

Cations adsorbed onto the surface of an n-GaAs photoanode have been found to increase the fill factor and open-circuit voltage of the cell, and a conversion efficiency of 12% (under AM1 solar radiation) has been attained by chemisorbing Ru(III) onto the photoanode. The action of the Ru ions on the surface density of the photoanode is explained in detail. 19 references.

Broadly tunable InGaAsP/InP laser based on a vertical coupler filter with 57‐nm tuning range

We have integrated a broadly tunable grating‐assisted vertical coupler as an intracavity filter to demonstrate a novel monolithic multiple‐quantum‐well InGaAsP/InP laser. The narrow, bandpass intracavity filter results in an extended cavity laser with a measured electrical tuning range of 57 nm with single‐frequency operation over most of that range.

Strain-compensated strained-layer superlattices for 1.5 μm wavelength lasers

Strain‐compensated strained‐layer multiple quantum well structures have been grown by introducing opposite strain into the barrier layers. Such structures show significant improvement in the photoluminescence spectra, i.e., narrower full width half maxima and stronger intensities. Lasers fabricated with such structures have exhibited low current thresholds (12 mA), high quantum efficiencies (28% per facet), which are constant over a wide current range.

Wavelength division multiplexing light source with integrated quantum well tunable lasers and optical amplifiers

We describe a photonic integrated circuit composed of three 1.5 μm wavelength multiple quantum well tunable lasers with a passive optical power combiner and an optical output amplifier. Independent channel operation with 1–2 mW/channel output power is demonstrated.

Low‐loss InGaAs/InP multiple quantum well optical electroabsorption waveguide modulator

An optical electroabsorption waveguide modulator is described based on the quantum‐confined Stark effect in an InGaAs/InP multiple quantum well waveguide. The optical modulator has a high on/off ratio (47:1) with very low insertion loss (2.9 dB) and a 3‐dB modulation bandwidth of 3.0 GHz at 0.1 mW optical input power.

Low internal loss separate confinement heterostructure InGaAs/InGaAsP quantum well laser

The structure and properties of a high performance InGaAs/InGaAsP separate confinement heterostructure multiple quantum well laser operating at 1.54 μm are described. The laser has low threshold current (18 mA), high quantum efficiency (22% facet), high cw output power (42 mW/facet), and weak dependence of the threshold currents and efficiencies on cavity length.

High performance tunable 1.5 μm InGaAs/InGaAsP multiple quantum well distributed Bragg reflector lasers

We describe the structure and performance of tunable four‐quantum‐well InGaAs/InGaAsP distributed Bragg reflector lasers. We observe total tuning range as large as 94 A, differential efficiency of 32%/front facet, thresholds of 17 mA, low‐chirp high‐speed digital operation, and linewidths as low as 5.75 MHz at only 2 mW output.

Broadly Tunable InGaAsP/Inp Buried Rib Waveguide Vertical Coupler Filter

We report the first demonstration of broadly electrically tunable (215 A), narrow‐band (∼20 A full width at half maximum), wavelength selective, grating‐assisted coupling between vertically stacked buried rib InGaAsP/InP channel waveguides. This current injection tuned device is suitable for integration in a variety of photonic devices and integrated circuits including broadly tunable extended cavity lasers, amplifier/filter, and demultiplexer/detector circuits.