激光直写氧化石墨烯可调光子筛

Tunable photon sieve based on laser direct writing graphene oxide

光子筛不受衍射极限限制且设计结构灵活,是一种新型衍射元件。相比于振幅型光子筛,相位型光子筛能量透过率更高,成像对比度更加尖锐,具有应用优势。然而,常见衍射光学器件面临加工复杂及难以调制等局限。石墨烯及其衍生材料具有良好的光电调制特性,被广泛用于衍射光学器件制备。利用激光直写技术可实现诱导还原氧化石墨烯,是一种简单高效的微纳加工技术。利用时域有限差分方法研究光子筛的衍射特性,并基于激光直写技术制备氧化石墨烯光子筛。通过不同激光功率加工可获得材料的折射率调制,器件实现了明显的焦距调制(1.62mm)和聚焦效率的提高(13.6%)。该方法有望为实现可调制衍射光学元件提供简便、灵活的设计与制备手段。

Photon sieve is a new type of diffraction element,which is not limited by diffraction limit and has flexible design structure.Compared with amplitude-type photon sieve,phase-type photon sieve has higher energy transmittance and sharper imaging contrast,which has application advantages.However,common diffractive optical devices face limitations of complex processing and difficulty in tuning.Graphene and its derivatives have good photoelectric tuning properties and are widely used in the preparation of diffractive optical devices.Laser direct writing technology can realize the induced reduction of graphene oxide,which is a simple and efficient micro-nano processing technology.In this paper,the diffraction characteristics of the photon sieve is studied by using the finite-difference time-domain method,and the graphene oxide photon sieve is prepared based on the laser direct writing technology.The refractive index modulation of the material can be obtained by processing with different laser power,and the device can achieve obvious focal length modulation(1.62 mm)and focus efficiency improvement(13.6%).This method is expected to provide a simple and flexible design and preparation method for realizing tunable diffractive optical elements.