Distributed Reflector Laser Diode Structure for Narrow Linewidth
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Solution Overview
Problem
Current laser diodes for FMCW lidar systems have limitations in terms of linewidth, which affect the range and precision of the light sources, and there is a need for a high-performance laser diode with a small length and low linewidth.
Innovation Solution
A distributed reflector laser diode is designed with a substrate having a DFB region and a DBR region, featuring a second lattice in the DBR region that is thicker than the first lattice in the DFB region, along with specific layer structures and manufacturing processes to achieve a reduced linewidth and increased reflection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional laser diode structure is used, then the device is simpler to manufacture, but the linewidth is wider and reflection efficiency is lower
Solution Approach 1:
The laser diode is divided into distinct functional regions: a DFB region with a first lattice for wavelength selection and an adjacent DBR region with a second lattice for feedback reflection. This segmentation allows each region to be optimized independently for its specific function, achieving narrow linewidth through the DFB region's precise lattice structure while the DBR region provides enhanced reflection efficiency, thereby resolving the contradiction between manufacturing precision and device complexity.
Solution Approach 2:
Different lattice structures are implemented in different regions of the laser diode. The DFB region contains a first lattice with specific periodicity for wavelength filtering, while the DBR region contains a second lattice with different periodicity optimized for reflection. This local differentiation of structure quality enables each region to perform its intended function optimally, achieving narrow linewidth and high reflection efficiency without requiring the entire device to be uniformly complex.
2Length of moving object
If the laser diode length is reduced, then the device is more compact, but the reflection efficiency decreases
Solution Approach 1:
The laser diode is segmented into a DFB region for wavelength selection and an adjacent DBR region for feedback reflection. By placing the DBR region immediately adjacent to the DFB region rather than separating them, the total device length is minimized while the DBR lattice provides sufficient reflection efficiency. This segmented arrangement allows the compact design to maintain reliable performance by concentrating reflective function in the adjacent DBR region.
Solution Approach 2:
The laser diode employs a composite structure combining two different lattice types (first lattice in DFB region, second lattice in DBR region) with different periodicities and optical properties. This composite lattice structure enables the device to achieve both compact length and high reflection efficiency by combining the wavelength-selective properties of the DFB lattice with the high-reflection properties of the DBR lattice in an integrated configuration.
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 distributed reflector laser diode achieves a small length and low linewidth, enhancing the reflection efficiency and performance of the laser diode, thereby improving the range and precision of FMCW light sources.
Implementation Method 1
a substrate including a distributed feed-back (DFB) region and a distributed Bragg reflection (DBR) region contacting the DFB region
Implementation Method 2
a heater layer on the insulating layer
Implementation Method 3
an active layer on the substrate of the DFB region
Data Source
AI summary
Disclosed are a distributed reflector laser diode and a method for manufacturing the same. The diode includes a substrate including a DFB region and a DBR region contacting the DFB region, an active layer on the substrate of the DFB region, a first lattice on the active layer, a second lattice provided on the substrate of the DBR region and thicker than the first lattice, an upper clad layer on the first lattice and the second lattice, an ohmic contact layer on the upper clad layer of the DFB region, an upper electrode on the ohmic contact layer, an insulating layer on the clad layer of the DBR region, and a heater layer on the insulating layer.