Adjustable refractive index modulation for a waveguide with SU-8 photoresist by dual-UV exposure lithography.
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.
Ong
Biow Hiem
BH
Photonics Research Center, School of Electrical and Electronic Engineering, Nanyang Technological Univeristy, Singapore.
Yuan
Xiaocong
X
Tjin
Swee Chuan
SC