Surface-emitting photonic crystal terahertz quantum cascade laser adopting uniform triangular prism photonic crystal with a double-metal waveguide

Abstract

Herein, we investigate surface-emitting photonic crystal terahertz quantum cascade lasers adopting double metal waveguide for high light extraction efficiency by utilizing finite-difference time-domain and filter diagonalization method. For the ease of fabrication and scalability of beam power, only a typical uniform 2D unit cell with triangular lattice and connected metal electrodes are considered in this study. Cylinder or uniform triangular prism photonic crystals are adopted as resonators within the selected unit cell structure. Candidate Γ-point modes for efficient surface-normal emission are searched based on the unit cell analysis as a first step. After that, far-field, field distribution, and light-extraction efficiency are calculated to verify the candidate modes’ suitability by deploying 15(16)x15 unit cells. Extracted results show that the surface-emitting quantum cascade lasers with triangular prism photonic crystal slabs have the possibility to attain high light-extraction efficiency with Gaussian beam shape even with compact chip size and high active region occupancy.

Realization of Low Dislocation Density AlN on Patterned Sapphire Substrate by Hydride Vapor‐Phase Epitaxy for Deep Ultraviolet Light‐Emitting Diodes

“…Usually, AlN is used as the template layer for the epitaxial AlGaN layer for DUV‐LEDs based on AlGaN, and therefore the quality of the AlN template is crucial for the epitaxial growth of high‐quality and high‐efficiency DUV‐LEDs. [ 5–8 ] Hydride vapor‐phase epitaxy (HVPE) is one of the prospective approaches for the preparation of freestanding AlN substrates and thick templates owing to its high growth rate and low carbon impurity incorporation. [ 9–11 ] Multiple groups have reported the growth of AlN directly on sapphire substrates by HVPE, but the crystal quality of AlN templates was relatively poor.…”