Introduction

This is the blog of Akitsu & Uno laboratory in University of Yamanashi.

The Author is Kazuyuki Uno and an assistant professor of University of Yamanashi, Japan.  He is a researcher of gas lasers like CO₂ lasers, excimer lasers, and etc.  He learned gas lasers from Dr. Jitsuno in ILE, Osaka University.

Our gas laser is a longitudinally excitation scheme to realize a simple, compact, and low-cost devise.  Our gas lasers are consisted of a laser tube, a storage capacitance, a spark gap, and a high-voltage pulse-power supply only.  So, our gas lasers do not have a preionization system and a fast gas flow system to realize an uniform discharge.  The laser tube size is a length of 10—30 cm and an inner diameter of 2—5 mm in UV lasers, and a length of 30—100 cm and an inner diameter of 10—20 mm in CO₂ lasers.

Our CO₂ laser (9.2—11.4 μm), for example, produces an output energy of 52.0 mJ with a spike pulse width of 145 ns and a pulse tail length of 58.8 μs (K. Uno, et al., Rev. Sci. Instrum. 85, 103111 (2014)).  In our CO₂ lasers, the output energy of the pulse tail is controllable.  Moreover, our CO₂ laser produces a tail-free short-pulse with a pulse width of 60—200 ns (10—20 mJ) and a log pulse with a pulse width of 30—100 μs (20—100 mJ). 

Our CO2 laser with 45-cm long discharge tube

Magnified time-scale view of spike pulse part of CO2 laser 

Overall waveform of CO2 laser

Our N₂ laser (337 nm), for example, produces an output energy of 345 μJ (K. Uno et al., Rev. Sci. Instrum. 84, 043103 (2013)).  Additionally, although UV gas lasers have a large beam divergence by a high gain, our N₂ laser also produces a good quality beam with a full-angle beam divergence of 0.3 mrad and an output energy of 2.6 μJ (K. Uno, et al., Rev. Sci. Instrum. 85, 096108 (2014)).

Our N2 laser with 20-cm long discharge tube

Discharge and oscillation

Laser beam of N2 laser

Our F₂ laser (157 nm), for example, produces an output energy of 140 μJ at a pressure of 40 Torr (M.A.M. El-Osealy et al., Opt. Commun. 207, 255-259 (2002)).