An ultra-sensitive plasmonic fiber-optic photothermal anemometer is proposed and demonstrated. The device consists of a highly-tilted fiber Bragg grating (TFBG) sensor, which is coated with a gold layer exciting surface plasmon resonance (SPR) and then carbon nanotubes as the photothermal conversion element. The carbon nanotubes deposited on the sensor surface efficiently convert light from the heating laser, which is wavelength matched to the SPR signature, into heat. Air flow draws away the surface heat, thus inducing both a strong SPR wavelength shift and a changed of the power modulation. Using this approach, the proposed anemometer accounts for a dynamic range from 0.05 m/s to 0.65 m/s for wind speed measurement. In addition, the real-time monitoring of wind speed has been proved by measuring the intensity of the heating laser source. This device is a valuable candidate for a wide range of potential applications in both scientific research and industrial production, given its simplicity and robustness in structure.
It is necessary that real-time and continuous monitoring of heavy metal ions in solution. Traditional electrochemical methods have security issues and background interference. To solve these problems, a new method based on surface plasmon resonance (SPR) electrochemical optical fiber sensor has been proposed. Combined with anodic stripping voltammetry for electrochemical measurement, SPR is used for detection of heavy metal ions simultaneous by coating metal ion lead onto the surface of the optical fiber sensor while recording the electrochemical signal, the characteristic is that SPR is highly sensitive and excludes electrochemical background interference. The gold-coated film optical fiber works as both a sensor and a working electrode, allowing real-time monitoring of heavy metal ions in solution. The advantages of optical fiber sensor, such as compact size, flexible shape and remote operation capabilities, opens a new way for high sensitive electrochemical detection.
A high speed TFBG-SPR sensing demodulation system based on microwave photonics interrogation is proposed theoretically. The wavelength shifting of the SPR envelope in optical domain is converted to the microwave pulse shifting in time domain. The RI resolution is improved by one order of magnitude compared with wavelength demodulation, and the sensing speed is as high as 40 KHz.