the second is the laser optical frequency shifted with regard to the central frequency
by the OEO radio-frequency generation. After photodetection of these two optical
frequencies, the RF oscillations can be extracted in the PD current. The phase of this
RF oscillation depends on the phase difference of optical oscillations transmitted on
the central frequency of laser generation and on the shifted optical frequency.
Fig. 5.5 Modeling of differential equations of QWLD with the positive selective feedback. The
transient processes of OEO oscillation setting without and with the delay in the positive feedback
loop. In abscissa axis—the normalized time, in ordinate axis—(а, d)—the inversed population;
(b, e)—intensity; (c, f)—RF oscillations of OEO generation current (the electrical current of laser
pumping
232
5 Optoelectronic oscillator (OEO) Differential Equations as the Laser System with. . .