Optical transmission employing modulation transfer to a new carrier by two-photon absorption

Claim 2

In an optical communication system, optical modulation apparatus comprising a source of an intensity modulated optical beam at frequency omega 1, a source of an unmodulated coherent optical beam at a frequency omega 2 not equal to omega 1, means including a body of material having two-photon absorption for respective photons of frequencies omega 1 and omega 2 for generating a photon having a frequency omega 3 which is equal to the sum omega 1 + omega 2, said body of material having an energy transparency range greater than twice the photon energy of the modulated beam and less than the sum of the photon energies of the modulated and unmodulated beams and having absorption for photons of frequency omega 3, means for directing said beams into said body with coincident intensities sufficient to produce significant two-photon absorption throughout a substantial pathlength in said body, and means for extracting for utilization a resultant intensity modulated beam at frequency omega 2.

Claim 3

In an optical communication system, apparatus according to claim 1 in which the body is a fiber of the material, said fiber having transverse dimensions and a low-loss optical environment suitable for optical guiding of the beams at both of said frequencies omega 1 and omega 2.

Claim 4

In an optical communication system, apparatus according to claim 1 in which the body is a film of the material and the directing means include means for coupling said beams through a broad surface of said film.

Claim 5

An optical communication system accordinG to claim 1 in which the sources of the beams have intensities I1 and I2, respectively, satisfying the relationship I1/ omega 1<I2/ omega 2.

Claim 6

An optical communication system according to claim 1 in which the sources of the beams have intensities I1 and I2, respectively, satisfying the relationship I1/ omega 1>I2/ omega 2.

Claim 7

In an optical communication system, optical modulation apparatus comprising a source of an intensity modulated optical beam at frequency omega 1, a source of an unmodulated coherent optical beam at a frequency omega 2 greater than omega 1, means including a body of material having two-photon absorption for respective photons of frequencies omega 1 and omega 2 for generating a photon having a frequency omega 3 which is equal to the sum omega 1 + omega 2, said body of material having an energy transparency range greater than twice the photon energy of the modulated beam and less than the sum of the photon energies of the modulated and unmodulated beams and having absorption for photons of frequency omega 3, means for directing said beams into said body with coincident intensities sufficient to produce significant two-photon absorption throughout a substantial pathlength in said body, and means for extracting for utilization a resultant intensity modulated beam at frequency omega 2.

Claim 8

In an optical communication system, optical modulation apparatus comprising a source of an intensity modulated optical beam at frequency omega 1, a source of an unmodulated coherent optical beam at a frequency omega 2 greater than omega 1, means including a body of material having two-photon absorption for respective photons of frequencies omega 1 and omega 2 for generating a photon having a frequency omega 3 which is equal to the sum omega 1 + omega 2, said body of material having an energy transparency range greater than twice the photon energy of the modulated beam and less than the sum of the photon energies of the modulated and unmodulated beams and having absorption for photons of frequency omega 3, means for directing said beams into said body with coincident intensities sufficient to produce significant two-photon absorption throughout a substantial pathlength in said body, and means for extracting for utilization a resultant intensity modulated beam at frequency omega 2.

Claim 9

In an optical communication system, apparatus according to claim 6 in which the body is a fiber of the material, said fiber having transverse dimensions and a low-loss optical environment suitable for optical guiding of the beams at both of said frequencies omega 1 and omega 2.

Claim 10

In an optical communication system, apparatus according to claim 6 in which the body is a film of the material and the directing means include means for coupling said beams through a broad surface of said film.

Claim 11

An optical communication system according to claim 6 in which the sources of the beams have intensities I1 and I2, respectively, satisfying the relationship I1/ omega 1<I2/ omega 2.

Claim 12

An optical communication system according to claim 6 in which the sources of the beams have intensities I1 and I2, respectively, satisfying the relationship I1/ omega 1>I2/ omega 2.

Claim 13

In an optical communication system, optical modulation apparatus comprising a source of an intensity modulated optical beam at frequency omega 1, a source of an unmodulated coherent optical beam at a frequency omega 2 not equal to omega 1, means including a body of material having two-photon absorption for respective photons of frequencies omega 1 and omega 2 for generating a photon having a frequency omega 3 which is equal to the sum omega 1 + omega 2, said body of material having an energy transparency range greater than twice the photon energy of the modulated beam and less than the sum of the photon energies of the modulated and unmodulated beams and having absorption for photons of frequency omega 3, a passive optical guide adjacent to said body, means for directing said beams into said guide with coincident intensities sufficient to produce significant two-photon absorption by evanescent wave coupling throughout a substantial pathlength in said body, and means for extracting from said guide for utilization a resultant intensity modulated beam at a frequency omega 2.

Claim 14

In an optical communication system, optical modulation apparatus comprising a source of an intensity modulated optical beam at frequency omega 1, a source of an unmodulated coherent optical beam at a frequency omega 2 not equal to omega 1, means including a body of material having two-photon absorption for respective photons of frequencies omega 1 and omega 2 for generating a photon having a frequency omega 3 which is equal to the sum omega 1 + omega 2, said body of material having an energy transparency range greater than twice the photon energy of the modulated beam and less than the sum of the photon energies of the modulated and unmodulated beams and having absorption for photons of frequency omega 3, a passive optical guide adjacent to said body, means for directing said beams into said guide with coincident intensities sufficient to produce significant two-photon absorption by evanescent wave coupling throughout a substantial pathlength in said body, and means for extracting from said guide for utilization a resultant intensity modulated beam at a frequency omega 2.