Parametric amplifier using photo-cell reactance

Claim 1

A PARAMETRIC AMPLIFIER COMPRISING IN COMBINATION, A PHOTOCAPACITOR DEVICE CONSISTING OF A SEMICONDUCTOR CRYSTAL ELEMENT WITH A METAL FILM THEREON HAVING A DEPLETION LAYER AT THE JUNCTION BETWEEN THE SEMICONDUCTOR AND METAL ELEMENTS, A LIGHT BEAM INTENSITY-MODULATED WITH INFORMATION AT A FREQUENCY FS DIRECTLY APPLIED TO THE SENSITIVE METAL FILM SURFACE OF SAID PHOTOCAPACITOR DEVICE RESULTING IN THE RELEASE OF ELECTRONS ENTERING THE DEPLETION LAYER AND CAUSING THE GENERATION OF A SIGNAL CURRENT THEREIN WHICH RESULTS IN TURN IN A VARYING CAPACITANCE AT THE FREQUENCY FS ACROSS THE TERMINALS OF SAID DEVICE PROPORTIONAL TO THE VARYING INTENSITY OF THE VARYING LIGHT BEAM, A PUMP SOURCE FOR VARYING THE CAPACITANCE OF SAID DEVICE AT A FREQUENCY FP BY APPLYING A SECOND, MORE INTENSE, LIGHT BEAM MODULATED AT THE PUMP FREQUENCY FP TO THE PHOTOCAPACITOR DEVICE, A HIGH-Q CLOSED SIGNAL CIRCUIT INCLUDING THE VARIABLE CAPACITANCE OF SAID DEVICE AND RESISTANCE IN SERIES, IN WHICH AN R.-F. CURRENT OF FREQUENCY FS IS GENERATED BY THE MODULATED LIGHT BEAM, A HIGH-Q PARALLEL INDUCTANCE-CAPACITANCE RESONANT CIRCUIT TUNED TO THE DIFFERENCE FREQUENCY F1=FP-FS COUPLED TO THE SIGNAL CIRCUIT BY SAID PHOTOCAPACITOR, THE R.-F. SIGNAL CURRENT AT THE FREQUENCY FS AND THE CAPACITANCE VARIATION OF SAID PHOTOCAPACITOR AT THE FREQUENCY FP COMBINING TO GENERATE VOLTAGES AT THE SUM AND DIFFERENCE OF THESE FREQUENCIES ACROSS THE CAPACITOR, AND OUTPUT MEANS FOR TAKING OFF AN AMPLIFIED, LOW NOISE, OUTPUT SIGNAL OF THE FREQUENCY FS ACROSS SAID SERIES RESISTANCE IN SAID SIGNAL CIRCUIT OR OF THE DIFFERENCE FREQUENCY F1 ACROSS THE IDLER CIRCUIT, THE OUTPUT SIGNAL IN EACH CASE CONTAINING THE INFORMATION IN THE ORIGINAL MODULATED LIGHT BEAM.