SYNCHRONIZATION OF PASSIVELY MODE-LOCKED ERBIUM-DOPED FIBER LASERS AND ITS APPLICATION TO OPTICAL COMMUNICATION-NETWORKS

We synchronized two passively mode-locked erbium-doped fiber lasers us ing a phase lock loop with a large dynamic range and bandwidth, which is realized by using a novel acoustooptic-modulator-grating scheme. Cr oss-correlation of the two lasers shows the interlaser jitter is under 2 ps (same as the laser pulse width) for period as long as hours, To prove the quality of phase locking, we apply synchronized lasers in tw o all-optical network applications, one of which requires the lasers t o have the same wavelength and the second requires the lasers to be at different wavelengths, In the single wavelength application, the sync hronized lasers drive a cascade of two low-birefringence, polarization maintaining, optical logic gates with switching timing window of 4 an d 5 ps, respectively, We obtain nonlinear transmission of similar to 5 0% at a switching energy of 8 pJ and contrast ration of 16 dB, which a re comparable performance as that obtained using a single laser, In th e different wavelength application, we use 0.8 ps pulses to switch 2 p s pulses In a two-wavelength nonlinear optical loop mirror demultiplex er with timing window of 5.5 ps. Stable switching is reached at a effi ciency as high as 90% at switching energy of 0.8 pJ, and a contrast ra tio of 20 dB, Excellent agreement is found between the experimental da ta and the simulated results, which exclude the timing jitter.