InGaN Multi-Quantum-Well Laser Light Confinement Optimization
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Solution Overview
Problem
Nitride semiconductor lasers face challenges in achieving high differential efficiency due to In composition ratio fluctuations in the InGaN well layer, leading to increased light absorption and higher threshold currents, which limits their efficiency to less than 1.6 W/A.
Innovation Solution
The semiconductor light-emitting device employs a multi-quantum-well structure with a light confinement coefficient between 1.5% and 3.0% to reduce light absorption in the InGaN well layer, balancing mode gain and threshold current, thereby enhancing differential efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the light confinement coefficient is increased to improve differential efficiency, then light absorption in the well layer increases, but threshold current increases and differential efficiency deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the light confinement coefficient to a specific range (1.5% to 3.0%) rather than maximizing it. This parameter optimization balances light absorption reduction with threshold current control, achieving differential efficiency of 1.6 W/A or more while maintaining practical threshold current levels.
2Power
If the In composition ratio is increased to improve light emission, then mode gain increases, but light absorption increases and differential efficiency decreases
Solution Approach 1:
The patent optimizes the In composition ratio parameter within the InGaN well layer to achieve a balance between mode gain and light absorption. By controlling this composition parameter along with the light confinement coefficient, the patent achieves high differential efficiency without excessive light absorption.
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 allows for differential efficiency of 1.6 W/A or more while maintaining a practical threshold current, reducing the current required for equivalent light output and minimizing heat generation, thus improving the performance and efficiency of nitride semiconductor lasers.
Implementation Method 1
a light confinement coefficient (%) is set to 1.5 or more and 3.0 or less, the light confinement coefficient indicating a proportion of light in the at least two InGaN well layers to overall waveguide light of the device at the time of light emission
Data Source
AI summary
A semiconductor laser, having an active layer with a double-quantum-well structure, includes two InGaN well layers, each of which has a thickness of 5 nm. The threshold current deteriorates to a relatively small degree while differential efficiency is improved considerably in a region having a light confinement coefficient Γ of 3.0% or less. The light confinement coefficient indicates the proportion of light in the well layers with respect to light in the light emitting device, during light emission. When the light confinement coefficient Γ is less than 1.5%, the threshold current increases considerably and the improvement in differential efficiency becomes small. It is therefore preferable that the lower limit of the light confinement coefficient Γ be about 1.5%. A differential efficiency of 1.6 W/A or more is obtained when light the confinement coefficient Γ is 3.0% or less, and a differential efficiency of 1.7 W/A or more is obtained when the light confinement coefficient Γ is 2.6% or less.