Use of hollow core fibers, fiber lasers, and photonic crystal fibers for spark delivery and laser ignition in gases

摘要

The fiber-optic delivery of sparks in gases is challenging as the output beam must be refocused to high intensity (～200 GW/cm~2 for nanosecond pulses). Analysis suggests the use of coated hollow core fibers, fiber lasers, and photonic crystal fibers (PCFs). We study the effects of launch conditions and bending for 2 m long coated hollow fibers and find an optimum launch f# of ～55 allowing spark formation with ～98% reliability for bends up to a radius of curvature of 1.5 m in atmospheric pressure air. Spark formation using the output of a pulsed fiber laser is described, and delivery of 0.55 mJ pulses through PCFs is shown.