LCOS Local Buffers for Voltage Stability

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Solution Overview

Problem

Existing liquid crystal on silicon (LCOS) systems for optical switches face challenges in managing varying capacitance loads, which can lead to instability in voltage supply and affect the routing of optical signals.

Innovation Solution

The implementation of a LCOS system that includes multiple pixels, a pixel voltage supply source, an external buffer, and local buffers to buffer the voltage source and external buffer from subsets of pixels, reducing capacitance load variations and stabilizing the voltage supply.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a voltage source supplies voltage directly to multiple pixels in an LCOS system, then the system structure remains simple, but varying capacitance loads from the pixels cause instability in voltage supply

Engineering Contradiction:
Improvevoltage supply stabilityVSAvoidbuffer circuit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the pixel array into multiple subsets, with each subset connected to a dedicated local buffer. This segmentation isolates the capacitance load variations of different pixel subsets, preventing them from collectively affecting the voltage source stability. Each local buffer manages only its assigned subset's loading effects, thereby improving overall voltage supply stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces local buffers as intermediary components between the voltage source and pixel subsets. These buffers act as mediators that decouple the direct connection, allowing the voltage source to supply voltage without being directly affected by the varying capacitance loads of the pixels. The external buffer and local buffers together form a layered intermediary structure that protects the voltage source from load variations.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If local buffers are added to buffer subsets of pixels, then capacitance load variations are reduced and voltage supply is stabilized, but the device complexity increases

Engineering Contradiction:
Improveoptical signal routing reliabilityVSAvoidnumber of buffer components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the pixel array into multiple subsets, each served by a dedicated local buffer. This segmentation allows the system to manage complexity in a distributed manner rather than requiring a single complex buffer for all pixels. Each local buffer handles a manageable subset, making the overall system complexity more controllable while still achieving improved reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different buffering configurations to different parts of the system: an external buffer for the overall voltage source and local buffers for specific pixel subsets. This local quality approach allows targeted buffering where most needed, optimizing the balance between reliability improvement and complexity addition, rather than uniformly buffering all connections.

Inventive Principle:
Principle #3Local quality

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 stabilizes the voltage supply and reduces load variations, enhancing the reliability and efficiency of optical signal routing in LCOS-based optical switches.

Implementation Method 1

Through introduction and alteration of electrical voltage applied to the pixels, the pixels create an electrically controlled grating that routes the particular channel in a deflected direction

Methodology Applied
Scientific EffectLiquid crystal electro-optic effect: Electro-Optic Effects

Implementation Method 2

The external buffer is configured to buffer the voltage source from the pixels. The local buffer is configured to buffer the external buffer from a subset of pixels of the plurality of pixels

Methodology Applied
Scientific EffectCapacitance buffering: Capacitance

Data Source

PatentEP2949127B1Local buffers in a liquid crystal on silicon chip
Publication Date: 2018.10.24 FINISAR CORP
  • EP2949127B1 patent drawingFigure 1A
  • EP2949127B1 patent drawingFigure 1B
  • EP2949127B1 patent drawingFigure 2

AI summary

An example embodiment includes a liquid crystal on silicon (LCOS) system. The LCOS system includes multiple pixels, a pixel voltage supply source (voltage source), an external buffer, and a local buffer. The voltage source is configured to supply an analog ramp to the pixels. The external buffer is configured to buffer the voltage source from the pixels. The local buffer is configured to buffer the external buffer from a subset of pixels of the plurality of pixels.