Semiconductor Laser With Quantum Filter Structure
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Solution Overview
Problem
Quantum cascade lasers require large biases for cascaded radiative transitions, limiting their operation in reduced bias conditions and efficiency in infrared wavelengths.
Innovation Solution
A semiconductor laser design featuring a mesa structure with an active region of quantum well structures and a quantum filter structure that allows optical transitions of unipolar carriers without cascaded radiative transitions, using a superlattice structure for carrier filtering and parallel connections to enhance optical gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If cascaded radiative transition is used to enhance optical gain in infrared wavelengths, then laser oscillation in infrared regions is realized, but large bias is inevitably required which prohibits operation in reduced biases
Solution Approach 1:
The patent extracts the quantum filter structure from the cascaded configuration and places it on the side surface of the active region. This separation allows the quantum filter to selectively transmit carriers without requiring the complex cascaded structure, thereby reducing the bias requirement while maintaining optical gain enhancement.
Solution Approach 2:
The quantum filter structure acts as an intermediary element that mediates between the active region and the external environment. By positioning it on the side surface, it enables selective carrier transmission and optical gain enhancement without imposing the large bias requirements of cascaded structures.
2Productivity
If quantum filter structure is placed on side surface of active region, then carrier filtering efficiency is improved, but device structure complexity increases
Solution Approach 1:
The patent moves the quantum filter structure from the traditional planar configuration to the side surface of the active region. This dimensional change enables effective carrier filtering by utilizing the vertical side surface geometry, achieving high filtering efficiency without significantly complicating the overall device structure.
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
Enables efficient light emission in infrared regions with reduced bias requirements, increasing laser gain and flexibility in quantum well structure design while avoiding cascaded radiative transitions.
Implementation Method 1
a quantum filter structure on at least one of the first side surface, the second side surface, and the third side surface of the active region
Implementation Method 2
emits light by using intersubband transitions of unipolar carries in active layers arranged in series
Data Source
AI summary
A semiconductor laser includes a mesa structure disposed on a principal surface of a substrate, the mesa structure extending in a direction of an axis parallel to the principal surface, the mesa structure including an active region that includes a quantum well, the active region having top and bottom surfaces, and first, second, third and fourth side surfaces; an emitter region disposed on at least one of the first and second side surfaces, and the top and bottom surfaces; and a collector region including a quantum filter structure disposed on at least one of the side surfaces. The collector region is separated from the emitter region on the mesa structure. The first and second side surfaces extend in the direction of the axis. The third side surface extends in a direction intersecting the axis.