Optical micro cavities fabricated using direct Proton Beam Writing

摘要

Proton beam writing (PBW) is a high-resolution direct write lithographic technique suitable for the fabrication of microano optical components with smooth vertical sidewalk. In the present work PBW was used to fabricate smooth micro cavities in negative tone photoresist SU-8 and Rhodamine B doped SU-8. Two different laser cavities based on whispering gallery mode resonators were fabricated using PBW. The laser cavities in Rhodamine B doped SU-8 resist were optically pumped with a pulsed frequency doubled Nd: YAG laser, and emits light in the chip plane at 643 nm. The presented laser cavities showed pump threshold as low as 3 μJ/mm~2, which is the lowest threshold reported in planar cavities fabricated in Rhodamine B dye based polymer laser cavities.