Segmented Grating Laser for Narrow Linewidth and Low Power
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Solution Overview
Problem
Current semiconductor lasers for high-speed optical communication systems are limited by large size, high power consumption, and complexity, particularly when attempting to achieve narrow linewidth and high yield, making them unsuitable for large-scale photonic integration and efficient phase modulation formats like PM DQPSK and PM DPSK.
Innovation Solution
A semiconductor laser design featuring a grating layer with first and second gratings and a segmented grating structure, where the segmented grating has a coupling coefficient value between the first and second gratings, allowing for a longer effective length and reduced power consumption while maintaining a desired output power ratio, and is integrated into a photonic integrated circuit for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laser cavity length is increased to achieve narrow linewidth, then the linewidth is improved, but the power consumption and device area increase exponentially
Solution Approach 1:
The grating structure is divided into multiple discrete gratings spaced along the laser cavity, with non-grating portions between them. This segmentation allows the laser to achieve narrow linewidth through the distributed grating structure without requiring excessive cavity length, thereby reducing power consumption and device area while maintaining fundamental mode suppression.
2Reliability
If the laser cavity length is increased to achieve narrow linewidth, then the linewidth is improved, but the device area increases
Solution Approach 1:
The grating structure is divided into multiple discrete gratings spaced along the laser cavity, with non-grating portions between them. This segmentation allows the laser to achieve narrow linewidth through the distributed grating structure without requiring excessive cavity length, thereby reducing power consumption and device area while maintaining fundamental mode suppression.
3Power
If the coupling coefficient is reduced to maintain output power ratio while increasing laser length, then the output power ratio is maintained, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Different sections of the grating structure have different coupling coefficients - the discrete gratings have higher coupling coefficients at their locations, while the non-grating portions have zero coupling. This local variation in coupling strength allows the laser to maintain the desired output power ratio without requiring uniform reduction of coupling coefficient throughout the entire cavity, thereby simplifying device design and manufacturing.
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 design achieves a narrow linewidth and low power consumption, enabling efficient high-speed data transmission with reduced complexity and increased yield, suitable for advanced phase modulation formats, and allows for compact integration in photonic circuits.
Implementation Method 1
distributed feedback (DFB) lasers
Implementation Method 2
grating structures within semiconductor lasers
Data Source
AI summary
The present invention provides for a semiconductor laser having a narrow linewidth and low power consumption for optical communication applications. According to various embodiments of the invention, a semiconductor laser is provided which includes a grating layer comprising a plurality of segmented gratings, each including a non-grating portion and a grating portion. The segmented gratings are configured to enhance a fundamental mode of the semiconductor laser while sufficiently suppressing modes other than the fundamental mode, providing a narrow linewidth for example. The segmented gratings are also configured to provide an effective length longer than an actual length of the semiconductor laser, leading to smaller device areas and corresponding lower power consumption. A photonic integrated circuit is also provided which includes a plurality of semiconductor lasers, consistent with the present invention, as well as additional optical elements, all provided on a single substrate.