Manoj Mridha

Manoj Mridha received his B-Tech degree in Engineering Physics from Indian Institute of Technology, Guwahati, India in the year 2011. Since September 2011, he is a Master student at l’Institut National de Recherche Scientifique – Énergie, Matériaux et Télécommunications (INRS-EMT), under the supervision of Prof. R. Morandotti and Prof. F. Vidal. Manoj worked in the area of Optical Vortices, Optical Tweezers during his internships. His Bachelor's Thesis was on "Optical Fiber Bragg Grating Sensors for Structural Health Monitoring". He is currently working on Terahertz Waveguides for Spectroscopic applications.

 

 

Research Interests

His primary focus is on developing low dispersion broadband THz Waveguide with less dispersion for spectroscopic application. He is also interested in Integrated and Quantum Optics.

 

 

 

Honors and Awards

1. Tuition fees exemption for International students for pursuing Master of Sciences at Institute National Le Research Scientifique (INRS), Montreal, Quebec, Canada.

 
 
Publications
1. Mishra, S.K. Mohan, D. Gupta, A.K. Mridha, “Study of Singular Phases in Laser Cavity modes”, M.K. Photonics Design Center, Instrum. R&D Establ. (DRDO), Dehradun, India , Emerging trends in Electronic and Photonic Devices & Systems, 2009, IEEE Conferences 2009 Page(s):572-575.
 
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Conferences
1. M. Kumar Mridha, M. Daneau, A. Mazhorova, M. Clerici, M. Peccianti, P.-L. Lavertu, X. Ropagnol,     F. Vidal, and R. Morandotti, “Low Dispersion, broadband propagation of THz pulses in a Two-Wire waveguide”, International Workshop on Optical Terahertz Science and Technology (OTST), Kyoto, Japan, April 1-5, 2013 (poster).
 
2.  M. Kumar Mridha, M. Daneau, A. Mazhorova, M. Clerici, M. Peccianti, P.-L. Lavertu, X. Ropagnol,  F. Vidal, and R. Morandotti, “Two-wire waveguides for Broadband, Low-Dispersion Propagation of  Terahertz Pulses”, Photonics North Conference, Ottawa, Canada, June 3-5, 2013 (oral). 
 
3.  M. Kumar Mridha, A. Mazhorova, M. Daneau, M. Clerici, M. Peccianti, P.-L. Lavertu, X. Ropagnol,  F. Vidal, and R. Morandotti, “Broadband, low dispersion propagation of THz pulses in a Two-Wire  waveguide”, CAP Congress 2013, Montreal, Canada, May 26-31 (oral). 
 
4.  M. Kumar Mridha, M. Daneau, A. Mazhorova, M. Clerici, M. Peccianti, P.-L. Lavertu, X. Ropagnol,  F. Vidal, and R. Morandotti, “Low Dispersion, broadband propagation of THz pulses in a Two-Wire  waveguide”, International Workshop on Optical Terahertz Science and Technology (OTST),  Kyoto, Japan, April 1-5, 2013 (poster).
 
 
Contacts

Ultrafast Optical Processing Group

INRS-EMT Université du Québec

1650 Blvd. Lionel Boulet, Varennes, Quebec J3X 1S2, Canada

Tel: +1 (514) 228 - 6802,   Fax: +1 (450) 929 - 8102

E-mail:   This e-mail address is being protected from spambots. You need JavaScript enabled to view it alt-mail:  This e-mail address is being protected from spambots. You need JavaScript enabled to view it .ca

 


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Research Project 


Low Dispersion, broadband propagation of THz pulses in a Two-Wire waveguide

Terahertz (THz) waveguides are the subject of an intensive research aimed at transferring THz radiation over long distances while preserving the pulse amplitude and phase. Standard approaches are not suitable since most of the THz generation techniques deliver extremely large bandwidth pulses, corresponding to single-cycle electric wave packets, which will strongly disperse in dielectric waveguides. This issue is even more important considering that one of the main applications of THz radiation is time-domain spectroscopy, where the temporal coherence of the probing pulse is a must. On the other hand, dispersion-less waveguides have been known at longer wavelengths, e.g. microwave and radio-signals, for several years [1]. As previously proposed also by Mbonye and coworkers for gigahertz signals [2], we have investigated a two-wire configuration properly scaled for the transmission of THz signals We found that low dispersion could be achieved for a broad THz bandwidth over 20 cm of propagation by employing two Copper wires (250 ?m in diameter) separated by a 300 ?m gap in air. Figure 1 shows the measured THz signal (normalized) for both (a) the signal injected into the waveguide and (b) the one transmitted by the two-wire waveguide and measured via electro-optical sampling. In Fig. 1 (c) the normalized amplitude spectra are shown for both the input and the transmitted pulse. The recorded data clearly demonstrate that the single-cycle character of the input pulse is preserved even after 20 cm of propagation, with negligible modulations in the power spectral density, on a more than 2 THz bandwidth. Remarkably, the two-wire waveguide supports a quasi-TEM mode confined on a very small area in between the wires. Figure 2, taken from reference [3], shows the Quasi-TEM mode in the transverse plane of the two-wire waveguide placed sub wavelength apart. This mode pattern was numerically calculated for wire of radius 150µm placed 200µm apart in free space. As can be seen in the inset, the mode is confined in a very small region and is polarized perpendicular to the wire and along the transverse plane carrying the two wires as indicated by the arrows. This spectacular property of this waveguide opens up new intriguing perspectives e.g. for high-spatial resolution imaging. 

 

 
Fig. 1: Measured normalized terahertz pulse for both (a) the reference signal and (b) the transmitted one over the 20 cm waveguide; (c) normalized amplitude spectra of the reference and the waveguide signal.
 
 
 
 
 
 
Fig. 2: Mode field distribution in the transverse plane between two copper wires of radius 150µm placed 200µm apart; the arrows indicating the local field polarization direction.
 
 
References
[1]  R.E. Collin, Foundations for Microwave Engineering, JohnWiley & Sons, Inc., NJ, US (2001).

[2]  M. Mbonye et al., Applied Physics Letters, 95, 233506 (2009).          

[3]  P. Tannouri et al., Chinese Optics Letters9, 110013 (2011).