4.3.1.2 Oscillation Delay in the FB Channel of the Optical Resonator
It is necessary to bear in mind that in the laser, there may exist the delay of the field
oscillations in the optical FB channel besides inertial properties, which are defined
by carriers’ lifetime T 1 on the upper operating level. In the laser, the resonator length
exceeds the optical wavelength of laser oscillations, and the light delay is T R per one
passage through the FB loop. We note that having passed through the FB loop,
oscillations again pass in the optical amplifier input with the delay by time of
resonator passing (here we mean the resonator of traveling-waves): T R ¼ n 0 L R /c.
We emphasis that the mentioned system of three differential equations (two
equations of second order and the one equation of first order) is complicate for
engineering calculations of QWLD characteristics and is not optimal for investigation OEO as a whole (Fig. 4.10).
We would like to note that the traditional laser analysis, as a rule, is based on the
transfer to balance kinetic equations and its examinations. However, at that, we loose
the valuable information about phase relationships, i.e., information on the phase of
field strength oscillations and phase noises. At that, we cannot estimate the effects of
many other parameters upon the generation development. In the future, we shall
Fig. 4.9 Laser modulation by the sine pumping signal of the small amplitude with the constant bias
from the external generation. The transient scenario in the laser at sine variation of the pumping
level (by the amplitude of the first harmonics) at constant pumping level. Time-functions for
normalized values (a) the pumping current J 0 (1), (b) the population difference N (10
16 1/cm
3
),
(c) the normalized strength square (E)
2 ¼(E 0L )
2
(1), (d) the time-function E 0L , N 0 . The limit cycle in
the time diagram E 0L , N 0 (d) is shown
4.3 Laser Kinetic Equations and the Pumping System
153
It is necessary to bear in mind that in the laser, there may exist the delay of the field
oscillations in the optical FB channel besides inertial properties, which are defined
by carriers’ lifetime T 1 on the upper operating level. In the laser, the resonator length
exceeds the optical wavelength of laser oscillations, and the light delay is T R per one
passage through the FB loop. We note that having passed through the FB loop,
oscillations again pass in the optical amplifier input with the delay by time of
resonator passing (here we mean the resonator of traveling-waves): T R ¼ n 0 L R /c.
We emphasis that the mentioned system of three differential equations (two
equations of second order and the one equation of first order) is complicate for
engineering calculations of QWLD characteristics and is not optimal for investigation OEO as a whole (Fig. 4.10).
We would like to note that the traditional laser analysis, as a rule, is based on the
transfer to balance kinetic equations and its examinations. However, at that, we loose
the valuable information about phase relationships, i.e., information on the phase of
field strength oscillations and phase noises. At that, we cannot estimate the effects of
many other parameters upon the generation development. In the future, we shall
Fig. 4.9 Laser modulation by the sine pumping signal of the small amplitude with the constant bias
from the external generation. The transient scenario in the laser at sine variation of the pumping
level (by the amplitude of the first harmonics) at constant pumping level. Time-functions for
normalized values (a) the pumping current J 0 (1), (b) the population difference N (10
16 1/cm
3
),
(c) the normalized strength square (E)
2 ¼(E 0L )
2
(1), (d) the time-function E 0L , N 0 . The limit cycle in
the time diagram E 0L , N 0 (d) is shown
4.3 Laser Kinetic Equations and the Pumping System
153