Integrated PLC Optical Receiver for WDM Signal Demodulation

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Solution Overview

Problem

Conventional optical receiver implementations for WDM systems require multiple planar lightwave circuits (PLCs) with tight alignment, leading to increased size and manufacturing costs, and complex optical and electrical circuitry for demodulating DQPSK signals.

Innovation Solution

A high-capacity optical receiver design featuring a planar lightwave circuit with a substrate integrated tunable filter, demultiplexer, and optical processor, which includes a bit-delay interferometer and variable optical attenuator, allowing for efficient demultiplexing and demodulation of WDM signals on a single substrate, reducing signal loss and footprint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple discrete PLCs are used for optical receiver components, then functional requirements are met, but alignment precision and manufacturing complexity increase

Engineering Contradiction:

Improvesignal alignmentVSAvoidPLC alignment tolerance

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent combines multiple optical receiver components (tunable filter, demultiplexer, optical processor) that were previously implemented on separate PLCs into a single integrated PLC device. This integration eliminates the need for precise alignment between multiple discrete PLCs, thereby resolving the technical contradiction by maintaining signal alignment reliability while reducing manufacturing precision requirements.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If multiple discrete PLCs are used for optical receiver components, then functional requirements are met, but device footprint and manufacturing cost increase

Engineering Contradiction:

Improvereceiver functionalityVSAvoidoptical circuit footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent integrates multiple optical receiver components onto a single PLC substrate, consolidating what was previously a distributed multi-PLC architecture. This merging reduces the overall device footprint and simplifies manufacturing while maintaining full receiver functionality, directly addressing the contradiction between functional reliability and physical size.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If multiple discrete PLCs are used for optical receiver components, then functional requirements are met, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvesignal processing capabilityVSAvoidoptical circuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent consolidates multiple discrete PLC components into a single integrated device, reducing system complexity by eliminating inter-PLC connections and interfaces. The integration maintains all necessary signal processing capabilities while simplifying the overall device structure and reducing manufacturing complexity.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If conventional receiver implementations are used, then existing technology is maintained, but signal loss and manufacturing costs increase

Engineering Contradiction:

Improvetechnology compatibilityVSAvoidsignal loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent integrates the tunable filter, demultiplexer, and optical processor on a single PLC substrate, eliminating optical interfaces between separate components. This integration reduces signal loss by removing connection points while maintaining compatibility with existing WDM and DQPSK technologies.

Inventive Principle:

Principle #5Merging (Combining)

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

The integrated design enhances the capacity and reduces manufacturing costs by minimizing signal loss and aligning complexities, while maintaining high signal processing efficiency for DQPSK signals.

Implementation Method 1

The tunable filter is configured to filter at least one of a bandwidth or a wavelength of a Wavelength Division Multiplexed (WDM) optical input signal

Methodology Applied

Scientific EffectWavelength filtering: Filter (optical)

Implementation Method 2

The optical processor includes a bit-delay interferometer communicating with a respective one of the plurality of outputs of the demultiplexer

Methodology Applied

Scientific EffectOptical interference: Interference

Data Source

PatentUS8213799B2Optical receiver including a filter on a planar lightwave circuit

Publication Date: 2012.07.03 INFINERA CORP

AI summary

A planar lightwave circuit (PLC) includes a substrate, a tunable filter, a demultiplexer (DEMUX), and an optical processor each disposed on the substrate. The tunable filter is configured to filter at least one of a bandwidth or a wavelength of a Wavelength Division Multiplexed (WDM) optical input signal. The DEMUX is connected to the tunable filter and configured to receive a filtered WDM optical input signal at an input and to supply one of a plurality of channels of the filtered WDM input signal at a respective one of a plurality of outputs. Each of the plurality of channels corresponds to one of a plurality of wavelengths of the filtered WDM input signal. The optical processor includes a bit-delay interferometer communicating with a respective one of the plurality of outputs of the DEMUX. The optical processor is configured to receive one of the plurality of channels from the DEMUX and output a plurality of demodulated optical signal components.