Optical Switch Port Arrangement for Crosstalk Reduction
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Solution Overview
Problem
Optical switches using liquid crystal on silicon (LCOS) suffer from crosstalk issues where optical signals are inadvertently output to unintended ports, degrading crosstalk characteristics.
Innovation Solution
An optical switch design featuring a spatial optical modulator with a light incident layer, reflective layer, and a condensing lens, where the spatial optical modulator is positioned at the focal point of the condensing lens, and the optical fiber ports are arranged such that x2≠2x1+x0, preventing secondary reflected light from reaching unintended ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If optical switches use LCOS for switching paths of optical signals with input ports and output ports arranged at equal intervals along a certain direction, then the optical switching operation can be realized by diffracting optical signals, but parts of optical signals may be output to other unintended output ports, degrading crosstalk characteristics
Solution Approach 1:
The patent applies asymmetry by arranging output ports at unequal intervals rather than equal intervals. Specifically, the arrangement satisfies the condition that the distance between the first output port and the second output port is not equal to the distance between the second output port and the third output port. This asymmetric arrangement prevents secondary reflected light from reaching unintended output ports, thereby improving crosstalk characteristics while maintaining optical switching functionality
Solution Approach 2:
The patent changes the geometric parameter of port arrangement from equal intervals to unequal intervals. By adjusting the positions of output ports to satisfy the specific distance relationship condition, the patent modifies the spatial parameters of the optical system to prevent harmful secondary reflections from reaching unintended ports, thus resolving the crosstalk issue
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 significantly improves crosstalk characteristics by ensuring that secondary reflected light is not output to unintended ports, enhancing the optical switch's performance.
Implementation Method 1
LCOS is a spatial optical modulator that is able to modulate a phase of incident light by liquid crystal to diffract it
Implementation Method 2
The LCOS is configured to diffract angles of incident light beams in directions of these arrangements
Implementation Method 3
a condensing lens that is disposed between the optical input-output port and the spatial optical modulator, and optically couples the optical input-output port and the spatial optical modulator
Implementation Method 4
a light reflective layer, and a spatial optical modulation layer disposed between the light incident layer and the light reflective layer
Data Source
AI summary
An optical switch includes: an input-output port with three or more ports arranged along a direction; a modulator that includes an incident layer, a reflective layer, and a modulation layer disposed between these layers, spatially modulates light entering the incident layer from any port of the input-output port, and outputs the light spatially-modulated toward any of other ports of the input-output port; and a condensing lens that optically couples the input-output port and the modulator, wherein x2≠2x1+x0 holds where: a coordinate axis is along the direction of the input-output port and an optical axis of the lens is set as an origin of the coordinate axis; x0, x1, and x2 respectively are coordinates of a first port to/from which light is input/output, and a second port and a third port from/to which light input to or output from the first port is output/input; and x1,x2>0.