Abstract-Efficient continuous-wave laser operation at 2.982 µm is achieved with a Dy 3 :fluoride fiber pumped using an inhouse-built 1.1 µm ytterbium (III) fiber laser. The laser output power reached is 554 mW, with a maximum slope efficiency of 18% with respect to the launched pump power. Additionally, the measured spontaneous luminescence within the visible wavelength range, under 1.1 µm pumping, is presented and attributed to excited state absorption (ESA). The influence of the ESA on the laser performance is discussed. The results confirm that high output powers from Dy: fluoride fiber laser pumped at 1.1 µm are possible. Index Terms-Mid infrared fiber laser, Dysprosium doped glass, Mid infrared sources

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A fiber ring laser sensor setup utilizing FBGs (Fiber Bragg Gratings) for simultaneous measurement of ambient temperature and relative humidity (RH) is presented. Two FBGs are incorporated as tunable filters for a dual-wavelength laser emission, where one FBG was coated with Polyimide (PI) in order to achieve sensitivity to RH changes, while the other bare FBG was used for temperature sensing. An increase in RH would induce a strain on the grating, which results in a variation in the resonance wavelength of the PI-coated FBG. This causes a shift in the laser emission wavelength. Being insensitive to RH changes, the bare FBG was employed to measure temperature. The dual-wavelength fiber ring laser sensor created thus allows to determine simultaneous measurement of RH and temperature. The RH sensitivities observed by the PI coated FBG to RH and temperature are 3.6 pm/%RH and 12.15 pm/°C respectively. The temperature sensitivity of the bare FBG was observed to be 9.6 pm/°C. The main advantage of the proposed setup is an optical signal to noise ratio (OSNR) higher than 55 dB and a 3 dBbandwidth less than 0.02 nm, which points out efficient capabilities for both precise sensing and remote detection applications.