Wavelength Converter Thermal Stress Mitigation
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Solution Overview
Problem
The existing wavelength converters using periodically poled lithium niobate (PPLN) face issues with thermal stress due to mismatched thermal expansion coefficients between the light waveguide core, substrate, and support member, leading to variations in light coupling efficiency and effective refractive index, which affect the stability of output light intensity.
Innovation Solution
A wavelength converter configuration with a support structure that contacts the light waveguide core at its end surface to mitigate thermal stress, using a substrate with a lower refractive index and a temperature control element to stabilize the wavelength conversion element, and a metal housing with a support structure positioned to manage thermal expansion and elastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a support member is used to hold the wavelength conversion element, then mechanical stability is improved, but thermal stress increases due to mismatched thermal expansion coefficients
Solution Approach 1:
A support structure made of a material with thermal expansion coefficient matching the substrate is introduced as an intermediary between the substrate and the metal housing. This intermediary absorbs and compensates for thermal expansion differences, preventing thermal stress from being transmitted to the wavelength conversion element while maintaining mechanical stability.
Solution Approach 2:
The thermal expansion coefficient parameter of the support structure is specifically selected to match that of the substrate. By changing this material parameter, the support structure becomes thermally compatible with the substrate, eliminating thermal stress during temperature variations while providing the necessary mechanical support.
2Stability of the object's composition
If the wavelength conversion element is firmly mounted to control position, then positional stability is improved, but light coupling efficiency varies due to elastic deformation
Solution Approach 1:
The elastic modulus parameter of the support structure is selected to be lower than that of the light waveguide core. This parameter change allows the support structure to be compliant and adaptable to the light waveguide core's dimensions, maintaining precise light coupling while providing positional stability through its constrained geometry.
Solution Approach 2:
The support structure is designed with dynamic characteristics that allow it to adapt to thermal expansion and contraction of the substrate. The structure can elastically deform within acceptable limits to maintain contact with the light waveguide core, ensuring consistent light coupling efficiency while providing overall positional stability.
3Productivity
If high light intensity is used to improve conversion efficiency, then wavelength conversion efficiency is improved, but heat generation increases causing temperature rise
Solution Approach 1:
The support structure acts as a thermal intermediary between the substrate and the metal housing. It provides a controlled thermal pathway that dissipates heat generated by high-intensity light while preventing excessive temperature rise in the wavelength conversion element, enabling sustained high-efficiency operation.
Solution Approach 2:
The patent replaces active thermal management mechanisms with a passive thermal management approach using the support structure's material properties and geometry. The support structure's thermal conductivity and heat capacity are optimized to passively dissipate heat, eliminating the need for complex active cooling systems while maintaining wavelength conversion efficiency.
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
This configuration stabilizes light coupling efficiency and effective refractive index, ensuring consistent output power intensity and stable operation, even under high light intensity incidence, by controlling thermal stress and expansion coefficients.
Implementation Method 1
The light waveguide core 11 has a periodically poled structure to produce a nonlinear optical effect
Implementation Method 2
a temperature control element joined to a portion excluding both end portions in another main surface of the substrate, and configured to support the wavelength conversion element and control a temperature of the wavelength conversion element
Implementation Method 3
thermal stress due to mismatched thermal expansion coefficients between the light waveguide core, substrate, and support member
Implementation Method 4
at occurrence of elastic deformation due to a thermal stress during wavelength conversion
Data Source
AI summary
A wavelength converter stabilizes output light intensity in which the light coupling efficiency to a light waveguide core is not easily varied. A mounting structure is adopted in which a substrate of a wavelength conversion element is a material with a lower refractive index for signal light than that of the core, and a support structure that suppresses elastic deformation by supporting the element through a contact at a tip end surface at a position corresponding to both end portions of the core at the occurrence of elastic deformation due to the thermal stress of the element is provided. The support structure is provided at a portion apart from a temperature control element at the top surface of a metal housing bottom surface member, and its top surface is disposed in the vicinity of a portion corresponding to both end portions of the core of the element in a support member.