Laser Module Temperature Control via Drive Current Feedback

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Solution Overview

Problem

Conventional semiconductor laser modules struggle to maintain a constant optical output intensity due to temperature changes, leading to instability in optical communication systems.

Innovation Solution

Incorporating a temperature detecting element and an output controller that calculates and adjusts the drive current based on temperature information to maintain a desired optical output intensity, using correction tables to account for changes in the output optical system's distortion caused by temperature fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If temperature control is not implemented, then device complexity is reduced, but optical output intensity stability deteriorates

Engineering Contradiction:

Improvestructure complexityVSAvoidoptical output intensity stability

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent implements feedback control by detecting the actual optical output intensity with a light receiving element and comparing it with the target intensity. The output controller then adjusts the drive current based on this feedback to maintain constant optical output intensity despite temperature changes, eliminating the need for complex temperature control systems.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the control parameter from temperature control to direct optical intensity control. By measuring the actual optical output intensity and adjusting the drive current based on intensity feedback rather than temperature feedback, the system achieves stable optical output without requiring temperature control mechanisms.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If monitor optical intensity is used for control, then optical output intensity stability is improved, but measurement precision deteriorates due to optical system distortion

Engineering Contradiction:

Improveoptical output intensity stabilityVSAvoidoptical intensity measurement accuracy

Core Design Contradiction:

Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The patent replaces optical measurement with electrical measurement. Instead of using optical intensity detection that is affected by optical system distortion, the system uses a current detecting element to measure the drive current and uses this electrical measurement as the basis for control, avoiding optical measurement errors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary relationship between drive current and optical output. Rather than directly measuring optical intensity which is distorted by temperature, the system measures drive current (which has a known correlation with optical output) and uses this as an indirect but more accurate measure for control purposes.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If wavelength control is implemented, then wavelength accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvewavelength accuracyVSAvoidcontrol system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the output controller multi-functional by having it perform both optical intensity control and wavelength control functions. The same controller that adjusts drive current for intensity stabilization also manages wavelength control based on detection element feedback, eliminating the need for separate dedicated wavelength control hardware.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 ensures a stable optical output intensity, even with temperature changes, by accurately correcting for optical loss and wavelength shifts, thereby enhancing the performance of semiconductor laser modules in optical communication systems.

Implementation Method 1

as the temperature changes, the output optical system is distorted due to thermal expansion

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a semiconductor laser 10 which outputs a laser beam L

Methodology Applied

Scientific EffectLaser emission: Laser

Implementation Method 3

semiconductor laser 10 which outputs a laser beam L

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 4

a thermoelectric coller (TEC) 88 is provided

Methodology Applied

Scientific EffectPeltier effect: Peltier Effect

Data Source

PatentUS7907650B2Laser module, control method of the same, control data of the same, and control data generation method

Publication Date: 2011.03.15 SUMITOMO ELECTRIC DEVICE INNOVATIONS

AI summary

A laser module includes a semiconductor laser, an output optical system provided on an optical output side of the semiconductor laser, a temperature detecting element that detects a temperature of the output optical system; and an output controller that calculates a drive current to set an optical output intensity of the laser module at a desired value on the basis of temperature information obtained by the temperature detecting element, and outputs the drive current to the semiconductor laser.