Fabrication of a third-order polymer chirped waveguide Bragg grating with tapered core size by contact lithography

Abstract

A polymer chirped waveguide Bragg grating (CWBG) that uses uniform grating structures on a tapered waveguide core is designed and demonstrated. Third-order uniform grating structures were formed in the bottom cladding by inexpensive contact lithography and then a channel waveguide with tapered core size was fabricated on top of it to realize the CWBG. The reflection spectrum of the fabricated polymer CWBG was measured, and the 3 dB bandwidth is 2.9 nm, which is about 6.5 times the 3 dB bandwidth (0.45 nm) of the fabricated uniform waveguide Bragg grating. In addition, the measured reflectivity is larger than 16 dB. The reflection spectrum of the fabricated CWBG was numerically simulated, which agreed well with the experimental result.