Generating ultrashort flat-top optical pulses with a fiber-loop time lens system

摘要

For generating short flat-top optical pulses, traditional methods are either bandwidth limited or have low controllability (in pulse width and shape). We propose a fiber-loop based time-lens system to realize ps-level flat-top pulses, and theoretically study their features under various parameter circumstances. This time-lens system, functioning as many stacked time-lenses, introduces great controllability for the generated pulse's characteristics through tuning both the phase modulation device and the dispersion-compensating setup. To achieve high-quality narrow flat-top pulses (with steep pulse edges), several factors including phase modulation function, modulation strength and dispersion compensating status must be optimized simultaneously. In simulation, after 50 loops of parabolic phase modulation and chirp compensation, the flat-top pulse's duration can be narrowed to 2.8 ps with edge widths of 1.7 ps. This kind of ps-scale flat-top pulse is very desirable for application in various areas.