240 Hz linewidth Brillouin laser from a microrod whispering gallery mode resonator
William Loh, Aurelien C. Coillet, Frederick N. Baynes, Scott B. Papp, Scott A. Diddams, Joe Becker
We demonstrate an ultra-low noise laser that oscillates based on the stimulated Brillouin scattering nonlinearity in an optical microresonator. Our Brillouin laser employs a microrod resonator whose larger mode volume compared to conventional resonators increases the systems thermal time constant by two orders of magnitude to the level of 9.4 ms (or 17 Hz). The longer thermal response results in an averaging of the thermal fluctuations, which is the dominant source of noise at low frequencies common to all microresonator devices. We investigate the steady-state performance of this laser and analyze its operation state through measurements of the lasers mode detuning and lineshape. We also characterize its noise performance in terms of fluctuations in both frequency and amplitude and show that laser linewidths on the order of 235 Hz can be realized from a microcavity device 6 mm in diameter. Our results indicate a fundamental mechanism for noise that is common to all microresonator devices and due to the inherent coupling between intracavity power and mode frequency.
, Coillet, A.
, Baynes, F.
, Papp, S.
, Diddams, S.
and Becker, J.
240 Hz linewidth Brillouin laser from a microrod whispering gallery mode resonator, New Journal of Physics, [online], https://doi.org/10.1088/1367-2630/18/4/045001
(Accessed November 28, 2023)