FAC Beam Steering for Flat-Mounted Diode Beam Stacking

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Solution Overview

Problem

Existing laser diode packages face challenges in achieving high brightness and minimizing losses due to stair-step architectures that increase thermal resistance, manufacturing complexity, and material limitations, leading to reduced power and reliability.

Innovation Solution

The use of flat-mounted diode packages with fast axis collimators that redirect and stack beams vertically, eliminating stair-steps and allowing for improved thermal management and beam alignment, using optical methods to separate beams in a vertical direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If stair-step architecture is used to separate laser diodes vertically, then beam separation is achieved, but thermal resistance increases and manufacturing complexity increases

Engineering Contradiction:
Improvebeam separationVSAvoidjunction temperature
Core Design Contradiction:
ShapeVSTemperature

Solution Approach 1:

The patent transitions from vertical separation in the Z-dimension (stair-step architecture) to angular separation in the X-Y plane. Multiple laser diodes are mounted on a flat substrate and their beams are redirected at different angles by FACs to achieve spatial separation without increasing height or thermal resistance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent replaces the mechanical stair-step structure with an optical beam steering system using FACs. Instead of physically elevating diodes to separate beams, the system uses optical elements to redirect beams at different angles, eliminating the need for complex mechanical positioning while achieving the same beam separation effect.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Shape

If stair-step architecture is used to separate laser diodes vertically, then beam separation is achieved, but device complexity increases

Engineering Contradiction:
Improvebeam separationVSAvoidmanufacturing complexity
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The patent uses angular separation in the X-Y plane instead of vertical separation in the Z-dimension. This allows all diodes to be mounted on a flat substrate at the same height, simplifying the mechanical structure and manufacturing process while still achieving beam separation through optical redirection.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The FACs serve multiple functions: they collimate the fast axis of each laser diode's beam and simultaneously redirect the beam at a specific angle. This dual functionality eliminates the need for separate collimation and steering elements, reducing overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Shape

If FACs are arranged at off-axis angles to redirect beams, then beam stacking is improved, but optical alignment complexity increases

Engineering Contradiction:
Improvebeam stackingVSAvoidoptical alignment
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The patent optimizes the FAC angle parameter to balance beam stacking quality and alignment tolerance. By selecting specific off-axis angles for the FACs, the system achieves effective beam separation and stacking while maintaining reasonable alignment tolerances that are compatible with standard manufacturing capabilities.

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

This approach reduces junction temperatures, simplifies manufacturing, and enhances laser diode performance by improving thermal dissipation and beam quality, enabling efficient beam stacking and coupling into optical fibers.

Implementation Method 1

a first fast axis collimator (FAC) optically coupled to the beam as emitted from the exit facet and configured to direct the beam along a redirected beam axis having a non-zero angle with respect to the optical axis of the first laser diode, wherein the first FAC has an optical axis arranged at an angle with respect to the optical axis of the first laser diode to produce the non-zero angle of the redirected beam axis

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3750218B1Diode laser apparatus with FAC lens out-of-plane beam steering
Publication Date: 2026.01.14 NLIGHT INC
  • EP3750218B1 patent drawingFigure 1~2
  • EP3750218B1 patent drawingFigure 3~4
  • EP3750218B1 patent drawingFigure 5A~5B

AI summary

Apparatus include a first laser diode situated to emit a beam from an exit facet along an optical axis, the beam as emitted having perpendicular fast and slow axes perpendicular to the optical axis, a first fast axis collimator (FAC) optically coupled to the beam as emitted from the exit facet and configured to direct the beam along a redirected beam axis having a non-zero angle with respect to the optical axis of the first laser diode, a second laser diode situated to emit a beam from an exit facet of the second laser diode along an optical axis parallel to the optical axis of the first laser diode and with a slow axis in a common plane with the slow axis of the first laser diode, and a second fast axis collimator (FAC) optically coupled to the beam as emitted from the exit facet of the second laser diode and configured to direct the beam along a redirected beam axis having a non-zero angle with respect to the optical axis of the second laser diode.