a) Cross sectional image of InP-based Quantum Cascade Laser (QCL) grown on InP-on-Si template; (b) Higher magnification cross-sectional image of QCL showing the semi-insulating Fe:InP lateral regrowth region and deposited SiO 2 insulator region. See "High Power, Room Temperature InP-Based Quantum Cascade Laser Grown on Si." (S. Slivken and M. Razeghi, Article #2300206).