A LIGHT-TRANSMITTING 2-DIMENSIONAL PHOTODETECTOR ARRAY USING A-SI PINPHOTODIODES AND POLY-SI TFTS INTEGRATED ON A TRANSPARENT SUBSTRATE

A light-transmitting two-dimensional photodetector array (32 x 32 cell s) using amorphous silicon (a-Si) pin photodiodes and polysilicon (pol y-Si) thin film transistors (TFT's) integtrated on a transparent subst rate has been developed for use in a free-space optical switching netw ork. The fabrication and the characteristics of the photodetector arra y are discussed. With driving circuits and sensing amplifiers, this ph otodetector array shows a minimum detectable power of -25 dBm and an i nsertion loss of 0.4 dB for an incident optical beam with a diameter o f 550 mum. By monitoring the positions and the states of input optical beams, this photodetector array can be used to control the optical pa ths in photonic switching systems, such as a 1024-input-port optical c oncentrator.