Semiconductor Laser Window Region Screening Without COD Damage

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Solution Overview

Problem

Conventional semiconductor laser element screening methods at elevated temperatures lead to increased time requirements and risk of catastrophic optical damage (COD) due to low laser driving currents, which can cause end-face damage during normal use and testing.

Innovation Solution

A semiconductor laser element with a waveguide and window region structure, where the laser optical output has a maximum value at a first driving current and is reduced to at most 20% of this value at a second driving current, preventing damage, and a testing method to determine defectiveness by measuring characteristics at both current values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If screening is conducted at elevated temperature, then catastrophic optical damage is reduced, but screening time increases

Engineering Contradiction:

ImprovereliabilityVSAvoidscreening time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the temperature parameter from elevated temperature to room temperature (25°C ± 3°C) while simultaneously optimizing the current parameter by identifying a specific current range (I1 to I2) where the laser optical output is suppressed to at most 20% of the maximum value. This parameter combination achieves both rapid screening and end-face damage prevention

Inventive Principle:

Principle #35Parameter changes

2Productivity

If high driving current is used for screening, then screening time is reduced, but end-face damage occurs

Engineering Contradiction:

Improvescreening speedVSAvoidend-face damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent identifies and utilizes a specific current range (I1 to I2) where the laser optical output is suppressed to at most 20% of the maximum value. This current parameter change enables high-speed screening without causing end-face damage, as the reduced optical output prevents catastrophic optical damage while still providing sufficient signal for effective screening

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies partial action by using a driving current that is higher than the current for maximum optical output (I1) but controlled to remain below the damage threshold (I2). This partial current application achieves screening functionality while intentionally suppressing the optical output to prevent damage

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12107393B2Semiconductor laser element, testing method, and testing device

Publication Date: 2024.10.01 NUVOTON TECH CORP JAPAN

AI summary

A semiconductor laser element that includes a semiconductor layer including a waveguide formed in an intra-layer direction of the semiconductor layer and a window region formed in a front-side end face of the waveguide, has a current-laser optical output characteristic in which, at an operating temperature of 25° C.±3° C., a laser optical output has a maximum value at a first driving current value and the laser optical output is at most 20% of the maximum value at a second driving current value greater than the first driving current value, and is not damaged at the second driving current value.