Optical Device Ridge Waveguide Grating Alignment
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Solution Overview
Problem
The challenge lies in achieving stable wavelength operation for semiconductor lasers, particularly in maintaining single-mode operation and temperature stability, which is hindered by the complexity of aligning grating elements with sub-micron accuracy and the interference of fine structures during manufacturing, leading to poor yield and productivity in optical device assembly.
Innovation Solution
The optical device comprises a semiconductor laser light source, a grating element with a ridge-type optical waveguide and a Bragg grating, and an optical transmission element, where the grating element has an incident surface for incoming light and an emitting surface for desired wavelength emission, and the optical transmission element has a larger near-field diameter to improve alignment tolerance and productivity, allowing for individual mounting and alignment of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a grating element is monolithically formed in the semiconductor laser, then wavelength stability is improved, but manufacturing complexity and alignment difficulty increase
Solution Approach 1:
The patent divides the optical system into separate components: a semiconductor laser light source and a grating element mounted on a separate substrate. This segmentation allows each component to be manufactured and optimized independently, reducing overall manufacturing complexity while maintaining wavelength stability through the grating's Bragg reflection mechanism
2Manufacturing precision
If sub-micron alignment accuracy is required for grating element mounting, then optical coupling efficiency is improved, but productivity and manufacturing yield deteriorate
Solution Approach 1:
The patent introduces a substrate as an intermediary component that carries both the semiconductor laser light source and the grating element. This intermediary provides a common reference plane and positioning structures that facilitate easier alignment compared to direct mounting, thereby improving productivity without sacrificing optical coupling efficiency
Solution Approach 2:
The patent modifies the mounting parameters by providing a mounting surface with specific geometric features (such as positioning protrusions and recesses) that transform the alignment requirement from sub-micron precision to a more achievable tolerance level, thus improving manufacturing productivity while maintaining adequate optical coupling
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 wavelength stability and temperature control, improves alignment accuracy, and increases productivity by allowing for more tolerant optical axis deviation and efficient coupling, resulting in stable laser operation with reduced power variations across temperature ranges.
Implementation Method 1
a distributed Bragg reflector (DBR) laser have been developed. These lasers are configured to include a diffraction grating in the semiconductor and to oscillate only at a specific wavelength by making use of the wavelength dependency thereof
Implementation Method 2
Since only a light having a specific wavelength is reflected in a predetermined direction from the diffraction grating, the wavelength of the laser light becomes constant
Data Source
AI summary
An optical device includes a semiconductor laser light source, a grating element and an optical transmission element. The grating element includes a ridge-type optical waveguide having an incident surface to which a semiconductor laser light is incident and an emitting surface from which an outgoing light having a desired wavelength is emitted, and a Bragg grating formed in the ridge-type optical waveguide. The light transmission element includes an optical transmission part having an incident surface to which the outgoing light from the ridge-type optical waveguide is incident. A near-field diameter in a horizontal direction at the incident surface of the optical transmission part is greater than a near-field diameter in the horizontal direction at the emitting surface of said ridge-type optical waveguide.