Frequency dependence of slab coupled optical sensor sensitivity

This paper presents the frequency-dependent sensitivity of slab-coupled optical fiber sensors (SCOSs). This dependence is caused by the frequency characteristics of the relative permittivity. We show experimentally the frequency dependence of SCOS sensitivity for frequencies in the range of 1 kHz to 1 MHz for SCOS fabricated with both potassium titanyl phosphate (KTP) and lithium niobate (LiNbO3). We conclude that x-cut KTP SCOSs are preferred for measuring fields above 300 kHz as they are 1.55x more sensitive than x-cut LiNbO3 SCOSs to the higher frequency fields. However, since KTP SCOSs experience increasing permittivity for low frequencies, SCOSs made with LiNbO3 may be used for low frequency sensing applications due to their flat sensitivity response. For a 10 kHz electric field, an x cut LiNbO3 SCOS is approximately 3.43x more sensitive than an x-cut KTP SCOS. (c) 2013 Optical Society of America