Tunable Filter Wavelength Selection via Movable Mirror Substrate
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Solution Overview
Problem
Conventional tunable filters face challenges in accurately selecting desired wavelength distributions due to difficulties in manufacturing precise membrane thicknesses and refractive indexes, and in accurately moving mirrors and shielding bodies, which affects their precision and reliability in wavelength selection.
Innovation Solution
A tunable filter design incorporating an optical branching element, a light focusing element, a mirror or slit substrate with multiple reflection or slit regions, and a driver that moves the substrate to adjust the reflection or slit positions, allowing for precise control over wavelength selection and focusing of dispersed light onto a common plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of membranes in the multilayer membrane is increased to achieve narrower wavelength selection, then the manufacturing precision requirement increases, but the ease of manufacture deteriorates
Solution Approach 1:
The invention divides the wavelength selection function into two independent parts: (1) a fixed multilayer membrane that disperses light into wavelength-specific belts, and (2) a movable mirror substrate with reflection regions that selectively reflect desired wavelengths. This segmentation allows the multilayer membrane to have fewer layers (easier manufacturing) while the mirror substrate handles the precise wavelength selection through positional adjustment.
Solution Approach 2:
The mirror substrate is designed to be movable in the direction perpendicular to the belt-shaped light distribution, allowing dynamic adjustment of which wavelength band is reflected. This dynamic positioning enables precise wavelength selection without increasing the complexity or number of layers in the fixed multilayer membrane structure.
2Adaptability or versatility
If the mirror and shielding body are moved to select wavelength, then the wavelength selection flexibility improves, but the movement precision requirement increases
Solution Approach 1:
The invention changes the dimension of movement from lateral (in the plane of light distribution) to perpendicular (out of the plane). The mirror substrate moves in the direction perpendicular to the belt-shaped light distribution, which allows wavelength selection through positional adjustment without requiring high-precision lateral movement mechanisms. The reflection regions are arranged to correspond to different wavelength bands, and moving the substrate perpendicular to the light distribution direction enables selection of different wavelengths.
3Measurement precision
If the multilayer membrane thickness and refractive index are precisely controlled to achieve desired wavelength distribution, then the wavelength selection accuracy improves, but the manufacturing complexity increases
Solution Approach 1:
The invention extracts the precise wavelength selection function from the multilayer membrane structure and transfers it to the movable mirror substrate. Instead of relying on precisely controlling the thickness and refractive index of multiple membrane layers, the design uses a simpler multilayer membrane for basic dispersion and achieves precise wavelength control through the positional adjustment of reflection regions on the mirror substrate.
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 design enables accurate and flexible wavelength selection with improved precision and tolerance to movement errors, allowing for sharp and digital wavelength characteristics, and continuous shifting of wavelength selection, enhancing the reliability of tunable filters in optical communication networks and measurement systems.
Implementation Method 1
an optical branching element for spatially dispersing an incident light for each of wavelengths in the incident light to output the dispersed lights and for making a selected reflected light be incident toward an incident direction of said incident light
Implementation Method 2
a light focusing element for focusing the lights of respective wavelengths dispersed for each of wavelengths in said optical branching element on an identical plane with keeping a relative relationship of incident position
Implementation Method 3
a mirror substrate which is provided in a movable state at a position on which belt-shaped lights from said light focusing element are focused, and includes a plurality of reflection regions different for each of the lights of wavelengths to be selected, wherein said reflection regions are arranged at an arbitrary position toward a direction different from a distribution direction of said belt-shaped lights
Data Source
AI summary
A light is incident on a refractive diffraction grating 13, and is distributed for each of wavelengths at different angles to be outputted. A lens 14 converts the distributed lights into belt-shaped lights, and the belt-shaped lights are incident on a mirror substrate 15 having selective reflection regions 17-1 to 17-x. By moving the mirror substrate 15 toward a direction different from a distribution direction of the belt-shaped lights, only the light of any one of wavelengths is reflected. Then, the light returning to the refractive diffraction grating 13 is reflected to an incident direction of the original light. Accordingly, a tunable filter which is able to select a light of an arbitrary wavelength by moving the mirror substrate 15 can be realized.