All-fiber electrooptical mode-locking and tuning

Active mode-locking of a fiber laser with an all-fiber electrooptic modulator is demonstrated. A 1.4-V driving signal was used, creating subnanosecond single pulses at the fundamental frequency of the cavity (12 MHz). The modulator was a packaged Mach-Zehnder interferometer incorporating a poled twin-hole fiber in one of the arms. The switching voltage was 230 V at 1550 nm, with extinction ratio similar to 20 dB. The interferometer could be electrooptically tuned by 3.5 nm.