High Sensitivity Ultraviolet Sensor Based on Gallium Oxide Coated Hollow Core Fiber

A novel solar blind ultraviolet (UV) sensor based on a gallium oxide (Ga2O3) thin film-coated hollow core fiber (HCF) is first proposed by theoretical and experimental methods. Ga2O3 thin film acts as an active layer to convert UV irradiation to the changes in the interference spectrum since the refractive index of Ga2O3 is sensitive to UV light. An optimized 400 °C annealing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\beta }$ </tex-math></inline-formula>-Ga2O3 thin film is coated on the HCF’s surface by a sol-gel immerse-heating process. The surface morphology and elemental analysis show that both Ga and O are uniformly distributed on the HCF surface. The sensor performance is carried out under a response wavelength of 254 nm. The experimental results show that both peak position and intensity are linearly changing with the UV irradiation power increases. The sensitivities of the interference peak position and intensity are 18.9 and 37.6 pm/(mW/cm2), respectively. The temperature stability measurement shows that the intensity of the interference peak linearly increases with temperature increasing from 85 °C to 225 °C, a sensitivity of 1.07 pm/°C is obtained. The proposed sensor has competitive sensitivity and can be applied in industrial, military, and environmental regions.