Figure 42

Figure 42: Examples of the sum quantum noise power (double-sided) spectral densities of the Sagnac speed-meter interferometer (thick solid line) in comparison with the Fabry–Pérot–Michelson based topologies considerd above (dashed lines). Left: no optical losses, right: with optical losses, ηd = 0.95, the losses part of the bandwidth − 1 γ2 = 1.875 s (which corresponds to the losses −4 Aarm = 10 per bounce in the 4 km length arms). “Ordinary”: no squeezing, ϕLO = π ∕2. “Squeezed”: 10 dB squeezing, 𝜃 = 0, ϕLO = π ∕2. “Post-filtering”: 10 dB squeezing, 𝜃 = 0, ideal frequency-dependent homodyne angle [see Eq. (408View Equation)]. For the Fabry–Pérot–Michelson-based topologies, J = J aLIGO and γ = 2π × 500 s− 1. In the speed-meter case, J = 2J aLIGO and the bandwidth is set to provide the same high-frequency noise as in the other plots (− 1 γ = 2π × 385 s in the lossless case and −1 γ = 2π × 360 s in the lossy one).