A photon coupled circuit comprises a high quantum efficiency semiconductor light emitter (TDA) coupled with high quantum efficiency with a semiconductor light detector (OLD). Bias current is provided to both the light detector (OLD) and light emitter (TDA). The light output of the light emitter (TDA) is modulated by the current flowing therein and the current flowing (io) in the detector (OLD) is modulated by the light received from the light emitter (TDA). The quantum transfer efficiency or current gain in greater that 0.5 and a portion of the current flowing in the light detector (OLD) is applied as feedback to reinforce or oppose the curent flowing in the light emitter (TDA).
