Hollow Core Optical Fibre Based Gas Discharge Laser Systems

Abstract

The humble electrically pumped gas laser has undergone little development in its fifty year life span due to the lack of an effective method to confine light within a hollow waveguide of any appreciable length in which an electrical discharge could be contained. New technologies in the field of anti-resonant guiding hollow core fibres present an opportunity to re-invent the gas laser. A recent breakthrough in the field demonstrated that DC pumped glow discharges of a helium and xenon gas mixture could not only be sustained in such a fibre, but also exhibited signs of gain on a number of mid-IR neutral xenon laser lines.The research presented in this thesis is a continuation of that project. The system was redesigned to incorporate two mirrors so that a cavity could be constructed. The previously hinted at gain on the 3:51 μm xenon line was confirmed through a series of CW measurements of the cavity, as was a polarisation of the laser due to a polarisation dependent output coupler.Further observation of the discharges revealed that they were of a pulsed nature, and that the mid-IR laser light was present in the discharge afterglow. A response to the cavity mirrors was observed in this afterglow pulse on the 3:11 and 3:36 μm xenon lines in addition to the 3:51 μm line previously seen. Through fast detection a modulation of the output power due to cavity mode beating effects was detected. The high gain and narrow bandwidth of the xenon laser lines resulted in a frequency pulling effect, and the mode separation in the `hot' laser cavity was measured to be lower than in the `cold' cavity.It was observed through pressure optimisation experiments in helium-xenon that higher output powers could be achieved by using lower partial pressures of xenon. This was exploited with neon-xenon mixtures, where the lower ionisation potential of neon allowed a lower pressure of xenon. Discharges were also achieved in helium-neon and argon gas mixtures.

Date of Award	2 Jan 2018
Original language	English
Awarding Institution	University of Bath
Supervisor	William Wadsworth (Supervisor)