Fiber-optic sensing technique using a thin-film bandpass filter was demonstrated. A bandpass filter on
fiber-end (BOF) sensor has broad spectrum curve which can detected by simple reflectometer. It has a
possibility to construct inexpensive multi-sensing systems. BOF sensor can detect ordinary temperature
with accuracy of ± 0.5˚C, and it has possibility to use for fiber-optic pressure sensing and hydrophone.
