Multi-Channel AOM Phase Modulation for Beam Stability

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Solution Overview

Problem

Acousto-optic modulators in laser systems suffer from beam pointing errors and intensity fluctuations due to thermal transients and inter-channel acoustic crosstalk, which affect the stability and precision of quantum state manipulation systems.

Innovation Solution

A multi-channel acousto-optic modulator system with phased array transducer electrodes and RF drivers configured to drive electrodes with different phases, implementing phase modulation instead of amplitude modulation to reduce thermal gradients and inter-channel crosstalk, thereby maintaining constant RF power and improving beam stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If amplitude modulation is used in acousto-optic modulators, then beam intensity control is achieved, but thermal transients cause beam pointing errors and intensity fluctuations

Engineering Contradiction:
Improvebeam intensity controlVSAvoidbeam pointing stability
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent changes the modulation parameter from amplitude to phase. The acousto-optic modulator applies phase modulation instead of amplitude modulation, where the acoustic wave introduces a phase shift to the optical beam proportional to the acoustic amplitude. This phase modulation approach eliminates thermal transients and their associated beam pointing errors while maintaining beam intensity control through the phase-dependent diffraction efficiency.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If multiple channels are used in acousto-optic modulators, then multi-beam control is achieved, but inter-channel acoustic crosstalk occurs

Engineering Contradiction:
Improvemulti-beam controlVSAvoidinter-channel crosstalk
Core Design Contradiction:
Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent segments the acoustic field into independent channels using separate piezoelectric transducers for each optical channel. Each transducer generates an acoustic wave that is spatially and temporally independent, allowing individual phase modulation of each optical beam without affecting other channels. This segmentation eliminates inter-channel acoustic crosstalk while maintaining multi-beam control capability.

Inventive Principle:
Principle #1Segmentation

3Reliability

If phase modulation is implemented, then thermal gradients are reduced, but device complexity increases due to phased array transducers

Engineering Contradiction:
Improvebeam stabilityVSAvoidphased array transducer configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple independent piezoelectric transducers into a phased array configuration that shares a common optical path and acousto-optic medium. By merging the transducers in this way, the system achieves phase modulation capability and reduced thermal gradients while minimizing the increase in device complexity through shared components and integrated control electronics.

Inventive Principle:
Principle #5Merging (Combining)

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 phase modulation approach significantly reduces beam deflection and intensity fluctuations, enhancing pointing stability and reducing polarization corruption, making it suitable for precise applications like quantum state manipulation and ion trap systems.

Implementation Method 1

An electric RF signal oscillates and drives the transducer to vibrate and create sound waves within the transparent medium

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

create sound waves within the transparent medium which effect the properties of an optical field in the medium via the photo elastic effect, in which a modulating strain field of an ultrasonic wave is coupled to an index of refraction

Methodology Applied
Scientific EffectPhotoelastic effect: Photoelasticity

Implementation Method 3

The index of refraction is changed by moving periodic planes of expansion and compression in the acousto-optic bulk material. Incoming light scatters because of the resulting periodic index modulation and interference, similar to Bragg diffraction.

Methodology Applied
Scientific EffectBragg diffraction: Bragg Diffraction

Data Source

PatentEP3319017B1Multi-channel laser system including an acousto-optic modulator (AOM) and related methods
Publication Date: 2020.03.18 HARRIS CORP
  • EP3319017B1 patent drawingFigure 1
  • EP3319017B1 patent drawingFigure 2
  • EP3319017B1 patent drawingFigure 3~4

AI summary

A method may include generating a laser light beam with a laser source, splitting the laser light beam into a first front side beam and a back side beam for a back side of an ion trap using a first beamsplitter, directing the front side beam to a second beamsplitter using an input telescope, and splitting the first front side beam into a plurality of second front side beams directed to a common acousto-optic medium using a second beamsplitter. The common acousto-optic medium may have a respective plurality of electrodes coupled to the common acousto-optic medium for each of the second front side beams. The method may further include directing the plurality of second front side beams to a front side of the ion trap using an output telescope, and generating a respective RF drive signal for each of the plurality of electrodes using a plurality of RF drivers.