Fabrication of Si-based waveguide splitters using photosensitive sol–gel method

✍ Scribed by Zhezhe Wang; Gaoyang Zhao; Xiaolei Zhang; Ying Lei

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 454 KB
• Volume: 282
• Category: Article
• ISSN: 0030-4018
• DOI: 10.1016/j.optcom.2008.11.066

✦ Synopsis

In this paper, a photosensitive sol-gel method for 1 Â 8 Y-branch optical splitter is reported. The poly (methyl methacrylate) (PMMA) cladding films with different thicknesses (above 10 lm) on Si substrates are prepared on Si substrates by dip-coating, the root-mean-square roughness (Rrms) of which is less than 0.7 nm. The UV photosensitive organic-inorganic composite SiO 2 /ZrO 2 /H core films are then coated on these PMMA cladding films using photosensitive sol-gel method. The refractive indexes of PMMA cladding films examined by spectroscopic ellipsometer are 1.4854, 1.4815 and 1.4806 at 0.85, 1.31 and 1.55 lm, while that of the SiO 2 /ZrO 2 /H gel films are 1.5569, 1.5489 and 1.5472 lm, respectively, which is larger than that of PMMA cladding films. Therefore, the composite structure of SiO 2 /ZrO 2 /H gel films on PMMA-on-Si substrates could be used to fabricate waveguide splitter. Based on the inherent photosensitivity of the SiO 2 /ZrO 2 /H gel film, 1 Â 8 Y-branch optical power splitters with a thickness of 5 lm are fabricated by irradiating the gel film with UV light through a mask followed by dissolving the nonirradiated area in a suitable solvent. The line-width and output spacing of this splitter are 25 and 110 lm, respectively. The observed near-field pattern indicates that the light with a wavelength of 1.53-1.56 lm can be transmitted and split into eight branches in the optical splitter, which is fabricated by using the above technique.