Detector-modulator for an optical communications system

Claim 2

A DETECTOR-MODULATOR FOR AN OPTICAL COMMUNICATIONS SYSTEM COMPRISING: A. A NARROW ENERGY-GAP SEMICONDUCTOR MEANS CAPABLE OF PRODUCING AN ELECTRON-HOLE PLASMA BY MULTIPHOTON ABSORPTION IN RESPONSE TO IRRADIATION BY A MODULATED COHERENT OPTICAL CARRIER HAVING A PREDETERMINED WAVELENGTH, B. A BAISING CIRCUIT MEANS CONNECTED TO SAID SEMICONDUCTOR MEANS RESULATING FROM SAID PLASMA TO PROVIDE AN OUTPUT SIGNAL PROPORTIONAL TO THE MODULATION OF SAID COHERENT OPTICAL CARRIER, AND C. A MODULATING VOLTAGE MEANS CONNECTED TO SAID SEMICONDUCTOR MEANS TO APPLY A MODULATING VOLTAGE ACROSS SAIS SEMICONDUCTOR MEANS IN RESPONSE TO A MODULATING SIGNAL TO ACCORDINGLY CREATE A SECOND PLASMA IN SAID SEMICONDUCTOR MEANS WHICH MODULATES SAID COHERENT OPTICAL CARRIER BY FREEHOLE ADSORPTION THEREOF,

Claim 3

A detector-modulator as recited in claim 1, wherein said semiconductor means comprises indium antimonide which is capable of producing said plasma when maintained at a temperature in a predetermined range of temperatures, and further comprising means maintaining said semiconductor means at one of said temperatures in said range.

Claim 4

A detector-modulator as recited in claim 1, wherein said biasing circuit means includes a power supply having first and second terminals, the potential on said first terminal serving as a reference potential and the potential on said second terminal bein coupled to said semiconductor means, and resistance means having one side connected to said semiconductor means and a second side connected to said reference potential.

Claim 5

A detector-modulator as recited in claim 3, wherein said modulating voltage means includes an amplifier producing a voltage across said semiconductor means having a magnitude sufficient to produce said second plasma by electron-hole injection.

Claim 6

A detector-modulator as recited in claim 4, wherein said amplifier produces a voltage having a magnitude sufficient to produce said plasma by impact ionization.

Claim 7

AN OPTICAL COMMUNICATIONS SYSTEM COMPRISING: A. A FIRST TRANSCEIVER MEANS INCLUDING A SOURCE OF A MODULATED COHERENT OPTICAL CARRIER HAVING A PREDETERMINED WAVELENGTH, AND B. A SECOND TRANSCEIVER MEANS INCLUDING NARROW ENERGYGAP SEMICONDUCTOR MEANS CAPABLE OF PRODUCING AN ELECTRON-HOLE PLASMA BY MULTIPHOTON ABSORPTION IN RESPONSE TO IRRADIATION BY SAID COHERENT OPTICAL CARRIER AND A BIASING CIRCUIT MEANS FOR DETECTING EXCESS CONDUCTIVELY IN SAID SEMICONDUCTOR MEANS REULTING FROM SAID PLASMA TO PROVIDE AN OUTPUT SIGNAL IN PROPORATION TO THE MODULATIO OF

Claim 8

AN OPTICAL COMMUNICATIONS SYSTEM COMPRISING: A. A FIRST TRANSCEIVER MEANS INCLUDING A SOURCE OF A MODULATED COHERENT OPTICAL CARRIER HAVING A PREDETERMINED WAVELENGTH, AND B. A SECOND TRANSCEIVER MEANS INCLUDING NARROW ENERGYGAP SEMICONDUCTOR MEANS CAPABLE OF PRODUCING AN ELECTRON-HOLE PLASMA BY MULTIPHOTON ABSORPTION IN RESPONSE TO IRRADIATION BY SAID COHERENT OPTICAL CARRIER AND A BIASING CIRCUIT MEANS FOR DETECTING EXCESS CONDUCTIVELY IN SAID SEMICONDUCTOR MEANS REULTING FROM SAID PLASMA TO PROVIDE AN OUTPUT SIGNAL IN PROPORATION TO THE MODULATIO OF

Claim 9

An optical communications system as recited in claim 6, wherein said source of a modulated coherent optical carrier comprises a carbon dioxide laser, and said semiconductor means comprises indium antimonide.

Claim 10

An optical communication system comprising: a. a first transceiver means including a source of a modulated coherent optical carrier having a predetermined wavelength; b. a second transceiver means including a narrow energy-gap semiconductor means capable of producing an electron-hole plasma by multiphoton absorption in response to irradiation by said coherent optical carrier and a biasing circuit meAns for detecting excess conductivity in said semiconductor means resulting from said plasma to provide an output signal in proportion to the modulation of said carrier; c. said first transceiver means additionally including a second narrow energy-gap semiconductor means capable of producing an electron-hole plasma by multiphoton absorption in response to irradiation by modulated coherent optical carrier having a predetermined wavelength, and biasing circuit means for detecting excess conductivity in said second semiconductor means resulting from said plasma to provide an output signal proportional to the modulation of said coherent optical carrier; d. said second transceiver means also including a modulating voltage means to apply a modulating voltage across said semiconductor means in response to a modulating signal to accordingly create the second plasma in said semiconductor means which modulates said coherent optical carrier by free-hole absorption thereof; and, e. each of said first and second transceiver means includes means for reflecting the coherent optical carrier which has been detected and modulated by that transceiver means back to said other transceiver means.

Claim 11

An optical communication system comprising: a. a first transceiver means including a source of a modulated coherent optical carrier having a predetermined wavelength; b. a second transceiver means including a narrow energy-gap semiconductor means capable of producing an electron-hole plasma by multiphoton absorption in response to irradiation by said coherent optical carrier and a biasing circuit meAns for detecting excess conductivity in said semiconductor means resulting from said plasma to provide an output signal in proportion to the modulation of said carrier; c. said first transceiver means additionally including a second narrow energy-gap semiconductor means capable of producing an electron-hole plasma by multiphoton absorption in response to irradiation by modulated coherent optical carrier having a predetermined wavelength, and biasing circuit means for detecting excess conductivity in said second semiconductor means resulting from said plasma to provide an output signal proportional to the modulation of said coherent optical carrier; d. said second transceiver means also including a modulating voltage means to apply a modulating voltage across said semiconductor means in response to a modulating signal to accordingly create the second plasma in said semiconductor means which modulates said coherent optical carrier by free-hole absorption thereof; and, e. each of said first and second transceiver means includes means for reflecting the coherent optical carrier which has been detected and modulated by that transceiver means back to said other transceiver means.

Claim 12

An optical communications system as recited in claim 8, further comprising a plurality of said second transceiver means arranged in a closed-loop communication system with said first transceiver means, wherein a first of said plurality of second transceiver means detects the modulated optical carrier transmitted by said first transceiver means, wherein each of the succeeding ones of said plurality of second transceiver means detects and modulates the coherent optical carrier transmitted by a preceding one of said plurality of second transceiver means, and wherein said first transceiver means detects and modulates the coherent optical carrier provided by a last one of said plurality of second transceiver means.

Claim 13

An optical communications system as claimed in claim 9, further comprising multiplexing means establishing a communication cycle including a plurality of communication periods, one for said first transceiver means and for each of said plurality of second transceiver means, and wherein said first transceiver means and each of said plurality of second transceiver means includes means responsive to said multiplexing means for enabling said source of a modulated coherent optical carrier, and said modulating voltage means, respectively, only during the assigned communication period for said transceiver means.