Polymer waveguide biosensors with Bragg gratings

Abstract

Biophotonic sensors based on polymer waveguide with Bragg reflection grating are demonstrated in this work. Waveguide Bragg reflectors were designed by using the effective index method and the transmission matrix method. The grating pattern was formed by exposing laser interference pattern on a photoresist. On top of the inverted rib waveguide, the grating was inscribed into the core layer by the O2 plasma etching. In order to perform the bio-molecule detection experiment, a calixarene molecule was self-assembled on top of thin Au film deposited on the waveguide Bragg reflector. To measure the response of the sensor, several PBS solutions with different concentrations of potassium ion from 1 pM to 100 μM were dropped on the sensor surface. The shift of Bragg reflection wavelength was observed from the PBS solution with lowest potassium concentration, 1 pM.