Crystallized Glass Substrate for Optical Multiplexer Thermal Stability
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Solution Overview
Problem
Optical wavelength multiplexers/demultiplexers face challenges in maintaining positional accuracy between optical elements due to temperature changes, leading to increased size and complexity in control systems.
Innovation Solution
A crystallized glass plate with a specific composition and thermal expansion characteristics, including 55-75% SiO2, 20.5-27% Al2O3, 2-8% Li2O, 1.5-3% TiO2, 0.1-0.5% SnO2, 3.8-5% TiO2+ZrO2, and both β-quartz and β-spodumene solid solutions, is used to minimize thermal expansion differences within the range of -40°C to 80°C, ensuring minimal deformation and maintaining optical element alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional glass materials are used for the substrate, then the manufacturing process is simple, but the relative positional relationship between optical elements changes when temperature changes
Solution Approach 1:
The patent changes the thermal expansion parameter of the substrate material by selecting a specific crystallized glass composition (containing β-quartz and β-spodumene solid solutions) whose thermal expansion characteristics match those of the optical elements. This parameter matching ensures that the relative positional relationship between optical elements remains stable across temperature changes, eliminating the need for complex control systems.
Solution Approach 2:
The patent uses a composite crystallized glass material containing multiple crystal phases (β-quartz solid solution and β-spodumene solid solution) to achieve specific thermal expansion properties. This composite material structure allows the substrate to have tailored thermal characteristics that match the optical elements, thereby maintaining positional accuracy without requiring additional adjustment mechanisms.
2Reliability
If optical path adjustment devices are added to compensate for temperature changes, then positional accuracy is maintained, but the size of the device increases
Solution Approach 1:
The patent extracts the thermal expansion compensation function from the optical path adjustment device and transfers it to the substrate material itself. By selecting a crystallized glass with matched thermal expansion characteristics, the substrate inherently compensates for temperature-induced dimensional changes, eliminating the need for separate adjustment devices and reducing overall device size.
Solution Approach 2:
The substrate material performs the thermal compensation function for itself and the mounted optical elements through its inherent thermal expansion properties. The crystallized glass substrate automatically maintains the relative positional relationship between optical elements across temperature changes without requiring external control systems or adjustment mechanisms.
3Reliability
If feedback control systems are implemented to adjust optical paths, then positional accuracy is maintained, but the control system becomes more complex
Solution Approach 1:
The patent converts the harmful effect of thermal expansion into a beneficial property by selecting a crystallized glass substrate whose thermal expansion characteristics match those of the optical elements. This material selection transforms the temperature-induced dimensional changes from a problem requiring active control into an inherent property that automatically maintains positional accuracy.
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 approach allows for an optical wavelength multiplexer/demultiplexer that does not require path adjustment, maintaining relative positional stability and reducing the need for complex control systems by minimizing thermal expansion variations.
Implementation Method 1
a value (ΔL max -ΔL min ) /L obtained by dividing a difference between a maximum value ΔL max and a minimum value ΔL min of ΔL in a range of -40°C to 80°C by L is 8×10 -6
Implementation Method 2
both β-quartz solid solution and a β-spodumene solid solution as a crystal phase
Implementation Method 3
containing a β-quartz solid solution and a β-spodumene solid solution as a crystal phase
Data Source
Figure 1~2
Figure 3
AI summary
What is achieved is an optical wavelength multiplexer/demultiplexer not necessarily requiring the function of adjusting the optical path. A value (ΔLmax-ΔLmin)/L obtained by dividing a difference between a maximum value ΔLmax and a minimum value ΔLmin of ΔL in a range of -40°C to 80°C by L is 8×10-6 or less where L represents a length of a crystallized glass (1) at 30°C and ΔL represents a difference between a length (Lt) of the crystallized glass (1) at each of the temperatures and the length (L) thereof at 30°C.