III-V Laser Device With Decoupled Bragg Grating For Reflectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser devices face challenges in achieving high reflectivity and efficient coupling between active and passive guides due to the dependency of reflectivity on the width of the rib waveguide, making it difficult to produce both high reflectivity and efficient mode conversion.
Innovation Solution
A III-V heterostructure laser device is designed with a Bragg grating decoupled from the rib waveguide width, allowing for a wider grating to enhance reflectivity while maintaining a thin rib for optimized coupling, and featuring two Bragg gratings on either side of the gain medium for improved reflectivity and single-mode operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rib waveguide width is increased to enhance reflectivity, then the reflectivity improves, but the coupling efficiency between active and passive guides deteriorates
Solution Approach 1:
The device is segmented into two functionally independent components: a Bragg grating structure dedicated to providing reflectivity, and a rib waveguide structure dedicated to providing mode conversion and coupling. This segmentation allows each component to be optimized for its specific function without compromise.
Solution Approach 2:
The reflectivity function is extracted from the rib waveguide by implementing the Bragg grating as a separate element. The grating can be etched independently in the cladding layer, allowing the rib waveguide to maintain its optimal narrow width for coupling while the grating provides the necessary reflectivity.
2Loss of energy
If the rib waveguide width is decreased to improve coupling efficiency, then the coupling between active and passive guides improves, but the reflectivity deteriorates
Solution Approach 1:
The device is segmented into two functionally independent parts: the rib waveguide for coupling and the Bragg grating for reflectivity. This allows the rib to be narrow (0.4-0.7 μm) for efficient coupling while the grating width is independently determined by reflectivity requirements.
Solution Approach 2:
The reflectivity function is extracted from the rib waveguide structure and implemented separately through the Bragg grating. This extraction allows the rib waveguide to be optimized for its primary function of mode conversion without being constrained by reflectivity requirements.
3Reliability
If the etch depth is increased to enhance reflectivity, then the reflectivity improves, but the fabrication complexity and difficulty increase
Solution Approach 1:
The Bragg grating is implemented with local quality variations in the cladding layer rather than requiring deep etching through the entire waveguide structure. The grating can be formed by modulating the thickness or refractive index of the cladding layer, which is less complex than deep etching while achieving the same reflectivity effect.
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 increases the reflectivity and coupling efficiency between the Bragg grating and the gain medium, reducing the influence of etch depth on feedback coupling and simplifying the fabrication process, thereby enhancing the performance of the laser device.
Implementation Method 1
at least one Bragg grating is arranged on that side of the slab waveguide which is proximal relative to the gain medium
Implementation Method 2
The coupling between the laser source and the waveguide is by evanescent wave
Data Source
AI summary
The invention relates to a III-V heterostructure laser device (1) arranged in and/or on silicon, comprising:a III-V heterostructure gain medium (3); andan optical rib waveguide (11), arranged facing the gain medium (3) and comprising a slab waveguide (15) equipped with a longitudinal rib (17), the optical rib waveguide (11) being arranged in the silicon.The optical rib waveguide (11) is oriented so that at least one Bragg grating (19, 19a, 19b) is arranged on that side (21) of the slab waveguide (15) which is proximal relative to the gain medium (3) and in that the rib (17) is placed on that side (23) of the slab waveguide (15) that is distal relative to the gain medium (3).