Compact VCSEL Emitter Design with Interdigitized Isolation

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Solution Overview

Problem

The challenge in designing a vertical-cavity surface-emitting laser (VCSEL) array is to increase emitter density while maintaining performance, as prior designs are limited by the minimum spacing between emitters due to fabrication and design considerations, making it difficult to reduce the size of emitters without compromising output power, wavelength, or reliability.

Innovation Solution

A compact emitter design utilizing a split architecture for emitter layers, such as the P-Ohmic metal layer and implant isolation layer, where extended portions of these layers are interdigitized with oxidation trenches, allowing for reduced spacing between emitters without altering alignment tolerances or minimum widths, thereby reducing the overall size of the emitter by approximately 20%.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the spacing between emitters is reduced to increase emitter density, then the area per emitter is reduced, but the minimum spacing required for fabrication and design is violated

Engineering Contradiction:

Improvearea per emitterVSAvoidminimum spacing between emitters

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The emitter layers (implant isolation layer and P-Ohmic metal layer) are segmented into a circular portion and multiple extended portions that extend radially outward. This segmentation allows the layers to interdigitate with oxidation trenches, effectively utilizing the space between trenches and reducing the overall emitter footprint while maintaining fabrication precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The emitter layers extend radially outward in multiple dimensions rather than remaining confined to a simple circular shape. The extended portions project between oxidation trenches in the radial direction, effectively using three-dimensional space to reduce the two-dimensional footprint of each emitter.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Area of stationary object

If the emitter size is reduced to increase emitter density, then the area per emitter is reduced, but the output power and performance are compromised

Engineering Contradiction:

Improveemitter sizeVSAvoidoutput power

Core Design Contradiction:

Area of stationary objectVSPower

Solution Approach 1:

Different portions of the emitter layers have different functions: the circular portion provides the core emitter structure, while the extended portions provide electrical connection and isolation functions. This local differentiation allows the emitter to maintain performance while reducing overall size, as each region is optimized for its specific function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The extended portions of the emitter layers serve multiple functions: they provide electrical connection, isolation between adjacent emitters, and structural support. This multi-functionality allows the emitter to maintain performance characteristics while occupying less space.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Area of stationary object

If the spacing between emitters is reduced, then the area per emitter is reduced, but the alignment tolerances and minimum widths are compromised

Engineering Contradiction:

Improvearea per emitterVSAvoidalignment tolerances and minimum widths

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The emitter layers are segmented into distinct circular and extended portions, with each segment having a defined function. This segmentation allows for clear design rules and alignment tolerances to be established for each segment independently, simplifying the overall fabrication process despite the reduced spacing.

Inventive Principle:

Principle #1Segmentation

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 design achieves increased emitter density in a VCSEL array while maintaining performance characteristics similar to prior emitter designs, reducing the size and cost of integrated circuits on which the array is constructed without sacrificing output power, wavelength, or emission profile.

Implementation Method 1

a plurality of oxidation trenches, where an oxidation trench, of the plurality of oxidation trenches, may be positioned at least partially between the first extended portion, of the first plurality of extended portions, and a second extended portion of the first plurality of extended portions

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS20230006422A1Compact emitter design for a vertical-cavity surface-emitting laser

Publication Date: 2023.01.05 WELLS FARGO BANK NA

AI summary

A surface emitting laser may include an isolation layer including a first center portion and a first plurality of outer portions extending from the first center portion, and a metal layer including a second center portion and a second plurality of outer portions extending from the second center portion. The metal layer may be formed on the isolation layer such that a first outer portion, of the second plurality of outer portions, is formed over one of the first plurality of outer portions. The surface emitting laser may include a passivation layer including a plurality of openings. An opening may be formed over the first outer portion. The surface emitting laser may include a plurality of oxidation trenches. An oxidation trench may be positioned at least partially between the first outer portion and a second outer portion of the second plurality of outer portions.