In a recent pioneering work,^† phase-resolved measurements of a THz QCL structure were performed using ultrafast pulses. This powerful method probes the dynamics of QCL structures in a time- and phase-resolved fashion, directly measuring important properties such as gain and loss.

In this project, we extend the previous work to THz QCLs based on metal-metal waveguides, and investigate a variety of gain media including resonant-tunneling and scattering-assisted injection schemes. The key enabling element is a monolithically integrated TDS emitter that efficiently generates and emits THz pulses into the quantum structures to be investigated. Such an integrated emitter will also allow future integration of lumped THz devices (for example, transistors) and distributed amplifiers based on THz QCL gain medium.

Selected publications:

• ^†Josef Kröll, Juraj Darmo, Sukhkeep S. Dhillon, Xavier Marcadet, Michel Calligaro, Carlo Sirtori, and Karl Unterrainer, “Phase-resolved measurements of stimulated emission in a laser,” Nature, 449, 698 (2007). [PDF]
• David Burghoff, Tsung-Yu Kao, Dayan Ban, Alan Wei Min. Lee, Qing Hu, and John Reno, “A terahertz pulse emitter monolithically integrated with a quantum cascade laser,” Appl. Phys. Lett. 98, 061112 (2011). [PDF]
• David Burghoff, Tsung-Yu Kao, Dayan Ban, Alan Wei Min Lee, John L. Reno, and Qing Hu, “Gain measurements of terahertz quantum cascade lasers using independent mode-matched emitters,” THE 11TH INTERNATIONAL CONFERENCE ON INTERSUBBAND TRANSITIONS IN QUANTUM WELLS (ITQW2011), Sardinia, Italy, September 1-17 (2011). [PDF]
• David Burghoff, Chun Wang Ivan Chan, Qing Hu, John Reno, “Gain measurements of scattering-assisted terahertz quantum cascade lasers,” Appl. Phys. Lett. 100, 261111 (2012). [PDF]

Time-domain study (TDS) of THz quantum structures

In a recent pioneering work,^† phase-resolved measurements of a THz QCL structure were performed using ultrafast pulses. This powerful method probes the dynamics of QCL structures in a time- and phase-resolved fashion, directly measuring important properties such as gain and loss.

In this project, we extend the previous work to THz QCLs based on metal-metal waveguides, and investigate a variety of gain media including resonant-tunneling and scattering-assisted injection schemes. The key enabling element is a monolithically integrated TDS emitter that efficiently generates and emits THz pulses into the quantum structures to be investigated. Such an integrated emitter will also allow future integration of lumped THz devices (for example, transistors) and distributed amplifiers based on THz QCL gain medium.

Selected publications:

• ^†Josef Kröll, Juraj Darmo, Sukhkeep S. Dhillon, Xavier Marcadet, Michel Calligaro, Carlo Sirtori, and Karl Unterrainer, “Phase-resolved measurements of stimulated emission in a laser,” Nature, 449, 698 (2007). [PDF]
• David Burghoff, Tsung-Yu Kao, Dayan Ban, Alan Wei Min. Lee, Qing Hu, and John Reno, “A terahertz pulse emitter monolithically integrated with a quantum cascade laser,” Appl. Phys. Lett. 98, 061112 (2011). [PDF]
• David Burghoff, Tsung-Yu Kao, Dayan Ban, Alan Wei Min Lee, John L. Reno, and Qing Hu, “Gain measurements of terahertz quantum cascade lasers using independent mode-matched emitters,” THE 11TH INTERNATIONAL CONFERENCE ON INTERSUBBAND TRANSITIONS IN QUANTUM WELLS (ITQW2011), Sardinia, Italy, September 1-17 (2011). [PDF]
• David Burghoff, Chun Wang Ivan Chan, Qing Hu, John Reno, “Gain measurements of scattering-assisted terahertz quantum cascade lasers,” Appl. Phys. Lett. 100, 261111 (2012). [PDF]