Surface Emitting Semiconductor Laser Extended Cavity Single-Mode Stability

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Solution Overview

Problem

Existing surface emitting semiconductor lasers face challenges in maintaining single-mode operation at higher optical power levels, as increasing the oxide aperture diameter to achieve higher power often results in multi-mode oscillation, making it difficult to stabilize single-mode output above 3 mW.

Innovation Solution

The implementation of an extended cavity structure with a cavity extending region and an emission surface additional film, which includes a central and outer circumferential portion with different film thicknesses, to suppress slow-light resonance and maintain single-mode operation even with larger oxide aperture diameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the oxide aperture diameter is increased to achieve higher optical power, then the optical power output is improved, but multi-mode oscillation occurs and single-mode operation becomes unstable

Engineering Contradiction:

Improveoptical power outputVSAvoidsingle-mode operation stability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The emission surface additional film is divided into a central portion and an outer circumferential portion with different film thicknesses. The central portion has a first film thickness while the outer circumferential portion has a second film thickness greater than the first. This segmentation allows different regions to provide different optical functions, enabling high power output while maintaining single-mode operation stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the emission surface are given different film thicknesses to create local quality variations. The central portion with thinner film allows higher power extraction, while the outer circumferential portion with thicker film suppresses slow-light resonance and maintains mode stability. This local quality differentiation resolves the contradiction between power and stability.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the cavity length is extended to include multiple resonance wavelengths, then the reflection band includes at least two resonance wavelengths, but slow-light resonance occurs in the high refractive index region

Engineering Contradiction:

Improvereflection band coverageVSAvoidslow-light resonance

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The emission surface additional film acts as an intermediary layer between the high refractive index region and the external environment. By introducing this additional film with specific thickness variations, the harmful slow-light resonance is suppressed while maintaining the beneficial multi-wavelength reflection band coverage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The film thickness parameter is varied across the emission surface to control optical resonance. The central portion has a first thickness while the outer circumferential portion has a greater second thickness, creating parameter changes that suppress slow-light resonance in the high refractive index region while maintaining adaptability for multiple resonance wavelengths.

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 allows for stable high-power single transverse mode and single longitudinal mode operation by reducing the difference in equivalent refractive index and reflectance, thereby attenuating slow-light resonance and enabling higher optical power output.

Implementation Method 1

suppress possible resonance in the high refractive index region of the light confining layer and the cavity extending region

Methodology Applied

Scientific EffectSlow-light resonance: Resonance

Implementation Method 2

reducing the difference in equivalent refractive index and reflectance

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

The first semiconductor multilayer reflector, the cavity extending region, the active region, and the second semiconductor multilayer reflector determine a reflection band that includes at least two resonance wavelengths

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS8824520B2Surface emitting semiconductor laser, surface emitting semiconductor laser device, optical transmission device, and information processing apparatus

Publication Date: 2014.09.02 FUJIFILM BUSINESS INNOVATION CORP

AI summary

A laser includes: a substrate; a first reflector including pairs of high and low refractive index layers; an active region forming a resonator; a second reflector including an emission surface and pairs of high and low refractive index layers; an extending region thicker than oscillation wavelength, extending the length of the resonator, and including a conductive semiconductor material; a confining layer including a high refractive index region and a surrounding low refractive index region; and an additional film allowing the oscillation wavelength to transmit therethrough. The first and second reflectors, the extending region, and the active region determine a reflection band including resonance wavelengths, in one of which oscillation occurs. The additional film includes central and outer circumferential portions having different thicknesses to suppress resonance in the high refractive index region and the extending region. The central and outer circumferential portions overlap the high and low refractive index regions, respectively.