Fluorescence sensor for volatile trace explosives based on a hollow core photonic crystal fiber

A novel hollow core photonic crystal fiber (HC-PCF) volatile trace explosive sensor based on the fluorescence quenching was proposed, which was made by coating the allyl tetraphenylethylene (AL-TPE) fluorescence nanofilm onto the inner surface of a HC-PCF core air hole. The theory of the fluorescence quenching was used to analyze the principle of explosives sensing. The effects of the refractive index (RI) and thickness of the fluorescence film on the light intensity at the core inner wall were analyzed theoretically and numerically. The results show that when the RI of the fluorescence film was close to 1.45 and the thickness was close to 150 nm, the normalized intensity of the light field energy at the core inner wall was 9.72%. The HC-PCF fluorescence explosive sensor was fabricated by a multiple cleaving filling technique and a pressure driven coating method. The experimental results show that the sensitivity of 2,4,6-trinitrotoluene (TNT) detection was 0.309/ppb and the minimum detection limit was 0.340 ppb for the sensor with a film thickness of 155 nm. The response time (T90) of 2,4-dinitrotoluene (2,4-DNT) was 120 s for the sensor with a film thickness of 110 nm.