Asymmetric Waveguide Doping for High-Power Single-Mode Diode Lasers
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Solution Overview
Problem
High-power pulsed diode lasers operating in the 1400-1700 nm range face challenges in achieving effective output power due to higher optical losses at high currents in InGaAsP and AlGaInAs quaternary compound materials, primarily caused by inhomogeneous carrier accumulation and two-photon absorption, which limit their efficiency and power output.
Innovation Solution
The solution involves doping a desired donor density in the n-side of the waveguide layer to reduce inhomogeneous carrier accumulation and internal optical losses, achieving this by optimizing the doping level in the n-doped waveguide part to control charge carrier density and enhance the optical efficiency of the semiconductor apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high current is applied to achieve high output power, then the output power increases, but optical losses increase due to inhomogeneous carrier accumulation and two-photon absorption
Solution Approach 1:
The patent applies different doping levels to different regions of the waveguide layer. Specifically, the active region has a first doping level while the cladding region has a second doping level that is different from the first. This local differentiation of doping quality reduces inhomogeneous carrier accumulation in specific regions, thereby reducing optical losses while maintaining high output power capability.
Solution Approach 2:
The patent changes the doping parameter (carrier concentration) in the waveguide layer to optimize performance. By adjusting the doping levels in different regions of the waveguide, the patent modifies the electrical and optical properties to reduce carrier accumulation effects and two-photon absorption losses, enabling high power operation with reduced optical losses.
2Loss of energy
If doping level is increased to reduce carrier accumulation, then optical losses decrease, but manufacturing complexity increases
Solution Approach 1:
The patent implements local quality by creating distinct doping regions within the waveguide layer. The active region and cladding region are doped at different levels, which can be achieved through standard semiconductor fabrication techniques such as selective epitaxial growth or ion implantation with spatial masking. This approach reduces optical losses without requiring overly complex manufacturing processes.
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 significantly reduces optical losses and increases the output power of the semiconductor apparatus, particularly at high injection levels, by effectively managing carrier accumulation and absorption, thereby improving the wall-plug efficiency and supporting high-power pulsed operation.
Implementation Method 1
higher optical losses at high currents in InGaAsP and AlGaInAs quaternary compound materials, primarily caused by inhomogeneous carrier accumulation and two-photon absorption
Data Source
AI summary
An apparatus is configured to operate in a single fundamental transverse mode and the apparatus includes a waveguide layer between an n-doped cladding layer and a p-doped cladding layer. The waveguide layer includes a first waveguide part, and an active layer located between the first waveguide part and the p-doped cladding layer, the active layer being asymmetrically within the waveguide layer closer to the p-doped cladding layer than the n-doped cladding layer. The refractive index of the n-doped cladding layer being equal to or larger than the p-doped cladding layer. A first end of the first waveguide part is adjacent to the n-doped cladding layer. A second end of the first waveguide part is adjacent to a first end of the active layer. A desired donor density is doped in the first waveguide part for controlling the carrier density dependent internal optical loss in the first waveguide part at high injection levels.