Application of optical frequency division to radio frequency for simultaneous cancellation of the impact of laser and clock frequency noise on gravitational wave detection

To demonstrate the application of optical frequency division (OFD) in space-based gravitational wave (GW) detection, we conduct a ground-based test experiment utilizing optical interferometers and a purely optically divided radio frequency (RF) signal. The optically divided RF signal is generated using a microwave-referenced optical frequency comb. The comb frequency noise during OFD is suppressed by employing the transfer oscillator scheme, and the additional frequency instability in optical-to-10-MHz frequency division is 5 × 10⁻¹³ and 2 × 10⁻¹⁵ at 1 s and 1000 s, respectively. When this optical-to-10-MHz signal is used as the reference clock for frequency/phase measurement in GW detection, it can simultaneously reduce the impact of laser and clock frequency noise on GW detection, yielding a detection noise floor down to 10⁻⁶ Hz∕Hz1∕2 at 1 mHz by utilizing the time-delay interferometer technique. This noise level meets the requirements of most space-based GW detectors. We also demonstrate that a division noise of no more than 10⁻¹¹ is sufficient for comb-assisted GW detection.