Lateral External-Cavity VCSEL Geometry for Compact Beam Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The fabrication of compact semiconductor lasers with external resonator cavities is complicated by the need for accurate alignment and increased thickness, which hinders the development of efficient and scalable optoelectronic devices.
Innovation Solution
A vertical-cavity surface-emitting laser (VCSEL) is integrated with a block of transparent material forming a resonant cavity, where the entrance face is aligned with the beam axis and the exit face is laterally displaced, allowing for a compact design with improved light reflection and diffraction capabilities using gratings and reflective coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an external cavity is used to improve beam quality and frequency selection, then the laser length increases, but the device complexity and fabrication difficulty increase
Solution Approach 1:
The patent transitions from a conventional longitudinal external cavity configuration to a lateral external cavity configuration. The resonant cavity extends laterally from the VCSEL output face rather than longitudinally, changing the spatial dimension in which the external cavity is implemented. This dimensional change allows the beam quality improvement function to be achieved without increasing the longitudinal length of the laser device, thereby resolving the contradiction between beam quality and device length.
2Manufacturing precision
If an external cavity is used to improve frequency selection and spatial mode control, then the resonant cavity length increases, but the divergence of the output beam increases
Solution Approach 1:
By implementing the external cavity laterally rather than longitudinally, the patent achieves frequency selection and spatial mode control without extending the beam propagation path. The lateral configuration allows the resonant cavity to be positioned perpendicular to the beam axis, enabling frequency control while maintaining a compact longitudinal footprint and reducing beam divergence.
3Manufacturing precision
If accurate alignment is implemented to improve laser performance, then the manufacturing precision increases, but the fabrication complexity increases
Solution Approach 1:
The patent integrates the external cavity structure with the VCSEL substrate by forming the cavity on the same substrate. The resonant cavity is constructed using transparent material blocks that are laterally positioned relative to the VCSEL output, merging the light source and resonator into a single integrated structure. This integration reduces the number of separate components requiring alignment, thereby maintaining manufacturing precision while reducing fabrication complexity.
4Manufacturing precision
If the resonant cavity is extended to improve beam control, then the laser length increases, but the device becomes less compact
Solution Approach 1:
The patent achieves effective beam control by extending the resonant cavity in the lateral dimension rather than the longitudinal dimension. This allows the external cavity to provide the necessary optical path length for frequency selection and mode control while maintaining a compact overall device volume. The lateral configuration enables the cavity to be positioned adjacent to rather than along the beam propagation path, reducing the device footprint.
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 configuration enhances the spatial mode profile and spectral selectivity of the emitted beam, enabling the production of compact and efficient optoelectronic devices with improved beam quality and reduced fabrication complexity.
Implementation Method 1
the entrance face includes a grating configured to diffract the emitted light into the block toward the cavity axis
Implementation Method 2
the light propagates through the resonant cavity from the entrance face to the exit face by total internal reflection between first and second sides of the block of the transparent material
Implementation Method 3
the exit face includes a grating configured to retro-reflect a first portion of the light propagating in the cavity
Implementation Method 4
a vertical-cavity surface-emitting laser (VCSEL) light source formed on the substrate and configured to emit coherent light at a predefined wavelength
Data Source
AI summary
An optoelectronic device includes a semiconductor substrate and a vertical-cavity surface-emitting laser (VCSEL) light source formed on the substrate and configured to emit coherent light at a predefined wavelength along a beam axis perpendicular to a surface of the substrate. A block of a transparent material is mounted on the surface of the substrate and forms, with the VCSEL, a resonant cavity at the predefined wavelength having an entrance face that is aligned with the beam axis and an exit face that is laterally displaced with respect to the entrance face along a cavity axis running parallel to the surface of the substrate.