A thyristor-based photoreceiver based on the dual-channel double-heterostructure optoelectronic switch

A new approach to photoreceiver design is described based on the functionality of an optoelectronic thyristor. The receiver eliminates the transimpedance amplifier and the decision circuit by utilizing the internal gain of the thyristor and its nonlinear thresholding property. The sensitivity is determined by the shot noise on the input signal to be 360 photons per bit at a bit-error rate of 10^-9. The speed of the photoreceiver is determined by the switching times of the thyristor. An output voltage signal from 0 to 1.5 V is obtained with switch on and off times of 12.5 ps and input photocurrent densities of 10⁴ A/cm². The switch off time is equally as fast as the switch on due to the absence of stored charge in the modulation doped structure. The key to the high speed is the utilization of the third and fourth terminal contacts to the thyristor and the integration of the biasing transistors, which control the switching currents. An input optical signal of 0.5 mW will achieve this bandwidth in a device size of 0.2 μm×12.5 μm.