金刚石衬底的V_2O_5薄膜激光损伤阈值研究

Laser Limiting Performance of V_2O_5 Thin Films on Diamond Substrates

目的探究V_2O_5薄膜厚度对其抗激光损伤性能的影响。方法通过射频反应磁控溅射法在光学级单晶金刚石衬底表面制备了不同膜厚的V_2O_5薄膜。采用脉宽为10 ns、波长为1064 nm的脉冲激光器对薄膜样品进行光学响应曲线测试,测得薄膜相变前后透过率变化情况及相变开关时间,以判断薄膜是否发生损伤,并根据损伤几率得到激光损伤阈值。结果实验制备的薄膜为组分单一的多晶V_2O_5,在(001)面具有明显择优取向。同一膜厚下(350 nm),随着激光能量密度的增加,薄膜的相变关闭时间由1.48 ms单调减小至0.64 ms,相变回复时间则由11.6 ms单调增加至20.4 ms,相变后的透过率由19%单调减小至8%,回复后的透过率由77%单调减小至51%。薄膜膜厚在150～550 nm的范围内,其激光损伤阈值随着膜厚的增加呈现出先增后减的趋势;当膜厚等于250 nm时,激光损伤阈值达到最大值,为260 mJ/cm^2;膜厚为550 nm时,激光损伤阈值最小,仅为209 mJ/cm^2。结论 V_2O_5薄膜厚度对其抗激光损伤性能具有较大的影响,合理地控制膜厚,能够有效提高激光损伤阈值,从而提高基于金刚石衬底的V_2O_5薄膜的抗激光损伤能力。

The work aims to investigate the effect of V2O5 film thickness on laser damage resistance. V2O5 thin films with different thickness were prepared on optical grade single crystal diamond substrates by radio frequency reactive magnetron sputtering. The optical response curves of the thin films were tested by a pulsed laser with a pulse width of 10 ns and a wavelength of 1064 nm. The changes of transmittance and the switching time before and after phase transformation were measured to determine whether the thin films were damaged, and the laser damage threshold was obtained according to the damage probability. The prepared films were polycrystalline V2O5 with single component and had obvious preferred orientation on(001) surface.At the same film thickness(350 nm), with the increase of laser energy density, the phase transition closure time of the films decreased monotonously from 1.48 ms to 0.64 ms, and the phase transition recovery time increased monotonously from 11.6 ms to20.4 ms. The transmissivity decreased monotonously from 19% to 8%, and the transmissivity decreased monotonously from77% to 51%. In the range of 150~550 nm of film thickness, the laser damage threshold increased first and then decreased with the increase of the film thickness;When the film thickness was 250 nm, the laser damage threshold reached the maximum value of 260 mJ/cm^2;when the film thickness was 550 nm, the minimum value was 209 mJ/cm^2. The thickness of V2O5 film has great influence on laser damage resistance. Reasonable control of film thickness can effectively improve the laser damage threshold,thus improving the laser damage resistance of V2O5 film based on diamond substrate.