Fig. 2: Phase and frequency stability of the optical transmission measured at the remote site.
From: Point-to-point stabilized optical frequency transfer with active optics
Red trace, free-space link phase stabilization off, tip-tilt active optics off (data from Microsemi); blue trace, free-space link phase stabilization on, tip-tilt active optics off (data from Ettus); orange trace, free-space link phase stabilization on, tip-tilt active optics on (data from Ettus); and gray trace, system noise floor with both phase stabilization systems transmitting over parallel optical fiber (data from Microsemi). a Power spectral density of the phase noise (Sϕ(f)) after transmission. b Fractional frequency stability presented as modified Allan deviation (σy(τ)). The dashed traces are calculated from raw data; the solid traces are calculated from data with quadratic drift removed; and the error bars represent a standard fractional frequency measurement confidence interval set at \(\pm {\sigma }_{y}(\tau )/\sqrt{N}\), where N is the number of phase measurements. On both plots, the black dashed lines show key gradients of interest.
