Passively Q-Switched Er:YAP Single Crystal Laser at 2.92 μm using Graphene Saturable Absorber

High-power mid-IR lasers at a wavelength of around 3 μm are suitable for medical and industrial applications because water has strong absorption in a wavelength of this region. From this reason, various Er
³⁺
-doped materials such as Er:YAG [1], Er:Y
₂
O
₃
[2], and Er:Lu
₂
O
₃
[3] have been actively investigated to demonstrate Q-switched lasers which generate giant pulse with high peak power. Recently, a YAlO
₃
(YAP) has also attracted much attention as the high power with efficient laser material in addition to these mediums. The YAP has the high thermal conductivity (~10 W/mK) similar to YAG, low phonon energy, and good mechanical properties. Thus, YAP can be expected to perform laser output with high efficiency from the above observations. In this regard, recent studies have reported on continuous-wave (CW) laser operation by diode-pumping Er:YAP at around 2.7 μm [4]. However, a Q-switched Er:YAP laser in this wavelength region has never been demonstrated. Therefore, in this study, we have attempted demonstration of a Q-switched Er:YAP crystal laser at around 3 μm using graphene saturable absorber.