Vertical Laser Emitter With On-Chip Beam Shaping
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Solution Overview
Problem
Conventional VCSEL diodes suffer from limitations in beam quality, beam shape, and output power, requiring external optics for collimation and shaping, and are restricted by small wafer sizes and sparse diode distribution during manufacturing.
Innovation Solution
A light emitting unit with a stack of layers on a substrate, including reflective elements and a gain element, integrated with a beam shaping element that comprises sub-wavelength structures, allowing for on-chip beam steering and shaping, eliminating the need for external optics and enabling higher output power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional VCSEL topology and materials are used, then the laser beam can be emitted perpendicularly from the top surface, but the beam quality and beam shape are limited with a divergence angle of about 20-30 degrees
Solution Approach 1:
The patent merges the beam shaping function with the VCSEL structure by integrating a beam shaping element directly into the laser diode stack. This combines the light generation and beam shaping functions into a single integrated device, eliminating the need for separate external optics and reducing overall system complexity while enabling customizable beam shapes and reduced divergence angles.
Solution Approach 2:
The patent introduces sub-wavelength structures with periodicities in the range of 100-500 nm, adding a nanoscale dimensional layer to the conventional VCSEL structure. This nanoscale periodic modulation enables precise control over beam divergence and shape by manipulating light at a dimension smaller than the wavelength, achieving beam shaping without external optics.
2Shape
If external optics are added for collimation and focusing, then beam quality improves, but device complexity and size increase
Solution Approach 1:
The patent merges the beam shaping function with the VCSEL structure by integrating a beam shaping element directly into the laser diode stack. This combines the light generation and beam shaping functions into a single integrated device, eliminating the need for separate external optics and reducing overall system complexity while enabling customizable beam shapes and reduced divergence angles.
Solution Approach 2:
The beam shaping element is segmented into multiple sub-wavelength structures with specific periodicities arranged in different orientations. These segmented structures independently control different aspects of beam shaping, allowing precise control over beam divergence in orthogonal directions and enabling complex beam profiles to be achieved within the integrated structure.
3Productivity
If conventional manufacturing techniques are used, then production can proceed, but wafer sizes are restricted and diodes are sparsely distributed reducing efficiency
Solution Approach 1:
The patent changes the critical parameter from diode diameter to sub-wavelength periodicity (100-500 nm). This parameter change enables much smaller feature sizes that can be densely packed across large wafer areas, increasing the number of functional units per wafer from sparse distribution to high-density arrays, thereby significantly improving manufacturing efficiency and reducing costs.
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
The solution provides a compact light emitting unit with customizable beam direction, divergence, and cross-sectional shape, increasing output power and manufacturing efficiency by integrating beam shaping directly onto the substrate, reducing the need for external optics and enabling higher power and precision in laser diode production.
Implementation Method 1
a first reflective element configured to reflect light at the laser wavelength
Implementation Method 2
a gain element configured to amplify the light at the laser wavelength
Implementation Method 3
a second reflective element configured to partially reflect the light at the laser wavelength, and to emit the laser light
Implementation Method 4
the beam shaping element comprises a plurality of structures spaced apart in a direction of an extension of a layer of the beam shaping element and wherein a size of the structures of the plurality of structures and/or a distance between adjacent structures is smaller than the laser wavelength
Data Source
AI summary
According to an aspect of the present inventive concept there is provided a light emitting unit, for emitting laser light at a laser wavelength, arranged on a planar surface of a substrate. The unit comprises a first reflective element to reflect light at the laser wavelength, a gain element to amplify the light, and a second reflective element to partially reflect the light, and to emit the laser light. The elements form a stack of layers integrated onto the planar surface. Each layer is parallel with the planar surface, and the gain element is arranged between the first and second reflective elements.The unit comprises a beam shaping element integrated with the stack. The beam shaping element is configured to shape the emitted laser light. The beam shaping element comprises a plurality of structures spaced apart in a direction of an extension of a layer of the beam shaping element. A size of the structures and/or a distance between adjacent structures is smaller than the laser wavelength.