Contents lists available at ScienceDirect
Applied Surface Science
journa l homepa ge:
www.elsevier.com/locate/apsusc
Full Length Article
Fabrication of high integrated microlens arrays on a glass substrate for 3D
micro-optical systems
Yang Wei
a,b
, Qing Yang
a,b,
⁎
, Hao Bian
a,c
, Feng Chen
a,c,
⁎
, Minjing Li
a,b
, Yanzhu Dai
c
, Xun Hou
c
a
State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, ShaanXi, People’s Republic of China
b
School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, ShaanXi, People’s Republic of China
c
Shaanxi Key Laboratory of Photonics Technology for Information, School of Electronics & Information Engineering, Xi’an Jiaotong University, Xi’an 710049, ShaanXi,
People’s Republic of China
ARTICLE INFO
Keywords:
Microlens array
Femtosecond laser microfabrication
Integrated micro-optics
Imaging patterns
ABSTRACT
Microlens array have been developed as an essential element in integrated micro-optical systems. However,
rapidly fabrication of high integration, high fill factor and multi-layer microlens arrays on a hard material is still
a challenge. Here, facilely designed high integrated double-sided concave microlens arrays were proposed. These
concave microlens arrays possess nearly 5000 close-packed microlenses on a double sides glass substrate, which
were created by femtosecond laser wet etch process. The optical properties of integrated microlens arrays were
investigated, which exhibit novel diverse imaging patterns, such as coaxial nested rectangular-shaped, coaxial
nested hexagonal-shaped, non-coaxial nested hexagonal-shaped imaging patterns, etc. Moreover, diverse ima-
ging patterns can be simply realized by controlling the shape, the size of the microlenses and the arrangement of
the microlens arrays on the double-sided glass chips.
1. Introduction
Integrated micro-optical components, such as grating, photonic
crystal, microlens array (MLA), have been emerged as crucial optical
elements for the opto- electro- mechanical system
[1–7]. Integrated
MLA, like high fill factor single layer MLA, which will increase the
usage ratio of the light can be considered as a typically 2D integrated
optical element. Likewise, multi-layers MLAs which integrate the MLAs
on the direction of light propagation will contribute to the 3D in-
tegrated micro-optical systems. These integrated MLAs can be poten-
tially applied in laser homogenization
[8–12], holographic laser pro-
jection
[13], optical inspection [14,15] , light emission [16,17], etc
[18,19]. Multi-layers MLA, especially for double-sided MLAs which can
be considered as the integrated fly-eye, is one promising optical ele-
ment for efficient homogeneous illumination
[20–22]. Compared with
the single layer MLA, the double-sided MLAs can shape the light beam
into a suitable optical pattern, enhance the ability of homogenization
and increase the uniformity of the light distribution. Moreover, double-
sided MLAs are 3D integrated optical elements which show competent
for miniaturization optical systems.
Several methods have been proposed to fabricate the MLA, such as
atomic layer deposition
[23], lithography with expensive masks [24],
self-assembly
[25], printing [7], reconfigurable micro-templating [26],
thermal reflow
[27]. Due to the inherent limit, these methods were
restricted by certain defects, such as complexity and high cost of fab-
rication process, poor efficiency and soft materials, which restrict
practical applications. For instance, Li et al. presented a vapor-induced
dewetting method for fabricating MLAs on polymeric surfaces
[28].
This method concentrates on the polymer materials which is im-
practical in high temperature and complex applications. In particular,
this method cannot realize high-fill factor and coaxial microlenses on
double sides of substrate. Huang et al. fabricated a double-sided MLA by
a glass molding technique. Nevertheless, this method is restricted to
poor efficiency and lack of controllability
[29]. As a consequence, ra-
pidly fabrication of high fill factor, shape and size controllable micro-
lenses and high coaxial double-sided 3D integrated MLAs are still a
challenge.
Femtosecond laser micromachining have been demonstrated pro-
cessing microstructures in a wide range of materials during our pre-
vious work
[30–33]. Here, we introduce a novel structure of integrated
double-sided concave microlens arrays (DSC-MLAs) on a glass chip
which will contribute to the 3D micro-optical systems. The fabrication
method involved a femtosecond laser wet etch (FLWE) process, which
shows high e
fficiency for the whole fabrication process can be finished
https://doi.org/10.1016/j.apsusc.2018.06.267
Received 26 March 2018; Received in revised form 13 June 2018; Accepted 27 June 2018
⁎
Corresponding authors at: State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, ShaanXi, People’s Republic of
China.
E-mail addresses:
chenfeng@mail.xjtu.edu.cn (Q. Yang), yangqing@mail.xjtu.edu.cn (F. Chen).
Applied Surface Science 457 (2018) 1202–1207
Available online 28 June 2018
0169-4332/ © 2018 Elsevier B.V. All rights reserved.
T