Plots of phase sensitivity Δ φ as a function of total mean photon number of the PS-TMSVS for different values of (k,l) at φ = 10 − 3 . (a) Symmetric PS-TMSVS, k = l; (b) Asymmetric PS-TMSVS, k=l+1. The upper black line denotes the SNL limit, while the below black dashed lines represents the HL limit.