Simulation Investigation of Ultra-Broadband Rectangular and Sawtooth Waveform Generation with Sampled Fiber Grating and Femtosecond Laser

High-speed and broadband waveform generation based on using a Sinc2 sampled fiber grating (SFG) combined with a femtosecond laser source is investigated. The Sinc2 SFG provides linear wavelength divided multiplexing (WDM) time delay lines (TDLs) with sub-picosecond delay steps, and two types of reflectivity spectrum with flat-top and linear profiles for a large number of wavelength channels. The femtosecond laser is used as a broadband source. Simulation results demonstrate that the generation of rectangular and sawtooth waveforms is achieved through numerical modeling based on wavelength-to-time mapping using a grating TDL and an ultrafast laser. Results show, for example, that a rect waveform is generated with a repetition frequency (frep) of 125 GHz, a period (T) of 8 ps, and a rise-fall time of 4% T; a sawtooth waveform is generated with a frep of 69.5 GHz, a period of 14.39 ps, a rise time of 2.8% T, and a ramp linearity of 0.1% standard deviation.