an array of photon counting phototoreceivers is constructed as an imager with micro - digitized pixels . each photoreciever comprises a vertical cavity optical amplifier as an optical amplifier , an avalanche photodiode as detector and an analog - to - digital converter in an integrated structure . the adc serves as a 1 - bit digitizer and uses a resonant tunneling bipolar transistor rtbt . while the preferred embodiment of the invention have been described , it will be apparent to those skilled in the art that various modifications may be made to the embodiments without departing from the spirit of the present invention . such modifications are all within the scope of the present invention .