Optical fiber sensor network integrating SAC-OCDMA and cladding modified optical fiber sensors coated with nanomaterial

Abstract

Three modified single mode optical fiber ammonia sensors coated with nanocomposite of polyaniline/graphite nanofiber (PANI/GNF) are integrated with optical code division multiple access utilizing spectral amplitude coding (SAC-OCDMA) optical fiber sensors network. The sensors are modified using both etching and tapering processes. A thin layer of PANI/GNF is spared on the etched–tapered SMF sensors. The sensors based on the evanescent wave absorption are investigated by measuring the output optical power in the C-band wavelength range (1535–1560 nm) at room temperature. SAC-OCDMA using Khazani Syed (KS) code is deployed as it has the capability to remove multiple access interference (MAI) and it is cost effective. The performance of the developed optical fiber sensor network based on star topology is investigated remotely over 3 km using Erbium doped fiber amplifier for NH3 sensing in terms of received optical power, crosstalk, and optical signal-to-noise ratio (OSNR). OSNR is observed to vary with fiber diameter and NH3 concentration level. The smaller tapering diameter and higher NH3 concentrations generate lower OSNR at the output of the related decoder. The measured OSNR for the developed optical fiber sensor network was 22 and 18.45 dB when sensors implied in the network exposed to 0.125% and 1% NH3 concentrations, respectively.