resonator technologies. For main characteristic comparison of OEO with traditional
electronic and optoelectronic oscillators, Table 2.2 shows their technical characteristics. The carrier frequency, the retuning range, the long-term frequency stability,
the power spectral density of the phase noise, overall dimensions can be concerned
to these characteristics. In this Table 2.2, the main types of oscillators are presented,
and for them the following designations are introduces: (1) Osc QR—an oscillator
with quartz resonator, (2) Osc SAW—an oscillator on surface acoustic waves,
(3) Osc DDR—an oscillator with disk dielectric resonator from ceramic alloys,
(4) Osc DDRLS—an oscillator with the disk dielectric resonator from the leucosapphire, (5) Osc YIG—an oscillator with the YIG resonator, (6) OEO RF FODL—
an optoelectronic oscillator with RF FODL, (7) OEO ODR—an oscillator with the
optical disk resonator, (8) Laser FSS—a laser femtosecond synthesizer, (9) QFS on
Cz—the quantum frequency standard of the cesium cell.
Basing on mechanisms of oscillations delay and of energy accumulating in
oscillators with various types of resonators, they can be conditionally divided on
acoustic (quartz [62] and SAW [63, 64]), electromagnetic (YIG, DQR, and DDRLS
[25, 28–30]), and optoelectronic (RF FODL, ODR—optical disk resonators ODR
[32–36]). Oscillators of laser femtosecond synthesizer (FSS) and the quantum
frequency standard (QFS) can be also attributed to optoelectronic converters
according to formation methods of radio-frequency oscillation.
In Table 2.2 the following abbreviation are used: “PSD PN”—power spectral
density of phase noise at offset 1 kHz/10 kHz from the 10 GHz-carrier. “Long-term
freq. instab.”—long-term frequency instability. “Tuning range”—the range of frequency tuning, “Comm. name”—Commercial name.
In the quantum frequency standard, the transformation of the optical frequency,
which is equal to about 200 GHz, into the RF frequency 6.4 GHz is performed using
quantum resonance properties of the cesium atom. In the oscillator “Laser FSS,” the
transformation of the optical frequency 438 THz into the frequency 10 GHz is
performed using beats of two “phased” optical frequencies on the photodetector.
With RF frequency growth, the increase of acoustic losses occur in the quartz and
SAW resonators (or delay lines). This leads to resonator Q-factor reduction in the
microwave range. Among “electromagnetic” resonators, in which the electrical
oscillations conversion into the electromagnetic microwave field is provided. At
that, the disk dielectric resonator from the leuco-sapphire has the maximal Q-factor.
The main shortcoming of the dielectric resonator from the leuco-sapphire is its
strong dependence of the resonance frequency and its phase-frequency response
upon temperature (the temperature instability of the resonance frequency of the
leuco-sapphire resonator is about 10
À4 1/
C and is determined by the temperature
dependence of permittivity and the loss angle tangent of material).
We note for comparison that in OEO, in contrast to the oscillator on the leucosapphire resonator, the stabilized RF FODL on the optical quartz fiber is applied. The
own frequency instability of OEO (without external devices for frequency tuning) is
10
À5 to 10
À6 1/
C [13] and is determined by the temperature dependence of the
quartz refraction index. The frequency tuning range of OEO with RF FODL for
48
2 Nanostructural Optoelectronic Oscillators with the Fiber-Optical Delay Line
electronic and optoelectronic oscillators, Table 2.2 shows their technical characteristics. The carrier frequency, the retuning range, the long-term frequency stability,
the power spectral density of the phase noise, overall dimensions can be concerned
to these characteristics. In this Table 2.2, the main types of oscillators are presented,
and for them the following designations are introduces: (1) Osc QR—an oscillator
with quartz resonator, (2) Osc SAW—an oscillator on surface acoustic waves,
(3) Osc DDR—an oscillator with disk dielectric resonator from ceramic alloys,
(4) Osc DDRLS—an oscillator with the disk dielectric resonator from the leucosapphire, (5) Osc YIG—an oscillator with the YIG resonator, (6) OEO RF FODL—
an optoelectronic oscillator with RF FODL, (7) OEO ODR—an oscillator with the
optical disk resonator, (8) Laser FSS—a laser femtosecond synthesizer, (9) QFS on
Cz—the quantum frequency standard of the cesium cell.
Basing on mechanisms of oscillations delay and of energy accumulating in
oscillators with various types of resonators, they can be conditionally divided on
acoustic (quartz [62] and SAW [63, 64]), electromagnetic (YIG, DQR, and DDRLS
[25, 28–30]), and optoelectronic (RF FODL, ODR—optical disk resonators ODR
[32–36]). Oscillators of laser femtosecond synthesizer (FSS) and the quantum
frequency standard (QFS) can be also attributed to optoelectronic converters
according to formation methods of radio-frequency oscillation.
In Table 2.2 the following abbreviation are used: “PSD PN”—power spectral
density of phase noise at offset 1 kHz/10 kHz from the 10 GHz-carrier. “Long-term
freq. instab.”—long-term frequency instability. “Tuning range”—the range of frequency tuning, “Comm. name”—Commercial name.
In the quantum frequency standard, the transformation of the optical frequency,
which is equal to about 200 GHz, into the RF frequency 6.4 GHz is performed using
quantum resonance properties of the cesium atom. In the oscillator “Laser FSS,” the
transformation of the optical frequency 438 THz into the frequency 10 GHz is
performed using beats of two “phased” optical frequencies on the photodetector.
With RF frequency growth, the increase of acoustic losses occur in the quartz and
SAW resonators (or delay lines). This leads to resonator Q-factor reduction in the
microwave range. Among “electromagnetic” resonators, in which the electrical
oscillations conversion into the electromagnetic microwave field is provided. At
that, the disk dielectric resonator from the leuco-sapphire has the maximal Q-factor.
The main shortcoming of the dielectric resonator from the leuco-sapphire is its
strong dependence of the resonance frequency and its phase-frequency response
upon temperature (the temperature instability of the resonance frequency of the
leuco-sapphire resonator is about 10
À4 1/
C and is determined by the temperature
dependence of permittivity and the loss angle tangent of material).
We note for comparison that in OEO, in contrast to the oscillator on the leucosapphire resonator, the stabilized RF FODL on the optical quartz fiber is applied. The
own frequency instability of OEO (without external devices for frequency tuning) is
10
À5 to 10
À6 1/
C [13] and is determined by the temperature dependence of the
quartz refraction index. The frequency tuning range of OEO with RF FODL for
48
2 Nanostructural Optoelectronic Oscillators with the Fiber-Optical Delay Line