Passive Optical Circuit Breaker Using Thermal Expansion
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Solution Overview
Problem
Conventional optical switches in aircraft fuel systems do not completely interrupt optical power, posing safety risks in potentially explosive environments and requiring electrical power for operation, which is undesirable.
Innovation Solution
A passive optical circuit breaker using a substrate with a micro-opto-mechanical system (MOMS) comprising optical waveguide portions with different thermal coefficients of expansion, where excessive optical power generates heat to deflect a bendable arm, interrupting the optical path and preventing power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional optical switches are used to limit optical power transmission, then optical power can be reduced, but complete interruption of optical power is not achieved and electrical power is required for operation
Solution Approach 1:
The patent employs thermal expansion phase transition of the bendable arm material. When excessive optical power is detected, the absorptive waveguide converts optical energy to thermal energy, heating the bendable arm and causing it to expand thermally. This phase transition in the material's dimensional state deflects the first optical waveguide portion from alignment with the second optical waveguide portion, completely interrupting the optical path and blocking optical power transmission.
Solution Approach 2:
The patent replaces active electrical control mechanisms with a passive thermal-mechanical system. Instead of using electrical actuators or control electronics to switch the optical path, the invention uses thermal expansion of the bendable arm material to mechanically deflect the waveguide portions. This substitution eliminates the need for electrical power while achieving reliable optical power interruption through purely thermal and mechanical means.
2Object-affected harmful factors
If active optical switches are used to control optical power, then optical power can be limited, but electrical power is required which is undesirable in potentially explosive environments
Solution Approach 1:
The patent implements a self-service mechanism where the optical circuit breaker uses the excessive optical power itself as the triggering signal. The absorptive optical waveguide portion converts the harmful excessive optical energy directly into thermal energy, which then activates the thermal expansion of the bendable arm. This self-service approach eliminates the need for external electrical power sources, sensors, or control systems, making the device inherently safe for use in potentially explosive environments while still achieving effective optical power control.
3Use of energy by moving object
If optical waveguide portions with different thermal coefficients of expansion are used, then passive operation is achieved, but device complexity increases
Solution Approach 1:
The patent exploits differential thermal expansion between materials with different thermal coefficients of expansion. The bendable arm is constructed from or coated with material having a higher thermal coefficient of expansion than the substrate and waveguide portions. When the absorptive waveguide heats up due to excessive optical power, the differential expansion causes the bendable arm to deflect, which in turn deflects the first optical waveguide portion from alignment with the second waveguide portion. This principle enables passive operation while maintaining relatively simple device structure.
Solution Approach 2:
The patent employs composite material construction for the bendable arm, combining materials with different thermal properties. The bendable arm includes material with higher thermal coefficient of expansion (such as metal, elastomer, rubber, or plastic) bonded to or forming part of the optical waveguide portion. This composite structure enables the thermal-mechanical actuation mechanism while integrating multiple functions into a single component, thereby managing device complexity.
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
Ensures complete attenuation of excessive optical power, providing intrinsic safety without electrical components and avoiding material aging issues, while operating passively with received light power.
Implementation Method 1
a first high-loss portion, and wherein optical energy directed through the first high-loss portion exceeds a prescribed threshold causes the first optical waveguide portion to physically deflect
Implementation Method 2
the first optical waveguide portion comprises a material with a higher thermal coefficient of expansion (TCE) than the second optical waveguide portion
Data Source
AI summary
A passive optical circuit breaker includes a substrate and an optical waveguide assembly arranged relative to the substrate. The optical waveguide assembly includes a first optical waveguide portion having a first low-loss portion and a first high-loss portion, and a second optical waveguide portion having a second low-loss portion. The first low-loss portion and the second low-loss portion define a first optical path through the optical waveguide assembly, and optical energy directed through the first high-loss portion exceeding a prescribed threshold causes the first optical waveguide portion to physically deflect relative to the second optical waveguide portion and interrupt the first optical path through the optical waveguide assembly.