We are very happy to report recent work, published in Optics Letters, in which we study the impact of silicon nitride growth conditions - in particular the precursor gas ratio - on the refractive index of the deposited films and its subsequent impact on frequency comb generation in microresonator fabricated out of these films. We show that, although the silicon nitride remains close to the stoichiometric condition, the refractive index is changed enough to greatly impact microresonator dispersion, which in turn significantly modifies the characteristics of the generated frequncy combs. In addition to experimentally demonstrating that this change in material dispersion impacts the generated frequency combs, we also show how careful adjustment of the geometric dispersion, for instance through tuning of the film thickness, can compensate.
Moille, G., D. Westly, G. Simelgor, and K. Srinivasan, "Impact of the precursor gas ratio on dispersion engneering of broadband silicon nitride microresonator frequency combs", Optics Letters, vol. 46, pp. 5970–5973, 2021.