Abstract-Enhanced Broadband Terahertz Radiation from Two-Colour Laser Pulse Interaction with Thin Dielectric Solid Target in Air

 

Sonal Saxena, Suman Bagchi, Mohammad Tayyab, Juzer Ali Chakera, Saurabh Kumar,  Devki Nandan Gupta 

https://link.springer.com/article/10.1007/s10762-021-00801-x

We report enhanced broadband terahertz (THz) generation and detailed characterization from the interaction of femtosecond two-colour laser pulses with thin transparent dielectric tape target in ambient air. The proposed source is easy to implement and exhibits excellent scalability with laser energy. Spectral characterization using Fourier transform spectrometer reveals yield enhancement of more than 150% in the THz region of 0.1–10 THz with respect to conventional two-colour laser plasma source in ambient air. Further, the source spectrum extends up to 40 THz with an enhancement of flux >30%. Experimental results, well supported with two-dimensional particle-in-cell simulations, establish that the transient photo-current produced by the asymmetric laser pulse interaction with air plasma as well as near solid density plasma formed on the tape surface is responsible for the enhanced terahertz generation. The source will be useful for the multidisciplinary activities and ongoing applications of the laboratory-based terahertz sources.

Abstract-Single-Shot Terahertz Time Profiling Using Curved Wavefront

Sonal Saxena, Suman Bagchi, Bobbili Sanyasi Rao,   Prasad Anant Naik,  Juzer Ali Chakera

https://ieeexplore.ieee.org/document/8398423/


We report an improved single-shot electro-optic sampling (EOS) based detection scheme to measure the time profile of a terahertz (THz) pulse using inherent curvature of a converging wavefront. A simple addition to conventional multishot EOS technique enables single-shot recording of THz time profile. While the temporal resolution of the proposed method is limited only by the duration of the probe laser pulse, the spatial resolution can be externally controlled with ease. Our method is easy to implement and has the potential to provide better signal-to-noise ratio compared to other single-shot methods. An interesting spin-off of the proposed technique is that the quintessential space-to-time calibration process itself reveals the spatial profile of the THz radiation. The technique is simple yet versatile and capable of characterizing THz radiation emitted by high-power THz sources employing ultrashort intense lasers and modern-day particle accelerators. As a proof of principle demonstration, we provide measurement and characterization of the THz pulse emitted by two-color laser-produced plasma in ambient atmosphere using 45 fs Ti:sapphire laser pulses. Our method faithfully reproduces the THz waveform measured by conventional scanning EOS technique.

Abstract-A simple and straightforward technique for single shot measurement of terahertz profile

Sonal Saxena, B.S. Rao, J.A. Chakera, P.A. Naik

(Submitted on 18 Feb 2016)

http://arxiv.org/abs/1602.05739

A new detection scheme capable of acquiring the entire spatiotemporal profile of terahertz radiation in a single laser shot is being demonstrated. The design allows temporal resolution of the order of transform-limited pulse duration of the probe, which is an absolute benefit over the compromised resolution of otherwise prevalent single-shot detection schemes based on spectral encoding of terahertz waveform on a temporally chirped readout pulse. This makes the technique perfectly suitable for sensitive spectroscopy studies. The single shot detection technique presented here relies on space-to-time mapping of terahertz temporal profile by use of a converging probe intensity front. The present approach does not require any specialized optics and is implemented using very straightforward alignment procedure. It has shown to reproduce the temporal waveform of terahertz radiation faithfully.