Photonic Crystal Laser Stack With Tunnel-Coupled Quantum Wells
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Solution Overview
Problem
Existing semiconductor lasers, particularly photonic crystal surface-emitting lasers (PCSELs), face challenges in simplifying fabrication and achieving improved laser characteristics, requiring complex structures and multiple waveguides that can lead to defects and increased costs.
Innovation Solution
An optoelectronic component comprising a stack with a photonic crystal and a gain medium, where the gain medium includes quantum wells and tunnel junctions, and the photonic crystal is electromagnetically coupled to the gain medium, allowing for simplified fabrication and high-quality laser emission with reduced beam widening, even with thicker substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple waveguides and photonic crystal layers are used to increase laser power density, then the laser output power increases, but the fabrication complexity and defect risk increase
Solution Approach 1:
The patent merges multiple waveguide functions into a single waveguide structure by implementing a photonic crystal layer that extends across the entire waveguide. This single photonic crystal layer provides the necessary feedback and mode selection for multiple modes simultaneously, eliminating the need for separate photonic crystal layers for each waveguide while maintaining high power density output.
Solution Approach 2:
The photonic crystal layer is designed to perform multiple functions simultaneously: it provides optical feedback for laser oscillation, enables multi-mode operation, and maintains beam quality. This universal structure handles what would traditionally require multiple separate components, simplifying the overall device architecture while achieving the desired power density.
2Ease of manufacture
If coupled waveguides are implemented to simplify fabrication, then the number of photonic crystal layers is reduced, but the laser characteristics may be compromised
Solution Approach 1:
The patent transitions from a vertical stacking approach (multiple photonic crystal layers at different heights) to a lateral extension approach (single photonic crystal layer extending across the entire waveguide width). This dimensional change maintains the necessary optical feedback mechanisms while simplifying fabrication by reducing the number of layers that need to be precisely aligned and stacked.
3Shape
If thin substrates are used to maintain optical properties, then beam collimation is preserved, but the substrate thickness limitation increases fabrication difficulty
Solution Approach 1:
The patent introduces a distributed Bragg reflector (DBR) layer as an intermediary between the active region and the substrate. This DBR layer provides the necessary optical feedback and mode selection, allowing the use of thicker substrates for mechanical stability while maintaining excellent beam collimation properties. The DBR acts as a mediator that decouples the optical performance requirements from the mechanical substrate thickness constraints.
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 enables the production of high-power density lasers with improved collimation and reduced defects, facilitating the use of thicker substrates without compromising optical properties, thus simplifying the fabrication process and reducing costs.
Implementation Method 1
The gain medium is configured to emit the electromagnetic wave
Implementation Method 2
With the help of the tunnel junctions, the individual quantum wells can be coherently coupled at a small spatial distance
Implementation Method 3
an in-plane laser resonator with a photonic crystal structure is realized. The same structure also reflects part of the light to form the output beam
Implementation Method 4
The stack is arranged on a substrate that is transparent in the region of an electromagnetic wave to be emitted
Data Source
AI summary
An optoelectronic component includes a stacked arrangement including a photonic crystal and a gain medium. The gain medium includes a layer sequence composed of two quantum wells and at least one tunnel diode and is set up to emit an electromagnetic wave. The photonic crystal is electromagnetically coupled to the gain medium. The stacked arrangement is disposed on a substrate. Alternatively or additionally, the gain medium includes at least one quantum well. The photonic crystal is structured in a dielectric layer and electromagnetically coupled to the gain medium.