How do I calculate the link budget for an RF over fiber system including optical losses?

The RF link budget for an RFoF system accounts for the RF-to-optical conversion, optical transport losses, and optical-to-RF conversion to determine the end-to-end RF gain and noise figure: (1) RF link budget: P_RF_out = P_RF_in + G_E/O + G_fiber + G_O/E (all in dB). Where P_RF_in = input RF power (dBm), G_E/O = RF-to-optical conversion gain (dB, typically negative: -10 to -30 dB for passive links), G_fiber = fiber transport gain (negative: the fiber loss), and G_O/E = optical-to-RF conversion gain (dB). The overall link gain: G_link = G_E/O + G_fiber + G_O/E. (2) Optical loss budget: fiber loss: 0.2 dB/km at 1550 nm, 0.35 dB/km at 1310 nm. Connector loss: 0.3-0.5 dB per connector pair (SC, LC, FC connectors). Splice loss: 0.05-0.1 dB per fusion splice, 0.2-0.5 dB per mechanical splice. WDM mux/demux: 1-3 dB per passthrough. Optical splitter: 3n dB for 2^n way split (e.g., 1×4 split = 6 dB). Margin: 2-3 dB for aging, temperature, and repair splices. Total optical loss: L_opt = L_fiber + L_connectors + L_splices + L_components + L_margin. (3) RF gain impact: the RF link gain is proportional to optical power squared: ΔG_RF = 2 × ΔP_optical (in dB). A 3 dB optical loss causes 6 dB of RF loss. This is because: the RF signal power at the photodetector is P_RF ∝ (I_PD)² ∝ (P_optical)². (4) Example link budget: RFoF system at 1550 nm, 10 km fiber, 4 connectors, 2 splices. Fiber loss: 10 km × 0.2 = 2.0 dB. Connector loss: 4 × 0.4 = 1.6 dB. Splice loss: 2 × 0.1 = 0.2 dB. Margin: 2.0 dB. Total optical loss: 5.8 dB. RF loss from fiber: 2 × 5.8 = 11.6 dB. If the RFoF module has -20 dB intrinsic RF gain (back-to-back): net link gain = -20 - 11.6 = -31.6 dB.