Thin InP Spacer Layer Reduces Lateral Current Spreading in High Speed Lasers
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Solution Overview
Problem
Traditional DFB lasers and high-speed ridge waveguide lasers experience excessive lateral current spreading, leading to reduced carrier injection into the active region, which negatively affects gain, differential gain, and overall performance characteristics.
Innovation Solution
The structure of the high-speed laser minimizes lateral current spreading by reducing the thickness of layers between the mesa and the active region, optimizing the thickness of layers such as the InP spacer layer, AIA confinement layer, and AGIA SCH confinement layer to enhance carrier confinement and photon production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of layers between the mesa and active region is reduced, then lateral current spreading is minimized and carrier injection efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the InP spacer layer to a specific range (5-20 nm) to minimize lateral current spreading while maintaining manufacturability. This precise parameter control resolves the contradiction by finding the optimal thickness value that improves carrier injection efficiency without excessively increasing manufacturing difficulty
Solution Approach 2:
The InP spacer layer acts as an intermediary element between the mesa and the active region. This intermediate layer specifically controls lateral current spreading without directly affecting other laser structures, allowing precise manipulation of current flow paths while maintaining overall device manufacturability
2Reliability
If the InP spacer layer thickness is optimized to minimize lateral current spreading, then gain and differential gain are improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by making the InP spacer layer thickness specific to the region between the mesa and active region, rather than uniformly changing all layer thicknesses. This localized modification improves gain and differential gain in the critical current flow region without unnecessarily complicating the overall device structure
Solution Approach 2:
The laser structure is segmented into distinct functional layers, with the InP spacer layer specifically positioned and dimensioned to address lateral current spreading. This segmentation allows independent optimization of this critical layer without affecting the complexity of other laser 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 approach improves DC and RF performance by maximizing carrier injection efficiency, reducing device voltage and resistance, and minimizing heat generation, resulting in optimized gain and resonance frequency.
Implementation Method 1
excessive lateral current spreading in various layers between the bottom of the ridge and the active region that results in reduced injection of carriers into the action region
Implementation Method 2
reduced injection of carriers into the action region... maximizing carrier injection efficiency
Implementation Method 3
The DFB laser produces a stream of coherent, monochromatic light by stimulating photon emission from a solid state material
Implementation Method 4
One facet is typically coated with a high reflective material that redirects photons produced in the active region toward the other facet
Implementation Method 5
A grating is included in either the top or bottom layer to assist in producing a coherent photon beam
Data Source
AI summary
Embodiments disclosed herein relate to high-speed lasers such as FP and DFB lasers. In one embodiment, the high speed laser comprises a substrate, an active region positioned above the substrate, a mesa positioned above the active region, and one or more layers disposed between the active region and the mesa, wherein the thickness of at least one of the one or more layers is implemented to at least partially minimize the distance between the mesa and active region such that lateral current spreading between the mesa and the active region is at least partially minimized.