Extended-Cavity Single-Frequency Semiconductor Lasers using Ring Filters in Low-Loss SiN Technology

摘要

), the latter chosen for its ideal combination of high index contrast and low propagation loss. It was recently shown that the low loss in this platform allows to extend the optical length of the integrated cavity substantially to about 0.5 m. At the same time low loss enables sharp intracavity spectral filtering by cascading micro-ring resonators (MMRs) with various different roundtrip lengths and high quality factors. With such a hybrid laser, we observed single-frequency oscillation with sub-kHz (290 Hz) intrinsic linewidth, which is the lowest value that has ever been demonstrated with a chip-based diode laser.