# US 12,007,602 B2 · Quantum enhanced optical modulator or sensor

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- Number: US 12,007,602 B2
- Document ID: US12007602B2
- Status: Granted
- Kind: B2
- Application number: 17/740,027
- Filed: 2022-05-09
- Published: 2022-11-24
- Granted: 2024-06-11
- Earliest claimed: 2021-05-07
- Assignees: The Board of Trustees of the Leland Stanford Junior University
- Applicants: The Board of Trustees of the Leland Stanford Junior University
- Inventors: Amir H. Safavi-Naeini; Timothy Patrick McKenna; Hubert S. Stokowski
- Web page: https://patentgrep.com/patent/US12007602B2

## CPC

- G02B 6/12004: {Combinations of two or more optical elements}
- G02F 1/212: {Mach-Zehnder type}
- G02B 6/12007: {forming wavelength selective elements, e.g. multiplexer, demultiplexer}
- B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals
- G02B 6/29344: {operating by modal interference or beating, i.e. of transverse modes, e.g. zero-gap directional coupler, MMI}
- G02B 2006/1204: {Lithium niobate (LiNbO3)}
- G02B 2006/12097: {Ridge, rib or the like}
- G02B 2006/12138: {Sensor}
- G02B 2006/12142: {Modulator}
- G02F 2203/50: Phase-only modulation
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- 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
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

In an integrated optical device, squeezed light is used internally to effectively increase an optical modulation effect. One exemplary device operates by squeezing the light at the input, then sending it through an electro-optic stage where its phase picks up the signal of interest, and finally anti-squeezing it to obtain a displaced coherent state. Thus the displacement is amplified by the level of squeezing that is achieved inside the device and it is thereby less sensitive to loss. Since this device behaves simply as an electro-optic modulator, albeit one with an exponentially enhanced sensitivity, no extra considerations are needed to integrate the modulator into a system. Such devices can be operated as modulators or as sensors, and can make use of optical phase shift effects other than the electro-optic effect.

## Claims

### Claim 1

Apparatus comprising:
a squeezer configured to transform input coherent-state light to input squeezed-state light;
a passive waveguide splitter configured to receive the input squeezed-state light, and configured to output first squeezed-state light and second squeezed-state light;
a phase shifter configured to impose a relative phase shift between the first squeezed-state light and the second squeezed-state light according to an input of the phase shifter;
a passive waveguide combiner configured to receive the first squeezed-state light and the second squeezed-state light from the phase shifter, and configured to provide output squeezed-state light;
an anti-squeezer configured to receive the output squeezed-state light and configured to provide output coherent-state light.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the squeezer, the passive waveguide splitter, the phase shifter, the passive waveguide combiner and the anti-squeezer are all included in an integrated photonic circuit having a waveguide-coupled optical input and having a waveguide-coupled optical output.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein the integrated photonic circuit is a lithium niobate integrated photonic circuit.

### Claim 4 (depends on 2)

The apparatus of claim 2, wherein the passive waveguide splitter is a multi-mode interference device.

### Claim 5 (depends on 2)

The apparatus of claim 2, wherein the passive waveguide combiner is a multi-mode interference device.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein the phase shifter is a phase modulator, wherein the input to the phase shifter is a provided electrical signal, whereby the apparatus is a modulator that modulates the output coherent-state light according to the provided electrical signal.

### Claim 7 (depends on 1)

The apparatus of claim 1, wherein the phase shifter is a phase sensor, wherein the input to the phase shifter is an unknown signal, whereby the apparatus is a sensor of the unknown signal using the output coherent-state light.