Laboratory for the Diagnostics of Novel Optical Materials for Advanced Lasers

Scientific results:

• We have laid  scientific and technological groundwork that allows to perform a complete cycle of works to implement new laser media into the manufacture of optical nodes and components with unique characteristics for the creation of lasers that simultaneously have a high mean power over time and peak power. It also allows to forecast the optical and laser properties of new media and compile recommendations for manufacturers concerning the chemical composition of new samples when it is necessary to change some laser characteristics.
• The Laboratory has established close connections with leading Russian and foreign manufacturers of all types of laser materials: glasses, monocrystals and ceramics for the testing of our designs. For the diagnostics of produced samples we have developed methods of measuring photoelastic, thermo-optical, nonlinear-optical, laser, magneto-optical and spectral characteristics in the temperature range from 80 to 300 К.
• We have proposed and experimentally checked a new method of thermodiffusion welding of garnet crystals.
• Our researchers have proposed and experimentally checked new methods of determining the thermal conductivity of junctions and the thermal conductivity of solid bodies with the use of phase-shift interferometry.
• We have designed and created a whole series of unique Faraday isolators, including cryogenic, based on TGG ceramics, CeF3 and TSAG crystal, as well as relying on TAG, Ce:TAG and Si,Ti:TAG ceramics (in collaboration with leading international manufacturers of magneto-optical media).
• The Laboratory has developed lasers based on quantrons we created that have active elements (AE) of the prospective geometries «thin rod» and «thin disc», relying on which we implemented long-time stable operation of a unique laser with a nanosecond pulse energy of 1 J and a frequency of repetition of pulses of 11,5 kHz. Also on the basis of a disc quantron we achieved an increase in the power from 5 W to 50 W in 32 reflections from the active element.
• We have a laser based on Nd:YAG for the pumping of powerful titanium-sapphire amplifiers of chirped pulses with an energy of 220 J in an impulse with a duration of 30 ns with high beam quality that works with a pulse repetition frequency of 0,02 Hz.
• Our researchers have created a Faraday rotator employing a TGG crystal with a record aperture 40 mm for kilowatt-level radiation (in collaboration with the Research Institute of Materials Science).
• We have developed a technology for producing a prospective Tb₂O₃ magneto-optical and performed measurements of the Verdet constant in the wavelength range from 80 to 1750 nm and at temperatures from 80 to 300 К. We developed various technologies for manufacturing wide-band ceramic media with high thermal conductivity, for instance, MgAl₂O₄ (in collaboration with the G. G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences).
• We are working to optimize the parameters of the growth of new magneto-optical monocrystals for a Faraday isolator for high mean power (in collaboration with the A. V. Shubnikov Institute of Crystallography of the Russian Academy of Sciences).

Implemented results of research:

• We have developed measurement and technological benches that entered service at the Institute of Applied Physics of the Russian Academy of Sciences and are used in the research and education process for the diagnostics of a wide range of characteristics of optical media for research purposes. 

• Our researchers have developed design documentation and technological instructions  for the technological process of producing experimental samples, using which we were able to manufacture experimental samples of an amplifier based on an active element with a thin slab geometry, a high-power hybrid laser with a disc terminal amplifier, a high-power hybrid laser with a thin-rod terminal amplifier, a multi-pass signal amplification scheme in a disc active element, a quantron based on a composite disc active element, a quantron based on a slab active element, a compact high-power Faraday isolarot, an amplifier based on an active element with a thin rod geometry made of Yb:YAG with an increased output diameter of the active element , a multi-pass amplifier based on a disc active element.

• Members of the academic team of the Laboratory have prepared and implemented into the education process 12 new training courses in the domain of our project.
• 3 Doctor of Sciences and 13 Candidate of Sciences dissertations have been prepared and defended.
• We provided occupational retraining to personnel: 15 people (students of the Faculty of Radiophysics of the Lobachevskiy Nizhniy Novgorod State University). 
  

Collaborations:

• EGO — European Gravitational Observatory (Italy): «Memorandum of understanding for academic collaboration in developing vacuum-compatible Faraday isolators with high power for next-generation detectors of gravity waves on the basis of a laser interferometer» — the development of a Faraday isolator, including the optimization of  magnetic systems that could be used in gravity wave detectors.
  
• SIOM — Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences (China PR): an agreement for conducting research on the topic «Study of the optimization of the micro-structure of TAG ceramics and advantages of its use for the modulation of powerful lasers» — a comprehensive study of the magneto-optical and thermo-optical characteristics of samples of prospective magneto-optical ceramics of terbium aluminum garnet (TAG) doped with various admixtures (Zr, Si, Ti etc.) created at the SIOM).
• University of Applied Sciences Northwestern Switzerland (Switzerland): experimental and theoretical research of amplification coefficients in a titanium-sapphire crystal with pumping by several individual diodes with a wavelength of 450 nm; we have demonstrated good potential of the scheme for the creation of a wide-band regenerative amplifier.
• LIGO — Laser Interferometer Gravitational-Wave Observatory (USA): research of magneto-optical media in the range from 1 to 2 μm, which can be used in gravitation wave detectors.
• KERI — Korea Electrotechnology Research Institute (South Korea): an agreement on conducting and transferring results of research work to study the feasibility of creating a two-cascade amplification system for a femtosecond laser.
• Institute of Applied Physics (Germany): the Russian Foundation for Basic Research project «Study of the range of applicability of the next generation of volume chirping Bragg gratings recorded using femtosecond laser pulses».
• A consortium comprised by: the Institute of Applied Physics of the Russian Academy of Sciences, A. M. Prokhorov General Physics Institute of the Russian Academy of Sciences, N. I. Lobachevskiy Nizhniy Novgorod State University (Russia): the agreement with the Ministry of Science and Higher Education for 2020–2022 «Creation and development of the world-class research center «Photonics Center» within the priority direction of scientific and technological development «Advanced digital technologies and artificial intelligence, robotized systems, next-generation materials».
• Industrial partner «AVESTA» LLC: an agreement with the Ministry of Science and Higher Education of Russia, Federal Target Program, 2018–2020 «Amplifiers based on prospective geometries for the creation of pico- and femtosecond lasers with high mean power».