# US 10,837,827 B2 · System and method for photonic analog-to-digital conversion

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- Number: US 10,837,827 B2
- Document ID: US10837827B2
- Status: Granted
- Kind: B2
- Application number: 16/826,008
- Filed: 2020-03-20
- Published: 2020-09-24
- Granted: 2020-11-17
- Earliest claimed: 2020-03-20
- Assignees: Luminous Computing, Inc.
- Applicants: Luminous Computing, Inc.
- Inventors: Mitchell A. Nahmias; Michael Gao
- Web page: https://patentgrep.com/patent/US10837827B2

## CPC

- G01J 1/44: Electric circuits {(for command of an exposure part G03B7/02)}
- G01J 1/0437: {using masks, aperture plates, spatial light modulators, spatial filters, e.g. reflective filters}
- G01J 1/0488: {with spectral filtering}
- G01J 1/4228: {arrangements with two or more detectors, e.g. for sensitivity compensation}
- G02F 7/00: Optical analogue/digital converters
- H03M 1/12: Analogue/digital converters ({H03M1/001 – } H03M1/10 take precedence)
- G01J 2001/4242: {Modulated light, e.g. for synchronizing source and detector circuit}
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)

## Abstract

A system for analog-to-digital conversion, preferably including one or more optical inputs, optical sources, phase remodulators, and/or photonic circuits, and optionally including detector banks and/or digital electronics. A method for analog-to-digital conversion, preferably including receiving an optical input signal, generating a phase-modulated optical signal, and/or generating a plurality of optical outputs, and optionally including generating a plurality of electrical outputs and/or encoding a digital representation of the outputs.

## Claims

### Claim 1

A method for analog-to-digital conversion, the method comprising:
receiving an analog input signal and a first optical carrier;
based on the analog input signal, modulating a phase of the first optical carrier to generate a phase-modulated optical signal;
at a photonic circuit, receiving the phase-modulated optical signal and a second optical carrier;
at the photonic circuit, generating a spatially-separated plurality of optical outputs based on the phase-modulated optical signal, comprising, at a coupler of the photonic circuit, interfering the phase-modulated optical signal with the second optical carrier;
at a detector bank comprising a plurality of detectors, receiving the spatially-separated plurality of optical outputs, wherein each optical output of the spatially-separated plurality of optical outputs is received by a different detector of the plurality of detectors; and
at the detector bank, generating a set of binary outputs, comprising, for each optical output of the spatially-separated plurality of optical outputs: generating, based on the optical output, a respective binary output of the set;
wherein the set of binary outputs is indicative of a value associated with the analog input signal.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first optical carrier is substantially identical to the second optical carrier.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
receiving an optical carrier input; and
splitting the optical carrier input into the first and second optical carriers.

### Claim 4 (depends on 1)

The method of claim 1, wherein the analog input signal is an optical signal.

### Claim 5 (depends on 4)

The method of claim 4, wherein modulating the phase of the first optical carrier to generate the phase-modulated optical signal comprises, at a non-linear optical element:
receiving the analog input signal and the first optical carrier; and
modulating the phase of the first optical carrier via a non-linear optical effect.

### Claim 6 (depends on 5)

The method of claim 5, wherein the first optical carrier is the analog input signal.

### Claim 7 (depends on 6)

The method of claim 6, wherein the non-linear optical effect results in self-phase modulation of the first optical carrier within the non-linear optical element.

### Claim 8 (depends on 5)

The method of claim 5, wherein:
the first optical source comprises light within a first wavelength band;
the analog input signal comprises light within a second wavelength band, wherein the first and second wavelength bands are non-overlapping; and
the non-linear optical effect results in cross-phase modulation of the first optical carrier within the non-linear optical element.

### Claim 9 (depends on 8)

The method of claim 8, further comprising, after modulating the phase of the first optical carrier, separating the light within the second wavelength band from the phase-modulated optical signal via spectral filtering.

### Claim 10 (depends on 1)

The method of claim 1, wherein:
the analog input signal is an electrical signal;
the analog input signal is received at a phase modulator; and
the phase modulator modulates the phase of the first optical carrier to generate the phase-modulated optical signal.

### Claim 11 (depends on 10)

The method of claim 10, wherein the phase modulator is a microresonator.

### Claim 12 (depends on 10)

The method of claim 10, wherein:
the first optical carrier comprises light within a plurality of wavelength channels;
the phase modulator is a wavelength-selective modulator associated with a modulation band, wherein the modulation band is tunable, in response to the analog input signal, over a modulation window that spans the plurality of wavelength channels; and
modulating the phase of the first optical carrier to generate the phase-modulated optical signal comprises modulating the phase of light of a first wavelength channel of the plurality.

### Claim 13 (depends on 12)

The method of claim 12, wherein:
the plurality of wavelength channels consists of k wavelength channels;
the spatially-separated plurality of optical outputs consists of m single-channel outputs; and
generating the spatially-separated plurality of optical outputs further comprises:
receiving, from the coupler, a spatially-separated plurality of multi-channel signals consisting of n multi-channel signals, wherein n=m/k; and
for each multi-channel signal of the plurality, at a respective spectral filter bank, splitting the multi-channel signal into k single-channel outputs.

### Claim 14 (depends on 10)

The method of claim 10, further comprising:
receiving an optical analog signal; and
generating the analog input signal based on the optical analog signal.

### Claim 15 (depends on 1)

The method of claim 1, wherein the first and second optical carriers are substantially static.

### Claim 16 (depends on 1)

The method of claim 1, wherein the coupler comprises a multi-mode interference coupler.

### Claim 17 (depends on 1)

The method of claim 1, wherein the set of binary outputs defines a one-hot representation of the value.

### Claim 18 (depends on 17)

The method of claim 17, further comprising, based on the set of binary outputs, generating a serialized digital representation of the value.

### Claim 19 (depends on 1)

The method of claim 1, wherein each binary output of the set is an electrical output.

### Claim 20 (depends on 1)

The method of claim 1, wherein the value is indicative of an intensity of the analog input signal.