<p>A chloride ion sensor based on a multitaper modulated fiber fabricated via arc discharge is proposed and studied experimentally and theoretically. The sensing unit consists of four periodic tapers with a diameter of 28.24 μm, a period of 676 μm, and a total length of 2.7 mm. The results show that the concentration sensitivity values are 170 pm/(g/L) at a wavelength of 1303.60 nm and 220 pm/(g/L) at a wavelength of 1389.84 nm when the chloride ion concentration is increased from 0 to 40 g/L. The proposed sensor is characterized by a simple manufacturing process, a compact structure, and a low cost, and this sensing unit has great potential for application in marine chloride detection and environmental safety monitoring, especially for monitoring building corrosion and water pollution.</p>
A linear cavity all normal dispersion Yb-doped fiber laser based on the reflection volume grating and the SESAM(Semiconductor Saturable Absorber Mirror) has been demonstrated. Stable wavelength continuous tuning passively mode-locked laser pulse is obtained at room temperature with the repetition frequency of 16.52MHz. The spectral bandwidth of passively mode-locked pulse is 0.33nm at the central wavelength of 1032nm with the maximum average output power of 10.3mW and the monopulse energy of 0.64nJ. The central wavelength of the mode-locked pulse is tuned in the range of 1011.8~1050.7nm with the tuning range of 38.9nm by rotating the volume grating in taking advantage of its dispersion and wavelength selection characteristic. The fiber laser can be used as the optical source in DWDM/OTDM communication system or OCT system due to its wavelength tuning characteristic.