Compact and efficient Cr:LiSAF lasers pumped by one single-spatial-mode diode: a minimal cost approach

Abstract

In this study, we report a minimal-cost and minimal-complexity Cr:LiSAF laser that is pumped only by one inexpensive single-spatial-mode diode. The pump diode, which was originally developed for DVD-writers, provides 130 mW of output power at 660 nm with an efficiency of 30%. This simple pump source enables the construction of a Cr:LiSAF laser that (i) has an estimated total material cost below US$ 5k, (ii) has a footprint of about 20×30  cm, (iii) does not require active cooling, and (iv) can be driven by batteries. All of these make this system ideal for applications that require portability. In continuous-wave (cw) laser experiments, we have demonstrated lasing thresholds as low as 2 mW, slope efficiencies as high as 52%, and output powers up to 58 mW. A record cw tuning range extending from 780 to 1110 nm has also been obtained. In cw mode-locking experiments using a saturable Bragg reflector at 850 nm, the Cr:LiSAF laser produced 100 fs pulses with an average power of 38 mW at a repetition rate of 235 MHz. Using a more compact laser cavity, we have also obtained 130 fs pulses with an average power of 33 mW at a repetition rate of 757 MHz. The corresponding electrical-to-optical conversion efficiencies in cw and cw mode-locked regimes were 12.8% and 8.4%, respectively. These results show that, with the progress in laser-diode and optical mirror technology in the last decade, reasonable output powers can now be obtained from Cr:LiSAF lasers that are pumped only by one single-spatial-mode diode. We believe that this compact, low-cost, and simplistic Cr:LiSAF laser system may be an attractive source for several applications including amplifier seeding.