For all the imaging and sensing applications involving THz quantum cascade lasers, the emission beam pattern and quality are extremely important. On the other hand, the long wavelength at THz (~100 µm) relative to the cross section of the laser ridge (several 10 µm) yields a highly divergent beam pattern from conventional edge-emitting Fabry-Perot ridges.

In this project, we are developing novel emitters with high beam qualities, unidirectional emission, and electrical tunable DFB lasers. All these features are important for imaging and sensing applications.

Selected publications:

• J.L. Adam, I. Kašalynas, J.N. Hovenier, T.O. Klaassen, J.R. Gao, E.E. Orlova, B.S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Beam pattern of Terahertz quantum cascade lasers with sub-wavelength cavity dimensions,” Appl. Phys. Lett. 88, 151105 (2006). [PDF]
• E. E. Orlova, J. N. Hovenier, T. O. Klaassen, I. Kasalynas, A. J. L. Adam, A. Baryshev, J. R. Gao, T. M. Klapwijk, B. S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Antenna Model for Wire Lasers,” Phys. Rev. Lett. 96, 173904 (2006). [PDF]
• Sushil Kumar, B. S. Williams, Q. Qin, A. W. M. Lee, Q. Hu, and J. L. Reno, “Surface-emitting distributed feedback terahertz quantum-cascade lasers in metal-metal waveguides,” Optics Express, 15, 113-128 (2007). [PDF]
• Alan Wei Min Lee, Qi Qin, Sushil Kumar, Benjamin S. Williams, Qing Hu, John L. Reno, “High-power and high-temperature THz quantum-cascade lasers based on lens-coupled metal-metal waveguides”, Optics Letters, 32, 2840 (2007). [PDF]
• T. Y. Kao, Q. Hu, and J. L. Reno, “Phase-Locked Arrays of Surface-Emitting Terahertz Quantum-Cascade Lasers,” Appl. Phys. Lett. 96, 101106 (2010). [PDF]
• Tsung-Yu Kao, Qing Hu, and John L. Reno, “Perfectly Phase-matched Third-order DFB Terahertz Quantum-Cascade Lasers,” Opt. Lett. 37, 2070 (2012). [PDF]
• Tsung-Yu Kao, Xiaowei Cai, Alan W.M. Lee, John L. Reno, and Qing Hu, “Antenna Coupled Photonic Wire Lasers,” Optics Express, 23, 17091- 17100, (2015).[PDF]
• Tsung-Yu Kao, John L. Reno, and Qing Hu, “Phase-locked laser arrays through global antenna mutual coupling,” Nature Photonics, 10, 541 (2016). [PDF] [Cover]
• Ali Khalatpour, John L. Reno, Nazir P. Kherani, and Qing Hu, “Unidirectional Photonic Wire Laser,” Nat. Phot. 11, 555 (2017). [PDF]
• Ali Khalatpour, John L. Reno, and Qing Hu, “Phase-locked photonic wire lasers by π-coupling,” Nat. Phot. 13, 47 (2019). [PDF]

Novel emitting structures

For all the imaging and sensing applications involving THz quantum cascade lasers, the emission beam pattern and quality are extremely important. On the other hand, the long wavelength at THz (~100 µm) relative to the cross section of the laser ridge (several 10 µm) yields a highly divergent beam pattern from conventional edge-emitting Fabry-Perot ridges.

In this project, we are developing novel emitters with high beam qualities, unidirectional emission, and electrical tunable DFB lasers. All these features are important for imaging and sensing applications.

Selected publications:

• J.L. Adam, I. Kašalynas, J.N. Hovenier, T.O. Klaassen, J.R. Gao, E.E. Orlova, B.S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Beam pattern of Terahertz quantum cascade lasers with sub-wavelength cavity dimensions,” Appl. Phys. Lett. 88, 151105 (2006). [PDF]
• E. E. Orlova, J. N. Hovenier, T. O. Klaassen, I. Kasalynas, A. J. L. Adam, A. Baryshev, J. R. Gao, T. M. Klapwijk, B. S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Antenna Model for Wire Lasers,” Phys. Rev. Lett. 96, 173904 (2006). [PDF]
• Sushil Kumar, B. S. Williams, Q. Qin, A. W. M. Lee, Q. Hu, and J. L. Reno, “Surface-emitting distributed feedback terahertz quantum-cascade lasers in metal-metal waveguides,” Optics Express, 15, 113-128 (2007). [PDF]
• Alan Wei Min Lee, Qi Qin, Sushil Kumar, Benjamin S. Williams, Qing Hu, John L. Reno, “High-power and high-temperature THz quantum-cascade lasers based on lens-coupled metal-metal waveguides”, Optics Letters, 32, 2840 (2007). [PDF]
• T. Y. Kao, Q. Hu, and J. L. Reno, “Phase-Locked Arrays of Surface-Emitting Terahertz Quantum-Cascade Lasers,” Appl. Phys. Lett. 96, 101106 (2010). [PDF]
• Tsung-Yu Kao, Qing Hu, and John L. Reno, “Perfectly Phase-matched Third-order DFB Terahertz Quantum-Cascade Lasers,” Opt. Lett. 37, 2070 (2012). [PDF]
• Tsung-Yu Kao, Xiaowei Cai, Alan W.M. Lee, John L. Reno, and Qing Hu, “Antenna Coupled Photonic Wire Lasers,” Optics Express, 23, 17091- 17100, (2015).[PDF]
• Tsung-Yu Kao, John L. Reno, and Qing Hu, “Phase-locked laser arrays through global antenna mutual coupling,” Nature Photonics, 10, 541 (2016). [PDF] [Cover]
• Ali Khalatpour, John L. Reno, Nazir P. Kherani, and Qing Hu, “Unidirectional Photonic Wire Laser,” Nat. Phot. 11, 555 (2017). [PDF]
• Ali Khalatpour, John L. Reno, and Qing Hu, “Phase-locked photonic wire lasers by π-coupling,” Nat. Phot. 13, 47 (2019). [PDF]