Narrow-Linewidth Distributed Feedback Channel Waveguide Laser in Al$_2$O$_3$:Er$^{3+}$

We report on the fabrication and characterization of a distributed feedback channel waveguide laser in erbium-doped aluminium oxide on a standard thermally oxidized silicon substrate. Holographically-written surface-relief Bragg gratings have been integrated with the aluminium oxide waveguides via reactive ion etching of a silicon dioxide overlay film. The laser operates at a wavelength of 1545.2 nm and exhibits a threshold of 2.2 mW absorbed pump power, while it produces a maximum output power of 3 mW. The emission is TE polarized and has a Lorentzian linewidth of 1.70±0.58 kHz, which corresponds to a Q-factor of 1.14×E11