Heterogeneous DFB Laser Structure for Single Lateral Mode Suppression
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Solution Overview
Problem
Existing tunable lasers require complex control systems to maintain alignment, while fixed wavelength silicon photonic lasers face challenges in photonic integrated circuits due to calibration, power, and process control issues.
Innovation Solution
The implementation of a distributed feedback (DFB) laser architecture within photonic integrated circuits (PICs), which eliminates the need for wavelength calibration and simplifies control systems by using a grating built into a III-V epitaxial structure for optical feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tunable laser with filters is used to alter wavelength, then wavelength flexibility is improved, but device complexity increases due to complex control systems required to maintain alignment
Solution Approach 1:
The patent extracts the wavelength selection function from a complex tunable laser system with filters and control mechanisms, replacing it with a simpler fixed-wavelength DFB laser that achieves wavelength stability through integrated grating feedback rather than active control systems
Solution Approach 2:
The DFB laser structure incorporates a grating that provides automatic optical feedback to maintain single-lateral-mode operation and wavelength stability without requiring external control systems, allowing the laser to self-regulate its output
2Ease of operation
If fixed wavelength lasers are implemented in photonic integrated circuits, then control simplicity is improved, but manufacturing precision deteriorates due to process variation and calibration issues
Solution Approach 1:
The patent changes the operational parameters of the laser by integrating a grating structure that provides distributed feedback, making the laser wavelength determined by the grating period rather than cavity length, thereby reducing sensitivity to fabrication variations
Solution Approach 2:
The patent uses a composite structure combining III-V semiconductor material for the laser active region with silicon photonic waveguide for optical confinement and grating formation, leveraging the advantages of both materials to achieve robust single-mode operation
3Reliability
If conventional DFB lasers with facet coatings are used, then optical feedback is improved, but reliability deteriorates due to facet coating degradation and alignment issues
Solution Approach 1:
The patent removes the facet coatings entirely and replaces them with a distributed feedback grating structure that provides the necessary optical feedback through a different mechanism, eliminating the reliability issues associated with facet coating degradation
Solution Approach 2:
The grating structure acts as an intermediary element that provides optical feedback without requiring direct facet reflections, mediating the feedback mechanism through a more stable and integrated structure
4Productivity
If single lateral mode operation is achieved through rib waveguide design, then laser efficiency is improved, but manufacturing complexity increases due to precise rib positioning requirements
Solution Approach 1:
The patent merges the rib waveguide structure with the DFB grating structure into a single integrated feature, where the grating is formed directly in or on the rib waveguide, thereby achieving mode control and feedback function in one structure rather than separate components
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 solution allows for reduced power consumption, simplified laser control, and improved reliability by avoiding facet coatings associated with conventional DFB lasers, while achieving single lateral mode operation for enhanced efficiency and performance.
Implementation Method 1
a grating etched on a bonding surface of the III-V semiconductor structure to provide optical feedback to the laser active region to generate output light
Implementation Method 2
at least two laterally separated silicon portions extending in the longitudinal direction and overlapping, with respect to a lamination direction perpendicular to the longitudinal direction, two lobes of a second lateral mode of the output light in the laser active region
Data Source
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AI summary
A DFB laser includes a III-V semiconductor structure having a laser active region and a grating etched on a bonding surface to provide optical feedback to generate output light. The DFB laser includes a silicon structure having a silicon waveguide configured to receive the output light from a first end of the laser active region. The bonding surface of the III-V semiconductor structure is bonded to a surface of the silicon structure. The silicon structure includes a DFB region having surfaces defining at least two laterally separated silicon portions extending longitudinally and overlapping, with respect to a lamination direction, two lobes of a second lateral mode of the output light in the laser active region, to suppress lasing of a second order mode of the output light.