Extended Data Fig. 2: Optimization of feedforward stabilization.
From: Operation of an optical atomic clock with a Brillouin laser subsystem
a, Measurement of the differential temperature sensitivity of the SBS resonator’s two orthogonal-polarization modes. The linewidths of the modes are measured to be 1.2 MHz (blue arrows). For an applied temperature shift of ΔT = −0.25 °C, the centre frequency at 1,348 nm changes by 490 MHz, while the mode separation (black arrows) changes by 11.9 MHz. This corresponds to a feedforward correction ratio of 40:1. b, Time series trace of the 1,348-nm SBS laser’s frequency with the linear drift removed and the SBS amplitude unservoed. The lack of correspondence between the free-running SBS (red trace) and the polarization beat note (‘Pol. beat ×39’; blue trace) indicates the inability to cancel frequency drift when amplitude noise is present.
