Optical active fiber sensing technique based on the lasing wavelength demodulation for monitoring the human respiration and pulse

A novel optical active fiber sensing technique based on the lasing wavelength demodulation for monitoring the human pulse and respiration is firstly proposed and experimentally demonstrated in this work. A section of no core fiber (NCF) with optimal length is selected to act as a sensing head, as well as a filter in a ring cavity to construct a kind of fiber laser. The respiration rate (RR) and pulse rate (PR) signals are obtained by measuring the shifts of lasing wavelength that caused by respiration-induced body tremor and pulse vibration. The experimental results show that the corresponding RR and PR parameters can be sensitively measured. The suitable wavelet transform is adopted to acquire the respiration and pulse signals in detail. Our proposed technique has the advantages of high sensitivity, compact sensing head, stable response, and capability to simultaneously achieve the information of multiple parameters related to the human health monitoring.