Tunable continuous-wave deep-ultraviolet laser based on Ce:LiCAF

Abstract

We demonstrate chopped-cw lasing in a Ce:LiCAF oscillator directly generating deep-UV light around 290 nm. The cw output was achieved by asynchronous pumping of a Ce:LiCAF oscillator by a mode-locked frequency quadrupled Nd:YVO4 laser that generates 23 ps pulses of 266 nm light at a repetition rate of 80 MHz. The pump laser was chopped with 8.3% duty cycle to minimize thermal effects in the frequency quadrupling stage. The maximum output power achieved was 384 mW when pumped with 3.3 W of pulsed 266 nm light, with a slope efficiency of 33%. The laser output was tunable from 286 to 295 nm with the potential to be broadened over the full gain bandwidth of Ce:LiCAF from 280 to 315 nm.

Growth of solid solutions with colquiriite structure LiCa0,2Sr0,8AlF6: Ce3+

“…Especially, Ce doped LiCAF and LiSAF crystals have been gathering attentions as a novel neutron scintillator material with a good sensitivity to thermal neutron and fast decay time [1,2,3]. The advantages of these compounds over oxide crystals -the melting point is significantly lower (810 o C) and the band gap is much wider (11 eV).…”

Linewidth narrowing of a tunable mode-locked pumped continuous-wave Ce:LiCAF laser

“…Cerium (Ce)-doped fluoride lasers do just that; they produce output tunable in the 285 to 315 nm spectral range [4]. We have recently shown that Ce 3 :LiCaAlF 6 (Ce:LiCAF) lasers can be operated as mode-locked [5] and CW sources [6]. In this Letter, we now report narrowband tunable operation of a chopped continuous-wave Ce:LiCAF laser.…”

“…We have indeed shown that a frequency quadrupled 80 MHz mode-locked Nd laser can efficiently pump a Ce:LiCAF laser [5,6,11], with the advantage that the peak power of a mode-locked 1064 nm laser allows efficient frequency quadrupling to 266 nm without needing a resonant enhancement cavity. The Ce:LiCAF laser system can either generate short laser pulses with pulse repetition rates up to 1.10 GHz when setup for rational-harmonic mode-locking or generate CW output when pumped asynchronously [6,11]. The transition between mode-locked and CW behavior can be achieved easily by adjusting the length of the laser cavity.…”

“…Figure 1 shows a schematic of the laser cavity. The setup is similar to that described in [6] and [11]. The pump laser was a 78.75 MHz frequency quadrupled Nd:YVO 4 laser.…”

“…In [6] we already report tuning of a CW Ce:LiCAF laser using a Brewster prism over a range of 9.5 nm from 285.8 to 295.3 nm. The FWHM linewidth was 0.2 nm at around 291 nm and was narrower toward the extremes of the tuning range (0.1 nm at 286 nm and at 295 nm).…”