Institute of Low Temperatures and Structural Research, Polish Academy of Science, 50-422 Wroclaw, Poland.
Sci Rep. 2017 Jan 23;7:41281. doi: 10.1038/srep41281.
Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed. It was observed that the white light emission is highly dependent on the electric field intensity, allowing one to modulate the emission intensity. The electric field intensity ca. 0.5 V/μm was able to decrease the white light intensity by half. Origins of the laser-induced white light emission along with its characteristic features were discussed in terms of avalanche multiphoton ionization, inter-valence charge transfer and possible plasma build-up processes. It is shown that the laser-induced white light emission may be well utilized in new types of white light sources.
激光诱导的白光发射是从用聚焦连续波红外激光二极管束辐照的多孔石墨烯泡沫中观察到的。结果发现，发射强度随激光功率密度的增加呈指数增长，在约 1.5 W 时达到饱和水平，并具有稳定的发射条件。还观察到，白光发射是空间局限于照明激光光的焦点尺寸。还讨论了激光诱导的白光发射的其他一些特征。观察到白光发射高度依赖于电场强度，从而允许调节发射强度。约 0.5 V/μm 的电场强度能够将白光强度降低一半。根据雪崩多光子电离、价间电荷转移和可能的等离子体积累过程，讨论了激光诱导的白光发射的起源及其特征。结果表明，激光诱导的白光发射可很好地用于新型白光光源。
