Laboratory of solid-state lasers and coherent spectroscopy

• Arakcheev Vladimir Genrihovich researcher, Ph.D.
• Morozov Vyacheslav Borisovich Vice-director, Ph.D.
• Olenin Andrey Nikolaevich Ph.D.
• Tunkin Vladimir Grigor'evich Doctor of science
• Yakovlev Dmitriy Vladimirovich

• Bekin Aleksey Nikolaevich

• Miheev Nikita Glebovich
• Ustinov Daniil Igorevich

• coherent antistokes Raman spectroscopy (CARS) in picosecond and nanosecond time domains
• CARS of composite structures of nanopore matrices
• icosecond and nanosecond lasers physics

• Pulsed-diode-pumped, all-solid-state, electro-optically controlled picosecond Nd:YAG lasers
• Transient CARS spectroscopy of rotational transitions in H2: the statistical dependences of the Doppler and collision dephasing
• Collisionally induced dephasing and rotational energy transfer in CO2 Fermi dyad 'red' Q-branch 1285 cm-1
• Collisionally induced dephasing and rotational energy transfer in CO2 Fermi dyad 'blue' Q-branch 1388 cm-1
• Vibrational line shapes of liquid and sub-critical carbon dioxide in nano-pores
• All publications

The first experiments in the laboratory of solid-state lasers and coherent spectroscopy were done in 1974-1975 years. The goal of these experiments was the observation of the 4-th and 5-th harmonics of picosecond Nd-laser in crystals. The results obtained in these experiments were mentioned by Nobel prize winner N.Bloembergen in his Nobel speech as considerable results in nonlinear optics. In 1980, the laboratory began more complex experiments on the base of picosecond lasers, namely experiments realizing nonstationary picosecond CARS of molecular gases (CARS-coherent antiStokes Raman scattering). The corresponding experimental and theoretical works continued during 20 years. The picosecond CARS-spectrometer was constructed, which included fundamental oscillator, five amplifiers, picosecond parametric oscillator (substituted in future by picosecond dye-laser). In experiments with ammonium molecules, it was shown experimentally the important advantage of nonstationary CARS method, namely the absence of nonresonance signal at probe pulses delay more than the duration of exiting pulses. The collisional processes in different gases were investigated by picosecond CARS: ammonium, hydrogen, nitrogen, carbon dioxide. In experiments with molecular hydrogen, it was shown that in pulse responses, measured in picosecond CARS, the effect of Doppler dephasing slowing down by collisions is manifested strikingly. This effect corresponds to the Dicke narrowing effect in stationary spectroscopy. A serious of unique experiments was performed with molecular nitrogen cooled in hypersonic jet, where the transformation of Q-branch components beatings was observed. The picture of these beatings gave the possibility to determine the local rotational temperature of nitrogen molecules. The minimal temperature registered was equal to 11⁰K. The general conclusion from these works is that nonstationary CARS-spectroscopy, in which antiStokes signals (pulse responses from excited vibrational and rotational transitions) in considerable dynamical range up to five-six orders of magnitude are measured, gives the possibility to obtain detailed picture of dephasing processes and collisional effects in gases.

In the second half of 1980 years and in 1990 years, a serious of nonstationary CARS-spectroscopy experiments were performed on electronic transitions of rare-earth atoms –tallium, tullium and samarium in the atmosphere of inert gases. It was shown that the pulse responses are very sensitive to the spectral exchange in the system of the components observed even in the case of considerable Doppler broadening. The experimental technique of nonlinear transformation in atomic gases developed in these experiments was implemented to observe nutations at biharmonical excitation of Raman-active transitions. In the end of 1990 years and in 2000 years, a serious of nonstationary CARS-spectroscopy of Q-branches of carbon dioxide were performed. These experiments have explained the peculiarities of rotational relaxation and spectral exchange in the system of rotational components. From the beginning of 2000 year, the molecular media in near-critical and supercritical condition were investigated using the method of stationary CARS-spectroscopy. The effect of lower frequency Q-branch of carbon dioxide Fermi-doublet narrowing observed at it’s pressing in liquid and supercritical conditions was experimentally registered and was clearly interpreted.

In the last several years, the stationary CARS-spectroscopy experiments are performed in the laboratory on diagnostics of phase condition of molecular media in nanopore. The peculiarities of spectral contributions by molecular component of the gas phase, of molecular layer, absorbed on the surface of the pore, of condensed liquid- like phase and of nearboundary liquid layer near pore surface were investigated. It was shown that critical point of medium in nanopore is displaced in temperature and pressure.

During the whole period of the laboratory functioning, the works to improve the laser sources implemented in the experiments were performed. From the beginning of 2000, a development of solid state laser systems of new type based on laser diode and laser pumping was in action. Two types of picosecong oscillators with diode pumping and electro-optical generation control: with active-passive mode synchronization on the base of semiconductor saturating absorbers and also with rapid negative and positive feedbacks. The picosecond laser of high peak power for scientific and technological purposes developed on the base of the first scheme was marked by diploma in the concourses of Russian laser technique in 2009 and 2010. The second type of picosecond oscillator is developed for Laser-electron generator of very deficit in medicine, science and technique X-rays (International Laser Center MSU, Lebedev Physical Institute, Institute of Nuclear Physics MSU).

• the work with laser and measuring equipment
• registration and modeling of spectra
• optimization of laser resonator schemes
• theoretical calculation of radiation mode structure
• microcontroller and logical integral schemes programming (necessary for laser systems control and experiment automation)

• Тункин В.Г., Морозов В.Б., Оленин А.Н., Яковлев Д.В. в 2011 г. получили Золотую медаль на 4-м Инновационном форуме, проходившем под патронажем эмира Кувейта