Kavita Sharma

Non-linear behavior of ring-down time in cavity ring-down spectroscopy with tapered fibers

The effect of surrounding refractive index (n₂) on ring-down time (τ) is studied in conventional and amplified cavity ring-down spectroscopy with tapered fibers. Simulation and experimental results indicate that τ varies as rational function of n₂.

Design and modeling of tunable mid-IR fiber laser using thulium doped fibers

The design details of a tunable fiber ring laser emitting in the mid-IR is presented. Thulium doped fiber is used as the gain medium, and laser is found to be tunable from 1845 nm to 1945 nm, with the appropriate choice of cavity parameters.

Fiber-Based Cavity Ring-Down Technique for Refractive Index Sensing at 1953 nm Using Tapered Fibers

Conventional and amplified fiber-based cavity ring-down techniques (CRDT) are demonstrated for the first time in the 2-m wavelength region. The evanescent field in tapered fibers, used as an intra-cavity element, is utilized to perform refractive index (RI) measurement. These longer wavelengths have larger mode field diameter. This results in larger value of the evanescent field and higher sensitivity, confirmed by the numerical simulations. The effect of tapered fiber diameter is investigated both numerically and experimentally. It is found that smaller diameters provide higher sensitivity. The best detection limit achieved experimentally is 4.8 105 RIU at RI of 1.31 with a tapered fiber of length 4mm and a diameter of 5.35m, in conjunction with amplified CRDT. The detection limit can be further improved when the cavity is designed with components and fiber that are optimized for minimal loss at these wavelengths.

Noise analysis of fiber-based cavity ring-down spectroscopy using Allan variance

The noise in conventional fiber-based cavity ring-down spectroscopy (CRDS) is experimentally quantified by measuring Allan variance. It is found that CRDS is dominated by white noise, which can be reduced by increasing the measurement time.

Enhanced sensitivity in cavity ring down spectroscopy using Q-switched fiber lasers

A new technique for cavity ring down spectroscopy is demonstrated by utilising multipulsing in Q-switched fiber lasers. The ring down time is found to increase with absorption and the suggested scheme has improved detection sensitivity.