Extending the cavity length of diode lasers with feedback from Bragg structures and ring resonators is highly effective for obtaining ultra-narrow laser linewidths. However, cavity length extension also decreases the free-spectral range of the cavity. This reduces the wavelength range of continuous laser tuning that can be achieved with a given phase shift of an intracavity phase tuning element. We present a method that increases the range of continuous tuning to that of a short equivalent laser cavity, while maintaining the ultra-narrow linewidth of a long cavity. Using a single-frequency hybrid integrated InP-Si3N4 diode laser with 120 nm coverage around 1540 nm, with a maximum output of 24 mW and lowest intrinsic linewidth of 2.2 kHz, we demonstrate a six-fold increased continuous and mode-hop-free tuning range of 0.22 nm (28 GHz) as compared to the free-spectral range of the laser cavity.
|Number of pages||12|
|Publication status||Published - 19 Dec 2019|
van Rees, A., Fan, Y., Geskus, D., Klein, E. J., Oldenbeuving, R. M., van der Slot, P. J. M., & Boller, K-J. (2019). Ring resonator enhanced mode-hop-free wavelength tuning of an integrated extended-cavity laser. arXiv.org.