Organic–Inorganic Hybrid Sol–Gel Materials For Optical Waveguide Application

Abstract

Pandu gelombang optik jalur berasaskan bahan–bahan sol–gel organik–bukan organic (hybrid) direka, disimulasi dan dibentuk. Bahan–bahan sol–gel hybrid tersebut disediakan daripada vinyltriethoxysilane (VTES), tetraethoxysilane (TEOS) dan tetrabutoxytitanate (TTBu) malalui kaedah pemprosesan sol–gel. Pandu gelombang optik tersebut telah dibentuk di atas lapisan quartz menggunakan kaedah penyalutan berputar, lithografi langsung, dan goresan kimia basah. Beberapa lapisan sol telah dibentuk demi mendapatkan struktur pandu gelombang dengan ketebalan yang sesuai untuk laluan mod cahaya sebagaimana diperolehi daripada simulasi. Kebolehan pandu gelombang untuk memandu cahaya pada panjang gelombang 1550 nm telah dicirikan mengunakan kaedah direct end–face fiber butt–coupling. Struktur fizikal pandu gelombang tersebut telah diperhatikan melalui mikroskop berkuasa tinggi. Keputusan yang diperolehi menunjukkan bahawa bahan yang dicadangkan boleh digunakan dalam aplikasi pemanduan gelombang optik pada panjang gelombang 1550 nm. Simulasi menunjukkan bahawa pandu gelombang jalur satu mod dapat direalisasikan jika ketebalan dan kelebaran pandu gelombang tersebut berada pada suatu julat nilai tertentu. Julat nilai tersebut dapat diperolehi melalui pengawalan parameter–parameter penyalutan berputar dan pembentukan mikro. Kualiti keratan rentas yang baik juga diperhatikan telah diperolehi melalui kaedah pembelahan semulajadi. Kata kunci: Pemprosesan sol–gel; bahan organik–bukan organic; pandu gelombang jalur Ridge optical waveguides based on organic–inorganic (hybrid) sol–gel materials were designed, simulated and fabricated. The hybrid sol–gel materials were synthesized from vinyltriethoxysilane (VTES), tetraethoxysilane (TEOS) and tetrabutoxytitanate (TTBu) precursors by means of sol–gel processing technique. The optical waveguides were fabricated on quartz substrate using spin coating, direct photolithography, and wet chemical etching techniques. Multiple layers of sol were deposited so as to obtain waveguide structure with suitable thickness for mode propagation such as acquired from the simulation. Waveguiding ability of the ridge optical waveguides at 1550 nm wavelength was characterized using direct end–face fiber butt–coupling method. Physical structure of the waveguides was observed through high power microscope. Observation showed that the proposed material possesses the ability for waveguiding application at the wavelength of 1550 nm. Simulation showed that a single mode ridge optical waveguide could be realized provided that the structure thickness and width are within certain range. The range is attainable through proper control of spin coating and micropatterning parameters. Acceptable end–face quality resulted from natural cleaving process was also discovered. Key words: Sol–gel processing; organic–inorganic material; ridge optical waveguide