resonator on the leuco-sapphire crystal as well as the femto-second optoelectronic
frequency synthesizer of the RF range.
Authors repeatedly note that the main advantage of OEO and optoelectronic
methods of RF oscillations generation is not only a presence of the optical delay
line (up to 50 μs at total losses in FODL of À15 to À20 dB) or the optical resonator,
but the utilization of heterodyning methods of two spaced in frequency (by 10–
80 GHz) optical harmonics, for example, 129 and 139 THz. Exactly statistical
averaging at the same amplitude of harmonics and at their photodetection allows
achievement of the ultralow values of the phase noise (À130 to À147 dBm/Hz at
1 kHz-offset from the carrier of 10 GHz). In OEO, as in the femto-second synthesizer
in the RF range, there is a possibility to extract among initially generated optical
harmonics of two optical harmonics. At that, the harmonic difference can be, for
instance, 20 or 80 GHz, i.e., is the multiple of the final frequency of RF oscillations
in 2 or 8 times. We know that at frequency division by 2 or by 8, we can achieve of
the additional benefit in reduction of the phase noise.
In Chap. 3 we examined the modulation and heterodyning methods in OEO. At
that, authors placed in the OEO fiber-optical system of the optical filter, which is
capable to filter out or to reject of two optical harmonics. The optical filter, which
plays an important role, can be placed both in the positive feedback loop and outside
of it. We proved that the optical harmonic filtering can be performed by several
methods: of the main (central) and the side harmonic, or two side harmonics with the
main harmonic suppression. Another important conclusion of the modulation
methods’ analysis of the laser emission is the fact that in OEO DM and in OEO
MZ, the mode of radio frequency doubling is possible. In this mode, the significant
possibility of suppression is provided of the DC optical component, which essential
noise level worsens the suppression of the OEO phasenoises.
We stated that it is necessary to introduce in OEO of the optical rejection filter
tuned on the central optical frequency and to achieve of DC component suppression.
In OEO MZ, as authors show, we can achieve the effective suppression of the DC
optical carrier at the value of the ratio of the first harmonic voltage amplitude in the
MZ input to the amplitude of the DC bias in MZ in the mode “180
”, at that, the ratio
U 1MZ /U 0MZπ should be x ¼ U 1MZ /U 0MZπ ¼ 2.4.
The special pole in Chap. 3 is paid to laser representation in OEO as the main
source of fluctuations, which has the quantum nature. We show that the phase noise
dispersion of the laser σ
2
E is defined by the dispersion of carriers noise ξ N and
depends upon the life timeT 1 on the excited level. The phase noise level of OEO is
determined by the phase noise of the laser, which depends on the noise time T 1 .
In Chap. 4 authors investigate the laser (or QWLD) included in the OEO structure
with utilization of the classic methods of the oscillation theory. We developed the
quantum generator theory, from the point of view of radio physics. This approach is
described by V. Shtykov and S. Smolskiy in the excellent textbook on quantum
electronics [2].
In our book, at derivation of the constitutive equations of the laser in the
semiclassical approximation, we reduced the system from three differential
508
Conclusion
frequency synthesizer of the RF range.
Authors repeatedly note that the main advantage of OEO and optoelectronic
methods of RF oscillations generation is not only a presence of the optical delay
line (up to 50 μs at total losses in FODL of À15 to À20 dB) or the optical resonator,
but the utilization of heterodyning methods of two spaced in frequency (by 10–
80 GHz) optical harmonics, for example, 129 and 139 THz. Exactly statistical
averaging at the same amplitude of harmonics and at their photodetection allows
achievement of the ultralow values of the phase noise (À130 to À147 dBm/Hz at
1 kHz-offset from the carrier of 10 GHz). In OEO, as in the femto-second synthesizer
in the RF range, there is a possibility to extract among initially generated optical
harmonics of two optical harmonics. At that, the harmonic difference can be, for
instance, 20 or 80 GHz, i.e., is the multiple of the final frequency of RF oscillations
in 2 or 8 times. We know that at frequency division by 2 or by 8, we can achieve of
the additional benefit in reduction of the phase noise.
In Chap. 3 we examined the modulation and heterodyning methods in OEO. At
that, authors placed in the OEO fiber-optical system of the optical filter, which is
capable to filter out or to reject of two optical harmonics. The optical filter, which
plays an important role, can be placed both in the positive feedback loop and outside
of it. We proved that the optical harmonic filtering can be performed by several
methods: of the main (central) and the side harmonic, or two side harmonics with the
main harmonic suppression. Another important conclusion of the modulation
methods’ analysis of the laser emission is the fact that in OEO DM and in OEO
MZ, the mode of radio frequency doubling is possible. In this mode, the significant
possibility of suppression is provided of the DC optical component, which essential
noise level worsens the suppression of the OEO phasenoises.
We stated that it is necessary to introduce in OEO of the optical rejection filter
tuned on the central optical frequency and to achieve of DC component suppression.
In OEO MZ, as authors show, we can achieve the effective suppression of the DC
optical carrier at the value of the ratio of the first harmonic voltage amplitude in the
MZ input to the amplitude of the DC bias in MZ in the mode “180
”, at that, the ratio
U 1MZ /U 0MZπ should be x ¼ U 1MZ /U 0MZπ ¼ 2.4.
The special pole in Chap. 3 is paid to laser representation in OEO as the main
source of fluctuations, which has the quantum nature. We show that the phase noise
dispersion of the laser σ
2
E is defined by the dispersion of carriers noise ξ N and
depends upon the life timeT 1 on the excited level. The phase noise level of OEO is
determined by the phase noise of the laser, which depends on the noise time T 1 .
In Chap. 4 authors investigate the laser (or QWLD) included in the OEO structure
with utilization of the classic methods of the oscillation theory. We developed the
quantum generator theory, from the point of view of radio physics. This approach is
described by V. Shtykov and S. Smolskiy in the excellent textbook on quantum
electronics [2].
In our book, at derivation of the constitutive equations of the laser in the
semiclassical approximation, we reduced the system from three differential
508
Conclusion