Jianqi Hu

Linearly chirped mid-infrared supercontinuum in all-normal-dispersion chalcogenide photonic crystal fibers

We demonstrate all-normal dispersion supercontinuum generation in chalcogenide photonic crystal fibers pumped at 2070-2080 nm with a femtosecond fiber laser. At 2.9 kW peak power, the generated supercontinuum has a 3 dB bandwidth of 27.6 THz and -20 dB bandwidth of 75.5 THz. We experimentally investigated the supercontinuum evolution inside our sample fiber at various peak powers and fiber lengths and study the impact of fiber water absorption on the generated supercontinuum spectrum. Multiple tests with fiber length- ranging from 0.34 to 10 cm-provide insight on pulse evolution along fiber length. Our simulations, which utilizes the generalized nonlinear Schrodinger equation model, match perfectly the experiments for all tested pump powers and fiber lengths, and confirm that the output pulse has a linear chirp, allowing linear pulse compression.

Optical Sinc-shaped Nyquist pulse source based on a single Mach-Zehnder modulator

We present a precise and flexible Sinc-shaped Nyquist pulse source based on a single Mach-Zehnder modulator. The use of multi-harmonic RF signals provides direct control on the Nyquist pulse train generation. The variable comb source is demonstrated by selecting the number of RF components used to drive the optical modulator, leading from 3 to 9 comb lines. Furthermore, different operating points are reported to show the multi-harmonic comb generator potential to provide near-perfect Nyquist pulse source with pure rectangular optical spectrum or with minimized insertion loss.