Optical Switch Miniaturization via Spatial Light Modulator Phase Control
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Solution Overview
Problem
Conventional wavelength selective switches are limited by long distances between optical fibers and spatial deflection elements, leading to miniaturization challenges and increased module height due to high-order diffracted light causing crosstalk, which reduces the number of available ports.
Innovation Solution
The implementation of a spatial light modulating section with a phase distribution that compensates for the wavefront curvature, allowing for miniaturization by optimizing the distance between optical lenses and ports, and using a spectroscopic element to enhance port selection and reduce crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance from optical fibers to spatial deflection element is increased to accommodate conventional optical systems, then the optical system can function properly, but the overall size of the optical switch increases and miniaturization is prevented
Solution Approach 1:
The patent combines the spatial light modulator and concave mirror into a single integrated component, eliminating the need for separate elements and reducing the overall optical path length. This merging allows the optical switch to maintain functionality while achieving miniaturization.
Solution Approach 2:
The patent transitions from a conventional linear optical path to a folded optical configuration where light travels through the spatial light modulator and reflects off a mirror at an angle. This dimensional change in the optical path allows for a more compact arrangement of components, reducing the overall device size while maintaining proper optical functionality.
2Ease of operation
If conventional phase modulation switching is used, then switching function is achieved, but high-order diffracted light is generated causing crosstalk and reducing the number of available ports
Solution Approach 1:
The patent changes the phase modulation parameter from conventional linear phase to quadratic phase distribution across the spatial light modulator. This parameter change transforms the diffraction pattern, eliminating high-order diffracted light and the associated crosstalk while maintaining the switching function.
Solution Approach 2:
The patent converts the harmful effect of diffraction into a beneficial outcome by using quadratic phase modulation. Instead of suppressing diffraction, the design exploits it to create a focused beam pattern that directs light to specific output ports without generating harmful high-order diffracted light, thereby eliminating crosstalk.
3Adaptability or versatility
If the number of switch ports is increased to meet network demands, then connectivity is improved, but the required device area increases and module height increases
Solution Approach 1:
The patent uses angular multiplexing where multiple output ports are arranged in different angular directions rather than only in linear arrays. This allows multiple ports to be packed into a compact footprint by utilizing the angular dimension, increasing the number of ports without proportionally increasing the device area or module height.
Solution Approach 2:
The patent changes the phase modulation parameter to quadratic phase, which creates a focused beam pattern that allows multiple output ports to be positioned more closely together. This parameter change enables higher port density within the same physical footprint, increasing adaptability without expanding the device area.
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 approach enables the miniaturization of wavelength selective switches, doubles the number of switch ports, and suppresses crosstalk, resulting in a lower-profile optical switch module.
Implementation Method 1
a phase distribution is set for the spatial light modulating section, the phase distribution including a superimposition of a phase distribution that compensates for a radius of curvature of a wavefront of the optical signal obtained at a time of incidence and a phase distribution that allows the deflected optical signal to be coupled to the output port
Implementation Method 2
The propagated optical signal is converted by a cylinder lens 13 into a condensed beam in a direction perpendicular to the sheet of FIG. 10
Implementation Method 3
The optical signal reflected by the concave mirror then propagates as a dispersive beam in the vertical direction in the sheet of FIG. 10
Implementation Method 4
The wavelength division multiplexing signal having entered the diffraction grating 14 is angularly diverged by the diffraction grating 14 and thus diffracted in different directions depending on the wavelength
Data Source
AI summary
An optical switch includes an input port, output ports, and a spatial light modulating section that receives an optical signal from the input port to deflect the optical signal to a selected one of the output ports. A phase distribution with the same radius of curvature as that of a wavefront of the optical signal and a phase distribution that allows the deflected optical signal to be coupled to the output port are set for the spatial light modulating section.