A simple method for the generation of a chirp-free optical pulse train with tunable pulse width using a polarization modulator (PolM) and a zero-chirp intensity modulator (IM) is proposed and demonstrated. In the proposed system, a light wave with its polarization direction oriented at an angle of 45° with respect to the principal axis of the PolM is polarization modulated by a sinusoidal drive signal. An optical polarizer is connected after the PolM to convert the polarization-modulated signals to a pulse train with the main peaks having a narrow pulse width. Then, the main peaks are selected by the IM, leading to the generation of a short optical pulse train with a repetition rate that is identical to or twice the frequency of the sinusoidal drive signal, depending on the dc bias of the IM. The pulse width of the generated pulse is easily tuned by adjusting the phase modulation index of the PolM. An experiment is carried out, and a pulse train with a duty cycle as small as 8.16% is generated.
© 2009 Optical Society of America
Original Manuscript: March 4, 2009
Revised Manuscript: June 6, 2009
Manuscript Accepted: June 8, 2009
Published: July 10, 2009
Shilong Pan and Jianping Yao, "Generation of a chirp-free optical pulse train with tunable pulse width based on a polarization modulator and an intensity modulator," Opt. Lett. 34, 2186-2188 (2009)