polymer and the liquid. The estimated sensitivity of this refractive-index sensor is
about 5 10
4
.
A miniature hydrogen sensor consisting of a subwavelength diameter tapered
optical fiber coated with an ultrathin palladium film has also been reported [26].
The hydrogen changes the optical properties of the palladium layer and conse-
quently the absorption of the evanescent waves. Measurements at a wavelength
of 1550 nm show that the sensor’s response time (10 seconds) is several times
faster than that of several optical and electrical hydrogen sensors reported so far.
Moreover, the sensor is small, reversible, and suitable for detection of hydrogen
in the lower explosive limit.
11.6.3 Additional Applications
Besides integration into microphotonic ...