ELECTROABSORPTION MODULATORS FOR HIGH-BIT-RATE OPTICAL COMMUNICATIONS- COMPARISON OF STRAINED INGAAS INALAS AND INGAASP/INGAASP/

Conventional high-speed (>10 GHz) external modulators at 1.55 mu m exi st in various types and on several kinds of substrate material. Only e lectroabsorption modulators on InP have so far demonstrated polarizati on-independent operation at high speeds. In this paper, the properties of two strained multiple quantum well (MQW) modulators are reviewed i n the context of optical fibre communications in terms of loss, drive voltage, bandwidth (>40 GHz), eye diagram, bit error rate measurements and optical power handling capacity. An effective modulation polariza tion sensitivity of 0.6 dB is reported. The two components differ main ly in their saturation optical power levels. A new power saturation me chanism is proposed to explain the nonlinearity of the InGaAs/InAlAs m odulator.