Optical Filter Glass Ceramic for Stable Center Wavelength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical filters face issues with refractive index fluctuations due to temperature changes, lack of durability, and poor workability, particularly in bandpass filters used in wavelength division multiplexing systems.
Innovation Solution
A glass ceramic with specific compositions and properties, including thermal expansion characteristics, mechanical strength, and high light transmittance, is developed for optical filters, which can be used as a substrate for dielectric films to stabilize the center wavelength and enhance durability and workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass is used as substrate material for bandpass filter, then durability and heat resistance are improved, but refractive index fluctuates with temperature changes
Solution Approach 1:
The patent changes the thermal expansion parameter of the substrate material by using glass ceramic with specifically controlled composition (containing 40-70 wt% SiO2, 11-25 wt% Al2O3, 5-19 wt% Na2O, and other components) to achieve a thermal expansion coefficient of 70-95×10^-7/°C, which matches the dielectric film and stabilizes the center wavelength
Solution Approach 2:
The patent uses glass ceramic as a composite material that combines the advantages of glass (durability, heat resistance, optical transparency) with controlled thermal expansion properties. The glass ceramic contains specific crystal phases (MgAl2O4, MgTi2O4, Mg2SiO4, etc.) that provide both mechanical strength and thermal stability
2Strength
If glass ceramic with high mechanical strength is used, then durability is improved, but workability deteriorates due to high hardness
Solution Approach 1:
The patent optimizes the chemical composition parameters of the glass ceramic to achieve a balance between mechanical strength and workability. By controlling the content of network formers (SiO2, Al2O3) and network modifiers (Na2O, MgO, ZnO, TiO2), the patent achieves both high strength and appropriate hardness for manufacturing
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 glass ceramic provides thermal stability and mechanical strength, ensuring minimal refractive index fluctuations and excellent workability, making it suitable for bandpass filters in harsh conditions.
Implementation Method 1
an internal transmittance of the glass ceramic being 0.970 or more with respect to light having a wavelength of 1550 nm when a thickness of the glass ceramic is 1 mm
Implementation Method 2
having a thermal expansion coefficient from 70×10−7/° C. to 95×10−7/° C. at −30° C. to +70° C.
Data Source
AI summary
A glass ceramic for an optical filter and an optical filter are obtained that have both thermal expansion characteristics for preventing refractive index fluctuations at a usage temperature of a filter member and mechanical characteristics considering durability, and further have excellent workability. An internal transmittance of the glass ceramic for an optical filter is 0.970 or more with respect to light having a wavelength of 1550 nm when a thickness of the glass ceramic is 1 mm. The glass ceramic includes, by mass % in terms of oxide, 40.0% to 70.0% of a SiO2 component, 11.0% to 25.0% of an Al2O3 component, 5.0% to 19.0% of a Na2O component, 0% to 9.0% of a K2O component, 1.0% to 18.0% of one or more components selected from a MgO component and a ZnO component, 0% to 3.0% of a CaO component, and 0.5% to 12.0% of a TiO2 component.