LCoS Voltage Control via Bit Sequence Segmentation for Phase Jitter Reduction
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Solution Overview
Problem
Existing optical wavelength selective switches based on liquid crystal on silicon (LCoS) face challenges in reducing phase jitter of pixels, leading to degradation of optical signal-to-noise ratio (OSNR) and uneven filter spectra due to asynchronous voltage switching across different wavelengths.
Innovation Solution
The method involves controlling voltages of LCoS two-dimensional arrays by using bit sequences with the same duty ratios for pixel sets in different phase cycles in the port direction and the same bit sequences for adjacent pixels in the wavelength direction, ensuring synchronized phase modulation and reduced jitter across wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If different bit sequences are applied to adjacent pixels in the wavelength direction to reduce jitter, then phase jitter of pixels is reduced, but jitter of different wavelengths becomes asynchronous causing uneven filter spectrum
Solution Approach 1:
The patent divides the LCoS array into multiple pixel sets based on phase cycles in the port direction, and applies different bit sequences to different pixel sets. This segmentation allows independent control of voltage switching for each pixel set, enabling jitter reduction while maintaining synchronous filtering across all wavelengths through coordinated control of the segmented groups.
Solution Approach 2:
The patent applies different bit sequences to different pixel sets located in different phase cycles, giving each pixel set customized voltage control according to its specific phase characteristics. This local differentiation reduces phase jitter for each pixel set while the overall system maintains even filter spectrum through the coordinated operation of all pixel sets.
2Manufacturing precision
If voltage switching speed is increased to reduce phase jitter, then pixel phase stability improves, but OSNR degradation occurs due to asynchronous voltage switching across wavelengths
Solution Approach 1:
The patent uses periodic voltage switching controlled by bit sequences with specific duty ratios for different pixel sets. By coordinating the periodic action across different pixel sets with appropriate phase relationships, the system achieves fast voltage switching for jitter reduction while maintaining synchronous filtering that preserves OSNR.
Solution Approach 2:
The patent implements a control method that considers the phase cycle information of each pixel set when selecting bit sequences. This feedback mechanism ensures that voltage switching is coordinated across different wavelengths, reducing phase jitter while preventing OSNR degradation through synchronous filtering 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 approach effectively reduces phase jitter, maintains even filter spectra, and enhances the optical signal-to-noise ratio by synchronizing voltage switching across different wavelengths, thereby improving the performance of LCoS-based wavelength selective switches and ROADM devices.
Implementation Method 1
Different voltages are loaded onto a liquid crystal particle in the liquid crystal layer to implement different phase modulation on the pixel
Implementation Method 2
The phase of the pixel depends on a voltage loaded onto the pixel
Data Source
AI summary
Embodiments of the present application provide a method for controlling voltages of a liquid crystal on silicon (LCoS) two-dimensional array which includes a plurality of pixel sets, and the plurality of pixel sets include a first pixel set and a second pixel set. The method includes: determining a plurality of bit sequences, where the plurality of bit sequences include a first bit sequence and a second bit sequence; controlling a voltage of the first pixel set by using the first bit sequence; and controlling a voltage of the second pixel set by using the second bit sequence, where the first pixel set and the second pixel set are in different phase cycles in a port direction of the LCoS two-dimensional array, the first pixel set and the second pixel set have a same phase, and duty ratios of the first bit sequence and the second bit sequence are the same.