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Avtometriya

2023 year, number 1

1.
CONTINUOUS-WAVE BISMUTH-DOPED FIBER LASERS PUMPED BY MULTIMODE DIODES

A.S. Vakhrushev1, S.V. Alyshev1, A.M. Khegai1, E.G. Firstova1, A.V. Kharakhordin1, K.E. Riumkin1, M.A. Melkumov1, A.A. Umnikov2, F.V. Afanasiev2, A.N. Guryanov2, S.V. Firstov1
1Prokhorov General Physics Institute, Russian Academy of Sciences, Dianov Fiber Optics Research Center, Moscow, Russia
2G.G.Devyatyh Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhny Novgorod, Russia
Keywords: bismuth, luminescence, fiber, laser

Abstract >>
Recent results on continuous-wave bismuth-doped fiber lasers for a wavelength region of 1.3 - 1.5 μm pumped with laser diodes (multimode semiconductor laser diodes) are presented. A concept of the development of such devices by an example of the laser level scheme is considered. The main features of operation of cladding-pumped bismuth-doped fiber lasers and their performance characteristics (efficiency, output power, stability) are discussed. In addition, the possibility of optimizing the parameters of these devices by changing the geometry of the inner cladding and dual-wavelength pumping is considered.



2.
RAMAN GENERATION OF PS-PULSES AT О› = 3.9 µM IN A HOLLOW-CORE REVOLVER FIBER

A.V. Gladyshev1, D.S. Dubrovskii1,2, E.E. Zhuravleva1,2, A.F. Kosolapov1, Yu.P. Yatsenko1, I.A. Bufetov1
1Prokhorov General Physics Institute, Russian Academy of Sciences, Dianov Fiber Optics Research Center, Moscow, Russia
2Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia
Keywords: hollow-core fiber, stimulated Raman scattering, fiber laser, gas laser, mid-infrared, picosecond pulses

Abstract >>
Generation of ultrashort mid-infrared pulses in Raman gas fiber lasers is investigated. Using a hollow-core revolver fiber filled with a mixture of molecular deuterium and hydrogen gases, Raman generation of ultrashort pulses at λ = 3.9 μm is realized for the first time. The pulse duration of 4.6 ps is obtained, and the pulse energy as high as 10 μJ is achieved at λ = 3.9 μm.



3.
FIBER LASER DRIVEN THREE-MICRON SOURCE DEVELOPMENT BASED ON DIFFERENCE FREQUENCY GENERATION

J. R. Taylor
Femtosecond Optics Group, London, UK
Keywords: fiber lasers and amplifiers, MOPFA technology, difference frequency generation, parametric amplification, mid infra-red generation

Abstract >>
We review our development of wavelength tuneable, high average power, picosecond-pulse, mid- infrared sources in the three micron widow for proposed application in tissue ablation studies and with the objective of source simplification and exploring the potential of all-fiber integration. Initial systems were based on difference frequency generation (DFG) of two synchronous master oscillator power fiber amplifier (MOPFA) schemes. The generated idler was tuneable over the range 3.28-3.45 µm, delivering greater than 3 W of average power, with a maximum pump to total DFG power conversion efficiency of 78 %. By simplifying the seed sources through synchronised in-line modulation of cw diode laser sources, more than 6 W was generated 3.31-3.48 µm with similar efficiency and with near diffraction limited beam quality (M2 = 1.4). In an improved and significantly simplified experimental configuration a source emitting around 3 µm was developed employing a novel χ(3)(2) cascaded nonlinear conversion architecture. Picosecond pulses from a 1.064 µm mode-locked Yb:fiber pump laser were used to generate 1.65 µm signal pulses through χ(3) based four-wave mixing in a polarisation preserving photonic crystal fiber (PCF). The output of the PCF was then directly focused into a periodically poled lithium niobate crystal, generating idler radiation around 3 µm, with peak powers of ̴ 0.5 kW, via χ(2)-based three-wave mixing between the pump and signal pulses.



4.
FIBER OPTIC SOURCES OF QUANTUM SQUEEZED LIGHT

A. V. Andrianov1, N. A. Kalinin1, A. A. Sorokin1,2, E. A. Anashkina1, G. Leuchs1,2,3
1Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
2Max Planck Institute for the Science of Light, Erlangen, Germany
3Friedrich-Alexander-Universitat, Erlangen-Nurnberg, Erlangen, Germany
Keywords: Quantum optics, squeezed states of light, ultrashort pulses, Kerr effect, optical fibers

Abstract >>
Quantum squeezed states of light, characterized by a reduced quantum uncertainty in one of the quadrature variables below the uncertainty of the vacuum state (below the standard quantum limit), play an important role in modern fundamental and applied research. This paper provides basic information about the properties and manifestations of squeezed states. A brief review of methods for obtaining and detecting quantum squeezed light is given, with special attention paid to fiber systems. The Kerr mechanism for generating squeezed states, which is implemented in various variants of fiber systems, is considered in detail. An experimental scheme for generating polarization-squeezed states based on a polarization-maintaining nonlinear fiber is presented. Various factors limiting squeezing are considered.



5.
NONLINEAR DYNAMICS IN MULTIMODE OPTICAL FIBERS: RECENT ADVANCES

M. Rehan, R. Chowdhury, S. K. Varshney
Indian Institute of Technology Kharagpur, Kharagpur, India
Keywords: Multimode fibers, Graded-index fiber, nonlinear dynamics, spatiotemporal pulse shaping, Kerr self-beam cleaning, broadband continuum generation

Abstract >>
Nonlinear optics in multimode fibers (MMFs) has had a renaissance over the past two decades, driven by both basic and applied research. MMFs provide an ideal setting for studying multidimensional systems with their complicated collective dynamics. The uniqueness of MMF including the spatial degree of freedom, spatiotemporal dynamics, and inherent disorder make them an ideal tool for exploring novel physics beyond communication. Here, we briefly discuss an overview of nonlinear dynamics in MMFs by focusing their applications in spatiotemporal pulse shaping, self-beam cleaning, and broadband continuum generation. The nonlinearities in MMFs can be useful in linear and nonlinear imaging in microscopy and endoscopy configurations. The growing interest among researchers for nonlinearity in MMFs fibers is pretty evident, indicating a growth in the value of MMFs.



6.
MODE DECOMPOSITION METHOD FOR INVESTIGATING THE NONLINEAR DYNAMICS OF A MULTIMODE BEAM

M. Gervaziev1,2, M. Ferraro3, E. V. Podivilov1,2, F. Mangini3, O.S. Sidelnikov2, D.S. Kharenko1,2, M. Zitelli3, M.P. Fedoruk2, S.A. Babin1,2, S. Wabnitz2,3
1Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
3Sapienza University of Rome, Rome, Italy
Keywords: Mode decomposition, thermalization, multimode fiber

Abstract >>
We overview our recent experimental studies on the nonlinear spatial reshaping of multimode beams at the output of multimode optical fibers. We use a holographic mode decomposition technique, which permits us to reveal the variation of the spatial mode composition at the fiber output, as determined by either conservative (the Kerr effect) or dissipative (Raman scattering) nonlinear processes. For the first case, we consider the effect of spatial beam self-cleaning, and we compare experimental mode decompositions with predictions based on the thermodynamic theory, including the case of beams carrying nozero orbital angular momentum. For the second case, we analyze the beam mode content at the output of a Raman laser based on a graded index multimode fiber.



7.
MULTIMODE SOLITON CHANNELS IN SPACE DIVISION MULTIPLEXED TRANSMISSION SYSTEMS

M. Zitteli1,2, M. Ferraro1,2, F. Mangini1,2, S. Wabnitz1,2
1Universitа degli Studi di Roma La Sapienza, Roma, Italia
2Consorzio Nazionale Interuniversitario per le Telecomunicazioni, Roma, Italia
Keywords: Multimode fiber, space division multiplexing

Abstract >>
We experimentally and numerically demonstrate the inability for picosecond telecom pulses to form a single multimode soliton in a graded-index fiber. This property is useful in space-division multiplexed systems, to transmit independent soliton channels which do not merge into a single multimode soliton.



8.
BRILLOUIN LASERS AND SENSORS: TRENDS AND PERSPECTIVES

A.A. Fotiadi1,2, D.A. Korobko1, I.O. Zolotovskii1
1Ulyanovsk State University, Ulyanovsk, Russia
2University of Mons, Mons, Belgium
Keywords: Fiber lasers, stimulated Brillouin scattering, distributed fiber sensors

Abstract >>
The paper overviews new means of photonics based on the use of stimulated Brillouin scattering (SBS) in optical fibers. The main attention is paid to the original configurations of narrow-band low-noise lasers and their potential applications for distributed fiber-based measurements.



9.
EFFECTS OF LASER PHASE NOISE ON THE OPERATION OF COHERENT REFLECTOMETERS WHEN USING FIBERS WITH ARRAYS OF ARTIFICIAL REFLECTORS

E.A. Fomiryakov1,2, D.M. Bengalskii1, D.R. Kharasov1, O.E. Nanii1,2,3, S.P. Nikitin1,4, V.N. Treshchikov1,3
1Т8 Sensor, LLC, Moscow, Russia
2M.V. Lomonosov Moscow State University, Moscow, Russia
3Т8, LLC, Moscow, Russia
4FemtoVision, LLC, Moscow, Russia
Keywords: sensors, fiber-optic systems, heterodyning, Rayleigh coherent reflectometers

Abstract >>
A review of major noise processes affecting the operation of phase-sensitive coherent reflectometers is given. The overview may be useful for educational purposes. The measurement results obtained using modified single-mode fibers with artificial scatterers distributed along the fiber length are presented. The advantages of such fibers over the standard single mode fibers are demonstrated and analyzed. The relationship between the phase noise of the reflectometer signal and that of the probing laser is shown.



10.
SPECTRAL PROPERTIES OF DYNAMIC POPULATION GRATINGS IN YTTERBIUM DOPED FIBERS

R.V. Drobyshev, I.A. Lobach, S.I. Kablukov
Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Dynamic gratings, Ytterbium, self-sweeping

Abstract >>
In this work, spectral and phase properties of dynamic population gratings in various samples of ytterbium fibers are studied at various powers of recording and pumping radiation. It turned out that, despite differences between the samples, power dependences have a similar character, which is determined by the gain in the fiber and the saturation power in it. It is shown that the phase of the dynamic grating takes on a constant value, changing it only at the instant of the transition from the absorption grating to the gain grating. Significant influence of the phase component in dynamic population gratings in ytterbium doped fibers is experimentally shown.



11.
LOCALIZED SENSING OF PHASE TRANSITIONS IN NANOSIZED POLYMERS USING A THERMOPLASMONIC METASURFACE

E.A. Chernykh, S.S. Kharintsev
Institute of Physics, Federal State Autonomous Educational Institution of Higher Education "Kazan Federal University", Kazan, Russia
Keywords: thermoplasmonics, plasmonic nanostructures, titanium nitride, phase transitions, nanosized polymers, Raman spectroscopy

Abstract >>
Under the action of light in plasmon resonance conditions, metal nanoparticles induce heat at the nanoscale. This effect forms the basis for thermoplasmon probing of phase changes occurring in nanoscale systems, the study of which is a key task in modern material science. Despite the obvious simplicity of this approach, enhanced absorption of light by resonant nanostructures does not guarantee the desired optical heating in cases where the thermal conductivity of the medium significantly exceeds the thermal conductivity of the plasmonic nanostructure. We propose an approach for creating controlled heating of plasmonic nanostructures by nanostructuring the surface of a thermostat, which is demonstrated using a thermoplasmonic metasurface, which is an array of TiN:Si voxels - a vertical system of titanium nitride (TiN) and silicon (Si) nanostructures on a silicon substrate. Plasmonic TiN nanostructures play the role of nanoheaters, and varying the height of silicon heat conductor makes it possible to control the temperature of heating of voxels at a fixed value of the pump intensity by controlling heat localization. A possibility of probing phase transitions in nanoscale systems is demonstrated by an example of thin polymer films using a thermoplasmonic metasurface and Raman spectroscopy.



12.
TUNABLE PLASMONIC MATERIALS FOR THERMOPHOTONIC APPLICATIONS

A.V. Kharitonov, E.A. Chernykh, S.S. Kharintsev
Institute of Physics, Kazan Federal University, Kazan, Russia
Keywords: Thermophotonics, plasmonics, tunable materials, titanium oxynitride, optical heating, oxidization

Abstract >>
Optical heat generation and control at the nanoscale play a key role in many applications, such as photothermal therapy, photocatalysis, thermophotovoltaics, etc. Adjusting the photoheating temperature can be easily performed by tuning the intensity of the incident light. However, fine tuning of the temperature of nanostructures at a fixed light intensity still remains a challenging task. In this work, we propose a tunable optical nanoheater that consists of a titanium oxynitride (TiON) plasmonic antenna placed on top of a silicon cylinder. It has been experimentally shown that, at a fixed intensity of 5 MW/cm2, a change in the photoheating temperature up to 100 C can be achieved. The underlying approach is based on the controlled oxidation of TiON. This allows for flexible tailoring the permittivity of TiON. As a result, the photoheating temperature can be tuned, which is associated with the modification of the absorption cross-section of plasmonic nanostructure.