Dr. Hemanth Dinesan

Project Title: CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container)

Link to CARIBIC project

 

 

Room 118D, Lab 102

Tel:+353-(0)21-490-3294

Tel:+353-(0)21-490-2358

Fax:+353-(0)21-427-6949

Email: hemanth.dinesan-at-ucc.ie


 

Research Experience

2015-2017:        Postdoctoral fellow, Laser Spectroscopy Group, Physics department, University College Cork, Ireland.

CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container)


2011-2014:        Graduate research student, Seconda Università degli studi di Napoli, Italy.

Dual-laser absorption spectrometry for precision measurements of water spectra in the near-infrared region.


2010-2011:        Project Associate, Indian Institute of Technology (IIT), Kanpur, India.

Polarized fluorescence spectroscopy for the early diagnosis of cervical cancer.


2009-2010:        Master's Thesis, Fiber Optics and Photonics Division, Central Glass and Ceramic Research Institute (CGCRI), India. A detailed study of the Photodarkening effect in the Erbium-doped fiber lasers.

 

Education

2011-2014:       PhD in 'Novel physics methodologies in environmental research', specialized in Laser spectroscopy at Department of Mathematics and Physics, Second University of Naples, Italy.


2005-2010:       5 year Integrated Master of Sciences in Photonics at the International School of Photonics, Cochin University of Science And Technology (CUSAT), India.

 

Research Interests

  • High sensitivity molecular spectroscopy involving optical cavities.
  • Metrology, Primary methods and applications.
  • Non-linear spectroscopy.

 

PhD Thesis:

Group:             Seconda Universita Degli Studi di Napoli, Italy

Supervisor:       Prof. Livio Gianfrani

Title:             Dual-laser absorption spectrometry for precision measurements of water spectra in the near-infrared region

 

Context:


Water vapour is the most important greenhouse gas, product of most of the combustion processes and the most abundant polyatomic molecule. A detailed understanding of the water vapour spectrum is inevitable for the accurate modelling of the earth's atmosphere. Water has been a target molecule for the fields of fundamental metrology, atmospheric science and Paleo-climatology. Unfortunately the accuracies of the molecular spectral parameters given in the HITRAN database are not sufficient for some experiments aiming challenging uncertainty levels (OCO-2 and METEOMET). Lab-based spectrometers are being developed for contributing to the improvement in the HITRAN accuracies.

In this context we have developed a Lab-based dual-laser absorption spectrometer in the Molecules and Precision measurements (MPM) laboratory based up on a pair of offset-frequency locked Extended Cavity diode lasers working in the Master-Slave configuration. The Master/ reference laser has been absolutely frequency stabilized across a natural water transition at 1.39 micron by NICE-OHMS (Noise Immune Cavity Enhanced Optical Heterodyne Molecular Spectrometry). The probe laser (Slave) which has been offset-frequency locked to the master is tuned across the lines of interest This spectrometer gives a breakthrough in quantitative laser spectroscopy, since it provides an absolute frequency scale which enables high quality spectral acquisitions with high signal-to-noise ratio, reproducibility and fidelity, which is inevitable for performing high precision spectroscopic determinations. The frequency scale is limited only by the reference laser line-width (~7 kHz). We have successfully tested our spectrometer in the field of chemical metrology for the 17O/16O amount-ratio measurements with a precision of 0.6‰. The line-centre measurement of an HD16O transition has been performed with a relative stability of 10-10. Currently this spectrometer is being used for performing the third-generation experiment of Doppler-Broadening Thermometry (DBT), one of few experiments for the redefinition of Kelvin, which aims to determine the Boltzmann constant with a target uncertainty of 1ppm.

 

Publications

  • Hemanth Dinesan, Eugenio Fasci, Stefania Gravina, and Livio Gianfrani,

    Ultra-sensitive detection of deuterated hydrogen by means of NICE-OHMS,

    In preparation.


  • Hemanth Dinesan, Eugenio Fasci, A.D'Addio, Antonio Castrillo, and Livio Gianfrani,

    Characterization of an optical frequency standard at 1.39 m based up on noise-immune cavity enhanced optical heterodyne molecular spectroscopy.

    Opt. Exp. 23, 1757-1766 (2015).


  • F. Rohart, S. Mejri, P. S. T. Sow, S. K. Thokunaga, C. Chardonnet, B. Darquie, H. Dinesan, E. Fasci, A. Castrillo, L. Gianfrani and C. Daussy,

    Absorption line shape analysis beyond the detection limit: Application to the Boltzmann constant determination,

    Phys. Rev. A 90, 042506 (2014).


  • Hemanth Dinesan, Eugenio Fasci, Antonio Castrillo, and Livio Gianfrani,

    Absolute frequency stabilization of an extended-cavity diode laser by means of Noise-Immune Cavity-Enhanced Optical Heterodyne Molecular Spectroscopy

    Opt. Lett. 39, 2198-2201 (2014).


  • Antonio Castrillo, Hemanth Dinesan, Giovanni Casa, Gianluca Galzerano, Paolo Laporta and Livio Gianfrani

    Amount-ratio determinations of water isotopologues by dual-laser absorption spectrometry

    Phys. Rev. A 86, 052515 (2012).

 

Conferences

  • H. Dinesan, E. Fasci, S. Gravina, A. Castrillo, and L. Gianfrani,

    Ultra - sensitive detection of HD lines by means of NICE-OHMS,

    CLEO , June 21-25, Munich (2015).


  • E. Fasci, A. Castrillo, H. Dinesan, P. Amodio, M.D. De Vizia, L. Moretti, and L. Gianfrani,

    Spectroscopic determination of the Boltzmann constant at UniNa2,

    Fundamental constants meeting 1-6 Feb, Germany (2015).


  • H. Dinesan, E. Fasci, A. D'Addio, S. Gravina, A. Castrillo and L. Gianfrani

    A reference method for water vapor measurements based up on Cavity Ring-down Spectrometry

    International workshop on Metrology for Meteorology and Climate MMC, September 15-18, Slovenia (2014).


  • Eugenio Fasci, Hemanth Dinesan, Antonio Castrillo and Livio Gianfrani,

    A molecular clock based upon Noise-Immune Cavity-Enhanced Optical Heterodyne Molecular Spectroscopy

    FOTONICA, May 12-14, Naples (2014).


  • Hemanth Dinesan, Antonio Castrillo, Giovanni Casa, Gianluca Galzerano, Paolo Laporta and Livio Gianfrani

    Absolute frequency spectroscopy for the determination of 17O/16O amount-ratio in water

    FISMAT, September 9-13, Milan (2013).


  • Hemanth Dinesan, Eugenio Fasci, Giovanni Casa, Antonio Castrillo and Livio Gianfrani,

    Absolute frequency stabilization of an extended-cavity diode laser by Noise-Immune Cavity-Enhanced Optical Heterodyne Molecular Spectroscopy,

    FISMAT, September 9-13, Milan (2013).


  • Hemanth Dinesan, Eugenio Fasci, Giovanni Casa, Antonio Castrillo and Livio Gianfrani,

    Absolute frequency stabilization of an extended-cavity diode laser by Noise-Immune Cavity-Enhanced Optical Heterodyne Molecular Spectroscopy,

    HRMS, August 25-30, Hungary (2013).


  • Antonio Castrillo, Hemanth Dinesan, Giovanni Casa, Gianluca Galzerano, Paolo Laporta and Livio Gianfrani,

    Application of the Kalman filtering technique to the spectroscopic determination of the 17O/16O isotope ratio in water,

    SIF, September 17-21, Napoli (2012).