Native Green Laser Quantum Wells Overcoming Optical Loss
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Solution Overview
Problem
Current semiconductor laser devices are not suitable for high power and reliable lasing in the true green spectral range due to limited optical gain and high optical loss, making them unsuitable for applications like laser projection systems.
Innovation Solution
The development of native green laser semiconductor devices with an increased number of quantum wells and optimized laser structures, including a substrate, cladding layers, active region layers, and high reflectivity coatings, to achieve net optical gain greater than net optical loss, thereby overcoming optical and output losses and enabling lasing in the green spectral range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current semiconductor laser device structures are used, then device simplicity is maintained, but optical gain is insufficient and optical loss is high, preventing reliable green spectral range lasing
Solution Approach 1:
The laser device is segmented into multiple quantum wells (three or more) within the active region layers, each contributing to optical gain. This segmentation allows the system to overcome high optical loss by accumulating gain from multiple discrete regions rather than relying on a single quantum well, thereby achieving reliable green lasing.
Solution Approach 2:
The laser device employs composite material structures including InGaN quantum wells embedded in GaN barriers, with multiple active region layers containing different numbers of quantum wells. This composite approach optimizes optical gain while managing optical loss through material composition and structural design.
2Loss of energy
If the number of quantum wells is increased to overcome optical loss, then optical gain increases enabling green lasing, but device structure becomes more complex
Solution Approach 1:
The active region is divided into multiple discrete quantum wells separated by GaN barriers. By distributing three or more quantum wells across one or more active region layers, the design accumulates optical gain to overcome losses while maintaining manageable structural complexity through systematic repetition of quantum well-barrier units.
Solution Approach 2:
The patent extends the quantum well structure from a single layer to multiple active region layers stacked vertically. This dimensional extension allows additional quantum wells to be added in the vertical dimension, increasing total optical gain without proportionally increasing lateral device footprint or manufacturing complexity.
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 approach results in high power and efficient native green laser semiconductor devices with reduced internal and external losses, achieving lasing wavelengths up to 520 nm with low pumping power densities, suitable for consumer electronic devices such as laser projectors.
Implementation Method 1
The one or more active region layers include a number of quantum wells having a spontaneous emission peak wavelength that is greater than about 520 nm at a reference pumping power density. The pumping source is configured to pump each quantum well at a pumping power density such that a stimulated emission peak of each quantum well is within the green spectral range.
Implementation Method 2
Group-III nitride lasers convert externally supplied energy (from electrical current or pumping light) directly into lasing radiation at a desired wavelength that is generated inside its active region due to the radiative recombination of charge carriers in semiconductor valence and conduction bands.
Implementation Method 3
GaN or InGaN waveguide layers positioned proximate one or more cladding layers to confine light around the active region layer
Implementation Method 4
a cleaved facet having a high reflectivity coating along the {1-100} crystallographic plane
Data Source
AI summary
A semiconductor laser device operable to emit light having a desired wavelength in the green spectral range. The semiconductor laser device may include a pumping source and a laser structure including a substrate, a first cladding layer, and one or more active region layers. The one or more active region layers include a number of quantum wells having a spontaneous emission peak wavelength that is greater than about 520 nm at a reference pumping power density. The pumping source is configured to pump each quantum well at a pumping power density such that a stimulated emission peak of each quantum well is within the green spectral range, and the number of quantum wells within the one or more active region layers is such that a net optical gain of the quantum wells is greater than a net optical loss coefficient at the desired wavelength in the green spectral range.