Research:
Terahertz is electromagnetic radiation lying between infrared and microwave in the electromagnetic spectrum. Terahertz (THz) photons carry only a few meV energy. 1 THz photon carry only 4.1 meV. Hence, they are perfect to probe intraband scattering. Thus, time domain terahertz spectroscopy provides noncontact and non-destructive method for complex conductivity measurements. We study charge transport properties of different nanomaterials employing this spectroscopic technique.
Nanomaterials exhibit exotic transport properties under photoexcitation. We can study the scattering dynamics in-details using optical pump-terahertz probe spectroscopy. Any instant after photoexcitations can be unveiled through photoexcited conductivity dynamics. We use ultrafast optical pulses to generate and detect terahertz pulses. Another optical pulse is used to photoexcite the samples.
Terahertz (THz) emission spectroscopy is a novel experimental method for measuring ultrafast carrier dynamics in various systems. The dynamical process's THz waveform serves as the signal field, in contrast to pump-probe spectroscopies, which is analysized to understand exotic ultrafast properties of the nanomaterials.
Pump probe spectroscopy is the most basic experimental approach to explore ultrafast carrier dynamics. An ultrashort laser pulse is split into two parts in this method: a stronger beam (the pump) is used to excite the sample and induce a non-equilibrium state, and a weaker beam (the probe) is used to observe changes in the sample's optical constants (such as reflectivity or transmission) caused by the pump. The fluctuations in optical constants as a function of the delay between the arrival of the pump and probe pulses can be used to get information about the relaxation of electronic states in the sample.
Low dimensional materials often experiences hot phonon effect upon irradiation with ultrashort pulses. In the micro-fluidic media temporal hot-phonon-effect generates transients unstable bubbles which grows and collapse immediately generating shock wave in the vicinity. These after pulse effect can be employed for intracellular drug delivery of cancer cells almost with great cell vibility and transfection effect. Even this mechnisms can efficiently be used for exfoliating layerd materials which are of great interest for advanced optoelectronic applications. We are high interested to explore this field towards new and potenial device making platform.