Topological Bulk Laser Cavity for Stable Single-Mode Vertical Emission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vertical-cavity surface-emitting lasers (VCSELs) face challenges in increasing single-tube output power due to high-order oscillation modes and multi-mode operation, which lead to brightness reduction and mode instability, and the multilayer DBRs cause fabrication difficulties and poor heat dissipation, reducing device lifetime.
Innovation Solution
A topological bulk laser utilizing band-inversion-induced reflection with a novel confinement mechanism, incorporating topological and trivial photonic crystals, provides stable single-mode lasing with high directionality by confining optical modes near the center of the Brillouin zone, limiting feedback to a small range of wave vectors, and using a two-dimensional photonic crystal structure to enhance emission area and power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the emitting area of VCSEL is increased to increase single-tube output power, then output power is improved, but high-order oscillation mode starts to lase leading to brightness reduction and mode instability
Solution Approach 1:
The patent applies local quality by designing photonic crystal structures with specific local geometric parameters (hole radius, lattice constant, slab thickness) that create localized band inversion regions. These local structural characteristics generate topological surface states that confine optical modes to specific regions, enabling large emitting area while maintaining single-mode stability through localized topological protection.
Solution Approach 2:
The patent utilizes parameter changes by adjusting photonic crystal geometric parameters (hole radius ratio, lattice constant, slab thickness) to achieve band inversion. By changing these parameters, the system transitions from trivial to topological photonic crystal phases, creating topological surface states that provide robust single-mode confinement even with large emitting areas, thus resolving the contradiction between power and mode stability.
2Stability of the object's composition
If multilayer DBRs are used to form vertical microcavity with high Q, then optical field confinement is improved, but fabrication process becomes difficult and heat dissipation deteriorates
Solution Approach 1:
The patent extracts the complex multilayer DBR structure and replaces it with a simplified photonic crystal slab structure. By taking out the traditional DBR mirrors and using photonic band gap engineering in 2D photonic crystals, the system achieves comparable or superior optical confinement with much simpler fabrication processes, directly addressing the fabrication difficulty issue while maintaining optical field confinement.
Solution Approach 2:
The patent substitutes the mechanical multilayer DBR mirror system with a photonic crystal-based optical confinement mechanism. Instead of relying on multiple alternating high/low index layers (mechanical stacking), the system uses photonic band structure engineering and topological surface states to achieve optical confinement, simplifying fabrication and improving heat dissipation while maintaining high Q-factor.
3Use of energy by moving object
If thicker DBRs are used to provide effective feedback at long wavelength, then optical feedback is improved, but heat dissipation becomes poor and lifetime is reduced
Solution Approach 1:
The patent transitions from 1D vertical DBR mirror structure to 2D photonic crystal slab structure. By moving to another dimension (2D periodic modulation in the plane), the system achieves effective optical feedback at long wavelengths without requiring thick structures. The 2D photonic crystal provides in-plane confinement while maintaining thin profile, enabling better heat dissipation while preserving optical feedback efficiency.
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 topological bulk laser achieves stable single-mode vertical emission with high directionality, low threshold, narrow linewidth, and high side-mode suppression ratio, improving device stability and reducing fabrication complexity and heat dissipation.
Implementation Method 1
a band inversion of the dipole mode and the quadrupole mode occurs near the center of the Brillouin zone. This band structure is in topological state, forming topological photonic crystal.
Implementation Method 2
The presently disclosed topological bulk laser based on band-inversion-induced reflection adopts two-dimensional photonic crystal, including topological photonic crystal and trivial photonic crystal.
Implementation Method 3
Joining the trivial photonic crystal and topological photonic crystal to form an interface in the real space, there arises a new reflection and confinement mechanism
Data Source
AI summary
A topological bulk laser includes a topological photonic crystal (32) having an energy band inversion between dipole mode and quadrupole mode near the center of Brillouin zone and a trivial photonic crystal (31) not having band inversion for splicing to each other. The reflection and confinement of an optical field occurs at the interface; and the interface encloses to form a closed contour, thereby forming a laser cavity with an effective cavity feedback for lasing at the interior of the interface. This band-inversion-induced reflection mechanism induces single-mode lasing with directional vertical emission. At room temperature, the topological bulk laser can achieve low threshold, narrow linewidth, and a high side-mode suppression ratio, reduce the fabrication difficulty and costs, and improve heat dissipation and electrical injection efficiency, hence improving lifetime and stability of devices.