Balancing Optical Losses in Semiconductor Waveguides

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Solution Overview

Problem

In semiconductor optical waveguides, differential path losses between branches of couplers lead to imbalanced photodetector responsivities, affecting the accuracy of coherent detection systems by introducing variations in optical losses.

Innovation Solution

Applying a negative bias voltage to the waveguide sections of an optoelectronic device, specifically determining and applying bias voltages to equalize optical losses between waveguide sections, utilizing mechanisms such as the Franz-Keldysh effect and Free Carrier Plasma Effect to minimize absorption, thereby reducing optical loss differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a balanced detector is used to eliminate DC components, then the ability to remove DC components is improved, but differential path losses between branches cause imbalanced photodetector responsivities

Engineering Contradiction:

ImproveDC component elimination capabilityVSAvoidphotodetector responsivity balance

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies reverse bias voltage to the waveguide sections to dynamically adjust and balance the optical losses between different branches. By changing the electrical parameter (bias voltage), the optical properties of the waveguide are modified to compensate for manufacturing imperfections and achieve balanced photodetector responsivities.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces physical/mechanical adjustment methods with electrical control. Instead of mechanically adjusting waveguide dimensions or positions to balance losses, the invention uses electrical bias voltage applied to the waveguide sections to achieve the same balancing effect through the Franz-Keldysh effect.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If manufacturing is performed with standard tolerances, then manufacturing complexity is reduced, but optical loss differences between branches increase

Engineering Contradiction:

Improvemanufacturing tolerance requirementsVSAvoidoptical loss difference

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent enables the optical system to self-correct for manufacturing imperfections. By applying reverse bias voltage to the waveguide sections, the system automatically compensates for optical loss differences without requiring external calibration or adjustment mechanisms, making the system self-balancing.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention changes the electrical parameter (reverse bias voltage) of the waveguide sections to dynamically adjust optical properties. This allows standard manufacturing tolerances to be compensated for by electrical adjustment rather than requiring tight mechanical tolerances.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If waveguide dimensions are precisely controlled to balance losses, then optical loss balance is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveoptical loss balanceVSAvoidwaveguide fabrication complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent substitutes mechanical precision requirements with electrical control. Instead of requiring precise waveguide dimension control during fabrication, the invention uses reverse bias voltage applied to waveguide sections to achieve loss balancing, replacing complex mechanical precision requirements with simpler electrical adjustment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach effectively balances optical losses between waveguide sections, improving the Common Mode Rejection Ratio and ensuring consistent photodetector responsivities, enhancing the accuracy of coherent detection systems by minimizing variations in optical losses.

Implementation Method 1

utilizing mechanisms such as the Franz-Keldysh effect and Free Carrier Plasma Effect to minimize absorption

Methodology Applied

Scientific EffectFranz-Keldysh effect: Franz-Keldysh Effect

Implementation Method 2

utilizing mechanisms such as the Franz-Keldysh effect and Free Carrier Plasma Effect to minimize absorption

Methodology Applied

Scientific EffectFree Carrier Plasma Effect:

Data Source

PatentUS11899291B2Balancing losses in semiconductor optical waveguides

Publication Date: 2024.02.13 LUMENTUM TECHNOLOGY UK LTD

AI summary

A method of equalising optical losses, at a required operating wavelength, in waveguide sections in an optoelectronic device comprising a first semiconductor waveguide section and a second semiconductor waveguide section, the method comprising determining (1301) a first optical loss through the first waveguide section for a signal with the required operating wavelength, determining (1302) a second optical loss through the second waveguide section for the signal, determining (1303) a loss difference between the first optical loss and the second optical loss, determining (1304) a first bias voltage based on the loss difference and the operating wavelength, such that the loss difference is reduced, and applying (1305) the bias voltage to the first waveguide section.