Recently, we found that by terminating a long length of fiber of up to 2 km with an in-fiber cavity structure, the entire
structure can detect vibrations over a frequency range from 5 Hz to 100 Hz. We want to determine whether the structure
(including packaging) can be optimized to detect vibrations at even higher frequencies. The structure can be used as a
distributed vibration sensor mounted on large motors and other rotating machines to capture the entire frequency
spectrum of the associated vibration signals, and therefore, replace the many accelerometers, which add to the
maintenance cost. Similarly, it will help detect in-slot vibrations which cause intermittent contact leading to sparking
under high voltages inside air-cooled generators. However, that will require the sensor to detect frequencies associated
with vibration sparking, ranging from 6 kHz to 15 kHz. Then, at even higher frequencies, the structure can be useful to
detect acoustic vibrations (30 kHz to 150 kHz) associated with partial discharge (PD) in generators and transformers.
Detecting lower frequencies in the range 2 Hz to 200 Hz makes the sensor suitable for seismic studies and falls well into
the vibrations associated with rotating machines. Another application of interest is corrosion detection in large re-enforced
concrete structures by inserting the sensor along a long hole drilled around structures showing signs of
corrosion. The frequency response for the proposed long-gauge vibration sensor depends on packaging.