title: Adjustable refractive index modulation for a waveguide with SU-8 photoresist by dual-UV exposure lithography.
abstract: We present a new fabrication technique based on a two-step UV exposure lithographic process to marginally modulate the refractive index in commercial SU-8 photoresist. This technique achieves refractive index modulation as different regions undergo different thermal densification prior to UV-induced polymerization. A small refractive index contrast of 0.0008 or lower can be achieved, and this is especially useful for fabricating waveguides with a low level of propagation modes. This technique may be extended to other UV-curable epoxy photoresists and can easily be applied in the fabrication of optical elements such as optical interconnects and integrated optical sensors without the development process.
authors.affiliation: Photonics Research Center, School of Electrical and Electronic Engineering, Nanyang Technological Univeristy, Singapore.
authors.forename: Biow Hiem
authors.initials: BH
authors.lastname: Ong
authors.forename: Xiaocong
authors.initials: X
authors.lastname: Yuan
authors.forename: Swee Chuan
authors.initials: SC
authors.lastname: Tjin