Femtosecond Spectroscopy and Nonlinear Photonics Laboratory

Femtosecond laser pulses at the visible and near infrared frequencies are used for exploring the nature of light-matter interaction at ultrafast time scales, exploring nonlinear optical processes in physical/chemical/biological species, and generation of new electromagnetic radiation at much different frequency regions by wave-mixing in certain media.

For some of the basics of ultrafast optics and related experiments, students may refer to some notes on ultrafast optics and experiments. As applications of femtosecond laser pulses, a few examples from our own work are also provided on that page.

My research group has developed Femtosecond spectroscopy and nonlinear photonics laboratory at IIT Delhi with funding support from mostly Govt. funding agencies. This has helped us to device various experiments for conducting cutting edge research on condensed matter systems of our current interest. Please see the Publications to know the details. The home-built experimental setups are used to carry out experiments relating to ultrafast and nonlinear optics and spectroscopy, THz optics and spectroscopy, nonlinear optical physics, pulse shaping for coherent control, etc.

The laboratory has experimental setups developed in-house around a femtosecond laser system comprising of
- Ti:sapphire oscillator (<20fs)
- Chirped pulse Ti:sapphire amplifier (<40 fs)
- Optical parametric amplifier (50-150fs)

Two major experiments are: femtosecond time-resolved spectroscopy and THz time-domain spectroscopy. They can be performed under different conditions.

The setups are quite complex and need dedicated time. All are run and maintained by PhD students.

Optical parameteric amplifier comes handy in need for wavelength dependent experiments though there are several limitations.

The whole lab is fully controlled and, systems and experiments maintained by the dedicated team of students.

Liquid helium cryostat for low-temperature studies - This facility has been created in our lab with the funding support from DST and serves for our interests in various low temperature electrical and optical studies. Students get trained to use this very special tool for their research work. They have used it for studying low-temperature physics of various condensed matter systems such as carbon nanostructures and topological insulators. This particular device is currently being used in optical to terahertz frequency experiments on solids and two-dimensional materials.

Laboratory for materials devolopment - Dedicated laboratory facilities are used for developing interesting material systems for our research. The nanoscale research facility and the central research facility at IIT Delhi house many high end material fabrication and characterization equipments. Various materials synthesis techniques are used by the students in our group for their own research work.