CHARACTERIZATION OF BUTT-JOINT INGAASP WAVE-GUIDES AND THEIR APPLICATION TO 1310NM DBR-TYPE MQW GAIN-CLAMPED SEMICONDUCTOR OPTICAL AMPLIFIERS

Butt-joint waveguide couplings are fabricated for use in InP-based pho tonic integration, and characterized by scanning electron microscopy a nd optical transmission measurements. Several parameters have been opt imized in the characterization study: size and shape of the mask prote cting the first waveguide layer during butt-joint regrowth, and the cr ystallographic direction of the butt-joint interface. The studies show that high-quality butt-joints having negligible optical loss can be m ade with good fabrication tolerance. Using the optimized butt-joint, D BR-type, gain-clamped SOAs have been fabricated which are free of inte rnal -excess- reflections. A constant optical gain of 21 dB is obtaine d up to a signal output power of 25 mW. The devices show CATV grade li nearity in a 77 channel CATV linearity test at a distortion level of - 55 dB below carrier.