摘要： We use a drop-port geometry to characterize frequency combs generated from silicon nitride on-chip microresonators in the normal group velocity regime. In sharp contrast with the traditional transmission geometry, we observe smooth output spectra with comparable powers in the pump and adjacent comb lines. The power transfer into the comb may be explained to a large extent by the coupling parameters characterizing the linear operation of the resonances studied. Furthermore, comparison of thru- and drop-port spectra shows that much of the ASE noise is filtered out by transmission to the drop-port. Autocorrelation measurements are performed on the drop-port output, without the need to filter out or suppress the strong pump line as is necessary in thru-port experiments. Passively mode-locked pulses with low background are observed in a normal dispersion microcavity. 其他題名： Opt Express 出版者： United States: Optica Publishing Group 出版日期： 2013-09-23 出處： Optics Express, 2013-09, Vol.21 (19), p.22441- 資源來源： Optica Publishing Group Journals 識別號： ISSN: 1094-4087 識別號： EISSN: 1094-4087 識別號： DOI: 10.1364/oe.21.022441 識別號： PMID: 24104133
