Differential precisely controllable piezoresonant absolute pressure transducer with a manifold increase in sensitivity

A new system is developed for a multiple increase change in the output of transducer frequency that leads to an increase in its sensitivity. The system does not disturb the vacuum and it makes it possible to perform precise micrometric control of absolute pressure. Deceased. __________ Translated from Izmeritel’naya Tekhnika, No. 12, pp. 34–37, December, 2005.     

Differential toroidal resonator transducer of absolute pressure

The microwave-resonator transducer is a high-Q oscillatory circuit for measurement of high aircraft altitudes. Resonator-based transducers have high sensitivity. A symmetrical system ensures high thermal, vibration, and shock stability. Hysteresis is eliminated due to insignificant deformation of the elastic system. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 43–46, July, 2000.     

Laser diode modulation under multichannel digital 64-QAM and 256-QAM TV signals

A simulation model for laser diode modulation by multichannel 64-QAM and 256-QAM TV signals is developed. The signal/noise (S/N) ratio is used as a criterion for evaluating the quality of TV signals. The effect of nonlinearity of the light-current characteristic on the S/N ratio is studied. Simulation results are presented in the form of a dependence of the maximum number of transmitted channels on the optical modulation depth with certain requirements for S/N. The simulation model is implemented in the object-oriented programming language Delphi 7.     

Toward ultimate performance limits of thermoelectric (QVD) detectors

‘QVD’ detectors are based on thermoelectric heat-to-voltage (Q→V) conversion and digital (V→D) readout. In theory, they are competitive with superconducting tunnel junction detectors and transition edge sensor devices. We analyze the performance of the QVD detectors with different design architectures. It is concluded that the detectors with lanthanum–cerium hexaboride sensors can be very fast: up to 100 MHz counting rates for UV photons. In addition to traditional astrophysical applications, these detectors can be applied to the tasks of quantum computing and communication.     

Energy distribution on the focal plane of a parabolic cylindrical concentrator with angular defocusings

The concentrating capability of an ideal parabolic cylindrical reflector that is exposed to collimated radiation flux with longitudinal and transverse angular defocusings is examined. The energy distribution on the focal plane of the concentrator is studied.     

Estimation and Compensation for Signal-Signal Beating Interference in Direct Detection Fiber-Optical Transmission Systems of OFDM Signals

A mathematical model is developed for calculating the beating noise that occurs during photodetection of a single-band optical OFDM signal. The model allows one to estimate the spectral distribution of the beating noise and the distortion of the OFDM signal subcarrier levels due to fiber dispersion. The influence of the beating noise on orthogonal subcarrier channels, possible ways of increasing the system transmission capacity, and the method of noise compensation on the receiving side are investigated.     

Creation of Periodical Antiparallel Domain Structure in Lithium Niobate Crystals During Growth Process

The advantages of producing a periodically poled lithium niobate (PPLN) structure during crystal growth process are the possibility of obtaining thicker and wider structures that leads to greater useful surfaces in addition to the elimination of the subsequent poling process. We report in this paper a new technology of creating bulk periodically poled LiNbO 3 single crystals with antiparallel ferroelectric domains, by direct electric field poling during growth processes. Growth system configuration, crystal composition and geometry selection are explored to allow successful control of the direction of spontaneous polarization using external electric field. PPLN crystal samples with periodicity 20-100μm were grown using this electric field modulated growth technique.