Thick Layer for LCOS Assembly Thermal Mismatch
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Solution Overview
Problem
Liquid crystal on silicon (LCOS) assemblies in optical communication systems face misalignment due to temperature-induced changes in thermal expansion mismatch between components, leading to beam shift and steering angle issues, which can be costly and energy-intensive to correct.
Innovation Solution
Incorporating a thick layer with a specific thickness, typically greater than 5 micrometers, between the LCOS carrier and switching engine to reduce thermal sensitivity, thereby controlling temperature-induced curvature and maintaining alignment across a temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If components with different coefficients of thermal expansion are used in the LCOS assembly, then material selection flexibility and functional performance are improved, but temperature-induced misalignment and optical sensitivity worsen
Solution Approach 1:
A thick layer (at least 5 micrometers) of material is introduced as an intermediary between the LCOS carrier and the switching engine. This intermediate layer acts as a buffer that decouples the thermal expansion mismatch between components, allowing flexible material selection while reducing temperature-induced misalignment and optical sensitivity
Solution Approach 2:
The patent employs composite material structures where the thick layer is composed of materials with specific thermal and mechanical properties that bridge the gap between components with different coefficients of thermal expansion, thereby maintaining structural integrity while compensating for thermal mismatch
2Measurement precision
If thermoelectric coolers or heat sink materials are used to correct temperature-induced misalignment, then alignment precision is improved, but device complexity and energy consumption worsen
Solution Approach 1:
The thick layer is designed to passively compensate for thermal expansion mismatch through its inherent material properties and geometric configuration. The structure automatically adjusts for temperature variations without requiring active cooling systems, control electronics, or external power sources, thereby maintaining alignment precision while avoiding increased device complexity and energy consumption
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 thick layer significantly reduces temperature-induced beam shift or steering angle to less than 1 millidegree per degree Celsius, improving durability, reducing costs, and enhancing optical performance without the need for thermoelectric coolers or heat sink materials.
Implementation Method 1
The LCOS assembly may include components associated with multiple different materials. For example, the LCOS assembly may include an LCOS carrier of a first type of material, such as aluminum nitride and/or the like, associated with a first coefficient of thermal expansion and an LCOS die of a second type of material, such as silicon and/or the like, associated with a second coefficient of thermal expansion that differs from the first coefficient of thermal expansion by a threshold amount.
Implementation Method 2
Based on a mismatch between coefficients of thermal expansion and a thermal sensitivity of the LCOS assembly, a change in temperature may cause the LCOS assembly to become misaligned with one or more other optical elements of an optical communication system.
Data Source
AI summary
A liquid crystal on substrate (LCOS) assembly may include an LCOS carrier. The LCOS assembly may include at least one thick layer on the LCOS carrier and associated with a threshold thickness. The threshold thickness may be at least 5 micrometers. The LCOS assembly may include a switching engine on the at least one thick layer. The switching engine may include an LCOS die and an LCOS cover glass to enclose an LCOS liquid. The LCOS assembly may be associated with a thermal sensitivity of less than 0.5 millidegrees of curvature per degree Celsius for a particular temperature range.