Wavelength Selective Switch Elliptical Beam Shaping
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Solution Overview
Problem
Existing wavelength selective switches face challenges in accurately controlling optical paths due to beam shape elongation and pixel density limitations, leading to increased device size and limited bandwidth, especially when the optical axis is inclined relative to the diffraction grating.
Innovation Solution
A wavelength selective switch design incorporating an input/output unit, a wavelength dispersive element, and a free space optical system that converts the beam shape to have a smaller size in one plane and a larger size in another, with a long axis inclined relative to the first direction, utilizing a beam director with phase-modulating elements arranged to correspond to the beam shape, ensuring efficient deflection of wavelength components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the beam shape is elongated in the phase modulation direction and the number of pixels is increased, then the optical path control accuracy is improved, but the size of the phase modulation element increases
Solution Approach 1:
The patent transforms the beam shape from a circular cross-section to an elliptical cross-section, changing the dimensional distribution of optical energy. By making the beam elongated in the phase modulation direction (one dimension) while compressing it in the orthogonal direction, the patent achieves better pixel utilization without increasing the overall size of the phase modulation element. This dimensional transformation allows the beam to cover more pixels along the modulation axis while maintaining a compact form factor.
2Adaptability or versatility
If the optical axis is inclined with respect to the normal of the diffraction grating, then the beam can be deflected to different output ports, but the beam shape becomes inclined and pixels are not properly assigned, limiting bandwidth
Solution Approach 1:
The patent introduces asymmetry in the beam shape by creating an elliptical cross-section with the major axis inclined relative to the diffraction grating normal. This asymmetric beam configuration, combined with the inclined optical axis, allows the beam to properly align with the pixel array even when deflected to different output ports. The inclined elliptical shape ensures that the beam energy distribution matches the pixel arrangement, preventing pixel misassignment and maintaining full bandwidth utilization across all deflection angles.
3Productivity
If the beam shape is converted to an ellipse with inclined long axis, then pixel assignment is optimized and bandwidth is increased, but the optical system complexity increases
Solution Approach 1:
The patent changes the physical parameters of the beam, specifically transforming it from a circular to an elliptical cross-section with a specific inclination angle. This parameter change is achieved through optical elements that modify the beam's wavefront and intensity distribution. By carefully controlling the elliptical parameters (axis ratio and inclination angle), the patent optimizes pixel utilization and bandwidth without requiring complex additional optical components, thus achieving high productivity with manageable system complexity.
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 allows for precise control of optical paths and increased bandwidth by optimizing the beam director's phase modulation pattern, reducing the size of the wavelength selective switch while maintaining efficient deflection and output signal quality.
Implementation Method 1
a wavelength dispersive element dispersing the beam input from the input port into wavelength components along a second direction intersecting the first direction
Implementation Method 2
a beam director deflecting the wavelength component in the first direction to direct the wavelength component to the predetermined output port
Data Source
AI summary
A wavelength selective switch includes a wavelength dispersive element that divides a beam input from an input port, a beam director that deflects a wavelength component, and a free space optical system that optically couple a input/output unit, the wavelength dispersive element, and the beam director. The free space optical system converts a shape of the beam such that a size extending in a second plane is relatively smaller than a size extending in a first plane, and to have a long axis and a short axis in a third plane. The long axis is inclined with respect to the first direction. The beam director includes a beam directing region in which a plurality of beam directing elements are arranged. The beam directing region deflects the respective wavelength components toward the predetermined output port. The beam directing region is provided to correspond to the shape of the beam.