Optical Isomerization and Photo-Patternable Properties of GeO2/Ormosils Organic-Inorganic Composite Films Doped with Azobenzene

Xuehua Zhang,Wei Zhang,Shun Liu,Qian Wang,Yongjin Wang,Fangren Hu

doi:10.3390/coatings11070818

Xuehua Zhang, Wei Zhang + Show 4 more

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https://doi.org/10.3390/coatings11070818

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Journal: Coatings	Publication Date: Jul 6, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Nanjing University of Posts and Telecommunications

Abstract

GeO2/organically modified silane (ormosils) organic-inorganic composite films containing azobenzene were prepared by combining sol-gel technology and spin coating method. Optical waveguide properties including the refractive index and thickness of the composite films were characterized by using a prism coupling instrument. Surface morphology and photochemical properties of the composite films were investigated by atomic force microscope and Fourier transform infrared spectrometer. Results indicate that the composite films have smooth and neat surface, and excellent optical waveguide performance. Photo-isomerization properties of the composite films were studied by using a UV–Vis spectrophotometer. Optical switching performance of the composite films was also studied under the alternating exposure of 365 nm ultraviolet light and 410 nm visible light. Finally, strip waveguides and microlens arrays were built in the composite films through a UV soft imprint technique. Based on the above results, we believe that the prepared composite films are promising candidates for micro-nano optics and photonic applications, which would allow directly integrating the optical data storage and optical switching devices onto a single chip.

Highlights

Optical switches play an increasingly important role in all-optical networks [1,2].Azobenzene and its derivatives are one of the most widely used optical switches [3,4].Photosensitivity is the core of optical switch [5]
The surface morphology properties of the composite films doped with 5 wt. %
The root mean square (RMS) roughness of the composite films was measured, and the RMS roughness value is below 0.8 nm for all the samples, in the scanning range of 5 μm × 5 μm, which is small enough to meet the requirements of optical elements

Summary

Introduction

Optical switches play an increasingly important role in all-optical networks [1,2].Azobenzene and its derivatives are one of the most widely used optical switches [3,4].Photosensitivity is the core of optical switch [5]. Reversible molecular optical switch azobenzene is a compound with photochromic properties [6]. Azobenzene can undergo cis-trans reversible isomerization under ultraviolet light and visible light, leading to significant changes in molecular geometry and end-to-end distance, which means that azobenzene can be used as an optical switch [8]. Under the irradiation of ultraviolet light, the trans isomer is excited and immediately transformed into cis isomer. Under visible light or heated conditions, cis isomers are transformed into trans isomers [9]. Photoisomerization based on azobenzene makes polymers containing azobenzene molecules have photo-isomerization characteristics. These photosensitive materials do not need to be directly contacted and can be remotely controlled, avoiding the contamination of the materials [13]

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