The main problems under solution of the theoretical of our investigation are:
determination of QWLD parameter influence (the pumping current, the phase noise)
and the optical fiber influence (the geometric length, the refraction index, the
temperature dependence of the refraction index, etc.) onto characteristics of the
oscillating RF process in OEO, determination of the laser noise influence on the
OEO RF noise.
For mathematical modeling of the QWLD emission, we use, in particular, the
well-known semiclassical laser theory, taking into consideration the phase relationships of the electrical field strength. This is caused by the circumstances discussed in
the next sections.
2.1.3 Semiclassical Laser Theory
The semiclassical theory (of the semiclassical approximation) with account of phase
relationships constitutes the one of methodic fundamentals of our approach. This
means that for description of electromagnetic field (EMF) interaction with the active
substance of QWLD we use the classical Maxwell equations, and substance properties are described by the polarization vectors and the carrier population level on the
upper energy level. Further, we show that for the semiconductor QWLD, three
equations (for the laser field intensity, for the active substance polarization, and for
the population difference of energy levels) can be reduced to the system of two
equations for the field intensity and the population difference. In some cases, in the
present book (for instance, in Chap. 4), we use the balanced kinetic differential
equations of Stats-de-Morse, in which the connection of the photon density in
QWLD emission and the population difference level allows an analysis of dynamics
and the laser (or QWLD) transfer function. Nevertheless, at utilization of the
balanced equation method, as usually, we lose the phase relationships, which are
the main at analysis of QWLD phase noises and its influence on the OEO RF output
noises. Once more, we should note that most of OEO structures (with direct and
external modulation) under investigation can be related to circuits with the phase and
amplitude modulation of optical emission, and during photodetection with selfheterodyne mixing, an information about the subcarrier is contained in the phase
of optical emission.
The following specific character influences on the model choice and its limitations at OEO investigations:
• the noise quantum nature,
• the temporal and spatial coherence,
• the presence of spatial distribution on the intensity amplitude E 0 (R), on the phase
Φ 0 (R) and on amplitude m(R) and phase Δφ(R) fluctuations (where R is the
spatial parameter),
• the proportionality of overall sizes of optical channels and the phase detector area
in the microwave range with the laser wavelength.
2.1 Operation Principle and Functional Diagram of OEO with RF FODL
21
determination of QWLD parameter influence (the pumping current, the phase noise)
and the optical fiber influence (the geometric length, the refraction index, the
temperature dependence of the refraction index, etc.) onto characteristics of the
oscillating RF process in OEO, determination of the laser noise influence on the
OEO RF noise.
For mathematical modeling of the QWLD emission, we use, in particular, the
well-known semiclassical laser theory, taking into consideration the phase relationships of the electrical field strength. This is caused by the circumstances discussed in
the next sections.
2.1.3 Semiclassical Laser Theory
The semiclassical theory (of the semiclassical approximation) with account of phase
relationships constitutes the one of methodic fundamentals of our approach. This
means that for description of electromagnetic field (EMF) interaction with the active
substance of QWLD we use the classical Maxwell equations, and substance properties are described by the polarization vectors and the carrier population level on the
upper energy level. Further, we show that for the semiconductor QWLD, three
equations (for the laser field intensity, for the active substance polarization, and for
the population difference of energy levels) can be reduced to the system of two
equations for the field intensity and the population difference. In some cases, in the
present book (for instance, in Chap. 4), we use the balanced kinetic differential
equations of Stats-de-Morse, in which the connection of the photon density in
QWLD emission and the population difference level allows an analysis of dynamics
and the laser (or QWLD) transfer function. Nevertheless, at utilization of the
balanced equation method, as usually, we lose the phase relationships, which are
the main at analysis of QWLD phase noises and its influence on the OEO RF output
noises. Once more, we should note that most of OEO structures (with direct and
external modulation) under investigation can be related to circuits with the phase and
amplitude modulation of optical emission, and during photodetection with selfheterodyne mixing, an information about the subcarrier is contained in the phase
of optical emission.
The following specific character influences on the model choice and its limitations at OEO investigations:
• the noise quantum nature,
• the temporal and spatial coherence,
• the presence of spatial distribution on the intensity amplitude E 0 (R), on the phase
Φ 0 (R) and on amplitude m(R) and phase Δφ(R) fluctuations (where R is the
spatial parameter),
• the proportionality of overall sizes of optical channels and the phase detector area
in the microwave range with the laser wavelength.
2.1 Operation Principle and Functional Diagram of OEO with RF FODL
21