Assoc. Prof. Dr. Todor S. Petrov

tspetrov (at) issp (dot) bas (dot) bg, petrovts (at) yahoo (dot) co (dot)uk 

Born in September 27, 1962, Dryanovo, Bulgaria.

Main fields of scientific research:

• Development and investigation of new lasers;
• Nonlinear optics, Nonlinear processes in the solid state induced by powerful fs laser pulses;
• z-scan femtosecond technics;
• Laser interaction with materials;
• Laser assisted hydroxyapatite formation;
• Development of interference method for control of optical quality of free liquid flows.

Research and engineering experience:

• Development and optimization of unstable cavity for Copper Bromide Vapor Laser (CBVL).
• Development and an investigation of dye jet laser pumped by CBVL (conversion efficiency of ~60%); Development of new quartz nozzle for the dye laser.
• Development and investigation of dye jet amplifier lasing at 572 nm on a dye solution of Rhodamine 6G pumped only by the 510.6 nm CBVL   line.
• Experimental studies of non-linear frequency conversion of the CBVL radiation by β-­BBO, KDP and DKDP crystals. It was obtained 25% conversion efficiency for the both wavelengths of CBVL.
• Lifetime study of CBVL. It was developed hydrogen getter for controllable maintenance of the optimum working partial pressure of hydrogen in CBVL; "Cool spot" control of optimal ration between partial pressure of components in gas discharge tube of CBVL. The lifetime of laser tube was extended up to 1500 hours.
• Experimental experience and theoretical knowledge on He-Sr recombination laser.
• Capacitively coupled radio frequency (CCRF) excited He-CuBr ion laser. Pulsed and CW lasing at four infrared Cu+ lines (740.4 nm, 766.5 nm, 780.8 nm and 782.6 nm) was obtained at two different radio frequency: 13.56 MHz and 27.12 MHz.
• CCRF excited He-Cd ion laser. Pulsed and CW lasing on ten Cd⁺ lines (441.6 nm, 533.7 nm, 537.8 nm, 635.5 nm, 636.0 nm, 723.8 nm, 728.4 nm, 806.6 nm, 853.1 nm and 887.8 nm) was obtained at two frequencies - 13.56 MHz and 27.12 MHz. Lasing at 325 nm was achieved too, but only in pulsed mode. To our knowledge generation on the 853.1 nm and 887.8 nm transitions was obtained for the first time in a RF-excited discharge.
• CCRF excited He-Zn ion laser. Lasing on the more of the Ze⁺ laser lines was obtained at CW and pulsed mode of operation. RF generator worked on 13.56 MHz.
• CCRF excited He-Cu ion laser. Lasing on 780.8 nm Cu+ line was obtained in pulse mode of operation. RF was 27.12 MHz.
• Development of UV He-Au ion laser excited by longitudinal ns discharge. Simultaneous lasing on the 282.3 nm, 284.7 nm, 289.3 nm and 291.8 nm was obtained. The average output power of 290 mW has been measured for the strongest line 282.3 nm, in CW mode.
• Development of new windowless temperature sink holder for disk solid state laser. Working temperature of 100 K can be obtained and kept for 5 hours. The behavior of Yb³⁺:YO₃ ceramic was studied. The device was applied successfully in the Yb³⁺:YO₃ ceramic femtosecond laser. The same cooler was applied in several femtosecond systems.
• Laser-assisted hydroxyapatite formation by applying laser-liquid-solid interaction method.
• Development of new glass matrix TeO₂-Bi₂O₃-GeO₂. The material was optically and structurally characterized. The second order nonlinear susceptibility in temperature-assisted electrically poled sample was obtained. 
• Development of sub-picosecond z-scan methodic with virtual aperture for determination of nonlinear refractive index n₂ and multiphoton absorption.
• Generation of white by SPM process in Sapphire, BBO-glass samples (own developed), as in photonic crystal fibers.
• Femtosecond ellipsometry setup and measurements. The goal is to be measured optical parameters of some metals (Al, Ag, Au, Mo, etc.). The "pump beam" was 3rd harmonic of 748 nm of Ti: Sapphire amplified by excimer laser.
• White light interferometry method.

Work and Education:

• Associate Professor (Senior research fellow) - Laboratory of Metal Vapour Lasers, Institute of Solid State Physics, Bulgarian Academy of Sciences, since 2007
• Assistant Professor (Research fellow) - 1994 - 2007
• PhD degree - Institute of Solid State Physics, Bulgarian Academy of Sciences, 1993

PhD dissertation theme: "Frequency conversion of Copper Bromide Vapor Laser radiation"

• MSc. degree in physics and engineering - Department of Quantum Electronics and Laser Technique, Faculty of Physics, Sofia University, 1987 

Diploma dissertation theme: "Jet for dye lasers and optical control of its quality"

Qualification:

• Guest professor - Institute for Laser Science, University of Electro-Communications, Tokyo, Japan, 2002, 2004, 2005, 2006, 2007, 2008,2009, 2010, 2011, 2012, 2013.
• JSPS Fellowship - "Development of a new cooling holder for a disk laser without windows for femtosecond laser applications", Institute for Laser Science, University of Electro-Communications, Tokyo, Japan, 2003, 2006
• Guest Scientist position - "Micromachining by Copper Bromide Vapor Laser", Centre for Plasma and Laser Engineering, Institute of Fluid Flow Machinery, Polish Academy of Sciences,  Gdansk, Poland, 2001, 1995.
• Specialization Fellowship (VW-Stiftung) - "UV lasing in capacitively coupled Radio-Frequency excited He (Ne) Copper vapor discharge", AEEO, Ruhr Universität Bochum, Germany, 1997.

Language skills: English, Russian

Publications for the last 5 years:

1. G. Yankov, I. Stefanov, Kr. Dimitrov, I. Piroeva, L. T Dimowa, M. P. Tarassov, B. L. Shivachev, H. Yoneda and T. Petrov, Measurement of nonlinear refractive index and multiphoton absorption by the subpicosecond z-scan method of tellurite multicomponent glassy matrixes having nonlinear susceptibility, Physica Scripta, Phys. Scr.T157(2013) 014026 (5pp), (2013)
   
2. Boris L. Shivachev, Krassimir Kossev, Louiz, T. Dimow, Georgi Yankov,Todor Petrov, Rositsa P. Nikolova, Nadia Petrova, Synthesis, growth, structural, thermal, optical properties of new metal-organic crystals: Methyltriphenylphosphonium iodide thiourea and methyltriphenylphosphonium iodide chloroform hemisolvate, Journal of Crystal Growth 376 (2013) 41 –46, (2013)
3. G. Yankov, L. Dimowa, N. Petrova, M. Tarassov, K. Dimitrov, T. Petrov and  B. Shivachev, Synthesis, structural and non-linear optical properties of TeO2–GeO2–Li2O glasses, Optical Materials 35 (2), (2012) pp. 248-251, (2012)

Participation in projects:

National projects:

1. "Laser assisted structural and ultra-fast dynamical studies of nano-objects", National Science Fund - Ministry of Education and Science, Bulgaria, 2010 - 2011
2. "New multi-component tellurite glassy matrices processing variable non-linear optical properties", National Science Fund - Ministry of Education and Science, Bulgaria, 2008 - 2011 (Leader of the project)
3. "Laser Diagnostics in Archaeology", National Science Fund - Ministry of Education and Science, Bulgaria, 2008 - 2011
4. "Nanostructured coatings - new biomaterials for bone implants obtained by a method of laser-liquid-solid interaction", National Innovation Fund - Ministry of Economy and Energy, Bulgaria, 2007 - 2009
5. "Method for maintaining of hydrogen partial pressure in Copper Bromide Vapor Laser tube", National Science Fund - Ministry of Education and Science, Bulgaria, 2006 - 2007 (Leader of the project)
6. "Development of an in vitro system for layer growth from solutions on modified substrates", National Science Fund - Ministry of Education and Science, Bulgaria, (L1213), 2002 - 2005
7. "Lasing on copper ion lines in UV spectral range", National Science Fund - Ministry of Education and Science, Bulgaria, (№ F-702), 1997 - 1999
8. "Lasing in visible and UV spectral ranges in He-Cd transfer RF discharge", National Science Fund - Ministry of Education and Science, Bulgaria, (№ F-407), 1995 - 1997

International projects:

1. "Investigation and restoration protocols for Cultural Heritage rescue based on remote laser techniques", Bulgarian-Romanian bilateral program, Fund - Ministry of Education and Science, Bulgaria, 2010 - 2012
2. Agreement for joint research between Institute for Laser Science, University of Electro-Communication, Tokyo, Japan and Institute of Solid State Physics, Bulgarian Academy of Sciences, 2003 - 2009
3. "Development of a System Based on a High Power and High Efficiency Copper Bromide Laser for Precision Materials Processing", Germany, Bulgaria, Italy and Poland, NATO Programme Science for Piece (SfP - 972685), 1999 - 2002
4. "High beam quality UV lasers for Microelectronics", Germany, Hungary, Poland, Bulgaria, Belgium, The Netherlands, France, NATO Programme Science for Piece (SfP - 971989), 1999 - 2004
5. "Second harmonics generation with a CuBr vapor laser", Norseld Pty Ltd, Australia, 2000, (Leader of the project)
6. "40 Watt laser tube", Norseld Pty Ltd, Australia, 1998 - 2000
7. "Development of RF- and mW-excited rare gas metal vapor lasers for the UV and visible spectral ranges", AEEO - Ruhr Universität Bochum, Germany; ISSP - BAS, Bulgaria and Centre for Plasma and Laser Engineering, IFFM - PAS, Poland, supported by European Commission Copernicus Programme CIPA-CT 93-0219, 1994 - 1996

 Awards:

 

1. Nomination "Invention of the year - 2012" field Chemistry and Biotechnology of PATENT OFFICE of Republic of Bulgaria, 2012
2. Academic award for Physics as a member of scientific team headed by Prof. DSc Nikola Sabotinov, 1994