Scientific results:
On the basis of a DFB laser operating in the self-injection locking mode in the external ring fiber cavity, we have developed an experimental model of a two-frequency Brillouin laser with a width of each of the lines not exceeding 1 kHz. We demonstrate that for the stable operation of the system in the self-injection locking mode, a simple low-bandwidth active optoelectronic feedback circuit is sufficient. Ensuring stable resonance in the fiber configuration, such a solution allows to avoid using complex active means of stabilization, combining in one unified module the uniqueness of the characteristics inherent to double-resonance lasers and the use of the structure of the fully passive self-tuning fiber system. The achieved results broaden the understanding of the mechanism of self-injection locking in semiconductor lasers and open new opportunities for controlling their properties [Lopez-Mercado, C.A et al; Sensors 2021, 21, 6859, Spirin, V.V et al Optics & Laser Technology 2021, 141, 107156].
We have proposed a scheme for the stabilization of harmonic mode-locking in a ring fiber laser by acousto-optic frequency shifting. It has been experimentally demonstrated a configuration of a soliton laser operating in the telecommunication range (~1550 nm) with the frequency of pulses exceeding 10 GHz and a level of supermode noise mitigation level of about 30 dB [Korobko, D. A. et al, Optics & Laser Technology, 133, 106526 (2021)].
Our researchers have proposed new methods for supermode noise reduction and precise pulse repetition frequency adjustment of a fiber laser with harmonic mode-locking relying on the injection of radiation of an external continuous laser with adjustable wavelength [Ribenek, V. A. et al, (2021). Optics Letters, 46(22), 5687-5690., Ribenek, V. A. et al, (2021). Optics Letters, 46(22), 5747-5750, Ribenek, V. A. et al, (2022). Optics Letters, 47(19), 5236-5239].
The effect of supermode noise reduction in a fiber laser with harmonic mode-locking on the basis of injection of radiation of an external continuous laser was amended with new experimental observations, and it was explained by a series of numerical modeling experiments [D. A. Korobko, et al, "Resonantly induced mitigation of supermode noise in a harmonically mode-locked fiber laser: revealing the underlying mechanisms," Opt. Express 30(10), 17243 (2022)].
On the basis of a fiber telecommunication source, a system for chirped pulse amplification and a large-mode-area photonic-crystal fiber (PCF) with low birefringence, we have developed a laser system generationg ~ 100 fs pulses with energies of ~ 10 nJ in the 1600–1700 nm range. We have researched the characteristics of the output spectrum corresponding to Raman solitons in the context of various polarizations of the pumping pulse at the input of the PCF. It has been demonstrated, the wavelength of the maximum of the output spectrum can be tuned in the long (L) and the ultra-long (U) telecommunication range by regulating the state of polarization of the pumping pulse at constant output power [D. Stoliarov, et al., "Fibre laser system with wavelength tuning in extended telecom range," Optical Fiber Technology 72, 102994 (2022)].
We have researched the properties of arrays of parallel carbon nanotubes with double walls. It has been demonstrated that in such assemblies it is possible to generate ultra-slow modes of surface plasmon polariton (SPP), whose phase speed is several orders of magnitude lower than than the speed of light in vacuum and a high Q factor. It has been demonstrated that nonrelativistic electron beams with a speed of 106 m/s can be used for SPP excitation in arrays of double-walled carbon nanotubes. For SPP modes excited by an electron beam we have determined the frequency range of SPP waves and the speed of the electron beam that correspond to phase synchronism in a wide range of frequencies. It opens a path to the creation of decelerating structures based on dense arrays of multi-walled carbon nanotubes that employ energy transfer from pumping to SPP [A. S. Kadochkin, et al, "Excitation of Ultraslow High‐q Surface Plasmon Polariton Modes in Dense Arrays of Double‐Walled Carbon Nanotubes," Annalen der Physik 2100438 (2022)].
A series of experiments were conducted to study the effects of narrowband lasers operating in a specific range (1265-1270 nm) on cellular structures in vitro and in vivo. These experiments demonstrated that laser sources with higher spectral brightness and lower power can generate a greater amount of reactive oxygen species (ROS). It was shown that laser radiation with a central wavelength of 1265 nm induces the formation of ROS and the activity of superoxide dismutase in melanoma cells (B16 cell culture).
Fiber amplifiers have been developed to increase the output power of the proposed fiber lasers to the level of hundreds of milliwatts, significantly expanding their range of applications. The development employs both large mode area (LMA) fibers and specialized tapered Er-doped fibers. At this stage, a model describing Brillouin interactions in multimode fiber has been developed. The effects of sound propagation accompanying Brillouin scattering in multimode optical fibers are described, and their specific contribution to the Brillouin gain spectrum is demonstrated.
Education and personnel occupational retraining:
- One doctoral and four candidate theses have been prepared and defended.
- Five lab staff members have passed secondments at leading scientific centers in Europe, including Aston University, Imperial College London (United Kingdom), and Ecole Nationale d’Ingenieurs de Brest (France).
- Four young laboratory staff members have passed training at the V.A. Kotelnikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences (RAS).
- Courses and programs have been developed: the postgraduate program "Fundamentals of Nonlinear Optics," and courses for students of the Engineering-Physical Faculty of High Technologies "Nonlinear Laser Fiber Optics" and "Nonlinear and Quantum Optics."
Cooperation:
Imperial College London, Aston University (United Kingdom), University of Mons (Belgium), Tampere University (Finland), Ensenada Center for Scientific Research and Higher Education (Mexico), Leibniz Institute of Photonic Technology (Germany), Czech Academy of Sciences, École Nationale d'Ingénieurs de Brest (France), E. M. Dianov Fiber Optics Research Center of the Russian Academy of Sciences, V. A. Kotelnikov Institute of Radioengineering and Electronics of the Russian Academy of Sciences, Institute of Automation and Electrometry of the Siberian Branch of the Siberian Branch of the Russian Academy of Sciences, Institute of Nanotechnology of Microelectronics of the Russian Academy of Sciences, Novosibirsk State University, Research and Production Complex «Technology Center» (Russia): joint research and publications.
