Optical Node WSS Pixel Drive to Prevent Pixel Burning
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Solution Overview
Problem
Reflective spatial light modulators in optical networks suffer from pixel burning, which compromises their reliability.
Innovation Solution
An optical node device with a WSS array that includes two independent WSS devices sharing a single optical system and reflective liquid crystal display device, allowing independent operation and reducing optical complexity while minimizing pixel burning through a subframe driving method and alternating current driving of liquid crystal elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflective spatial light modulator is used in a WSS device, then the device can achieve wavelength selection and routing functions, but pixel burning occurs which reduces reliability
Solution Approach 1:
The patent applies periodic action by alternating the polarity of the voltage applied to liquid crystal pixels between consecutive frames. Specifically, even-numbered frames use a positive voltage polarity while odd-numbered frames use a negative voltage polarity. This periodic polarity reversal prevents charge accumulation and eliminates pixel burning, thereby improving the reliability of the reflective spatial light modulator in WSS devices.
2Adaptability or versatility
If multiple WSS devices are used independently, then routing flexibility is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple independent WSS devices into a single integrated device. The single WSS device includes a reflective spatial light modulator with multiple pixel arrays that can be independently controlled to perform the functions of multiple separate WSS devices. This consolidation maintains routing flexibility while reducing overall device complexity by eliminating redundant components and optical paths.
Solution Approach 2:
The patent implements universality by designing a single WSS device with multi-functional pixel arrays that can perform various routing functions. The liquid crystal pixels can be configured to route different wavelengths to different output ports, and the same hardware can adapt to different routing configurations without requiring separate dedicated devices for each function.
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
Improves reliability by preventing pixel burning and enhancing gradation performance, allowing high-speed communication networks to maintain signal quality and reduce noise interference.
Implementation Method 1
a liquid crystal display element LC having a liquid crystal LCM held between a reflective electrode PE and a common electrode CE
Implementation Method 2
The WSS that utilizes a spatial light modulator using a reflective liquid crystal display device
Data Source
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AI summary
Each of multiple pixels of a spatial light modulator of an optical node device includes: a first switching circuit and a first signal holding circuit that sample and hold normal gradation data or inverted gradation data; and a second switching circuit and a second signal holding circuit that sample the normal gradation data or the inverted gradation data held in the first signal holding circuit at a common timing to all of the multiple pixels, hold the normal gradation data or the inverted gradation data for one subframe period, and apply the normal gradation data or the inverted gradation data to a reflective electrode. The spatial light modulator drive unit applies alternating current voltage having a positive polarity and a negative polarity to liquid crystal by inverting voltage in a common electrode of a liquid crystal display element and supplies a voltage having an amplitude different from an amplitude between the normal gradation data and the inverted gradation data to the common electrode.