Dispersion tailoring in wedge microcavities for Kerr comb generation

The shaping of group velocity dispersion in microresonators is an important component in the generation of wideband optical frequency combs. Small resonators-with tight bending radii-offer the large free-spectral range desirable for wide comb formation. However, the tighter bending usually limits comb formation as it enhances normal group velocity dispersion. We experimentally demonstrate that engineering the sidewall angle of a small-radius (∼100µm), 3-µm-thick silica wedge microdisk enables dispersion tuning in both normal and anomalous regimes, without significantly affecting the free spectral range. A microdisk with a wedge angle of 55° (anomalous dispersion) is used to demonstrate a 300 nm bandwidth Kerr optical frequency comb.