Sensor Applications Based on the Cutoff Properties of Liquid-Filled Ge-Doped Microstructured Fibers

The cutoff properties of the fundamental mode of liquid filled Ge-doped microstructured fiber can be exploited in a novel set of wavelength encoded sensor applications. A number of temperature, strain and vibration sensors have been implemented using a Ge-doped core Y-shaped microstructured fiber. The temperature sensitivity of the cutoff wavelength is 25 nm/°C, more than two orders of magnitude higher than the values reported for fiber Bragg gratings. Similarly, the strain sensitivity is 16.8 pm/μ∈, about one order of magnitude higher than a fiber Bragg grating. Amplitude interrogation of the sensor heads can be implemented in rather easy configurations using a light emitting diode or a laser diode, without requiring an accurate selection of the laser wavelength. This permits, for example, the development of vibration sensors with fast time response, at least better than 0.1 ms.