All-optical A/D conversion using integrated nonlinear guided wave optical circuitry

Claim 3

A method as in claim 1, comprising also directing a predetermined portion of the threshold signal from the last level sensing means to an additional individual optical output means for providing an indication that the intensity of the analog optical input signal is greater than the last (highest) designated intensity.

Claim 4

Apparatus for receiving an analog optical input signal and for providing a digital optical output signal indicative of the intensity of the analog input signal, comprising means for directing the analog optical input signal along a path comprising a series of level sensing means for determining whether the intensity of the analog input signal is above a predetermined threshold and for providing a first binary optical threshold signal of a first predetermined intensity within a first predetermined range of intensities when the intensity of the analog signal is above the threshold, and for providing a second binary optical threshold signal of a second predetermined intensity within a second predetermined range of intensities substantially separated from the first range when the intensity of the analog input signal is not above the threshold; the first level sensing means providing a signal indicating whether the intensity of the input signal is greater than a first (lowest) designated intensity, the second level sensing means providing a signal indicating whether the intensity of the input signal is greater than a second (next to the lowest) designated intensity, the third level sensing means providing a signal indicating whether the intensity of the input signal is greater than a third (next higher, ie next to the next lowest) designated intensity, the fourth level sensing means providing a signal indicating whether the intensity of the input signal is greater than a fourth (next higher) designated intensity, and so on to the last level sensing means providing a signal indicating whether the intensity of the input signal is greater than a last (highest) designated intensity; means for directing a predetermined portion of the threshold signals from the first and second level sensing means to first exclusive-or gate (XOR) means, directing a predetermined portion of the threshold signals from the second and third level sensing means to second XOR means, directing a predetermined portion of the threshold signals from the third and fourth level sensing means to third XOR means, and so on, directing a predetermined portion of the threshold signals from the next-to-last and last level sensing means to a last XOR means (in number one less than that of the last level sensing means); each XOR means comprising means for providing a first binary optical signal (indicating inequality) of a third predetermined intensity within a third predetermined range of intensities when one of the threshold signals directed to it has the first predetermined intensity and the other threshold signal directed to it has the second predetermined intensity, and for providing a second binary optical signal (indicating equality) of a fourth predetermined intensity within a fourth predetermined range of intensities substantially separated from the third range when both of the threshold signals directed to it have the first predetermined intensity and when both of the threshold signals directed to it have the second predetermined intensity; and means for directing the digital optical signal from each XOR means to at least one of a plurality of individual optical output means according to a designated digital coding system, whereby each available combination of signals in the plurality of individual output means provides a digital indication of the specific range of optical intensities within which is the intensity of the analog optical input signal.

Claim 5

Apparatus for receiving an analog optical input signal and for providing a digital optical output signal indicative of the intensity of the analog input signal, comprising means for directing the analog optical input signal along a path comprising a series of level sensing means for determining whether the intensity of the analog input signal is above a predetermined threshold and for providing a first binary optical threshold signal of a first predetermined intensity within a first predetermined range of intensities when the intensity of the analog signal is above the threshold, and for providing a second binary optical threshold signal of a second predetermined intensity within a second predetermined range of intensities substantially separated from the first range when the intensity of the analog input signal is not above the threshold; the first level sensing means providing a signal indicating whether the intensity of the input signal is greater than a first (lowest) designated intensity, the second level sensing means providing a signal indicating whether the intensity of the input signal is greater than a second (next to the lowest) designated intensity, the third level sensing means providing a signal indicating whether the intensity of the input signal is greater than a third (next higher, ie next to the next lowest) designated intensity, the fourth level sensing means providing a signal indicating whether the intensity of the input signal is greater than a fourth (next higher) designated intensity, and so on to the last level sensing means providing a signal indicating whether the intensity of the input signal is greater than a last (highest) designated intensity; means for directing a predetermined portion of the threshold signals from the first and second level sensing means to first exclusive-or gate (XOR) means, directing a predetermined portion of the threshold signals from the second and third level sensing means to second XOR means, directing a predetermined portion of the threshold signals from the third and fourth level sensing means to third XOR means, and so on, directing a predetermined portion of the threshold signals from the next-to-last and last level sensing means to a last XOR means (in number one less than that of the last level sensing means); each XOR means comprising means for providing a first binary optical signal (indicating inequality) of a third predetermined intensity within a third predetermined range of intensities when one of the threshold signals directed to it has the first predetermined intensity and the other threshold signal directed to it has the second predetermined intensity, and for providing a second binary optical signal (indicating equality) of a fourth predetermined intensity within a fourth predetermined range of intensities substantially separated from the third range when both of the threshold signals directed to it have the first predetermined intensity and when both of the threshold signals directed to it have the second predetermined intensity; and means for directing the digital optical signal from each XOR means to at least one of a plurality of individual optical output means according to a designated digital coding system, whereby each available combination of signals in the plurality of individual output means provides a digital indication of the specific range of optical intensities within which is the intensity of the analog optical input signal.

Claim 6

Apparatus as in claim 3, comprising also means for directing a predetermined portion of the threshold signal from the last level sensing means to an additional individual optical output means for providing an indication that the intensity of the analog optical input signal is greater than the last (highest) designated intensity.

Claim 7

Apparatus as in claim 3, comprising also means for receiving an analog electrical signal and providing an analog optical signal having an intensity that is a monotonic function of the magnitude thereof as the input signal to the input directing means.

Claim 8

Apparatus as in claim 3, comprising also means responsive to each individual optical output means for providing an electrical signal indicating the level of intensity of the light received from each XOR means.

Claim 9

Apparatus as in claim 3, wherein the path along which the analog input signal is directed comprises channel waveguide means.

Claim 10

Apparatus as in claim 3, wherein the intensity of the analog input signal decreases monotonically as it travels along the path, and the level sensing means comprise a series of threshold gate means spaced apart along the path and each having substantially the same threshold level.

Claim 11

Apparatus as in claim 3, wherein the level sensing means comprise nonlinear waveguide threshold gate means.

Claim 12

Apparatus as in claim 3, wherein the XOR means comprise single-mode channel waveguide XOR gate means.

Claim 13

Apparatus as in claim 3, wherein the path along which the analog input signal is directed comprises channel waveguide means and a plurality of evanescent coupler means.

Claim 14

Apparatus as in claim 3, wherein each means for directing a portion of a threshold signal comprises beam splitting means.

Claim 15

Apparatus as in claim 3, wherein all of the directing means include channel waveguide means.

Claim 16

Apparatus as in claim 3, wherein the level sensing means comprise threshold gate means with orthogonal channels.

Claim 17

Apparatus as in claim 3, wherein the XOR means comprise waveguide XOR gate means having negative nonlinearity.

Claim 18

Apparatus as in claim 3, wherein the XOR means comprise waveguide XOR gate means having positive nonlinearity.