Method of modulating light with intrinsic semiconductor device and electrical signal modulator employing such device

Claim 1

APPARATUS FOR CHANGING THE FREQUENCY OF AN ELECTRICAL SIGNAL COMPRISING: A LIGHT SOURCE, A LIGHT MODULATOR OF SEMICONDUCTOR MATERIAL HAVING AT LEAST ONE PORTION CONTAINING CURRENT CARRIER IMPURITIES THEREIN WHICH FORMS A JUNCTION WITH A REGION OF INTRINSIC SEMICONDUCTOR MATERIAL NORMALLY SUBSTANTIALLY FREE OF CURRENT CARRIERS, A LIGHT SENSITIVE ELEMENT OF PHOTOCONDUCTOR MATERIAL POSITIONED TO RECEIVE THE LIGHT EMITTED BY SAID LIGHT SOURCE AFTER IT IS TRANSMITTED THROUGH SAID MODULATOR SO THAT THE IMPEDANCE OF SAID ELEMENT VARIES WITH SAID TRANSMITTED LIGHT AND THE MAJORITY OF THE LIGHT RECEIVED BY SAID ELEMENT PASSES THROUGH SAID INTRINSIC REGION, MEANS TO APPLY AN INPUT VOLTAGE OF ONE FREQUENCY ACROSS SAID VARIABLE IMPEDANCE OF SAID ELEMENT, AND MEANS FOR APPLYING A BIAS SIGNAL VOLTAGE OF ANOTHER FREQUENCY ACROSS THE JUNCTION IN SAID MODULATOR TO FORWARD BIAS SAID JUNCTION AND ALTERNATELY REMOVE SAID FORWARD BIAS IN ORDER TO VARY THE LIGHT TRANSMISSION CHARACTERISTIC OF SAID MODULATOR AND TO VARY THE IMPEDANCE OF SAID LIGHT SENSITIVE ELEMENT SO AS TO PRODUCE AN OUTPUT VOLTAGE ACROSS SAID VARIABLE IMPEDANCE RELATED IN FREQUENCY TO SAID BIAS VOLTAGE.