Title: Laser-feedback interferometry with quantum cascade lasers: a new technology for THz imaging and sensing
Speaker: Associate Prof. Aleksandar D. Rakic（University of Queensland）
Time: OCT. 26, 2015 14:30PM
Venue: No. 101 Meeting Room, IOS, CAS
Abstract: Over the past decade, the quantum cascade laser (QCL) has established itself as one of the most promising radiation sources for imaging applications at THz frequencies due to its ability to generate coherent continuous-wave emission with quantum noise-limited linewidths. This makes THz QCLs particularly suited to the development of coherent THz sensing and imaging systems.
In this talk, I will introduce laser-feedback interferometry utilising the self-mixing phenomenon in QCLs. In this scheme a portion of the emitted beam is coupled back into the laser cavity after reflectionfrom an external target. Optical retro-injection affects the laser's operating parameters; in particular, the laser emission frequency and the laser compliance voltage. By exploiting the interferometric nature of optical feedback in a THz QCL, the laser effectively becomes a highly sensitive and compact homodyning transceiver.
I will present recent advancements in the development of coherent THz imaging and sensing systems based on laser-feedback interferometry. Examples will include imaging and tissue analysis of excised porcine and murine tissue.
Biography：Aleksandar D. Rakic leads the Microwave, Photonics, andCommunications group at The University of Queensland,focusing on the development of technologies for sensingand imaging across the electromagnetic spectrum includingmicrowave, terahertz wave, and optical systems. Over thepast 10 years, Rakic group has pioneered the developmentof several world’s first laser-feedback interferometric sensors,including systems based on monolithic vertical-cavitysurface-emitting laser arrays (VCSELs), blue-green lasers, terahertz quantumcascade lasers, and mid-infrared interband cascade lasers. His current focusis on the development of sensing and imaging systems that exploit the THzspectrum for applications from security and defence to in vivo biomedical imaging.His other principal contributions relate to the design and characterizationof surface-emitting optoelectronic devices (VCSELs and light-emitting diodes).
He was appointed an Invited Professor at the University of Toulouse,(2007–2012), and Visiting Professor at the University of Leeds (2012). Heserved as General Chair of the “2004 Conference on Optoelectronic andMicroelectronic Materials and Devices” (COMMAD 04), Co-Chair of the“Symposium on Molecular and Organic Electronics and Organic Displays”within the 2006 International Conference on Nanoscience and Nanotechnology(ICONN 2006), Chair of the “Symposium on Compound SemiconductorMaterials and Devices” within the 2008 International Conference onElectronic Materials (ICEM 2008) and as Chair, IEEE AP/MTT QueenslandChapter. He is currently Associate Professor of Photonics within the Schoolof IT and Electrical Engineering, The University of Queensland.