23 April 2017 Fiber Bragg grating interrogation using a wavelength modulated 1651-nm tunable distributed feedback laser and a fiber ring resonator for wearable biomedical sensors
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Proceedings Volume 10323, 25th International Conference on Optical Fiber Sensors; 103234H (2017) https://doi.org/10.1117/12.2265617
Event: 25th International Conference on Optical Fiber Sensors, 2017, Jeju, Korea, Republic of
Abstract
This 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 30˚C – 80˚C. 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.
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Anirban Roy, Arup Lal Chakraborty, Chandan Kumar Jha, "Fiber Bragg grating interrogation using a wavelength modulated 1651-nm tunable distributed feedback laser and a fiber ring resonator for wearable biomedical sensors ", Proc. SPIE 10323, 25th International Conference on Optical Fiber Sensors, 103234H (23 April 2017); doi: 10.1117/12.2265617; https://doi.org/10.1117/12.2265617
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