Liquid Gradient Refractive Index Microlens for Dynamically Adjusting the Beam Focusing

Micromachines

Zichun Le¹  Yunli Sun²  Ying Du²  Shih-Kang Fan² 

[1] College of Sciences, Zhejiang University of Technology, Hangzhou 310023, China

关键词: in-plane liquid gradient index (L-GRIN) microlens;    optofluidics waveguide;    adjustable focal length;    convection-diffusion process;    beam focusing;    finite element method;   

DOI  :  10.3390/mi6121469

来源: mdpi

【 摘 要 】

An in-plane liquid gradient index (L-GRIN) microlens is designed for dynamically adjusting the beam focusing. The ethylene glycol solution (core liquid) withde-ionized (DI) water (cladding liquid) is co-injected into the lens chamber to form a gradient refractive index profile. The influences of the diffusion coefficient, mass fraction of ethylene glycol and flow rate of liquids on the refractive index profile of L-GRIN microlens are analyzed, and the finite element method and ray tracing method are used to simulate the convection-diffusion process and beam focusing process, which is helpful for the prediction of focusing effects and manipulation of the device. It is found that not only the focal length but the focal spot of the output beam can be adjusted by the diffusion coefficient, mass fraction and flow rate of liquids. The focal length of the microlens varies from 942 to 11 μm when the mass fraction of the ethylene glycol solution varies from 0.05 to 0.4, and the focal length changes from 127.1 to 8 μm by varying the flow rate of the core liquid from 0.5 × 10³ to 5 × 10³ pL/s when there is no slip between the core and cladding inlet. The multiple adjustable microlens with a simple planar microfluidic structure can be used in integrated optics and lab-on-chip systems.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.