Anna Mazhorova graduated from the Physics Department, M.V. Lomonosov’s Moscow State University, (Division of General Physics and Wave Processes, Moscow, Russia) in January 2009. She received her master Degree with Honors in Physics with the specialization in laser physics and nonlinear optics, defending an experimental thesis titled “Spectral-temporal transformation of the femtosecond laser radiation under filamentation in gaseous media” (one of the best master thesis in Physics). Her work concerned the design and realization of a new scheme for generation of few cycle (1 optical cycle is 2.7 fs) optical pulses by the filamentation of the intense femtosecond pulses generated from a high power Ti:Sa laser system. This project was done in collaboration with prof. See Leang Chin (Centre d’Optique, Photonique et Laser (COPL), Université Laval, Québec, Canada).
In August 2012 she defended her Ph.D. thesis, at Génie Physique, École Polytechnique de Montréal under the supervision of Prof. Maksim Skorobogatiy (Canada Research Chair in Micro and Nano Photonics). The thesis is entitled titled “Fabrication and characterization of fiber optical components for application in guiding, sensing and molding of THz and mid-IR radiation”. In addition, she investigated the possibility of using of THz light for physical, chemical and biochemical sensing.
During her PhD studies one of the projects concerned an E.coli bacteria sensor based on the evanescent field of the fundamental mode of a suspended-core terahertz fiber. This project has been done in collaboration with prof. Mohammed Zourob from Institut National de la Recherche Scientifique (INRS-EMT, Varennes). Following the exciting results achieved, she became (June 2012) one of the award winners of the “Étudiants-chercheurs étoiles” competition (Fonds de Recherche du Quebec Nature et Technologies) with her article entitled “Label-free bacteria detection using evanescent mode of a suspended core terahertz fiber”. Since October 2012 Dr. Mazhorova is a Post-Doctoral fellow at INRS-EMT in Roberto Morandotti’s group (UOP).
Efficient Second Harmonic Generation (SHG) with the Longitudinal Temperature Gradient along the LBO Crystal:
Anna Mazhorova is currently working on the experimental realization of the autoresonance effects in nonuniform second order nonlinear materials. One of the potential applications of this research is the design of highly-efficient frequency doubling devices allowing complete depletion of the pump wave . This kind of devices is expected to have a very large conversion bandwidth with a flat conversion spectral profile, similarly to what have been suggested and demonstrated in the case of four-wave mixing in tapered optical fibers .
As a first step towards the realization of the project we demonstrate an efficient technique for the second harmonic generation (SHG) based on the temperature gradient along a nonlinear crystal. The characteristics of Type I non-critical phase-matched SHG of broadband radiation in the LiB3O5(LBO) crystal with the temperature gradient imposed along the crystal were investigated.
The use of LBO crystal for second harmonic generation has the following advantages: high damage threshold (18.9 GW/cm2 for a 1.3ns laser at 1.054mm), relatively high deff (0.85 pm/V), no spatial walk-off and large acceptance angle for the case of type-I noncritical phase matching condition (=90° and =0°) at 1 um wavelength. The main limitation to efficient broadband frequency conversion comes from the chromatic dispersion of the nonlinear crystal, basically from the pulse group velocity mismatch. One of the possibilities to improve the efficiency of the frequency conversion process is a) to use shorter crystals or b) to use a higher power. However, the maximum applied power is limited by the damage threshold of the crystal. Also the conversion efficiency is proportional to the square of the interaction length, but the wavelength acceptance bandwidth is inversely proportional to the same interaction length, resulting in a trade-off between the conversion efficiency and bandwidth. One promising concept for improving the frequency conversion efficiency is through the use of a temperature gradient applied along the crystal . With the temperature gradient along the crystal, the phase-matching conditions are satisfied at different positions along the crystal for different wavelengths and efficient second harmonic generation takes place at a small distance until the wave-number mismatch is close to zero at the corresponding wavelength.