Direct wireless readout of fiber Bragg grating sensors using radio-over-fiber

Wireless readout of optical fiber sensors is of interest for a variety of applications. In the state of the art, the sensor data are digitized before the wireless transmission. We propose a wireless evaluation scheme for fiber Bragg gratings where the sensor signal is transmitted directly without any processing in a simplified sensor node. The underlying concept is explained in detail and validated experimentally. It is based on radio-over-fiber technology and evaluates not only the magnitude of the received analog electrical sensor signal but also the phase. Additionally, signal correction and signal processing schemes are discussed. A series of experimental measurements indicates not only advantages of the phase evaluation method over the magnitude evaluation method but also approves the general feasibility of the direct interrogation approach for wireless sensing applications. Future subjects of interest involve absolute accuracy considerations and maximum achievable sampling rates.