Real-time monitoring of toxic CS2 with high concentrations using a suitable terahertz photonic crystal fiber

Detection of toxic carbon disulfide (CS2) at high concentration, arising due to heavy industrial utilities, is an essen-tial requirement for a sustainable ecosystem and healthcare. However, research and development of appropriate sensor devices to monitor a very high concentration of CS2 are lacking. We design a polyethylene (PE) photonic crystal fiber (PCF) consisting of two interpenetrating periodic hexagonal lattices of teflon inclusions and air holes in the cladding, which can monitor ambient CS2 with extremely high precision in a wide concentration range. Here, we measure the time delay difference (TDD) associated with the difference between group velocities of the two supported modes due to changes in CS2 concentration in the prescribed holes. For a 10 cm long variant of the designed PCF operating at 0.75 THz frequency, we observe a linearly increasing TDD variation from similar to 2 to 13 ps due to change in CS2 concentration from 17 to 50%. However, when the CS2 concentration exceeds the 50% range, we observe decreasing TDD characteristics. In this high concentration regime (>50%), we monitor CS2 by analyz-ing second mode loss (SML) variation due to concentration change (at 0.98 THz frequency), where SML increases up to similar to 30 dB for similar to 100% ambient CS2 concentration. Here, we achieve a high concentration sensitivity where a variation of 1.6 dB SML is observed with a unit concentration change of CS2. The proposed scheme has an immense potential to boost the technologies for high-precision gas monitoring devices.(c) 2023 Optica Publishing Group

Automated summary

A polyethylene photonic crystal fiber is designed to monitor high concentration carbon disulfide with precision, showing a linearly increasing time delay difference in the range of 17% to 50% concentration. In the high concentration regime (>50%), the second mode loss increases up to around 30 dB for 100% ambient CS2 concentration. The proposed scheme has the potential to enhance high-precision gas monitoring devices.