UV–Visible Acousto-Optic Modulators for Single-Sideband Operation
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Solution Overview
Problem
Scaling acousto-optic devices to ultraviolet and visible wavelength ranges is challenging due to high acoustic frequencies and short wavelengths, leading to inefficient electro-mechanical transduction and difficulty in tuning, particularly for achieving single-sideband modulation.
Innovation Solution
An acousto-optic modulator with a waveguide and acoustic actuator that strongly confines both optical and acoustic energies, enabling strong optomechanical coupling and supporting dual- or single-sideband operations through intra- or inter-modal conversion, using specific materials and configurations to enhance coupling coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic frequencies are increased to achieve backward AO scattering at UV wavelengths, then single-sideband modulation is enabled, but electro-mechanical transduction efficiency deteriorates due to very short acoustic wavelengths
Solution Approach 1:
The patent transitions from traditional backward AO scattering (one-dimensional interaction) to forward AO scattering with orthogonal acoustic wave propagation (two-dimensional interaction). By launching acoustic waves normal to the light direction rather than counter-propagating, the system achieves single-sideband modulation at UV wavelengths without requiring extremely high acoustic frequencies that would cause transduction inefficiency.
Solution Approach 2:
The patent changes the acoustic wave propagation direction parameter from counter-propagating (backward) to orthogonal (forward). This parameter change allows the system to operate at lower acoustic frequencies while still achieving single-sideband modulation, thereby improving electro-mechanical transduction efficiency while maintaining measurement precision.
2Measurement precision
If acoustic frequencies are increased to achieve backward AO scattering, then single-sideband modulation is enabled, but device tunability deteriorates
Solution Approach 1:
By changing from backward to forward AO scattering geometry, the patent enables independent tuning of acoustic wave parameters without being constrained by the need for precise counter-propagating phase matching. This dimensional change in wave propagation approach significantly improves device tunability while maintaining single-sideband modulation capability.
3Reliability
If waveguide dimensions are reduced to confine optical and acoustic energies, then optomechanical coupling strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs composite waveguide structures combining different materials with complementary properties. This allows the waveguide to achieve strong confinement of both optical and acoustic energies through material interfaces rather than relying solely on extremely tight dimensional tolerances, thereby reducing manufacturing precision requirements while maintaining strong optomechanical coupling.
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 modulator achieves efficient phase modulation and single-sideband functionality, with coupling coefficients improved by two orders of magnitude, facilitating advanced optical signal processing applications.
Implementation Method 1
an acousto-optic modulator with a waveguide and acoustic actuator that strongly confines both optical and acoustic energies, enabling strong optomechanical coupling
Implementation Method 2
achieving backward AO scattering (analog of the traditional backward stimulated Brillouin scattering (SBS))
Implementation Method 3
a waveguide on a surface of the acoustic actuator (the waveguide guiding an optical signal)
Implementation Method 4
the acoustic actuator includes an active layer, a first electrode on a surface of the active layer, and a second electrode
Data Source
AI summary
An acousto-optic modulator that includes a waveguide on an acoustic actuator is disclosed. The waveguide carries an optical signal having a UV or visible wavelength. When the acoustic actuator is activated, the optical signal in the waveguide is bathed in intense acoustic waves. By using a waveguide having the appropriate dimensions to strongly confine both the optical signal and the acoustic waves, strong optomechanical coupling may be achieved between the optical and acoustic modes, resulting in an efficient modulator. By employing either intra-modal or inter-modal conversion, the modulator may be used to implement a variety of dual- or single-sideband functions, including an isolator, a phase modulator, a single-sideband frequency shifter, or a high-extinction shutter.