Fabrication of Cylindrical Microlens by Femtosecond Laser‐Assisted Hydrofluoric Acid Wet Etching of Fused Silica

Abstract

Micro‐optical elements play a key role in various advanced devices, including biomedical, photovoltaic, 3D display, and optical communication devices. As one of the typical micro‐optical elements, cylindrical microlens (CML) can modulate the wavefront phase of the incident light in only one direction. The process methods of CML have been developed and various methods are proposed for CML fabrication. For the simple and versatile fabrication of CML on hard brittle materials, femtosecond laser direct writing combined with hydrofluoric acid (HF) wet etching for removal of laser‐modified regions in fused silica is proposed here for high‐quality CML fabrication. A high‐accuracy CML can be processed by adjusting the HF etching time, femtosecond laser pulse energy, and the position of the laser exposure point. Crossed‐shaped CML can be realized by accurate control of the single laser pulse exposure positions at the intersection in two directions. A series of alphabet‐shaped CML, showing this fabrication method's flexibility is made. The characterization of the CML under a microscope system reveals a good optical focusing ability. The proposed method offers a practical route toward the manufacture of CML on hard brittle materials.

Structural Color Generation on Transparent and Flexible Substrates by Nanosecond Laser Induced Periodic Surface Structures

“…[ 18 ] The influence of fs laser scanning paths and the effect of laser polarization on the LIPSS fabrication process over silicon substrates revealed structural coloration through the overlapping of different angles. [ 19 ] A recent study investigates the LIPSS having approximately equal spatial periods and λ/n (λ is the wavelength and n is the refractive index) to the incident radiation on soda‐lime glass and borosilicate glass using a picosecond (ps) laser. [ 6d ] Linearly polarized nanosecond (ns) pulsed laser patterning of Indium‐Tin Oxide (ITO) film‐coated glass substrate revealed a LIPSS formation with a periodicity of 350 nm and the patterned ITO is electrically conductive and stable against strong acidic environments and able to electrodeposit polyaniline and silver nanoparticles.…”

Concave microlens arrays with tunable curvature for enhanced photodegradation of organic pollutants in water: A non‐contact approach

“…For example, mechanical machining, 26–28 thermal manipulating, 29,30 or direct laser writing 31–33 helps to create indentations that function as MLAs on the surface of matrices. Chemical wet‐etching is another method to directly form concave MLAs, where materials on the unprotected regions can be selectively removed after being immersed into etchants 34–36 . The requirements for precision and the expenses are too high in mechanical machining or laser writing, while the wet‐etching method can hardly prepare concave MLAs with the desired shape.…”

“…Chemical wet-etching is another method to directly form concave MLAs, where materials on the unprotected regions can be selectively removed after being immersed into etchants. [34][35][36] The requirements for precision and the expenses are too high in mechanical machining or laser writing, while the wetetching method can hardly prepare concave MLAs with the desired shape.…”