A passively Q-switched Ho:YVO4 Laser at 2.05 μm with Graphene Saturable Absorber

Abstract

Abstract:We report a passively Q-switched Ho:YVO 4 laser pumped at 1.94 µm with multilayer graphene as a saturable absorber. At the absorbed pump power of 9.3 W, the maximum average output power of 2.2 W was obtained in Ho:YVO 4 laser with minimum pulse width of 265.2 ns and pulse repetition rate of 131.6 kHz at 2052.1 nm. In addition, a beam quality factor of M 2~1 .7 was measured at the maximum output level. This is, as far as we know, the first time that graphene has been used in a passively Q-switched Ho:YVO 4 laser.

Passively Q-switched diode-pumped Tm, Ho:LuVO4 laser with a black phosphorus saturable absorber*

“…Recently, many two-dimensional (2D) materials such as graphene, [7] transition metal disulfides, [8][9][10][11] and topological insulators [12] were employed as the saturable absorber (SA) to achieve Q-switching thulium (Tm) or holmium (Ho)doped lasers at 2-µm. Compared with the above materials, black phosphorus (BP) with distinctive structure and properties [13,14] is an attractive and promising 2D material as a passive Q-switch SA.…”

Passively Q-Switched Operation of a Tm,Ho:LuVO4 Laser with a Graphene Saturable Absorber

“…Among the 2D materials, graphene is a 2D sheet of sp2-bonded carbon atoms with a honeycomb lattice [13]: this has attracted attention from workers in many disciplines, especially as it has special capabilities with regard to nonlinear saturable absorption. Graphene has very good thermal conductivity and optical properties, due to its zero-bandgap structure, and pure non-defective single-layer graphene with a thermal conductivity of up to 5300 W/m•K and its optical absorption is decided, independent of optical frequencies and optical conductivity constants [14]. Therefore, graphene is used as an SA in fiber and solid-state laser devices at a 1-2 µm wavelength range to achieve stable PQS and mode-locked laser emissions, owning to its ultrafast recovery time and moderate modulation depths [14][15][16][17][18].…”

“…Graphene has very good thermal conductivity and optical properties, due to its zero-bandgap structure, and pure non-defective single-layer graphene with a thermal conductivity of up to 5300 W/m•K and its optical absorption is decided, independent of optical frequencies and optical conductivity constants [14]. Therefore, graphene is used as an SA in fiber and solid-state laser devices at a 1-2 µm wavelength range to achieve stable PQS and mode-locked laser emissions, owning to its ultrafast recovery time and moderate modulation depths [14][15][16][17][18]. Loiko et al have demonstrated that a PQS mode of Ytterbium lasers with a graphene SA possessing a 1.9-µJ pulse energy and a 190-ns pulse duration were achieved from Yb-doped calcium niobium gallium garnet disordered garnet crystal [15].…”

“…Serres et al demonstrated a Tm:KLu(WO 4 ) 2 laser with an SA in 2015, and a 310-mW average output power was achieved [17]. Duan et al demonstrated a PQS mode Ho:YVO 4 laser at 2052.1 nm with a graphene SA in 2016, and a 265.2-ns pulse width at 131.6 kHz was acquired [14]. Zhang et al demonstrated a fiber laser operating at 1.94 µm with a graphene SA in 2012, and a 3.6-ps pulse width and a 0.4-nJ energy at 6.46 MHz were obtained in a thulium-doped fiber laser [18].…”

“…Compared with other vanadate crystals, the LuVO 4 crystal has larger absorption and emission cross-sections in the vicinity of 800 nm and 1.064 µm, respectively [29]. In addition, various Ho:LuVO 4 lasers (e.g., CW, Q-switched, actively mode-locked and single-longitudinal mode Ho:LuVO 4 laser) have been demonstrated [14,[21][22][23][24], which show that the LuVO 4 crystal is an attractive host material at 2 µm wavelength range. We demonstrated an AO Q-switched Tm,Ho:LuVO 4 laser in 2018.…”