Wavelength Selective Optical Switch Crosstalk Reduction
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Solution Overview
Problem
Wavelength selective optical switches experience significant inter-port crosstalk due to high-order diffracted components and Fresnel reflected light, which degrades the optical switching quality and fails to meet the desired signal leakage standards of at least 30 dB, especially in complex optical networks.
Innovation Solution
A wavelength selective optical switch design incorporating a space phase modulator with a multi-level optical phased array and strategically positioned output ports to minimize crosstalk, where the angle of reflection for other input and output ports is set to avoid high-order diffracted light, using a saw tooth waveform phase shift and controlled voltage on LCOS pixels to direct wavelengths effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-level optical phased array is used for wavelength selection, then wavelength selection capability is improved, but inter-port crosstalk increases due to high-order diffraction
Solution Approach 1:
The patent converts the harmful high-order diffraction light into a beneficial element by strategically positioning output ports to receive these diffracted beams. The space phase modulator generates high-order diffraction at equal angle spacing, and by placing output ports at positions corresponding to these diffraction angles, the previously harmful crosstalk becomes useful signal light, thereby improving system efficiency and reducing loss.
Solution Approach 2:
The patent transitions from conventional single-port output architecture to a multi-dimensional port arrangement where output ports are positioned in different angular dimensions. By utilizing the angular dimension created by high-order diffraction, the system accommodates multiple output ports simultaneously, each receiving light at specific diffraction angles, thus transforming a two-dimensional beam control problem into a three-dimensional spatial arrangement.
2Productivity
If output ports are positioned to receive high-order diffracted light, then signal utilization is improved, but crosstalk from unselected ports increases
Solution Approach 1:
The patent applies local quality by assigning different angular reception characteristics to different output ports. Each output port is positioned to receive light at a specific diffraction angle corresponding to its designated wavelength channel. This localized angular selectivity ensures that each port optimally receives its intended signal while being naturally isolated from other channels, thus improving signal utilization without introducing crosstalk.
3Ease of operation
If conventional wavelength selective switches are used, then basic wavelength switching is achieved, but inter-port crosstalk exceeds acceptable levels of 30-40 dB
Solution Approach 1:
The patent introduces asymmetry in the angular positioning of output ports relative to the input port. Instead of symmetric arrangement, output ports are positioned at asymmetric angles corresponding to high-order diffraction angles (e.g., ±30°, ±60°). This asymmetric configuration creates angular isolation between input and output ports, preventing feedback and reducing crosstalk to below 30 dB, thereby improving reliability while maintaining ease of operation.
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 reduces crosstalk between ports, enhancing the optical switching quality and ensuring compliance with stringent signal leakage requirements, thereby improving the performance of wavelength selective optical switches in optical communications systems.
Implementation Method 1
In a space phase modulator that uses a multi-level optical phased array, high-order diffraction is seen at equal spacing regardless of the order of diffraction.
Implementation Method 2
a wavelength dispersion element that spatially disperses signal light according to a wavelength of the signal light, and synthesizes reflected light
Implementation Method 3
a condenser element that condenses light dispersed by the wavelength dispersion element on a two-dimensional plane
Implementation Method 4
uses a multi-level optical phased array that periodically changes a phase shift quantity in the y-axis direction for the pixels on the x-axis in a saw tooth waveform
Data Source
AI summary
A wavelength selective optical switch includes an incidence/emergence unit that includes an input port at which signal light made up of light of numerous wavelengths is incident and an output port at which light signals of selected wavelengths are emergent, a wavelength dispersion element that spatially disperses signal light according to a wavelength of the signal light, and synthesizes reflected light, a condenser element that condenses light dispersed by the wavelength dispersion element on a two-dimensional plane, a space phase modulator arranged so as to receive incident light deployed on an xy plane made up of an x-axis direction deployed according to wavelength and a y-axis direction orthogonal to the x-axis direction, and having numerous pixels arranged in a lattice on the xy plane, and a space phase modulator drive unit.