3.1.1 The Structure of OEO Analysis
First of all, we would like to accent the reader’s attention on several methods of
oscillation generations, which allow obtaining the extremely low level of the phase
noise in OEO and gives the right to speak about the ultralow-noise mode of
microwave and mm-wave oscillators. These methods include:
• utilization in OEO of so-called quantum-well lasers with the low level of the
phase noise;
• application of the low-noise active delay line on 10–50 μs on the base of the
optical fiber;
• the self-heterodyning of the phase noise of two optical oscillation in the PD area
and their effective statistical suppression;
• utilization in the optical channel of the modulation method with the optical single
side frequency;
• transmission of modulated oscillations without optical carrier;
• application of single-frequency generation methods of the microwave and
mm-wave autonomous retarded oscillators.
Each from listed approaches cannot be considered as unknown, and their description can be found in manifold books and scientific and engineering papers. Nevertheless, there are not yet the theoretical descriptions of these methods’ utilization for
generation in the aggregate of RF oscillations in OEO in known publications.
These methods applied in the aggregate allow obtaining of the record-breaking
low levels of the phase noise spectral density in experimental OEO models: less than
À150 dBm/Hz at frequency offsets 1–10 kHz from carrier frequency of 10–30 GHz.
This has indisputably the universal importance in radio physics and quantum
electronics.
Starting from described methods of OEO generation, the theoretical analysis in
this book is performed by means of the mathematical description separately for the
laser model with fluctuations and for RF OEO itself taking into consideration of
noisy impacts. The laser analysis is executed on the base of the semiclassical model
in dipole approximation. We use the velocity (kinetic, balanced, or probabilistic)
equations. The semiclassical laser model is added also by the Langevinian noise
sources.
For OEO modeling, we use equations of phase and amplitude balance, the
symbolic “abbreviated” equations, the statistical fluctuation description of the autonomous RF oscillator, which are well-known in the nonlinear oscillation theory. The
special attention in our investigations is attracted to the mathematical model of
fluctuation correlator, which is formed by optical channels of the Mach–Zehnder
modulator and the photodetector. In OEO with direct amplitude modulation (DM),
this correlator is created specially in the optical channel. The main formulas and
functions are derived for DC components, first and second harmonics of laser optical
oscillations in OEO taking into account the laser phase noise. Then we discuss
3.1 Direct and External Laser Modulation in OEO
75
First of all, we would like to accent the reader’s attention on several methods of
oscillation generations, which allow obtaining the extremely low level of the phase
noise in OEO and gives the right to speak about the ultralow-noise mode of
microwave and mm-wave oscillators. These methods include:
• utilization in OEO of so-called quantum-well lasers with the low level of the
phase noise;
• application of the low-noise active delay line on 10–50 μs on the base of the
optical fiber;
• the self-heterodyning of the phase noise of two optical oscillation in the PD area
and their effective statistical suppression;
• utilization in the optical channel of the modulation method with the optical single
side frequency;
• transmission of modulated oscillations without optical carrier;
• application of single-frequency generation methods of the microwave and
mm-wave autonomous retarded oscillators.
Each from listed approaches cannot be considered as unknown, and their description can be found in manifold books and scientific and engineering papers. Nevertheless, there are not yet the theoretical descriptions of these methods’ utilization for
generation in the aggregate of RF oscillations in OEO in known publications.
These methods applied in the aggregate allow obtaining of the record-breaking
low levels of the phase noise spectral density in experimental OEO models: less than
À150 dBm/Hz at frequency offsets 1–10 kHz from carrier frequency of 10–30 GHz.
This has indisputably the universal importance in radio physics and quantum
electronics.
Starting from described methods of OEO generation, the theoretical analysis in
this book is performed by means of the mathematical description separately for the
laser model with fluctuations and for RF OEO itself taking into consideration of
noisy impacts. The laser analysis is executed on the base of the semiclassical model
in dipole approximation. We use the velocity (kinetic, balanced, or probabilistic)
equations. The semiclassical laser model is added also by the Langevinian noise
sources.
For OEO modeling, we use equations of phase and amplitude balance, the
symbolic “abbreviated” equations, the statistical fluctuation description of the autonomous RF oscillator, which are well-known in the nonlinear oscillation theory. The
special attention in our investigations is attracted to the mathematical model of
fluctuation correlator, which is formed by optical channels of the Mach–Zehnder
modulator and the photodetector. In OEO with direct amplitude modulation (DM),
this correlator is created specially in the optical channel. The main formulas and
functions are derived for DC components, first and second harmonics of laser optical
oscillations in OEO taking into account the laser phase noise. Then we discuss
3.1 Direct and External Laser Modulation in OEO
75