Prism-Based Beam Expander for Thermal Stability in Wavelength Selective Switches
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Solution Overview
Problem
Optical systems with dispersive elements, such as wavelength selective switches, face challenges in maintaining consistent diffraction angles due to temperature changes, which can cause wavelength components to deviate from the deflection region, narrowing the available wavelength band, and existing solutions like temperature compensation prisms increase system complexity and hinder downsizing.
Innovation Solution
A dispersive device with a beam expanding optical system comprising a pair of prisms with inclined faces, where the output angle variation due to temperature changes is configured to counteract the variation in diffraction angles from the dispersive element, using a combination of prisms with different refractive index changes and orientations to stabilize the diffraction angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a prism for temperature compensation is added to the dispersive optical system, then the stability of diffraction angles against temperature change is improved, but the device complexity and number of parts increase
Solution Approach 1:
The patent combines the beam expanding function and temperature compensation function into a single integrated optical system. The beam expander's prisms are configured to simultaneously perform beam expansion and compensate for temperature-induced diffraction angle variations, eliminating the need for separate temperature compensation prisms and reducing overall system complexity.
Solution Approach 2:
The prisms in the beam expander are designed to serve multiple functions: they expand the light beam while also providing temperature compensation. This multi-functionality allows the same optical components to address both beam size requirements and thermal stability, thereby reducing the total number of parts needed in the system.
2Volume of moving object
If the number of parts is reduced for downsizing, then the compactness is improved, but the ability to compensate for temperature changes deteriorates
Solution Approach 1:
The patent merges the temperature compensation function into the existing beam expander structure, allowing the same compact components to perform both beam expansion and thermal compensation without requiring additional space or parts.
Solution Approach 2:
The patent adjusts the parameters of the beam expander's prisms (such as their orientation angles and refractive index characteristics) to enable temperature compensation functionality. By optimizing these parameters, the system achieves thermal stability without adding components, thus maintaining compactness while improving reliability.
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 effectively reduces the influence of temperature changes on diffraction angles, maintaining wavelength component alignment and reducing system complexity by minimizing the number of parts, thus enhancing stability and compactness.
Implementation Method 1
a first prism and a second prism each having a pair of faces inclined relative to each other, and expands light containing a plurality of wavelength components by passing the light through each of the faces of the first prism and the second prism
Implementation Method 2
a dispersive element which emits the light expanded by the beam expanding optical system, at different diffraction angles by the respective wavelength components
Data Source
AI summary
A dispersive device has a beam expanding optical system which includes first and second prisms each having a pair of faces inclined relative to each other, and expands light containing a plurality of wavelength components by passing the light through each of the faces of the first and second prisms; and a dispersive element which emits the light expanded by the beam expanding optical system, at different diffraction angles by the respective wavelength components. A direction of variation of an output angle of the light emitted from the beam expanding optical system due to temperature change is configured to be a direction to suppress variation of the diffraction angles of the respective wavelength components emitted from the dispersive element due to the temperature change.