VCSEL Die Polarization Testing for High-Volume Defect Screening

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Solution Overview

Problem

Conventional methods for testing the polarization stability of VCSEL dies are impractical for high-volume production due to extended test durations, and there is a risk of damage or rotation during the transfer process.

Innovation Solution

A system and method utilizing beam splitters and polarizers to split emission light beams into non-polarized and polarized components, which are then measured by dedicated light sensors to assess polarization stability and performance, using a processor to analyze the data and identify defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an optical based goniometer system is used to test polarization stability of VCSEL die, then measurement precision is improved, but productivity deteriorates due to extended test duration

Engineering Contradiction:

Improvepolarization stability measurementVSAvoidproduction high-volume testing

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The emission light beam is segmented into multiple beams using beam splitters. The first beam splitter divides the beam into a first light beam (for total power measurement) and a second light beam. The second beam splitter further divides the second light beam into third and fourth light beams (for polarization component measurements). This segmentation allows simultaneous measurement of multiple parameters, enabling high-volume production testing while maintaining measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple measurement functions are merged into a single integrated optical system. The system combines total power measurement (first light sensor), polarization component measurement along first axis (second light sensor), and polarization component measurement along second axis (third light sensor) into one unified setup. This merging eliminates the need for sequential measurements required by conventional goniometer systems, dramatically reducing test duration while maintaining measurement precision.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of operation

If VCSEL die is transferred from wafer to predetermined position, then ease of operation is improved, but reliability deteriorates due to damage or rotation risk

Engineering Contradiction:

Improvedie transfer processVSAvoiddie integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system performs preliminary testing on the VCSEL die while it is still on the wafer or immediately upon placement at the predetermined position, before any further handling or processing. By measuring total light power, polarization components, and calculating polarization stability early in the process, potential defects are identified before the die undergoes additional transfer operations that could cause damage or rotation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The testing system enables self-inspection of the VCSEL die at the predetermined position without requiring removal or additional handling. The die tests itself by emitting light that is measured by the integrated optical system, eliminating the need for complex mechanical handling or repositioning that would increase damage risk.

Inventive Principle:

Principle #25Self-service

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

Enables efficient high-volume testing of VCSEL dies by quickly identifying defects and rotation issues, reducing damage risk and improving production efficiency.

Implementation Method 1

The first beam splitter is configured to split an emission light beam to a first light beam and a second light beam. The second beam splitter is configured to split the second light beam to a third light beam and a fourth light beam.

Methodology Applied

Scientific EffectBeam splitting:

Implementation Method 2

The first polarizer has a first polarization direction and is configured for the third light beam to pass through. The second polarizer has a second polarization direction and is configured for the fourth light beam to pass through.

Methodology Applied

Scientific EffectPolarization filtering: Polarisation

Implementation Method 3

The first light sensor is configured to receive the first light beam. The second light sensor is configured to receive the polarized third light beam. The third light sensor is configured to receive the polarized fourth light beam.

Methodology Applied

Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentUS20260018851A1System and method for testing vcsel die

Publication Date: 2026.01.15 PIXART IMAGING INC

AI summary

There is provided a system for testing a VCSEL die including a first beam splitter, a second beam splitter, a first polarizer, a second polarizer, a first light sensor, a second light sensor and a third light sensor. The first beam splitter divides an emission light beam of the VCSEL die to a first light beam and a second light beam. The second beam splitter divides the second light beam to a third light beam and a fourth light beam. The first polarizer has a first polarization direction and is arranged for the third light beam to pass through. The second polarizer has a second polarization direction and is arranged for the fourth light beam to pass through. The first light sensor receives the first light beam. The second light sensor receives the polarized third light beam. The third light sensor receives the polarized fourth light beam.