A þ B
ð
Þ
ΔT FOS
T FOS
¼ A À B
ð
Þ
T 2FOS À T 1FOS
2T FOS
ΔT 2FOS À ΔT 1FOS
T 2FOS À T 1FOS
:
ð7:56Þ
From Eq. (7.56), the condition of temperature compensation is
AÀB
AþB %
2T FOS
T FOS2 ÀT FOS1
.
The analysis of parametric dependence upon temperature variations in Eq. (7.55)
permit to conclude that in OEO with the differential RF FODL, it is possible to
obtain the high indices of long-term frequency dependence owing to the presence in
FOS at least two optical fibers of different length.
7.5.4 The Phase-Generator Measuring Method
of Differential Delays of the Optical Fiber at Its
Temperature Change
The functional structure of the phase-generator OEO is shown in Fig. 7.30. It
contains OEO with RF FODL and additionally the photodiode FD1 connected to
it through the optical mode selector (OMS) and the light guide FOS1. OEO is formed
by series-connected in the loop by the laser diode (LD) (of MLS), the optical mixer
(OM), FOS0, the optical selector (OS), the photodiode PD2, the nonlinear amplifier
(NA), the RF filter (RFF) and the coupler (С). In this structure, the measuring
devices: the phase-meter (“Δφ”), the frequency-meter (“f”) and the voltmeter
(“U”) are included. At that, the phase-meter measures the phase difference of RF
oscillations, which pass from the photodiodes PD1 and PD2. The frequency-meter
and the voltmeter measure the frequency and the amplitude of RF oscillations of
OEO, relatively. The main principle consists in utilization of phase measurements
(phase difference Δφ) of differential delays of optical emissions in the output of
FOS0 together with measurements of the frequency and the amplitude.
The phase-generator method developed and patented by authors [23] is used for
the complex investigation of quartz optical fibers for temperature variation within the
limits 0–150
С. On the base of this approach, the sensors and functional transducers
Fig. 7.30 The OEO
structure with application of
the patented “phasegenerator” method of phase
difference measurement.
(Patent belongs to authors
[23])
7.5 Parametric Frequency Instability of OEO with RF FODL at Temperature Impact of. . . 433
ð
Þ
ΔT FOS
T FOS
¼ A À B
ð
Þ
T 2FOS À T 1FOS
2T FOS
ΔT 2FOS À ΔT 1FOS
T 2FOS À T 1FOS
:
ð7:56Þ
From Eq. (7.56), the condition of temperature compensation is
AÀB
AþB %
2T FOS
T FOS2 ÀT FOS1
.
The analysis of parametric dependence upon temperature variations in Eq. (7.55)
permit to conclude that in OEO with the differential RF FODL, it is possible to
obtain the high indices of long-term frequency dependence owing to the presence in
FOS at least two optical fibers of different length.
7.5.4 The Phase-Generator Measuring Method
of Differential Delays of the Optical Fiber at Its
Temperature Change
The functional structure of the phase-generator OEO is shown in Fig. 7.30. It
contains OEO with RF FODL and additionally the photodiode FD1 connected to
it through the optical mode selector (OMS) and the light guide FOS1. OEO is formed
by series-connected in the loop by the laser diode (LD) (of MLS), the optical mixer
(OM), FOS0, the optical selector (OS), the photodiode PD2, the nonlinear amplifier
(NA), the RF filter (RFF) and the coupler (С). In this structure, the measuring
devices: the phase-meter (“Δφ”), the frequency-meter (“f”) and the voltmeter
(“U”) are included. At that, the phase-meter measures the phase difference of RF
oscillations, which pass from the photodiodes PD1 and PD2. The frequency-meter
and the voltmeter measure the frequency and the amplitude of RF oscillations of
OEO, relatively. The main principle consists in utilization of phase measurements
(phase difference Δφ) of differential delays of optical emissions in the output of
FOS0 together with measurements of the frequency and the amplitude.
The phase-generator method developed and patented by authors [23] is used for
the complex investigation of quartz optical fibers for temperature variation within the
limits 0–150
С. On the base of this approach, the sensors and functional transducers
Fig. 7.30 The OEO
structure with application of
the patented “phasegenerator” method of phase
difference measurement.
(Patent belongs to authors
[23])
7.5 Parametric Frequency Instability of OEO with RF FODL at Temperature Impact of. . . 433