Wavelength Selective Coupler for Photonic Chip Pump Light Blocking

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Solution Overview

Problem

Photonic integrated circuits require a large number of optical components to block pump light from entering the semiconductor layer, leading to increased cost and size due to the absorption of pump light causing signal power loss through free carrier absorption.

Innovation Solution

A photonic chip with a two-layer wavelength selective coupler is used, where the device layer is optically coupled with a port layer in a wavelength selective manner to block pump wavelengths while allowing signal wavelengths to pass through, eliminating the need for external optical isolators and reducing component count.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If optical isolators are used to block pump light from entering the semiconductor layer, then pump light blocking is achieved, but device complexity and system size increase

Engineering Contradiction:

Improvepump light blockingVSAvoidnumber of optical components

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the pump light blocking function with the existing waveguide structure by forming a wavelength selective coupler that integrates both signal transmission and pump rejection functionalities. This eliminates the need for separate optical isolators and reduces the total component count while maintaining effective pump light blocking.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The waveguide structure is designed to perform multiple functions simultaneously: it transmits signal light at the first wavelength while blocking pump light at the second wavelength. This multi-functional design eliminates the need for dedicated separate components for each function, thereby reducing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Object-affected harmful factors

If optical isolators are used to prevent pump light from entering the transceiver, then pump light blocking is achieved, but the size of the optical transceiver system increases

Engineering Contradiction:

Improvepump light blockingVSAvoidsize of optical transceiver system

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The patent combines the pump light blocking function into the existing waveguide structure through wavelength selective coupling, eliminating the need for separate optical isolators. This integration reduces the overall volume of the optical transceiver system while maintaining effective pump light blocking.

Inventive Principle:

Principle #5Merging (Combining)

3Power

If pump light enters the semiconductor layer to pump the EDFA, then optical amplification is achieved, but signal power is lost through free carrier absorption

Engineering Contradiction:

Improveoptical amplificationVSAvoidsignal power loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent segments the optical functions by separating signal light transmission and pump light blocking into different wavelength channels. The wavelength selective coupler allows signal light at the first wavelength to enter the semiconductor layer for amplification while blocking pump light at the second wavelength, thereby preventing free carrier absorption and signal power loss.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes wavelength as a distinguishing parameter to separate signal and pump light. By designing the coupler to be selective at different wavelengths, the system allows signal light to pass while blocking pump light, thus preventing the harmful interaction between pump light and the semiconductor layer that causes free carrier absorption.

Inventive Principle:

Principle #35Parameter changes

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 effectively blocks pump light from entering the device layer, reducing signal loss and eliminating the need for additional optical components, thereby decreasing the size and cost of the optical transceiver system.

Implementation Method 1

optically coupling the port waveguide to a device waveguide disposed in the device layer in a wavelength selective manner so that the device waveguide is optically coupled to the port waveguide at the first wavelength λ1 but is substantially optically decoupled at the second wavelength λ2

Methodology Applied

Scientific EffectWavelength selective coupling: Filter (optical)

Implementation Method 2

the device layer may be absorptive at the second wavelength

Methodology Applied

Scientific EffectAbsorption: Absorption (EM radiation)

Data Source

PatentUS11409036B2Input waveguide arrangement in a photonic chip

Publication Date: 2022.08.09 NOKIA SOLUTIONS & NETWORKS OY

AI summary

A photonic chip includes a device layer and a port layer, with an optical port located at the port layer. Inter-layer optical couplers are provided for coupling light between the device and port layers. The inter-layer couplers may be configured to couple signal light but block pump light or other undesired wavelength from entering the device layer, operating as an input filter. The port layer may accommodate other light pre-processing functions, such as optical power splitting, that are undesirable in the device layer.