Octave-Spanning Dispersive Slot Waveguide Based Chip-Level Ultrashort Pulse Stretcher

• Published in: IEEE access 2020, Vol.8, p.172086-172095
• Main Authors: Fang, Yuxi, Bao, Changjing, Wang, Zhi, Liu, Yange, Zhang, Lin, Li, Si-Ao, Zhang, Yiwen, Huang, Hao, Ren, Yongxiong, Pan, Zhongqi, Yue, Yang
• Format: Article
• Language: English
• Subjects: Bandwidth; Chromatic dispersion; dispersion; integrated optics; Optical fiber dispersion; Optical pulses; Optical waveguides; Refractive index; Silicon dioxide; Silicon nitride; silicon photonics; slot waveguide; Stretcher; Waveguides
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2020.3024855

A silicon nitride horizontal slot waveguide with silicon dioxide cladding is designed to achieve flat negative dispersion (< −600 ps/( \text {nm}\cdot \text {km} )) over an octave-spanning bandwidth (782 to 2100 nm). Simulations show that, when a 10-fs pulse with 1-W peak power is input into a 5-cm long waveguide, the pulse width becomes 448 times wider and its peak power is reduced to 2.23\times 10^{-3} W. After passing through another ideal positive dispersion element, we find that the output pulse peak power can be recompressed close to 1 W in the case of different input pulse widths. Moreover, for the input pulse with a much higher peak power, the pulse width of the output pulse can be compressed to a much narrower level because of the spectral broadening introduced by optical nonlinearity. A 100-fs input pulse with 10-kW peak power can be compressed to 12.5 fs with a peak power of 63 kW. Considering the time-domain broadening and the peak power reduction, such a slot waveguide with a flat negative dispersion could be used as a time stretcher for 10-fs level pulse in on-chip chirped pulse amplification (CPA) system.