Laser Facet Coating via Preliminary Layer and Rotation

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Solution Overview

Problem

During the coating process of semiconductor lasers, the uncoated facet is exposed to a plasma environment, leading to potential damage and a significant reduction in yield due to prolonged exposure, especially in processes like e-beam evaporation at elevated temperatures.

Innovation Solution

A method is developed where the laser is placed in an evacuated coating chamber, with a protective coating applied to one facet at a low energy to minimize damage to the uncoated facet, allowing rotation and full coating of both facets while maintaining protection, using ion beam deposition and e-beam evaporation techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a full coating is applied to one facet before rotating and coating the second facet, then the first facet receives complete protective coating, but the second facet remains uncoated and unprotected during the coating process, leading to damage from plasma exposure

Engineering Contradiction:

Improvefacet protectionVSAvoidplasma damage to uncoated facet

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A preliminary protective coating is applied to the first facet before the full coating process begins. This preliminary coating serves as a protective barrier that prevents plasma damage to the first facet during the subsequent full coating process, while allowing the second facet to be coated without damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coating process is segmented into multiple stages: first applying a preliminary coating to one facet, then rotating and applying full coating to both facets. This segmentation allows each facet to receive protection at the appropriate time, preventing plasma damage while ensuring complete coating coverage.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the coating process is extended to coat both facets fully, then complete protection is achieved, but the exposure time to plasma environment increases, causing more damage to uncoated facets

Engineering Contradiction:

Improvefacet protectionVSAvoidcoating process time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The preliminary coating is applied in advance to protect the first facet before the full coating process. This allows the full coating to proceed without delay while protecting both facets, eliminating the need to extend the process time for additional protection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coating process maintains continuous useful action by applying preliminary coating first, then immediately proceeding with full coating on both facets without interruption. This continuous process ensures complete protection while minimizing total exposure time to plasma environment.

Inventive Principle:

Principle #20Continuity of useful action

3Manufacturing precision

If high energy is used during coating deposition, then coating quality and adhesion are improved, but damage to the uncoated facet increases due to high-energy particle exposure

Engineering Contradiction:

Improvecoating qualityVSAvoidhigh-energy particle damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The preliminary protective coating is applied before the full coating process. This preliminary layer protects the first facet from high-energy particle damage during subsequent high-energy coating deposition, allowing optimal coating quality to be achieved without compromising facet integrity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The preliminary coating acts as an intermediary protective layer between the high-energy coating process and the first facet. This intermediary layer absorbs or deflects high-energy particles, protecting the underlying facet while allowing the full coating to be deposited with high quality.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 method effectively reduces facet damage during the coating process, enhancing the yield and performance of semiconductor lasers by protecting both facets from high-energy particles and environmental exposure.

Implementation Method 1

using ion beam deposition and e-beam evaporation techniques

Methodology Applied

Scientific EffectIon beam deposition: Ion Beam

Implementation Method 2

using ion beam deposition and e-beam evaporation techniques

Methodology Applied

Scientific EffectE-beam evaporation: Electron Beam

Implementation Method 3

placing the laser in an evacuated coating chamber

Methodology Applied

Scientific EffectVacuum: Vacuum

Data Source

PatentUS8277877B1Method for applying protective laser facet coatings

Publication Date: 2012.10.02 II VI DELAWARE INC

AI summary

A method for depositing protective coatings on front and rear facets of an optical device, such as a laser die, is disclosed. The protective coatings help prevent laser facet damage common to laser dies manufactured using known processes. In one embodiment, the method for coating the laser die includes placing the laser in an evacuated coating chamber before applying a first coating portion to a first facet of the laser. The first coating portion is applied to the first facet so as to form a protective covering thereon, but is applied at a coating energy that minimizes damage to the as-yet uncoated second facet. The laser is then rotated within the coating chamber, and a full coating is applied to a second facet of the laser. The laser is again rotated, and a full coating is applied atop the first coating portion to the first facet of the laser.