The presentation includes brief information concerning the Fiber Optics Research Center of the Russian Academy of Sciences. The results on the research and development of Bismuth-doped (Bi-doped) optical fibers, Bi-doped fiber lasers and optical amplifiers are discussed in detail. The first Bi-doped optical fibers were fabricated by the Fiber Optics Research Center together with the Institute of High-Purity Substances in 2005 using MCVD technique. To create Bi-doped fiber lasers and optical amplifiers operating in broad spectral region, it is necessary to use Bi-doped fibers with various core glass compositions. We selected the following fiber core glasses: Bi∶SiO2, Bi∶GeO2, Bi∶GeO2-SiO2, Bi∶Al2O3-SiO2, Bi∶P2O5-SiO2. In the results, a family of Bi-doped fiber lasers and optical amplifiers operating in the spectral region 1 150~1 800 nm is developed.

Surface nanoscale axial photonics (SNAP) is a novel platform for fabrication of photonic circuits at the optical fiber surface and their characterization with unprecedented sub-angstrom precision. Their fabrication usually consists of exposures to a CO2 laser beam, which locally anneals the optical fiber and releases tension frozen into the fiber during manufacture. This results in fabrication of microresonators with an effective radius variation on the order of nanometers. In this paper, the ideas and applications of SNAP technology and concentrate on our recent findings obtained in 2016~2017 are overviewed. In particular, it describes our theoretical and experimental results on SNAP at the capillary fiber for applications in microfluidics, frequency comb generation in SNAP bottle resonators, and optomechanics of SNAP bottle resonators.

Semiconductor laser is one of the most important components in optical fiber sensing system. The stability of its output power and wavelength determines the measurement accuracy of the whole optical fiber sensing system. In order to meet the measurement requirements of the sensing system, it is necessary to tune its wavelength, and after tuning to the required wavelength, it needs to have a higher stability. In this paper, the wavelength tuning of semiconductor lasers is studied by temperature control and driving current control. In the past, the tuning is mostly blind. Because the change of driving current will lead to the change of temperature, the two will affect each other. The tuning process is complex, time-consuming and difficult to tune to the best state. In this paper, a 2×2 matrix describing the relationship between wavelength λ and power P as output and driving current I and temperature T as input is presented. The values of four elements in the matrix are determined. Using this matrix, the optimum tuning driving current and temperature can be calculated directly according to the requirements of different wavelength and power, which makes the tuning process more efficient and accurate. High stability TECAL-XV-XV-DAH temperature controller, laser driving circuit and temperature control circuit are designed. Laser tuning with tuning range of 3.2 nm, precision of 0.01 nm, drift of less than 0.002 nm and power fluctuation less than 3 μW is realized.

Intensity for the research on the fiber end and send a Gaussian beam in the reflective surface under the premise of specular reflection and diffuse reflection, through the theoretical analysis of the establishment of a reflective intensity modulation optical fiber sensor function model is established. By the use of Matlab, the reflective surface roughness change and the parameters on fiber itself are analyzed. The effects of smooth mirror and completely diffuse reflector on the modulation characteristics and the effects of optical fiber on the axis spacing, core radius and numerical aperture of optical fiber on the modulation characteristics are studied. The results show that the intensity modulation characteristic of specular reflection is obviously better than that of diffuse reflection, and the peak value of modulation function is 5 times of that of diffuse reflection. In terms of the design of fiber sensor, the optical stress characteristics and measurement accuracy of the fiber sensor can be improved by reducing the spacing between the transmitting and receiving fiber axes, reducing the sending fiber core diameter, increasing the receiving fiber core diameter, and selecting the fiber with larger numerical aperture.

Based on the time-dependent theory, the emission property of two-dimensional anisotropic random laser under femtosecond laser pumping is theoretically investigated by using a Gaussian function to describe the pumping process. The temporal properties of the random laser emission including the peak intensity, delay time and pulse width, are traced with the variation of the sample size, surface filling-fraction and radius of the scatterer. The results show that the behavior of random lasing depends strongly on the system parameters, one can control the output waveshape through modify the above three parameters. The present work can offer more theoretical guidance for the application of the anisotropic random laser, especially the controllability of output waveshape.

To solve the authentic problem on traditional training simulators for photoelectric theodolite, a training simulator based on real image is designed, which consist of a virtual target generator and a virtual target stacker. The target information is picked up from real image, rotated and compressed before made into a virtual target array with some additional information. The virtual target array is added to the real-time background of photoelectric theodolite. The original scene is reconstructed, providing a more natural user interface and a more realistic simulation environment, which make it more easily for photoelectric theodolite operator to get trained at any time and any place.

A modulation microscopy system for specular surfaces is proposed. The system includes two telecentric lenses, a transflective lenses, a microscope objective, a CCD camera and a DMD digital projector. The fringe image generated by the digital projector is imaged by the telecentric lens and the microscope objective to the object surface of the microscope to obtain a virtual standard fringe pattern. The reflected image of the virtual fringe surface to be tested will return along the optical axis of the microscope objective. Entering the CCD image plane, the object to be measured moves along the optical axis under the control of a high-precision one-dimensional translation stage. According to the phase shift algorithm, the modulation image of each position can be calculated from the acquired fringe pattern, and the maximum modulation curve is found. The corresponding position can complete the three-dimensional shape measurement of the object to be tested. The experimental results show that the micro-modulation measurement method can obtain high-precision surface shape, and is especially suitable for surface shape measurement of objects with drastic changes in micro-morphology.

In order to achieve fast and accurate location of single-phase disconnection fault on transmission lines, shorten the power recovery time, a new fault location method based on optical polarization of OPGW optical sensing is proposed. According to the principle of Faraday magneto-optical effect, the optical fiber composite overhead ground wire (OPGW) is used as a sensor to capture and analyze the abrupt signal of the induced current generated by the phase conductor to the overhead ground wire before and after the single- phase wire breakage fault. The location of single-phase disconnection fault is realized. The experiment in the experimental environment is simulated to verify it. The results show that within a given current range, the current intensity obtained by the device is positively correlated with magnitude of the current, the device can effectively capture the abrupt signal at the moment of power failure, and the location result error is within ±250 m, which meets the requirement of engineering design.

The urgent need for high-precision azimuth measurement in the engineering field makes magneto- optical modulation azimuth measurement technology one of the key research directions in the domestic azimuth measurement field. The basic principle of magneto-optical modulation azimuth measurement technology is introduced. The research progress made in improving the azimuth measurement accuracy, reducing the synchronization time and data processing of the azimuth measurement is analyzed, and the technology development trend is discussed. The thesis is of reference value for the development of high-precision azimuth measurement technology and device required for the azimuth reference transfer research.

The grating is the core component of the grating spectrometer. The dispersion ability of the grating determines the spectral resolution of the spectrometer directly. The spectrometer based on the immersed grating uses the immersed grating as the dispersion component. The equation of the spectral resolution of the immersed grating is derived. With the same requirement of the spectral resolution, comparing the immersed grating with the ordinary reflection grating, using the immersed grating can realize high spectral resolution while greatly decreasing the volume and the weight of the spectrometer. The material of the immersed grating, the applications of the immersed grating in spaceborne and ground-based high spectral resolution spectrometers, and the manufacturing methods of the immersed grating are introduced. A 70 mm silicon immersed grating was designed and developed. The measured grating efficiency is >57%, the measured grating polarization is <3.2%, and the test results of all specifications meet the technical requirements.

Based on the film thickness theory model of planetary fixture, the film thickness distributions of hemispherical lens surface are studied theoretically. The film thickness formulas of typical points on the hemispherical surface are calculated, and then the thickness distributions in different situations are calculated by substitution method. The results show that the thickness non-uniformity in central region (within a 90-degreee angle) of the hemispherical surface could be controlled at about 10%, and that in edge region (over a 90-degreee angle) could be as high as 90%. Changing the location of evaporation source has no effect on improving the thickness non-uniformity of hemispherical surface. However, changing the evaporation source can improve the thickness non-uniformity. This research has certain theoretical guiding significance for the analysis and improvement of film thickness uniformity of hemispherical lens coating.

To remove nano-particles of ultra-smooth glass surfaces, white light interferometer and atomic force microscope are used to detect the ultra-smooth polishing samples after common wet cleaning and hydrofluoric acid cleaning. The results show that adding hydrofluoric acid(2%, V/V) cleaning for more than 10 minutes can effectively remove residual nano-particles.

We design and establish a multi-resolution digital holographic microscope with optical fiber. The laser passes through the optical fiber coupler and the optical fiber splitter to form the illumination light wave and the reference light wave respectively. The illuminated light wave is collimated by expanding beam, then it passes through the sample to form object light wave. Compared with ordinary digital holographic microscope, the system is more compact and stable. And it can achieve multi-resolution quantitative phase imaging by choosing different microscopic objectives by rotating the lens turret. First, the imaging accuracy and the spatiotemporal noise of the system is measured. The imaging accuracy is verified by measuring polystyrene beads with the known parameters. The spatial noise is below 2 nm, and the temporal noise is below 0.8 nm. Then, the single-mode fiber, micro-optical elements and biological samples are measured and accurate quantitative phase images are obtained. The experimental results demonstrate that the digital holographic microscope with optical fiber illumination has high stability and can achieve accurate quantitative phase imaging.

Different from the traditional two-dimensional pointing mirror system, the piezoelectric ceramic- based mirror system has high control precision, and the reflecting surface of the mirror is parallel to the X-axis of the three-dimensional coordinate system and it is difficult to obtain a simple analytical expression. In order to solve this problem, in this paper, the issue of optical axis offset and image rotation in two-dimensional pointing mirror system are analyzed. On the basis of optical reflection vector theory at first, we establish a two-dimensional pointing mirror mathematical model, in which the azimuth and elevation angles of the pointing mirror are obtained according to the target deflection angle decoupling, and then numerical solutions are used and the constraints of numerical solutions are proposed. The simulation results demonstrate that the two-dimensional pointing mirror deflection error is much smaller than the instantaneous field angle of the system. Finally, the problem of the image rotation caused by the two- dimensional pointing mirror is analyzed, and the image rotation error is less than 0.01°.

In this paper, based on CORTEX M4 master control chip GD32F450I, path planning of millimeter precision PTZ is completed by using cubic polynomial method, so as to reduce impact and vibration in motion and improve the motion accuracy of the PTZ. Using a double-loop control algorithm based on position loop and velocity loop control method, the position motion precision of the millimeter precision PTZ can be controlled quickly. For the pitch movement of the PTZ, it is also necessary to effectively eliminate the backlash error caused by the load torque by means of fluctuation difference compensation. The control accuracy of the millimeter precision PTZ can reach 0.004deg (azimuth) and 0.006deg (pitch).

In order to measure the time interval with high precision, a time-to-digital converter based on Field Programmable Gate Array (FPGA) was designed. The whole system is divided into two parts: “crude” measurement module and “fine” measurement module. The basic principle of the “rough” measurement module is the direct counting method. The “fine” measurement module uses the carry chain inside the FPGA to construct the delay chain. In this paper, the delay module is optimized by the method of position constraint and multi-chain joint measurement. Finally, the physical test shows that the measurement resolution of TDC is 6.757 ps, the measurement accuracy is 33.802 ps, the range of differential nonlinear DNL is (-1, 3.322) LSB, and the range of integral nonlinear INL is (-11.055, 9.594) LSB. This technique can be used to calibrate the delay time of photoelectric signal transmission.

The effects of hysteresis nonlinear characteristics and creep characteristics of PFSM on control accuracy are analyzed. The XGBoost model is applied to the dynamic hysteresis nonlinear feature modeling of PFSM. By extracting the voltage history characteristics of PFSM, the problem of one-to-many data in hysteresis nonlinearity is effectively solved. The extracted features include voltage of voltage value, frequency of change, direction of change, voltage increment, historical local maximum and local minimum values and time intervals, etc. The simulation results show that the model has good fitting effect on hysteresis nonlinearity and creep characteristics, and the fitting precision is increased by about 40 μrand compared with the static PI model. At the same time, it has the advantages of easy identification of model parameters and easy transplantation to embedded chip. The dynamic hysteresis nonlinear feature modeling method has theoretical significance and practical value.