In this project we aim to perform multidimensional spectroscopy using three optical frequency combs (or tri comb spectroscopy), which is a new tool to probe ultrafast dynamics of chemical compounds. It has no mechanical moving parts and allows the measurement of comb resolution multidimensional spectra at a very high acquisition rate. Generation of three highly coherent optical combs can be achieved through nonlinear spectral broadening of short optical pulses propagating through three cores of a highly nonlinear tri core fiber. The same setup can also be used for dual comb spectroscopy as well as hyperspectral imaging. (Funded through the Marie Curie Actions from EU)

Supervisor : Dr. Arnaud Mussot, University of Lille, CNRS, France

Collaborator : Dr. Steven Cundiff, University of Michigan, Ann Arbor, USA

High-resolution ultrasound based imaging techniques like photoacoustic (PA) imaging that require fast detection of acoustic waves, are often coupled with an opto-mechanical sensor like a Fabry-Pérot cavity (FPC) for enhanced sensitivity at high frequency. In this project, we demonstrated using an electro-optically modulated dual-comb based light source, fast acoustic wave sensing over a given bandwidth [1]. Utilizing a dual-comb vibrometry approach, we demonstrated a proof-of-principle of the technique, with real-time detection of 10 MHz acoustic waves simultaneously with three different teeth achieving a 20 ns temporal resolution. 

[1] Chatterjee, Debanuj, Louis Etien, Simon Boivinet, Hervé Rigneault, Thomas Chaigne, and Arnaud Mussot. "Real-Time Electro-Optic Dual Comb Detection of Ultrasound Waves." arXiv preprint arXiv:2503.19659, 2025. 

Supervisor : Dr. Arnaud Mussot, University of Lille, CNRS, France

Collaborator : Dr. Thomas Chaigne, Fresnel Institut, Marseilles, France

In this project we demonstrated the increment of signal-to-noise ratio (SNR) and/or the recording speed of dual comb spectroscopy (DCS) with time-programmed electro-optically modulated (EOM) frequency combs, in a simple all-fiber architecture. Unlike mode-locked laser based combs, where time-programming requires complex locking mechanisms, time-programming in EOM combs is simple and robust. Thus by directly engineering time-shifts into the pulse train of an EOM comb, the dead time of the interferogram signal in DCS was reduced. A SNR improvement of 11.6 dB or a 12 times reduction in recording speed was demonstrated experimentally [1]. These results open new possibilities for improvement of SNR and/or recording speed of EOM-based multi-comb spectroscopic techniques.

[1] Chatterjee, Debanuj, Eve-Line Bancel, Matteo Conforti, Siddharth Sivankutty, Hervé Rigneault, Pascal Szriftgiser, Steven Cundiff, and Arnaud Mussot. "Sensitivity Improvement in Dual Comb Spectroscopy With Time-Programmed Electro-Optic Frequency Combs." Journal of Lightwave Technology 43, no. 10 (2025): 4648-4658. 

Supervisor : Dr. Arnaud Mussot, University of Lille, CNRS, France

In this research we tried to generate a comb of entangled (frequency bin entanglement) photon states using four-wave mixing between a continuous wave pump and a frequency comb [1]. Such a resource of entangled photons have multiple applications in future quantum computation modalities [2]. We also validated the experimental results with numerical simulations based on the nonlinear Schrödinger equation.  

[1] Chatterjee, Debanuj, Gautam Kumar Shaw, and Anil Prabhakar. "Photon Pair Comb Generation Using Four Wave Mixing in a Highly Nonlinear Fiber." In 2022 Workshop on Recent Advances in Photonics (WRAP), pp. 1-2. IEEE, 2022.

[2] Bhardwaj, Aryan, Debanuj Chatterjee, Ashutosh Kumar Singh, and Anil Prabhakar. "Generation of Tunable Correlated Frequency Comb via Four-Wave-Mixing in Optical fibers." IEEE Photonics Journal (2025). 

Supervisor : Dr. Anil Prabhakar, IIT Madras, India 

This research project (Indo-Russian collaboration) aimed at developing fiber-based phase sensitive amplifiers (PSA) using dispersion tailored fibers (DTF). This dispersion tailoring along the fiber length helps in reduction of unwanted stimulated Brillouin scattering (SBS) allowing launching large powers into a fiber.  We numerically simulated the PSA [1] as well as SBS performances of different DTF profiles. We also experimentally validated a sinusoidal DTF amplification and SBS performance. 

[1] Chatterjee, Debanuj, Sugeet Sunder, Mrudula Krishna, Suchita Yadav, Alexej Sysoliatin, Konstantin Gochelashvili, Sergey Semjonov, Deepa Venkitesh, and Andrey Konyukhov. "A Comprehensive Study on Phase Sensitive Amplification and Stimulated Brillouin Scattering in Nonlinear Fibers with Longitudinally Varying Dispersion." In Photonics, vol. 11, no. 1, p. 3. MDPI, 2023. 

Supervisor : Dr. Deepa Venkitesh, IIT Madras, India 

Collaborator : Dr. Alexej Sysoliatin, Yuri Gagarin State Technical University, Saratov, Russia

This project aims at developing a fiber-based quantum key distribution (QKD) network in Chennai, India. It is a consorted effort of three different institutions : Indian Institute of Technology Madras (IITM), Centre for Development of Advanced Computing (CDAC) and Society for Electronic Transactions and Security (SETS). While IIT Madras focuses on the hardware layer, CDAC and SETS works on the software layers. A successful demonstration of a 2X1 star topology QKD network was implemented in the field with the coherent one way (COW) protocol with a quantum bit error rate (QBER) of 15%. This was the realization of India's first on-field fiber-based QKD network. 

Supervisor : Dr. Anil Prabhakar, IIT Madras, India 

A microwave photonic link carries RF signal modulated on an optical carrier signal [1]. In this research, we explore the possibility of employing a fiber phase sensitive amplifier (PSA) in a microwave photonic link. We numerically quantify the distortions (from third order intermodulation products) introduced by the PSA in the link by solving the nonlinear Schrödinger equation [2].  

[1] Capmany, José, and Dalma Novak. "Microwave photonics combines two worlds." Nature photonics 1, no. 6 (2007): 319. 

[2] Chatterjee, Debanuj, Yousra Bouasria, Weilin Xie, Tarek Labidi, Fabienne Goldfarb, Ihsan Fsaifes, and Fabien Bretenaker. "Investigation of analog signal distortion introduced by a fiber phase sensitive amplifier." JOSA B 37, no. 8 (2020): 2405-2415.  

Supervisor : Dr. Fabien Bretenaker, ENS Paris-Saclay, France

This research aims at modeling the propagation of seven continuous waves through a nonlinear fiber. Here we consider a dual-pump and degenerate signal-idler configuration. Such a configuration lead to phase sensitive amplification of a signal by the strong pumps through four-wave mixing interactions [1]. Due to the presence of two strong pumps, high-order waves are often efficiently generated in such a system. These high-order waves get coupled to the signal and can lead to detrimental effects with respect to signal amplification.

We develop exact analytical solutions for this system implementing a strong pump approximation. We also investigate couplings between constituent subsystems of the seven-wave system [2].

[1] Andrekson, Peter A., and Magnus Karlsson. "Fiber-based phase-sensitive optical amplifiers and their applications." Advances in Optics and Photonics 12, no. 2 (2020): 367-428. 

[2] Chatterjee, Debanuj, Yousra Bouasria, Fabienne Goldfarb, and Fabien Bretenaker. "Analytical seven-wave model for wave propagation in a degenerate dual-pump fiber phase sensitive amplifier." JOSA B 38, no. 4 (2021): 1112-1124. 

Supervisor : Dr. Fabien Bretenaker, ENS Paris-Saclay, France

In this research we theoretically predict the possibility of phase sensitive frequency conversion (PSFC) in a highly nonlinear fiber (HNLF), using only two pump waves. This means, we launch a HOI1 wave, and two pump waves in a HNLF, and at the output, either the signal or the HOI2 wave is generated depending on the phase of the input HOI1 [1]. We use the previously developed analytical seven-wave model to investigate this system. 

[1] Chatterjee, Debanuj, Yousra Bouasria, Fabienne Goldfarb, and Fabien Bretenaker. "Analytical modeling of phase sensitive frequency conversion with a nonlinear fiber in a dual pump architecture." In Nonlinear Optics, pp. NF2A-8. Optica Publishing Group, 2021. 

Supervisor : Dr. Fabien Bretenaker, ENS Paris-Saclay, France

In a fiber phase sensitive amplifier (PSA), the amplifier noise figure is often degraded due to the coupling of the signal to the vacuum modes through four-wave mixing. In this research we quantify the noise figure of a dual-pump PSA through a fully quantum as well as a semi-classical approach. The fully quantum approach requires analytical expressions of the output modes which were obtained using the analytical seven-wave model. However, when the system is strongly nonlinear, those expressions are invalid and we need to rely on semi-classical methods [1].

[1] Chatterjee, Debanuj, Yousra Bouasria, Fabienne Goldfarb, Yassine Hassouni, and Fabien Bretenaker. "Optimization of the conversion efficiency and evaluation of the noise figure of an optical frequency converter based on a dual-pump fiber phase sensitive amplifier." Optics Express 30, no. 25 (2022): 45676-45693.  

Supervisor : Dr. Fabien Bretenaker, ENS Paris-Saclay, France

This research focuses on detecting the orbitam angular momentum (OAM) Hall effect of light. When lights with positive and negative OAM charges get reflected off a slanted mirror, they acquire a spatial shift [1]. We developed a setup that can potentially detect this OAM Hall shift.

[1] Bliokh, Konstantin Y., and Andrea Aiello. "Goos–Hänchen and Imbert–Fedorov beam shifts: an overview." Journal of Optics 15, no. 1 (2013): 014001. 

Supervisor : Dr. Nirmalya Ghosh, IISER Kolkata, India