Semiconductor Laser Intersubband Transition Low Bias Operation
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Solution Overview
Problem
Conventional quantum cascade semiconductor lasers require large biases for operation due to the need for cascaded radiative transitions, which limits their ability to operate at reduced biases and increases power consumption.
Innovation Solution
A semiconductor laser design that utilizes intersubband transitions of unipolar carriers through quantum well structures with specifically arranged energy levels, allowing for light emission without the need for cascaded radiative transitions, thereby reducing the operating voltage and enhancing efficiency.
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 at reduced biases
Solution Approach 1:
The patent changes the fundamental operating mechanism from cascaded radiative transition to intersubband transition, altering the energy transition parameters. This allows population inversion to be achieved through a different physical process that does not require the same large bias voltages, thereby reducing power consumption while maintaining optical gain capability
Solution Approach 2:
The patent extracts the essential light-generating function from the cascaded radiative transition mechanism and implements it through intersubband transition in quantum well structures. This separation allows the laser to achieve infrared oscillation without being constrained by the large bias requirements of the original cascaded mechanism
2Illumination intensity
If cascaded radiative transition structure is implemented, then infrared laser oscillation is achieved, but power consumption increases due to large bias requirements
Solution Approach 1:
The patent changes the energy transition mechanism from cascaded radiative transition to intersubband transition, fundamentally altering how population inversion is achieved. This parameter change enables infrared laser emission while reducing the energy loss associated with large bias voltages, as the intersubband transition requires lower operating voltages
3Use of energy by moving object
If quantum well structures with optimized energy levels are used, then population inversion is facilitated at reduced voltages, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating specific quantum well structures with optimized energy levels at particular locations within the active region. These localized quantum wells are designed with precise thickness and composition to achieve the desired intersubband transitions, allowing population inversion at reduced voltages while confining the complexity to specific device regions
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 semiconductor laser achieves efficient light emission at reduced voltages, increasing laser gain through stimulated emission and reducing power consumption by facilitating population inversion with optimized energy levels in quantum well structures.
Implementation Method 1
A semiconductor laser according to one aspect of the present invention includes an active region disposed on a principal surface of a substrate, the active region including a plurality of quantum well structures
Implementation Method 2
The semiconductor laser achieves efficient light emission at reduced voltages, increasing laser gain through stimulated emission
Data Source
AI summary
A semiconductor laser includes a substrate having a principal surface; an active region disposed on the principal surface of a substrate, the active region including a quantum well structure, the active region having a top surface, a bottom surface facing the top surface, and side surfaces; an emitter region including a first semiconductor region of a first conductivity type on the top surface of the active region; and a collector region including a second semiconductor region of the first conductivity type on at least one side surface of the active region. The quantum well structure includes unit cells that are arranged in a direction of an axis intersecting the principal surface of the substrate.