Frequency range extension of actively mode-locked lasers integrated with electroabsorption modulators using chirped gratings

We have fabricated actively mode-locked lasers integrated with electroabsorption modulators and chirped gratings. A chirped grating with a large chirp rate of 1.45 Å/μm can be realized by using multiphase-shifted patterns. Short pulses of 4-6 ps were generated over a wide frequency range from 18.9-19.8 GHz. We observed jumps in the wavelength during detuning. These jumps arise from multiple lobes in the reflectivity spectrum. It is found that the wavelength jumps cause increases in the intensity noise. We showed that by reducing the grating length from 150 to 100 μm the sidelobes were suppressed and the detuning frequency range of over 1% could be realized. A smaller pulsewidth was obtained for the negatively-chirped gratings when compared to the positively chirped gratings