Photonic Integrated Laser Circuit for Reflection-Resistant Output

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Solution Overview

Problem

Single-mode semiconductor lasers are vulnerable to optical feedback, leading to mode hopping, frequency fluctuations, and noise due to minimal reflected light, especially in systems with counter-propagating beams, which can be mitigated by optical isolators but increase cost, size, and complexity.

Innovation Solution

Photonic integrated circuits (PICs) are designed to reduce sensitivity to reflections by incorporating semiconductor lasers with splitter, attenuator, and high-Q ring resonator configurations, eliminating the need for isolators and stabilizing laser performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical isolators are used to mitigate back-reflections, then laser stability is improved, but device complexity and size increase

Engineering Contradiction:

Improvelaser stabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the optical isolator component from the system by designing a laser cavity with inherent reflection immunity through asymmetric mirror configurations and controlled feedback paths, thereby maintaining laser stability while reducing device complexity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The laser system is designed to be self-regulating against back-reflections through intrinsic cavity design features including asymmetric mirror coatings and feedback control mechanisms that automatically compensate for reflections without requiring external isolator components

Inventive Principle:

Principle #25Self-service

2Reliability

If optical isolators are used to mitigate back-reflections, then laser stability is improved, but system size increases

Engineering Contradiction:

Improvelaser stabilityVSAvoidsystem size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent merges the reflection mitigation function directly into the laser cavity structure itself through asymmetric mirror designs and integrated feedback control, eliminating the need for separate optical isolator components and thereby reducing overall system size

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If counter-propagating beams are used to avoid Doppler broadening, then measurement precision is improved, but sensitivity to back-reflections increases

Engineering Contradiction:

Improvespectral precisionVSAvoidsensitivity to back-reflections

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent employs asymmetric mirror coatings and non-reciprocal optical path designs within the counter-propagating beam system, creating different transmission characteristics for forward and backward propagating light to suppress harmful back-reflections while maintaining spectral precision

Inventive Principle:

Principle #4Asymmetry

4Adaptability or versatility

If bidirectional light propagation is used, then system functionality is improved, but harmful backscatter effects increase

Engineering Contradiction:

Improvesystem functionalityVSAvoidbackscatter effects

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful backscatter effect into a beneficial feedback signal by designing optical paths where backscattered light is redirected through specific optical elements to provide stabilizing feedback to the laser source, transforming a harmful effect into a useful control mechanism

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

PICs provide reduced sensitivity to reflections, enabling stable operation and high-powered outputs without isolators, reducing system size and complexity while maintaining performance.

Implementation Method 1

high-Q ring resonator configurations

Methodology Applied

Scientific EffectOptical resonance: Resonance

Implementation Method 2

attenuator

Methodology Applied

Scientific EffectOptical attenuation: Absorption (EM radiation)

Data Source

PatentUS20260018856A1Photonic integrated circuits with reduced sensitivity to reflections

Publication Date: 2026.01.15 KOMLJENOVIC TIN

AI summary

A device has a first element, comprising a semiconductor laser; a second element, comprising an attenuator providing at least 10 dB of optical attenuation; a third element, comprising a first optical amplifier; and a fourth element, comprising a first output facet. An optical output from the first element is coupled to the second element, an optical output from the second element is coupled to the third element, and an optical output from the third element is coupled to the fourth element. The first, second, third and fourth elements are realized as a single photonic integrated circuit, fabricated on a common substrate.