A. Lokman

Tapered Plastic Optical Fiber Coated With HEC/PVDF for Measurement of Relative Humidity

A simple humidity sensor is proposed and demonstrated using a tapered plastic optical fiber (POF) as a probe. Its operation is based on intensity modulation technique using a tapered POF probe coated with a polymer blend of hydroxyethylcellulose/polyvinylidenefluoride (HEC/PVDF) composite that acts as the humidity sensitive cladding. The sensor is fabricated using an etching method and has a waist diameter of 0.45 mm and tapering length of 10 mm. As the relative humidity varies from 50% to 85%, the output voltage of the sensor increases linearly from 0.32 to 1.25 mV. The HEC/PVDF composite-coated sensor exhibits a sensitivity of 0.023 mV/% with a slope linearity of . The sensitivity of HEC/PVDF composite-coated cladding toward humidity stems from its ability to swell as humidity increases in the atmosphere resulting in a drop in its refractive index below that of the core and thus allowing more light to be transmitted through the tapered fiber.

Optical Fiber Relative Humidity Sensor Based on Inline Mach–Zehnder Interferometer With ZnO Nanowires Coating

A simple optical fiber relative humidity (RH) sensor was proposed and demonstrated using a dumbbell-shaped inline Mach-Zehnder interferometer (IMZI) as a probe. The humidity sensor was constructed by coating the tapered waist region of the IMZI with ZnO nanowires. Based on an optical interferometric technique, the response of the sensor probe was examined by changing the RH within a range of 35%-60% RH. A wavelength shift of 0.490 nm was achieved for a humidity variation from 35% to 60% RH. It was also found that the sensitivity of IMZI-based sensor improved from 0.0002 to 0.020 nm/%RH with the ZnO coating.

Compact fiber laser at L-band region using Erbium-doped Zirconia fiber

A compact Erbium-doped fiber laser (EDFL) operating in L-band region is demonstrated using a fabricated Erbium-doped Zirconia fiber (EDZF) for the first time. The fiber is fabricated by combining Zr and Al to achieve the maximum Erbium ion concentration of 4320 wt ppm. By using a fiber Bragg grating (FBG) in a ring configuration, the laser operates at 1579.6 nm with a slope efficiency of 13.6% and the threshold pump power of 25.1 mW. The lasing wavelength is obtained at Bragg wavelength with an output power of 13 dBm and a 3 dB spectral width of 0.02 nm using a piece of 2 m long EDZF in conjunction with 120 mW of 1480 nm pump power.

Electrostatic charge interaction: a case study on tapered PMMA fiber for calcium nitrate detection

Purpose – This paper aims to propose and demonstrate a simple fiber optic sensor using a tapered plastic multimode fiber as a probe for measurement of calcium nitrate concentrations in de-ionized water. Design/methodology/approach – The working mechanism is based on the observed increment in the transmission of the sensor that is immersed in calcium nitrate solution of higher concentration. The tapering of the plastic fiber is carried out by etching method using acetone, sand paper and de-ionized water. Findings – Tapered fiber with diameter 0.45 mm gives the highest sensitivity of 0.028 mV/% due to better interaction between the evanescent field and the calcium nitrate solution with a good slope linearity of more than 98 per cent for a 1.07 per cent limit of detection in a straight probe arrangement. The use of calcium and nitrate ions within the sensing medium demonstrates the strong dependency of the sensor output trend on the electrolytic nature of the chemical solutions. Originality/value – Demonstra...

Tapered plastic optical fiber coated with single wall carbon nanotubes polyethylene oxide composite for measurement of uric acid concentration

Purpose – A simple tapered plastic optical fiber (POF) sensor is proposed and demonstrated for measurement of uric acid concentrations in de-ionized water. The paper aims to discuss these issues. Design/methodology/approach – The sensor operates based on intensity modulation technique as the tapered POF probe which was coated by a single walled carbon nonotubes polyethylene oxide (SWCNT-PEO) composite is immersed into the uric acid solution. The probe was fabricated using an etching method and has a waist diameter of 0.46 mm and tapering length of 10 mm. Findings – As the concentration varies from 0 to 500 ppm, the output voltage of the sensor increases linearly from 6.13 to 7.35 mV with a sensitivity of 0.0023 mV/% and a linearity of more than 97.20 percent. The SWCNT-PEO composite coating increases the sensitivity of the proposed sensor due to the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber. Originality/value –...

Tapered Fiber Coated with Hydroxyethyl Cellulose/Polyvinylidene Fluoride Composite for Relative Humidity Sensor

A simple relative humidity (RH) sensor is demonstrated using a tapered fiber coated with hydroxyethyl cellulose/polyvinylidene fluoride (HEC/PVDF) composite as a probe. This coating acts as an inner cladding whose refractive index decreases with the rise in humidity and thus allows more light to be transmitted in humid state. A difference of up to 0.89 dB of the transmitted optical power is observed when RH changes from 50% to 80% in case of the silica fiber probe. The proposed sensor has a sensitivity of about 0.0228 dB/%RH with a slope linearity of more than 99.91%. In case of the plastic optical fiber (POF) probe, the output voltage of the sensor increases linearly with a sensitivity of 0.0231 mV/%RH and a linearity of more than 99.65% as the relative humidity increases from 55% to 80%.