Transmission System for Broadband Analog Signals Using External Modulation of Optical Radiation
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ERING DESIGN OF NUCLEAR PHYSICS EQUIPMENT
Transmission System for Broadband Analog Signals Using External Modulation of Optical Radiation V. I. Bogomolov*, Yu. V. Dmitriev, N. G. Ignat’ev, K. E. Korotkov**, P. S. Krapiva, I. N. Moskalenko, A. V. Moskvichev, and S. S. Piskov Dukhov All-Russian Research Institute of Automatics, Moscow, Russia *e-mail: [email protected] **e-mail: [email protected] Received June 22, 2017
Abstract—Fiber optic communication lines on the basis of the Mach–Zehnder intensity modulator can be used in studies of pulsed plasma for transmission of signals from detectors to data acquisition equipment. In this study, a system for transmission of nanosecond signals over fiber optic cables in the ranges of 1550 and 850 nm is demonstrated. A chronographic electro-optical detector is used for recording the signals in the range of 850 nm. Keywords: Mach–Zehnder modulator, fast processes, electro-optical detector, fiber optic cable, external modulation of optical radiation DOI: 10.1134/S1063778817110059
In studies of the processes in pulsed plasma produced by the interaction of powerful laser radiation with matter, the diagnostic instruments should insure recording of nanosecond pulses with subnanosecond time resolution [1]. The electromagnetic interference, crosstalk, and flow of ionizing radiation inherent for such experiments force one to place the diagnostic equipment in protected areas situated tens or hundreds of meters from the detectors or the interaction chamber. The use of coaxial cables at powerful physical installations for transmitting signals from the detectors to the instrumentation is hardly possible owing to the high losses which grow as the frequency increases and distort the transmitted signal, as well as owing to the sensitivity of the cables to pulsed ionizing radiation and electromagnetic fields [2, 3]. In addition, copper cables can create undesirable galvanic coupling between the data acquisition equipment, detectors, and, in some cases, parts of the experimental setup [3]. Unlike copper coaxial cables, fiber optic cables (FOC) are insensitive to electromagnetic interference and crosstalk and have low losses, a large transmission bandwidth, and low dispersion. Owing to these features of single-mode FOCs, the optical images of electric signals, including weak ones, can be transmitted over significant distances with minimal attenuation and distortion. The use of FOC automatically implements the galvanic isolation between detectors and signal recording equipment. A promising method of formation of the optical analogs of the signals is the method of external modu-
lation. It involves a source of optical radiation operating in the continuous mode with temperature and current stabilization and an external device modulating the parameters of optical radiation (intensity, polarization, phase). The method of external modulation has the following advantages: —Parameters of the optical radiation source and the modulator can be optimized independently of each other [4]. —The ma
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