Modulated Semiconductor Laser Layers for Lower Cavity Loss
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Solution Overview
Problem
High power semiconductor lasers face limitations in increasing power due to internal losses in the laser cavity, which hinder efficiency and reliability, as the level of doping in semiconductor layers cannot be reduced beyond residual levels, limiting the reduction of absorption and thermal resistance.
Innovation Solution
A semiconductor optoelectronic device with a modulated layer structure comprising stacks of sub-layers with varying doping levels and compositions, reducing photon absorption by modifying electro-optical properties, specifically redistributing oscillator strength to minimize internal losses and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the level of doping in semiconductor layers is reduced to minimize photon absorption, then internal losses are reduced, but the doping level cannot be reduced below residual levels, limiting further improvement
Solution Approach 1:
The semiconductor structure is segmented into multiple alternating layers with different doping levels (high-doped and low-doped layers), creating a superlattice structure. This segmentation allows the system to achieve lower effective doping while maintaining necessary electrical properties, thereby reducing internal losses beyond what a uniformly low-doped structure could achieve.
Solution Approach 2:
Different regions of the semiconductor structure are assigned different doping qualities - some layers have high doping for electrical conductivity while adjacent layers have low doping for reduced optical absorption. This local differentiation of quality allows simultaneous optimization of both electrical and optical properties, resolving the contradiction between maintaining doping functionality and minimizing losses.
2Productivity
If the cavity length is increased to distribute carrier injection and reduce current density, then efficiency and thermal management are improved, but internal losses increase due to longer propagation path
Solution Approach 1:
The cavity is effectively segmented into multiple sections by the alternating high-doped and low-doped layers, which distribute the optical field and carrier injection more uniformly throughout the structure. This segmentation allows longer cavity lengths to be used without proportionally increasing internal losses, as the loss distribution is modified by the periodic structure.
Solution Approach 2:
The periodic modulation of doping levels changes the optical and electrical parameters throughout the cavity, creating a photonic crystal-like effect that modifies light propagation and reduces effective internal losses. This parameter modulation allows the cavity to maintain lower loss characteristics even at increased lengths.
3Temperature
If the cavity length is increased to reduce thermal resistance, then temperature management is improved, but device complexity increases
Solution Approach 1:
The thermal management is achieved through segmentation of the structure into alternating layers that provide both optical functionality and thermal conduction pathways. The high-doped layers serve as thermal conduits while the low-doped layers minimize optical loss, creating a multi-functional structure that addresses thermal management without requiring separate thermal management 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
The modulated layer structure increases laser efficiency by reducing internal losses, allowing for longer cavity lengths and improved thermal management, resulting in higher power output and reliability, with efficiency gains of up to 10-11% for longer cavities.
Implementation Method 1
the thicknesses and distinctive features of the sub-layers being chosen so as to reduce the absorption of photons by the free carriers (holes, electrons) in the corresponding region by modifying the electro-optical properties of the conduction band and/or the valence band
Data Source
AI summary
The present invention relates to a semiconductor optoelectronic device (10) comprising a junction (12) consisting a stack of layers defining an N-doped region, an intermediate region and a P-doped region, at least one layer, called a modulated layer, of the N-doped region and/or of the P-doped region and/or of the intermediate region, being formed of a plurality of stacks of sub-layers, each sub-layer differing from the other sub-layers of the same stack by a feature of the material of the sub-layer, called a distinctive feature, the thicknesses and distinctive features of the sub-layers being chosen so as to reduce the absorption of photons in the corresponding region compared with a semiconductor optoelectronic device, known as a reference device, the only difference being that each modulated layer is replaced by an unmodulated layer of the same thickness as the modulated layer and with identical features except for the distinctive feature.