Singh Neetesh, Vermulen Diedrik, Ruocco Alfonso, Li Nanxi, Ippen Erich, Kärtner Franz X, Watts Michael R
Opt Express. 2019 Oct 28;27(22):31698-31712. doi: 10.1364/OE.27.031698.
Ability to selectively enhance the amplitude and maintain high coherence of the supercontinuum signal with long pulses is gaining significance. In this work, an extra degree of freedom afforded by varying the dispersion profile of a waveguide is utilized to selectively enhance supercontinuum. As much as 16 dB signal enhancement in the telecom window and 100 nm of wavelength extension is achieved with a cascaded waveguide, compared to a fixed dispersion waveguide. Waveguide tapering, in particular with increasing width, is determined to have a flatter and more coherent supercontinuum than a fixed dispersion waveguide when longer input pulses are used. Furthermore, due to the strong birefringence of an asymmetric silicon waveguide the supercontinuum signal is broadened by pumping simultaneously with both quasi-transverse electric (TE) and quasi-transverse magnetic (TM) mode in the anomalous dispersion regime. Thus, selective signal generation is obtained by controlling the dispersion for the two modes. Such waveguides offer several advantages over optical fiber as the variation in dispersion can be controlled with greater flexibility in an integrated platform. This work paves the way forward for various applications in fields ranging from medicine to telecom where specific wavelength windows need to be targeted.
选择性增强超连续谱信号的幅度并在长脉冲情况下保持高相干性的能力正变得越来越重要。在这项工作中，通过改变波导的色散分布所提供的额外自由度被用于选择性地增强超连续谱。与固定色散波导相比，级联波导在电信窗口实现了高达16 dB的信号增强以及100 nm的波长扩展。当使用更长的输入脉冲时，波导变窄，特别是宽度增加时，被确定具有比固定色散波导更平坦、更相干的超连续谱。此外，由于非对称硅波导的强双折射，在反常色散区域同时用准横向电（TE）和准横向磁（TM）模式泵浦时，超连续谱信号会变宽。因此，通过控制两种模式的色散可实现选择性信号产生。与光纤相比，此类波导具有多个优点，因为在集成平台中可以更灵活地控制色散变化。这项工作为从医学到电信等需要针对特定波长窗口的各种领域的应用铺平了道路。
