B. Terahertz Devices and Applications
The ability to engineer at the nanoscale has led to new classes of artificial materials and devices like metamaterials, nano-photonic devices and non-linear opto-electronic materials. In particular, significant research activity has been directed towards engineering materials and devices for the terahertz range of the electromagnetic spectrum, where the engineered spatial elements can be comparable to the wavelength of THz waves. Moreover, this frequency range – sandwiched between the high energy optical frequencies and the low energy microwaves and electronics, bridges an important gap between the traditional worlds of optics and electronics. Thus THz devices and materials find powerful applications in a variety of nano/micro scale devices, materials characterization, security and imaging; and the study of fundamental low energy excitations of molecules, semiconductors and metals.
Recent efforts in the Femtosecond Spectroscopy Unit have been directed towards developing novel THz sources and detectors, studying the properties of materials in the THz frequency range, and using low frequency THz radiation to manipulate states of matter. We have demonstrated the ability to generate broadband (upto 20 THz) radiation using interdigitated semi-insulating GaAs antennas , as well as high efficiency THz emitters using laser-ablated GaAs . Continued work in the group lies in the direction of studying and fabricating quantum cascade based devices by using deep subwavelength confinement within arrays of microcavities, enhancing the light-matter interaction. With this approach, we aim at realizing a range of new THz devices with improved performances such as lasers, electroluminescent diodes and amplifiers.
 P. J. Hale, et al. Opt. Exp. 22 26358 (2014)
 J. Madeo, et al. Opt. Letters 40 3388 (2015)