Roy, AnirbanAnirbanRoyChakraborty, Arup LalArup LalChakrabortyJha, Chandan KumarChandan KumarJha2025-08-302025-08-302017-01-01[9781510610910]10.1117/12.22656172-s2.0-85019083561https://d8.irins.org/handle/IITG2025/22560This paper demonstrates the interrogation of a fiber Bragg grating with a flat-topped reflection spectrum centred on 1649.55 nm using only a single mode tunable 1651.93 nm semiconductor laser and a fiber ring resonator. The Bragg shift is accurately measured with the fiber-optic ring resonator that has a free spectral range (FSR) of 0.1008 GHz and a broadband photo-detector. Laser wavelength modulation and harmonic detection are used to transform the gentle edges of the flat-topped FBG spectrum into prominent leading and trailing peaks, either of which can be used to accurately measure spectral shifts of the FBG reflection spectrum with a resolution of 0.9 pm. A Raspberry Pi-based low-cost embedded processor is used to measure the temperature-induced spectral shifts over the range 30C - 80C. The shift was linear with a temperature sensitivity of 12.8 pm/C. This technique does not use an optical spectrum analyzer at any stage of its design or operation. The laser does not need to be pre-characterized either. This technique can be readily extended to all types of tunable diode lasers and is ideally suited for compact field instruments.falseElectrical Engineering | Gujarat - 382355 | India | Indian Institute of Technology GandhinagarConference Paper1996756X20170103234HcpConference Proceeding1