Sensing Performance of Modified Single Mode Optical Fiber Coated With Nanomaterials-Based Ammonia Sensors Operated in the C-Band

Abstract

An etched tapered single mode optical fiber (SMF) coated with polyaniline (PANI) nanofibers is developed to detect ammonia (NH 3) in low concentrations. The SMF is etched with hydrofluoric acid and subsequently tapered using a glass processing workstation. The etched tapered SMF is coated with PANI via spray-coating deposition. This SMF modification significantly enhances the interaction of the evanescent field of the light propagating in the core with the PANI-sensing layer. The modified fiber sensor response is investigated by exposing the sensor to different concentrations of NH 3 over the C-band wavelengths of 1535-1565 nm. Integrating the modified optical fiber with the nanostructured PANI films produces highly sensitive optical sensor that operates at room temperature. The 50 µm etched tapered SMF coated with PANI produced response, recovery times, and sensitivity of 58 and 475 s, and 231.5%, respectively, in the C-band range. The limit of detection of the modified fiber sensor was 0.0025%, which is equal to 25 ppm. The developed sensor exhibits good repeatability, reversibility, and selectivity.

Modified Single Mode Optical Fiber Ammonia Sensors Deploying PANI Thin Films

“…The Tafzel ® polymer jacket enfolding the SMF was removed mechanically over 8 cm by a fiber a stripper. The fabrication processes for the three types of modified SMF platform will be elaborated in the following subsections [2,11].…”

“…The humidity and temperature are fixed at 67% and 25 C, respectively. As the second stage of etching is finished, the fiber is immersed in deionized water for 30 minutes to remove the remaining of the HF acid as well as to prevent further etching due to residual HF [2,11].…”

“…There is a critical demand to develop an alternate type of sensors to avoid disasters resulted from ammonia leakages or drawbacks related to electrical signal based sensors {Mohammed, 2019 #3943}. The optical fiber sensor is an outstanding alternate [2]. Mostly, modified multimode optical fiber (MMF) is deployed to fabricate current NH 3 optical fiber sensors.…”

“…Mostly, modified multimode optical fiber (MMF) is deployed to fabricate current NH 3 optical fiber sensors. Generally, the MMF sensors have lower sensitivity than the single optical fiber SMF sensors that not extensively explored for NH 3 sensing [2].…”

“…Researchers showed intensive focus on modified optical fiber platforms as sensing tools since they are more sensitive compared to the conventional fibers. Cladding modified SMF sensors with high sensitivity integrated with nanostructured thin films against ammonia can be deployed to avoid crises resulted from gas leakage such as ammonia [2]. These sensors have been gained popularity as practical tool to detect chemicals with low concentrations such as gases.…”