Thermocavitation: a mechanism to pulse fiber lasers

Abstract

In this paper, we present a novel mechanism for the generation of laser pulses based on the phenomenon of thermocavitation. Thermocavitation bubbles were generated within a glass cuvette filled with copper nitrate dissolved in water, where the tip of an optical fiber was placed very close to the bubble generation region. Once the bubble is generated, it expands rapidly and the incoming laser light transmitted through the optical fiber is reflected at the vapor-solution interface and reflected back into the fiber, which is coupled to an erbium-doped fiber ring laser. Laser pulses were extracted from the ring cavity and detected by a fast photodetector, which corresponds to a single thermocavitation event, obtaining a pulse repetition rate from 118 Hz to 2 kHz at 1560 nm, with a pulse width ranging from 64 to 57 µs. The repetition rate can be controlled by adjusting the laser power to induce thermocavitation. To our knowledge, this novel mechanism of laser pulses has not been reported in the literature.

Shorts pulse generation by optical cavitation using absorbent and non-absorbent solutions

“…When the tip of the optical fiber is placed in the solution, and there is no generation of microbubbles, the amount of light reflected toward the fiber is minimal. However, the amount of reflected light increases during the microbubble generation, as previously reported [13]. Therefore, the duration of the pulses is directly related to the growth and collapse time of the microbubble.…”

“…Recently, Zaca-Morán et al reported the generation of pulses in optical fiber lasers using the phenomenon of thermocavitation [13]. Thermocavitation bubbles were created by irradiating a highly absorbent solution of copper nitrate dissolved in water with a CW laser (λ= 980 nm) using laser power from 75 to 400 mW.…”