Théberge Francis, Mathieu Pierre, Thiré Nicolas, Daigle Jean-François, Schmidt Bruno E, Fortin Jean, Vallée Réal, Messaddeq Younès, Légaré François
Opt Express. 2016 Oct 17;24(21):24600-24610. doi: 10.1364/OE.24.024600.
We report mid-infrared (MIR) nonlinear absorption in AsS glasses which results from two-photon excitation of valence electron to the Urbach extension followed by strong linear absorption of excited states. The measured MIR nonlinear absorption can be 3 to 4 orders of magnitude stronger than the two-photon absorption in the near-infrared for similar laser intensities and does not result from contaminants, but it is intrinsic to AsS glasses. AsS fibers are widely used to generate supercontinuum by pumping them with high peak power laser pulses. For a 100 kilowatt peak power MIR soliton propagating in single mode AsS fiber, the nonlinear absorption can be of similar magnitude than the fiber background loss. Finally, for laser peak power around 1 MW, the MIR nonlinear absorption can be ~2 orders of magnitude larger than the fiber background loss in single mode AsS fiber.
我们报道了AsS玻璃中的中红外（MIR）非线性吸收，它是由价电子双光子激发到Urbach扩展态，随后激发态发生强烈线性吸收所导致的。在相似的激光强度下，所测得的MIR非线性吸收比近红外区域的双光子吸收要强3到4个数量级，并且它并非由杂质引起，而是AsS玻璃所固有的特性。AsS光纤被广泛用于通过用高峰值功率激光脉冲泵浦来产生超连续谱。对于在单模AsS光纤中传播的100千瓦峰值功率的MIR孤子，非线性吸收的量级可能与光纤本底损耗相当。最后，对于激光峰值功率在1兆瓦左右的情况，单模AsS光纤中的MIR非线性吸收可能比光纤本底损耗大~2个数量级。
