Mechanical optical switches generally offer lower insertion loss—often less than 1. 5 dB—because they rely on physically moving fibers or optical components to redirect the light path. Losses can be introduced by various means such as intrinsic material absorption, scattering, bending, connector loss and more. In fiber sensing systems, insertion loss has a direct impact on the signal-to-noise ratio (SNR) and sensing sensitivity. 75 dB, a fusion splice should stay under 0.