Femtosecond fiber laser at 10 GHz and its application as a multi-wavelength optical pulse source

In order to realize ultrafast optical communication in the future, it is necessary to develop a stable short pulse optical source that can be operated in the GHz frequency band. This paper reports the oscillation characteristic of a stable, harmonically and regeneratively mode-locked, fiber laser. This laser can produce stable pulses with a repetition rate of 10 GHz, a pulse width of 1.0 to 3.0 ps and a wavelength of 1.55 μm. Using this laser and a dispersion decreasing erbidium (Er)-doped fiber amplifier, femtosecond pulses with a wavelength of 1.55 μm, a pulse width of 170 to 250 fs and a repetition rate of 10 GHz were generated. Using an optical fiber amplifier with a much higher output power, the average optical output of 0.53 W was obtained, where the peak power of the femtosecond optical pulse was as high as 190 W. Using the 10 GHz femtosecond pulses with high power, pulses with eight wavelengths were generated where wavelengths were between 1.552 and 1.559 μm, and the pulse width and repetition rate were 16 to 17 ps and 80 GHz, respectively. This light source is expected to play an important role in multi-wavelength optical communication.