1) Fast melting & ultrasonics in refractory metals by nanosecond pulse laser radiation
We are developing all-optical technique for automated high temperature control of thermophysical properties of refractory materials using nanosecond laser pulse-induced heating, melting and ablation and their detection by laser vibrometry based on two-wave mixing photorefractive interferometry. This technique aims for laser pulse-based melting & real-time diagnostics of materials suitable for harsh conditions pertinent in nuclear & fusion energy and aerospace applications. We are also researching elastic properties of refractory metal nanofilms by nanosecond laser-induced surface acoustic waves.
2) Nanoscale thermal transport in solid structures by ultrafast optical pump-probe technique
This projects focuses on the control of nanoscale thermal transport degradation in swift heavy & slow light ion irradiated solids by ultrafast laser optical technique called picosecond time-domain thermorelfectance (TDTR) for nuclear and fusion energy applications. Phonon mediated thermal conduction in irradiated oxides, novel thin films and superlattice-based thermal barrier coatings are also studied. We are also assembling photoacoustic cell technique for thermal property measurements.
3) Visco-elastic properties of complex fluids, nanoparticle colloids, biomaterials and GHz phononic crystals by Brillouin spectroscopy
We are investigating hypersonic viscoelastic properties of complex fluids, nanoparticle colloids, and biomaterials (mammalian bones, plant leaves, human body fluids) by Brillouin light scattering micro-spectroscopy using scanning 6-pass tandem Fabry-Perot interferometry coupled with confocal microscope imaging and single photon counting. This project pursues variety of optical sensing applications in biomedical, agricultural and petroleum sectors. Using this technique we also investigate phononic band-gap properties of oil-infiltrated periodically nanostructured polymeric phononic band-gap crystals periodically nanostructured by femtosecond laser-induced two-photon polymerization for potential application in the control of GHz acoustic waves and heat. We have also demonstrated surface plasmon-mediated enhancement of Brillouin scattering.
4) UV-Raman micro-spectroscopy of Si-based nanostructures
We are investigating confined phonon modes and thermal conductivity in various Si-based nano-engineered structures using confocal ultraviolet Raman micro-spectroscopy for photovoltaics and nanoelectronics applications.