Generation & control of chaos in a single loop optoelectronic oscillator

We present a detailed study on the dynamics of a single Loop optoelectronic Oscillator (SLOEO), with the variation of feedback loop delay. The feedback delay can be varied by changing the length of the optical fiber delay line. From the numerical study it is observed that with the variation of the delay the oscillator produces chaotic oscillation following the sequence of Hopf bifurcation, stable periodic and period doubling oscillation. In OEO, incrementing the feedback loop delay increases the number of neighboring modes. The effect of these modes on the dynamics of the OEO is reported through simulation study. It has been seen that due to the generation of additional modes, instability grows in the system and the oscillator changes its state from periodic to chaotic oscillation. Consequently the effect of periodic external synchronizing signal is studied in the chaotic OEO. It is observed that application of an external periodic signal with suitably chosen amplitude and frequency can destroy the chaotic oscillation and produce single frequency oscillation. This mechanism has an additional advantage in the reduction of phase noise with regard to the use of larger delay in the loop. Moreover, the sync. signal increases the effective quality factor (Q) of the circuit thereby reducing the deleterious effect of phase noise.