Abstract
A new scalable self-referencing sensor network with low insertion losses implemented in Coarse Wavelength Division Multiplexing (CWDM) technology is reported. It allows obtaining remote self-referenced measurements with a full-duplex fibre downlead up to 35 km long, with no need for optical amplification. Fibre Bragg gratings (FBG) are used in order to achieve a reflective configuration, thus increasing the sensitivity of the optical transducers. Low-cost off-the-shelf devices in CWDM technology can be used to implement and scale the network. Ring resonator (RR) based incoherent interferometers at the measuring points are used as self-referencing technique. A theoretical analysis of power budget of the topology is reported, with a comparison between the proposed network and a conventional star topology. Finally, the new configuration has been experimentally demonstrated.
Highlights
Fibre-optic sensors (FOS) can operate at hostile and flammable environments and in the presence of electromagnetic interference
A new scalable self-referencing sensor network with low insertion losses implemented in Coarse Wavelength Division Multiplexing (CWDM) technology is reported
Ring resonator (RR) based incoherent interferometers at the measuring points are used as selfreferencing technique
Summary
Fibre-optic sensors (FOS) can operate at hostile and flammable environments and in the presence of electromagnetic interference. Assuming a generic scalable star topology with a cascade of CWDM devices to distribute the optical channels to a maximum number of optical sensors max N , the final ratio between output optical power ( ) RX P and input optical power( ) TX P is the following: In Eq (1), , f d IL IL represent the fixed losses at TX/RX central unit and the insertion losses of the devices used to implement the star, respectively; α , link L are the attenuation coefficient of the main fibre lead in dB/km and the lead length in km; IL RR , FBG R are the intrinsic insertion losses of the self-referencing configuration and the reflection losses of the FBG. An optical to electrical (OE) converter (Thorlabs D400FC) was used to capture the signals in the electrical domain (Fig. 7 and Fig. 9(b))
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