Dual-function electroabsorption waveguide modulator/detector for optoelectronic transceiver applications

A Franz-Keldysh effect InGaAsP electroabsorption waveguide device is utilized as a high-frequency, high-linear dynamic range modulator and photodetector. The dual-function modulator/photodetector can be useful in compact transmit/receive front end antenna architectures. Adjusting the electrical bias to the reverse-biased p-i-n diode, either efficient optical modulation or detection is demonstrated. As an electroabsorption modulator, a fiber optic link with a -17.4-dB RF loss and a 124-dB-Hz/sup 4/5/ suboctave spurious-free dynamic range is obtained with electrical biases in the 2 to 3 V range. As a waveguide photodetector, a 0.45-A/W fiber coupled responsivity, photocurrents up to 20 mA, and an output second-order intercept of +34.5 dBm are achieved at 7-V electrical bias.