Optik 125 (2014) 887–892 Contents lists available at ScienceDirect Optik jou rn al homepage: www.elsevier.de/ijleo Extrinsic surface scattering and intrinsic absorption loss of vinyl based hybrid organic–inorganic materials for optical waveguides applications Ahmad Sharmi Abdullah a,∗ , Amirjan Nawabjan a , Norazan Mohd Kassim a , Mohd Haniff Ibrahim a , Mohamad Zahid Abdul Malek b , Mat Tamizi Zainuddin b , Shamsul Azrolsani Abdul Aziz Nazri b a Lightwave Communication Research Group, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia b Advanced Material Research Centre (AMREC), SIRIM Berhad, Lot 34, Kulim Hi-Tech Park, 09000 Kulim, Kedah, Malaysia a r t i c l e i n f o Article history: Received 13 January 2013 Accepted 24 July 2013 Keywords: Sol–gel technique Hybrid material Optical waveguide Propagation loss a b s t r a c t Hybrid photosensitive materials were prepared by using vinyltriethoxysilane (VTES), tetraethoxysilane (TEOS) and tetrabutoxytitanate (TTBu) precursors through sol–gel technique. The materials are intended for optical telecommunication applications. Thus, high optical transmissions at the second and third optical telecommunication windows are essential. Extrinsic surface scattering due to surface roughness and intrinsic absorption due to aliphatic CH and OH groups are always ascribable to the optical power attenuations at aforementioned optical telecommunication windows. Optical waveguide based on hybrid sol–gel materials were fabricated, characterized and analyzed in order to investigate the extrinsic and intrinsic sources of attenuation and their contributions. The fabricated samples were characterized for propagation loss, surface condition, and Fourier transform IR (FTIR) absorption spectra. Propagation loss were measured by means of cut-back method as 1.6 and 6.9 dB/cm at 1310 and 1550 nm wavelengths, respectively. Surface scattering loss was modeled based on measured rms roughness of 0.724 nm and turned out to contribute less than 0.01% of the total propagation loss. FTIR absorption spectra show the persistent existence of aliphatic CH and OH groups within the final hybrid sol–gel materials. © 2013 Elsevier GmbH. All rights reserved. 1. Introduction Optical materials derived via sol–gel technique appear attrac- tive for optical telecommunication devices realization. Sol–gel technique provides economy and simplicity of materials synthe- sis and thin films fabrication. Materials properties can be adjusted from that of inorganic to hybrid [1,2]. Hybrid materials have less shrinkage problem, thus the formation of thick, crack-free and smooth surface thin films is possible [3,4]. Besides, hybrid materials with photosensitive organic components enable direct photolithography and wet chemical etching techniques for devices micro-patterning [5,6]. In addition, introduction of metal alkox- ides such as TiO 2 into the hybrid matrix provides modification of material refractive index [14,15]. Attenuation of optical power strongly impairs the optical devices performance. This phenomenon is contributed by the extrinsic and intrinsic losses. Extrinsic loss is due to devices sur- face scattering while intrinsic loss is a factor in the material ∗ Corresponding author. Tel.: +60 7 5535302; fax: +60 7 5566272. E-mail addresses: sharmi@utm.my, sharmi@fke.utm.my (A.S. Abdullah). properties, which is attributable to intrinsic scattering and absorp- tion processes [16]. Intrinsic scattering is determined by pores, phase separation, and precipitation and crystallization of metal alkoxides component inside the materials. These factors however were eliminated by short duration of thin film deposition and drying [17,18], and low temperature processes [19,20], which are applied in this work. Absorption induced loss is caused by CH and OH vibrations overtones and combinations that is absorbed in the near infrared (NIR) region [21]. Unfortunately, hybrid materials and the low temperature synthesis contribute to the presence of these CH and OH contents. In this work, vinyl trialkoxysilane precursor was used as the organic component for the photosensitive hybrid material. It is known to have shorter organic chain, thus the material was expected to show lower intrinsic absorption losses due to both aliphatic CH and OH contents in the NIR region [22]. In addition, thin film of vinyl based material was shown to have high transmittance at the second and third telecommunication windows (i.e. 1310 and 1550 nm wavelengths) [23]. Channel waveguides fabricated using vinyl based material was also shown to have low propagation loss at the 1310 nm wavelength in our previous work [24] and has been proven suitable for the application of multimode interference 0030-4026/$ – see front matter © 2013 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.ijleo.2013.07.065