IN-LINE QUANTUM-WELL WAVE-GUIDE PHOTODETECTORS FOR THE MEASUREMENT OFWAVELENGTH SHIFTS

A two-segment GaAs/InGaP/InGaAs p-i-n quantum-well waveguide photodiod e has been fabricated and demonstrated to function as a sensitive wave length monitor, The ratio of the two segments' photocurrents varies li nearly with wavelength in a region near the absorption band edge, A wa velength sensitivity on the order of 1 pm was measured for input optic al power levels above 30 mu W and signal averaging times of 0.2 s, An operating range from 980 to 1020 nm was achieved using electroabsorpti on tuning of the band edge, The intended application for this detector is wavelength demodulation of Bragg grating fiber optic strain sensor s, A strain sensor with resolution of +/-6 mu epsilon was demonstrated using a superluminescent diode and the inline detectors to monitor st rain-induced changes in the reflection wavelength of an in-fiber grati ng.