Wavelength Selective Switch Prism Linearizes Dispersion Angles
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Solution Overview
Problem
Wavelength selective switches face challenges due to non-linear dispersion angles of wavelength components, leading to deteriorated transmission bands and coupling efficiency, particularly when using micro mirror arrays or spatial light modulators, which are difficult to manufacture and control.
Innovation Solution
A wavelength selective switch is designed with a dispersion optical system, a light deflection element, a condensing element, and a prism optical system that linearizes frequency dependency of dispersion angles, ensuring wavelength components are centered on micro mirrors and maintaining efficient optical paths through the use of cascaded dispersion elements and prisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If micro mirrors are arranged at an equal interval in the dispersion direction, then the device complexity is reduced, but the transmission band is deteriorated due to non-linear dispersion angles
Solution Approach 1:
The patent introduces a dispersion correction optical system that changes the optical path lengths for different wavelength components, effectively linearizing the dispersion angle characteristics. This allows equal-interval micro mirror arrangement to achieve both simplified device complexity and improved transmission band reliability
Solution Approach 2:
The dispersion correction optical system acts as an intermediary between the diffraction grating and the micro mirror array, correcting the non-linear dispersion angles before light reaches the micro mirrors. This mediator system enables the micro mirror array to operate with equal spacing while maintaining proper wavelength alignment
2Reliability
If micro mirrors are arranged at an unequal interval to match spatial positions of wavelength components, then the transmission band is improved, but the manufacturing cost and difficulty increase
Solution Approach 1:
By introducing the dispersion correction optical system that modifies optical path lengths, the patent transforms the spatial positioning requirement from non-linear (requiring unequal mirror spacing) to linear (allowing equal spacing). This parameter change in the optical system enables standard manufacturing processes to be used
Solution Approach 2:
The dispersion correction optical system serves as a mediator that decouples the relationship between wavelength and spatial position, allowing the micro mirror array to use simple equal-interval arrangement while still achieving proper wavelength-specific routing through the corrected optical paths
3Power
If a second diffraction grating is used to double the dispersion angle, then the dispersion capability is improved, but the coupling efficiency is deteriorated due to non-matched optical paths
Solution Approach 1:
The dispersion correction optical system acts as an intermediary between the first and second diffraction gratings, correcting the optical path differences introduced by the cascaded grating arrangement. This ensures that wavelength components maintain proper alignment for high coupling efficiency into the micro mirrors
Solution Approach 2:
The dispersion correction optical system performs preliminary correction of the optical paths before light reaches the second diffraction grating and subsequent micro mirrors. This preliminary action ensures that all wavelength components are properly aligned, maintaining high coupling efficiency throughout the double-grating system
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 ensures linear spatial positioning of wavelength components on the light deflection element, maintaining constant channel intervals and improving coupling efficiency by matching dispersion surfaces and focal points, thus simplifying control and reducing manufacturing complexity.
Implementation Method 1
a dispersion optical system dispersing wavelength multiplexing light obtained by multiplexing the plurality of frequency components to the plurality of frequency components by giving a dispersion angle having nonlinear frequency dependency
Implementation Method 2
a condensing element that condensing the plurality of frequency components on the light deflection element
Implementation Method 3
a prism optical system optically coupled to the dispersion optical system and the condensing element, and adapting spatial positions of the frequency components incident on the light deflection element to change linearly for frequencies
Data Source
AI summary
A wavelength selective switch includes a dispersion optical system dispersing wavelength multiplexing light obtained by multiplexing the plurality of frequency components to the plurality of frequency components by giving a dispersion angle having nonlinear frequency dependency to each of a plurality of frequency components; a light deflection element deflecting the plurality of frequency components; a condensing element condensing the plurality of frequency components on the light deflection element; and a prism optical system optically coupled to the dispersion optical system and the condensing element, and adapting spatial positions of the frequency components incident on the light deflection element to change linearly for frequencies by linearizing the frequency dependency of the dispersion angles and making incident the plurality of frequency components on the condensing element.