Optomechanical Accelerometer With Ring-Resonator Stress Readout
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Solution Overview
Problem
Conventional optical accelerometers face challenges in large-scale production and chip-scale integration due to reliance on free-space optical cavities, and existing optomechanical accelerometers suffer from high thermal noise and limited mass, which affects sensitivity and thermal stability.
Innovation Solution
Integrated optomechanical accelerometers using silicon nitride photonic micro-ring resonators with a suspended proof mass that generates stress to alter the optical resonant frequency, allowing for stress-based displacement measurement and enabling chip-scale integration through fabrication methods compatible with CMOS processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional free-space optical accelerometers are used, then optical readout provides superior displacement resolution and resilience to electromagnetic interference, but they do not allow for large scale production or chip-scale integration
Solution Approach 1:
The patent merges the optical resonator and proof mass into a single integrated chip structure, eliminating the need for separate free-space optical components. The ring resonator is fabricated using standard semiconductor processing techniques, allowing the entire accelerometer to be manufactured as a monolithic chip that can be directly mounted in electronic circuits.
Solution Approach 2:
The patent replaces conventional mechanical optical readout systems with an optomechanical system where optical resonance frequency shifts detect acceleration. The optical field interacts with the mechanical proof mass through the resonator structure, converting mechanical displacement into optical frequency modulation without requiring complex mechanical optical components.
2Measurement precision
If conventional optical accelerometers are used, then they provide superior displacement resolution, but they involve bulky test masses
Solution Approach 1:
The patent embeds the proof mass within the structure of the ring resonator itself, nesting the movable element inside the optical cavity structure. The proof mass is positioned at the center of the ring resonator and is suspended by flexible beams, allowing it to be fully contained within the chip footprint rather than requiring external bulky mounting space.
Solution Approach 2:
The patent uses thin-film flexible beams to suspend the proof mass from the ring resonator structure. These thin-film elements provide the necessary mechanical compliance while occupying minimal space, allowing the proof mass to be compact yet functional within the integrated chip architecture.
3Ease of manufacture
If existing optomechanical accelerometers are used, then they enable chip-scale integration, but they suffer from high thermal noise and limited mass
Solution Approach 1:
The patent employs composite material structures in the resonator and proof mass fabrication. The device utilizes layers of different materials with complementary properties - such as high-strength, low-expansion materials for structural components and low-loss materials for optical resonators - to simultaneously achieve mechanical stability, thermal noise reduction, and optical performance.
Solution Approach 2:
The patent optimizes key parameters including the proof mass size, resonator frequency, and spring constant to operate at frequencies and amplitudes that minimize thermal noise. The system is designed to operate at frequencies well above the mechanical resonance of the proof mass, reducing thermal excitation while maintaining sensitivity.
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
Achieves high sensitivity and resolution comparable to state-of-the-art accelerometers with reduced thermal noise, facilitating large-scale production and integration, suitable for applications like inertial navigation and dark matter detection.
Implementation Method 1
the proof mass is movable along the perpendicular axis, and one or more springs coupling the proof mass with the first ring resonator. Mechanical displacement of the proof mass can be operable to modify the optical resonant frequency of the first ring resonator
Implementation Method 2
one or more springs can be configured to selectively stretch or contract when the proof mass is mechanically displaced along the perpendicular axis to generate stress or strain adjacent to the first ring resonator
Data Source
AI summary
An optomechanical accelerometer includes an optical ring resonator, a proof mass, and one or more springs coupling the proof mass with the optical ring resonator. The ring resonator defines a perpendicular axis centrally therethrough and an optical resonant frequency. The proof mass is movable along the perpendicular axis. The one or more springs are configured to selectively stretch or contract when the proof mass is mechanically displaced along the perpendicular axis to generate stress or strain on the first ring resonator. Mechanical displacement of the proof mass is operable to modify the optical resonant frequency of the first ring resonator.