Journal of Applied Physics
Delayed optical nutation inside a hollow-core photonic crystal fiber filled with acetylene
Manuel Ocegueda, Serguei I. Stepanov, Jordan Diaz, Nayeli Casillas, Eliseo Hernández, Priscilla E. Iglesias
Abstract
The delayed optical nutation effect has been used to evaluate the longitudinal relaxation time (T1) inside an acetylene-filled hollow-core photonic crystal fiber (HC-PCF) at room temperature. In this experiment, sequences of two short optical pulses of 30 ns and 15 ns in width, respectively, with the maximum peak power up to ∼2.5 W, were generated at a laser wavelength of 1530.37 nm, which corresponds to the acetylene ro-vibrational P9 absorption line. The gas pressure inside the 1 m-long HC-PCF varied in the range 0.1–1 Torr. Numerical simulations based on the optical Bloch equations allowed us to evaluate the longitudinal relaxation time as T1∼9ns, proving to be fundamentally limited by the transit-time broadening. Also, the obtained results revealed the influence of slow and fast molecules in the form of a non-exponential decay of the delayed-nutation signals.