Ring VCSEL Cavity Structure for High-Power Single-Frequency Output

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Solution Overview

Problem

Current Vertical Cavity Surface Emitting Lasers (VCSELs) face challenges in achieving higher performance and smaller feature sizes while maintaining single frequency operation, as larger diameter VCSELs typically do not support single mode/frequency operation.

Innovation Solution

The development of Coherent Ring Vertical Cavity Surface Emitting Lasers (CR-VCSELs) with a closed ring structure that supports a single transverse optical mode and multiple circumferential modes, allowing for single frequency operation over a larger area with increased optical power up to 1 W or more, using similar processing techniques to existing VCSELs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If VCSEL diameter is increased to achieve higher optical power, then power output is improved, but single mode operation is lost

Engineering Contradiction:

Improveoptical powerVSAvoidsingle mode operation

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The laser cavity is segmented into multiple discrete longitudinal modes spaced by the free spectral range. By designing the cavity length and refractive index profile, the patent ensures that only one longitudinal mode falls within the gain bandwidth, achieving single mode operation. The ring structure segments the optical path to enable precise control over mode selection while maintaining large aperture for high power.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a radially varying refractive index profile within the VCSEL structure, creating different optical properties at different radial positions. This local quality variation enables the large diameter VCSEL to maintain single mode operation by confining the optical field to a specific radial distribution that supports only the fundamental transverse mode while allowing high power extraction through the large aperture.

Inventive Principle:

Principle #3Local quality

2Power

If VCSEL diameter is increased to achieve higher optical power, then power output is improved, but beam quality deteriorates

Engineering Contradiction:

Improveoptical powerVSAvoidbeam emission pattern

Core Design Contradiction:

PowerVSShape

Solution Approach 1:

The patent transitions from conventional planar VCSEL geometry to a three-dimensional ring-shaped cavity structure. This dimensional change allows the optical field to be confined in the radial direction while extending in the azimuthal direction, enabling high power extraction through the large circumferential length of the ring while maintaining diffraction-limited beam quality through precise control of the radial mode distribution.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If processing complexity is increased to achieve better performance, then manufacturing precision is improved, but ease of manufacture deteriorates

Engineering Contradiction:

Improvesingle frequency operationVSAvoidfabrication process

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent achieves single frequency operation by precisely controlling key parameters including cavity length, refractive index profile, and ring geometry dimensions. By optimizing these parameters during the design stage, the complex performance requirements are translated into specific dimensional specifications that can be manufactured using standard semiconductor fabrication processes, balancing manufacturing precision with ease of manufacture.

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

CR-VCSELs enable single frequency operation over a larger area with increased optical power, addressing the limitations of existing VCSELs by controlling power output, coherence, and laser beam emission patterns through tailored ring geometry.

Implementation Method 1

a closed ring which supports a single transverse optical mode and multiple circumferential modes

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

Vertical Cavity Surface Emitting Lasers (VCSEL)... Coherent Ring Vertical Cavity Surface Emitting Lasers (CR-VCSEL)... single frequency operation

Methodology Applied

Scientific EffectStimulated emission: Laser

Data Source

PatentUS20250105596A1Coherent ring vertical cavity surface emitting laser

Publication Date: 2025.03.27 DALLAS QUANTUM DEVICES

AI summary

Disclosed examples include Coherent Ring Vertical Cavity Surface Emitting Lasers (CR-VCSEL). Examples includes Vertical Cavity Surface Emitting Lasers with a containing a Coherent Ring Vertical Cavity Surface Emitting Laser stack (CR-VCSEL stack) consisting of a first mirror layer, an active layer, an emission aperture, and a second mirror layer, under a top metal layer within a closed ring. The CR-VCSEL has a closed ring structure. The emission aperture width of the closed ring is such that the closed ring supports a single transverse optical mode, it but supports multiple circumferential optical modes around the ring within the closed ring geometry. The closed ring may have a length of from microns to millimeters. The transverse width of the closed ring and length of the closed ring may be tailored to control the CR-VCSEL power output, degree of coherence, and laser beam emission pattern.