DFWM Squeezed Light Source With Repump Noise Suppression

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Solution Overview

Problem

Current techniques for generating quadrature-squeezed light require high input powers and various optical components, making them impractical for low-power and portable applications.

Innovation Solution

A degenerate four-wave mixing (DFWM) squeezed light apparatus using one or more pump beams, a probe beam, a vapor cell, and a repump beam, configured to generate two-mode squeezed light with reduced excess noise, utilizing a balanced differential detector or joint homodyne detector, and a portable diode laser, with input powers no greater than 150 mW.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If current techniques are used to generate quadrature-squeezed light, then squeezing performance is achieved, but high input power and complex optical components are required

Engineering Contradiction:

Improvesqueezing performanceVSAvoidinput power

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent changes the operating parameters by using degenerate four-wave mixing in a vapor cell at room temperature, achieving squeezing with pump powers of only 50-150 mW compared to the high powers required by conventional methods. This parameter change enables low-power operation while maintaining squeezing performance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces complex mechanical optical component systems with a simpler vapor cell-based DFWM system. The vapor cell approach eliminates the need for multiple optical components and high-power laser systems, achieving the same squeezing function with reduced complexity and power consumption

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If current techniques are used to generate quadrature-squeezed light, then squeezing performance is achieved, but device size and complexity increase

Engineering Contradiction:

Improvesqueezing performanceVSAvoidoptical components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into a single vapor cell system. The vapor cell simultaneously provides the nonlinear medium for DFWM, the atomic vapor for the squeezing process, and the confinement structure, eliminating the need for separate optical components and reducing overall device complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The vapor cell serves multiple functions: it acts as the nonlinear optical medium, provides the atomic vapor for quantum correlations, and serves as the interaction chamber for all beams. This multi-functionality reduces the number of components needed while maintaining squeezing performance

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Use of energy by moving object

If pump power is reduced to achieve low-power operation, then power consumption decreases, but excess noise increases

Engineering Contradiction:

Improvepower consumptionVSAvoidexcess noise

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a repump beam as an intermediary to reduce atomic decoherence in the vapor cell. This repump beam suppresses spontaneous emission and reduces excess noise, enabling low-power operation (50-150 mW) to achieve squeezing without the noise penalty that would normally accompany reduced pump power

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The apparatus achieves squeezing of at least 3 dB below shot noise, providing a low-power, portable, and compact squeezed light source for improved optical measurements and quantum communication protocols.

Implementation Method 1

The atomic vapor is configured to interact with the overlapped pump and probe beams to generate an amplified probe beam and a conjugate beam

Methodology Applied

Scientific EffectDegenerate four-wave mixing:

Implementation Method 2

The repump beam is configured to optically pump the atomic vapor to a ground state and decrease atomic decoherence of the atomic vapor

Methodology Applied

Scientific EffectOptical pumping:

Implementation Method 3

The balanced differential detector or the joint homodyne detector is configured to measure squeezing due to quantum correlations between the amplified probe beam and the conjugate beam

Methodology Applied

Scientific EffectHomodyne detection: Homodyne Detection

Data Source

PatentUS12418155B2Low-power source of squeezed light

Publication Date: 2025.09.16 THE MITRE CORPORATION

AI summary

A degenerate four-wave mixing (DFWM) squeezed light apparatus includes one or more pump beams, a probe beam, a vapor cell, a repump beam, and a detector. The one or more pump beams includes an input power of no greater than about 150 mW. The vapor cell includes an atomic vapor configured to interact with overlapped pump and probe beams to generate an amplified probe beam and a conjugate beam. The repump beam is configured to optically pump the atomic vapor to a ground state and decrease atomic decoherence of the atomic vapor. The detector is configured to measure squeezing due to quantum correlations between the amplified probe beam and the conjugate beam. The one or more pump beams, the probe beam, and the repump beam are configured to generate two-mode squeezed light by DFWM with squeezing of at least 3 dB below shot noise.