Repetition rate variable and wavelength-tunable picosecond optical pulse source employing square-wave-driven intensity modulator and comb-like profiled fiber

We present a picosecond optical pulse source with repetition rate variability and wavelength tunability. The key to realize the repetition rate variability in our proposal is the method of generating seed pulse, where an intensity modulator is driven by a half-clock square wave. The advantage of this method is that the duration of the seed pulse is approximately half of the rise time and independent of repetition rate. In the experiment, we obtain a 15-ps seed optical pulse train, which is successfully compressed down to less than 1 ps with a 4.2-km-long comb-like profiled fiber. We confirm the repetition rate tunability of 9-15 GHz and the wavelength tunability of 1530-1560 nm.