and the photodiode, an electronic amplifier, and a filter with the Q-factor of 1000 are
included in this circuit. At large reserve in excitation, the OEO ring structure forms
the optical pulses with duration of 10–20 ps. The pulse jitter in not more than 0.1 ps.
8.5.6 Implementation of Fiber-Optical Sensors of Physical
Quantities on the OEO Basis
Experimental testing of the functional converters (FC) of the electric voltage and
current on the base of OEO with RF FODL is conducted by authors for the first
time. Measurements of FC main characteristics show an expediency of OEO
application for measuring of electrical voltages with large and small values in the
difficult in access places with the strong external spurious electromagnetic fields. In
the experimental breadboard of FC on the OEO base, the conversion slope of
“electric current-to-frequency” and “voltage-to-frequency” are relatively 3 kHz/A
and 1 kHz/V, which allows effective registration of voltages, currents, and electromagnetic fields in the wide range of amplitude values with the large dynamic
range 10
3
–10.
In the OEO breadboard of the electric current sensor, the maximal OEO frequency deviations are measured. They are Δf ¼ 5.0–10.0 kHz at variations of the AC
electric current amplitude I с ¼ 750–1500 A. We proved theoretically and experimentally a possibility of physical influence conversion into the OEO frequency.
It is shown that variations of mechanical displacement at measurement of two
parameters of OEO with RF FODL—the frequency f and the signal amplitude—
increase the measurement accuracy and reliability of mechanical displacements.
Double-parameter measurements allow the conduction of the complex compensation
against interference caused, for example, by a temperature or a pressure affecting to
the light guides. The minimal registered level (sensitivity) of such a converter of
“acoustic oscillations-to-OEO frequency”-type is about 30 mPa.
Authors conducted experimental investigations (of displacement, temperature,
electrical voltages, and currents) on the OEO base. In addition, experimental investigations are fulfilled during a creation of the breadboard on the OEO base for
studying of the light guide temperature influence on its parameters. Experimental
measurement breadboards and sensor characteristics are discussed below. This
section also contains description of the promising sensors on the OEO base using
the sensor “FBR-technology,” which allows conversion of the micro-displacement
variations in the material structure into variations of the light intensity. This technology of OEO with the differential delay line utilization as the converter on the light
intensity variations into the oscillation of radio-frequency allows development of
effective strain sensors. The application area of these strain sensors is vast. First of
all, this is fiber- and plastic aircraft construction and shipbuilding, the alternative
energy sources—turbines of wind generators, monitoring of oil and gas pipe lines,
manufacturing of the plastic pipes, bridge engineering, underground construction,
8.5 Practical Circuits of the Optoelectronic Oscillator Implementation
497
included in this circuit. At large reserve in excitation, the OEO ring structure forms
the optical pulses with duration of 10–20 ps. The pulse jitter in not more than 0.1 ps.
8.5.6 Implementation of Fiber-Optical Sensors of Physical
Quantities on the OEO Basis
Experimental testing of the functional converters (FC) of the electric voltage and
current on the base of OEO with RF FODL is conducted by authors for the first
time. Measurements of FC main characteristics show an expediency of OEO
application for measuring of electrical voltages with large and small values in the
difficult in access places with the strong external spurious electromagnetic fields. In
the experimental breadboard of FC on the OEO base, the conversion slope of
“electric current-to-frequency” and “voltage-to-frequency” are relatively 3 kHz/A
and 1 kHz/V, which allows effective registration of voltages, currents, and electromagnetic fields in the wide range of amplitude values with the large dynamic
range 10
3
–10.
In the OEO breadboard of the electric current sensor, the maximal OEO frequency deviations are measured. They are Δf ¼ 5.0–10.0 kHz at variations of the AC
electric current amplitude I с ¼ 750–1500 A. We proved theoretically and experimentally a possibility of physical influence conversion into the OEO frequency.
It is shown that variations of mechanical displacement at measurement of two
parameters of OEO with RF FODL—the frequency f and the signal amplitude—
increase the measurement accuracy and reliability of mechanical displacements.
Double-parameter measurements allow the conduction of the complex compensation
against interference caused, for example, by a temperature or a pressure affecting to
the light guides. The minimal registered level (sensitivity) of such a converter of
“acoustic oscillations-to-OEO frequency”-type is about 30 mPa.
Authors conducted experimental investigations (of displacement, temperature,
electrical voltages, and currents) on the OEO base. In addition, experimental investigations are fulfilled during a creation of the breadboard on the OEO base for
studying of the light guide temperature influence on its parameters. Experimental
measurement breadboards and sensor characteristics are discussed below. This
section also contains description of the promising sensors on the OEO base using
the sensor “FBR-technology,” which allows conversion of the micro-displacement
variations in the material structure into variations of the light intensity. This technology of OEO with the differential delay line utilization as the converter on the light
intensity variations into the oscillation of radio-frequency allows development of
effective strain sensors. The application area of these strain sensors is vast. First of
all, this is fiber- and plastic aircraft construction and shipbuilding, the alternative
energy sources—turbines of wind generators, monitoring of oil and gas pipe lines,
manufacturing of the plastic pipes, bridge engineering, underground construction,
8.5 Practical Circuits of the Optoelectronic Oscillator Implementation
497