印刷具有梯度折射率微结构的硫卤玻璃衍射光学元件的研究

通过一种高效而廉价的显微热极化工艺,在硫卤玻璃中刻印出覆盖可见到中红外波长且具有梯度折射率(GRIN)微结构的衍射光学元件(DOE)。研究了显微热极化的主要极化参数(极化电压U)对硫卤玻璃的微观形貌、微结构、衍射效果和梯度折射率的影响规律。在U为0.75~1.00 kV范围内发现了有效印刷GRIN微结构硫卤玻璃的形成区。表面形貌的深度、衍射级数随着U的增加而增加,但显微热极化对光学透过影响较小而不影响实际应用。显微热极化印刷后硫卤玻璃表面可以观察到周期长度为25 μm且最大相位差高达0.60λ(λ=632.8 nm)的GRIN微结构。其衍射性能的主要来源是近阳极一侧亚表面的K⁺迁移和玻璃结构重排形成周期性分布的GRIN微结构。

A Diffractive Optical Element with Gradient Refractive Index Micro-Structure Imprinted in Chalcohalide Glasses

A diffractive optical element (DOE) with a gradient refractive index (GRIN) micro-structure which was imprinted in the chalcohalide glass covering a range of visible to mid-infrared wavelengths, was prepared by an efficient and inexpensive micro-thermal poling process. The influence laws of polarization parameter (polarization voltage U) of micro-thermal poling on the morphology, micro-structure, diffraction effect and diffractive optical element of chalcohalide glass were investigated. The effective imprinting of GRIN micro-structure on chalcohalide glass was found to be in a range of 0.75 kV to 1.00 kV for U. The depths of surface morphology and the number of the diffraction orders increase with the increment of U, but the micro-thermal poling has little effect on optical transmission and doesn’t affect the practical applications. After the micro-thermal poling process, GRIN micro-structure with a period length of 25 μm and a maximum phase difference of up to 0.60λ (λ=632.8 nm) are observed on the surface of the chalcohalide glass. The main sources of its diffraction performance are the migration of K⁺ on the subsurface near the anode side and the periodic GRIN micro-structure formed by the rearrangement of glass structure.