Evanescent coupling between a side-polished single-mode optical fiber and a
single-mode, pH-sensitive Langmuir-Blodgett overlay is used to demonstrate an
intrinsic fiber-optic pH sensor. The sensor shows a wavelength sensitivity of
18.8 ± 0.8 nm/pH and a transmission sensitivity of 9.7 ± 0.8 dB/pH when
operating at 750 n
