Low-threshold Integrated Microlaser Emitting in the Blue Formed from Thulium Doped Silica

摘要

While there are several methods for creating a blue microlaser, most have very high lasing thresholds and are not integrated on a silicon substrate. The present work demonstrates a blue laser based on the upconversion of thulium in a doped silica sol-gel microtoroid resonant cavity integrated on a silicon wafer. The thulium is pumped at 1060nm, and emission occurs near 780nm and 450nm. The high intensity of the circulating optical field in the microcavity increases the photon interaction pathlength and interaction time with the thulium atoms, enabling sub-mW thresholds at both blue and near-IR lasing emissions.