Photonic Crystals and Quantum Dots for Infrared Imaging and Sensing

Weidong Zhou

Department of Electrical Engineering, NanoFAB Center

The University of Texas at Arlington, Arlington, TX 76019-0072, USA

E-mail: wzhou@uta.edu

Infrared (IR) photodetectors with wide spectral coverage (1 to 20mm) and controllable spectral resolution are highly desirable for absorption spectroscopy gas sensing and hyper-spectral imaging applications. Owing to the light-matter interaction modification, spectrally selective absorption can be achieved in photonic crystal defect cavities, making it a promising nanophotonic platform for the spectrally selective infrared sensing and hyper-spectral imaging. We present here the research results on the proposed photonic crystal quantum dot infrared photodetectors (PC-QDIPs or PCIPs). We show that significantly enhanced absorption at the defect mode can be obtained at surface-normal direction in a dielectric single-defect photonic crystal slab, with an absorption enhancement factor greater than 4,000, based on three-dimensional finite-difference time-domain technique. Complete absorption suppression within the photonic bandgap region can also be observed in defect-free photonic crystal cavities. The dot-in-a-well quantum dot heterostructure was designed and grown by Molecular Beam Epitaxy technology, with center absorption wavelength of 11um. The design and fabrication process will be discussed, along with the experimental results. A slight dark current increase was measured in the over-temperature dark-current measurement, largely due to the increased surface area and large surface recombination velocity. The spectrally selective enhancement in the PCIP devices was also depending on the spectral overlap of the QDIP absorption peak and the PC defect mode. The work is in collaboration with groups within and outside UTA, including AFRL, Duke University and University of New Mexico, etc. The work is supported by SPRING, AFOSR, AFRL CONTACT, TSGC, and NSF.

Bio: Dr. Weidong Zhou received his B.S. and M.E. degrees from Tsinghua University, China, and his PhD degree, from University of Michigan, Ann Arbor, in 1993, 1996, and 2001, respectively, all in Electrical Engineering. As a lead engineer, he worked at CIENA Corporation from 2001 to 2004, working on active photonic components and subsystems for WDM telecommunication systems. Currently Dr. Zhou is an assistant professor of Electrical Engineering at University of Texas at Arlington. His current research projects include photonic crystals, infrared sensors, silicon photonics and solar cells, with funding support from NSF, NSF SBIR, AFOSR Nano, AFOSR DURIP, SPRING, CONTACT, TSGC and UTA. To date, Dr. Zhou has authored or co-authored over 90 peer reviewed journal publications, conference presentations and invited talks. Dr. Zhou’s major awards include prestigious Outstanding Student of Beijing City (Beijing, 1992), Outstanding Graduates Award (Tsinghua Univ., Gold medal, 1993); IEEE/LEOS Graduate Student Fellowship award (IEEE/LEOS, 2000).