Efficient 1645-nm Er:YAG laser

Abstract

We report a resonantly fiber-laser-pumped Er:YAG laser operating at the eye-safe wavelength of 1645 nm, exhibiting 43% optical efficiency and 54% incident slope efficiency and emitting 7-W average power when repetitively Q switched at 10 kHz. To our knowledge, this is the best performance (conversion efficiency and average power) obtained from a bulk solid-state Q-switched erbium laser. At a 1.1-kHz pulse repetition frequency the laser produces 3.4-mJ pulses with a corresponding peak power of 162 kW. Frequency doubling to produce 822.5-nm, 4.7-kW pulses at 10 kHz was performed to demonstrate the laser's utility.

Host-dependence of Trivalent Erbium (Er3+) Spectra Relevant to Solid-state Lasers: Yttrium Aluminum Garnet (YAG) and Sesquioxides

“…The strongest emission lines overlap strong absorptions near 1530 nm and thus are useless for lasing, but there are very satisfactorily strong emission lines between 1617 and 1660 nm (stimulated emission cross sections of 5-6×10 -21 cm 2 ) that have little absorption to overcome to reach laser threshold. Er:YAG has been lased on these transitions by a number of groups, some using laser pumping and others the potentially simpler and more efficient method of diode pumping (5,(20)(21)(22)(23)(24)(25)(26). There are important differences between these room-temperature spectra and the corresponding spectra at liquid nitrogen temperature, as seen in figure 2.…”

Laser performance of in-band pumped Er : LiYF4and Er : LiLuF4crystals

“…Previously, lasing under in-band pumping was obtained in various erbium-containing materials, such as garnet [3,5], vanadate [6 - 9], sesquioxide [10] and tungstate [11,12] crystals. The maximum slope efficiency with respect to the absorbed pump power for the Er : LuVO 4 crystal pumped by a fibre laser was 64 % in the cw regime [8].…”

Efficient 1645 nm continuous-wave and Q‑switched Er:YAG laser pumped by 1532 nm narrow-band laser diode

“…One of the most promising eye-safe lasers, 1645 nm hybrid fiber-bulk erbium lasers, has been proven to be effective in achieving high output power and good beam quality [3][4][5][6][7]. The best results were reported to be a 60 W output with a slope efficiency of 80% for a continuous-wave (CW) operation [5] and 30 mJ pulses with a pulse width less than 20 ns at 20 Hz PRF for a Qswitched operation [7].…”