Proceedings of SPIE - The International Society for Optical Engineering (Proceedings of SPIE)
We discuss the possibility of polarization state reconstruction and measurement over 302 km by Superconducting Single- Photon Detectors (SSPDs). Because of the excellent characteristics and the possibility to be effectively coupled to singlemode optical fiber many applications of the SSPD have already been reported. The most impressive one is the quantum key distribution (QKD) over 250 km distance. This demonstration shows further possibilities for the improvement of the characteristics of quantum-cryptographic systems such as increasing the bit rate and the quantum channel length, and decreasing the quantum bit error rate (QBER). This improvement is possible because SSPDs have the best characteristics in comparison with other single-photon detectors. We have demonstrated the possibility of polarization state reconstruction and measurement over 302.5 km with superconducting single-photon detectors. The advantage of an autocompensating optical scheme, also known as "plugandplay" for quantum key distribution, is high stability in the presence of distortions along the line. To increase the distance of quantum key distribution with this optical scheme we implement the superconducting single photon detectors (SSPD). At the 5 MHz pulse repetition frequency and the average photon number equal to 0.4 we measured a 33 bit/s quantum key generation for a 101.7 km single mode ber quantum channel. The extremely low SSPD dark count rate allowed us to keep QBER at 1.6% level.
An example of the construction of acceleration sensors based on fiber-optical displacement transducers with external modulation. Designed the prototype of fiber-optical accelerometer and tested according to the elaborated methodology.
An important factor affecting the operation of any mechanical unit is the vibration of its individual components. Therefore, the development of tools for the continuous monitoring of vibration loads at critical points in the design of assemblies and mechanisms can be considered one of the most promising ways of increasing the quality and reliability of the technological equipment. Contactless fiber optic sensors with external amplitude modulation of the radiation flux can be a good basis for creating built-in vibration diagnostics of a wide class of industrial facilities, from high-precision robotic systems to systems operating in conditions of strong electromagnetic interference and harsh environments. The paper analyzes the main factors affecting the accuracy of the non-contact displacement measurement of an object via a fiber-optic sensor with external modulation. The structure and the algorithm of forming the measuring data of the sensor with automatic compensation of the influence of external factors intended for measuring the amplitude of vibration in industrial conditions are described. The results of the experimental research of the accuracy of the developed sensor on shape and surface quality of the controlled object, the sensor positioning errors during installation and state of the environment in the control zone are considered.
In the frame of the third-order nonlinear wave dispersion theory the equation of motion of a vector wave packets mass center taken in to account arbitrary inhomogeneity profile is obtained. As short vector wave packets localized motion as infinite motion is shown. Short vector wave packets localizations area can be as bigger as smaller in comparison with long vector wave packets localizations area. The effect depend from third-order linear dispersion parameter.
In most projects aimed at modernization of existing production lines and units a new group of mechatronic objects - interconnected multi-motor electric drives - is used. For the efficient and safe operation of this type of drives it is necessary to solve a number of problems, one of which is the development of methods and tools to synchronize the rotation of activators dynamically. The purpose of the research is to create a non-contact sensor for measuring the rotation of the activator. The basis of the developed sensor is a fiber optic converter with external modulation, with which you can implement a non-contact method of measuring displacement of reflective label installed on the shaft of remote devices. To compensate the non-informative factors affecting the accuracy of the position measurement, the original block diagram and processing algorithm were developed which provides stable and accurate registration of appearing the reflective labels under the fiber end when using the sensor in a production environment. The results of the research have made a theoretical basis for the design of the two measuring devices: a high-speed tachometer and a sensor for control of synchronicity rotation in the dynamic mode.
The interaction of short single-component vector solitons in the frame of the coupled third–order nonlinear Schrodinger equations taking into account third–order linear dispersion, self–stepping, self–stimulated Ramanscattering, cross–stepping and cross–stimulated Raman-scattering terms is considered. Conditions of reflection and propagation of the solitons through each other and also the condition of oscillator interaction (vector breather) are obtained.
The development of terahertz imaging instruments for security systems is on the cutting edge of terahertz technology. We are developing a THz imaging system based on a superconducting integrated receiver (SIR). An SIR is a new type of heterodyne receiver based on an SIS mixer integrated with a flux-flow oscillator (FFO) and a harmonic mixer which is used for phase-locking the FFO. Employing an SIR in an imaging system means building an entirely new instrument with many advantages compared to traditional systems. In this project we propose a prototype THz imaging system using an 1 pixel SIR and 2D scanner. At a local oscillator frequency of 500 GHz the best noise equivalent temperature difference (NETD) of the SIR is 10 mK at an integration time of 1 s and a detection bandwidth of 4 GHz. The scanner consists of two rotating flat mirrors placed in front of the antenna consisting of a spherical primary reflector and an aspherical secondary reflector. The diameter of the primary reflector is 0.3 m. The operating frequency of the imaging system is 600 GHz, the frame rate is 0.1 FPS, the scanning area is 0.5 × 0.5 m2, the image resolution is 50 × 50 pixels, the distance from an object to the scanner was 3 m. We have obtained THz images with a spatial resolution of 8 mm and a NETD of less than 2 K.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.