Reversed PLC Splitter Multiplexing for Optical Transceivers

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Solution Overview

Problem

Optical transceivers face challenges in scaling down while maintaining performance due to issues like insertion loss and polarization-dependent loss, which affect optical efficiency and power stability across channels, especially with temperature changes and wavelength drift.

Innovation Solution

A reversed planar lightwave circuit (PLC) splitter is used as an optical multiplexer, providing wavelength-independent branched waveguides that combine optical signals, reducing susceptibility to temperature-induced wavelength drift and offering consistent channel-to-channel power stability and increased connectivity flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional optical multiplexers are used, then channel density and speed can be increased, but insertion loss and polarization-dependent loss increase, reducing optical efficiency and power stability

Engineering Contradiction:

Improvechannel density and transmission speedVSAvoidinsertion loss and polarization-dependent loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent inverts the conventional PLC splitter configuration by reversing the input and output ports. This inversion transforms the device into an effective optical multiplexer while utilizing the wavelength-independent nature of the reversed splitter to achieve consistent insertion loss across all channels, thereby resolving the contradiction between high channel density and low insertion loss.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The reversed PLC splitter serves multiple functions: it acts as both a splitter and a multiplexer, and its wavelength-independent design provides universal performance across different optical channels. This multi-functionality allows the device to maintain optical efficiency while supporting high channel density and transmission speeds.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

If conventional wavelength-dependent multiplexers are used, then optical signals can be multiplexed, but the system becomes susceptible to temperature-induced wavelength drift, reducing power stability

Engineering Contradiction:

Improveoptical signal multiplexing capabilityVSAvoidpower stability against temperature drift

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

By inverting the PLC splitter configuration, the patent creates a multiplexer that is wavelength-independent. This means the device does not rely on specific wavelength matching between input signals and device characteristics, making it inherently immune to temperature-induced wavelength drift and thereby maintaining stable power output across varying thermal conditions.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the operational parameter from wavelength-dependent to wavelength-independent by inverting the PLC splitter. This parameter change eliminates sensitivity to wavelength variations caused by temperature changes, ensuring reliable and stable optical signal multiplexing across different environmental conditions.

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If optical transceivers are scaled down for smaller modules, then form factor is reduced, but maintaining nominal performance becomes more difficult due to increased loss and thermal management challenges

Engineering Contradiction:

Improvetransceiver module sizeVSAvoidoptical efficiency and thermal management

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The inverted PLC splitter configuration reduces the number of optical components and interfaces required in the transceiver module. By combining splitting and multiplexing functions in a single reversed device, the patent minimizes component count and optical path length, thereby reducing insertion loss and simplifying thermal management in compact form factors.

Inventive Principle:

Principle #13The other way round (Inversion)

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 reversed PLC splitter maintains consistent power across channels, reduces temperature-dependent insertion loss variations, and enhances connectivity flexibility, enabling efficient multiplexing of optical signals in optical transceivers.

Implementation Method 1

The optical multiplexer includes a plurality of mux input ports optically coupled to the respective TOSAs for receiving the optical signals, a plurality of branched waveguides extending from the mux input ports to the mux output port

Methodology Applied

Scientific EffectOptical waveguide: Waveguide (optics)

Data Source

PatentUS9923635B2Optical transmitter or transceiver including reversed planar lightwave circuit (PLC) splitter for optical multiplexing

Publication Date: 2018.03.20 APPLIED OPTOELECTRONICS INC(US)

AI summary

A multi-channel optical transmitter or transceiver uses a reversed planar lightwave circuit (PLC) splitter as an optical multiplexer to combine optical signals at different channel wavelengths into a multiplexed optical signal. The reversed PLC splitter includes splitter output ports that are used as the mux input ports and a splitter input port that is used as the mux output port. The mux input ports may be optically coupled to respective transmitter optical subassembly (TOSA) modules with or without optical fibers. The PLC splitter includes wavelength independent branched waveguides that combine the optical signals received on the mux input ports into the multiplexed optical signal on the mux output port.