Polymer microlasers with a suspended cavity design

• Suspended micro-lasers are fabricated in a single layer dye doped polymer using proton beam writing.
• Lasing threshold as low as 0.5 μJ/mm2 is observed with these suspended cavities.
• By suspending these cavities, lasing threshold is improved by a factor of 2.
• Directional laser output is obtained in whispering gallery mode cavity with spiral design.

We report on the fabrication of microlasers with suspended cavity design in a thin layer of Rhodamine B doped SU-8 polymer using proton beam writing. Optical characterization of the fabricated three-dimensional microlasers under ambient atmosphere results in low lasing threshold of 0.5 μJ/mm2, which is an improvement by factor of 2 when compared to planar microlasers. The directional behavior is also observed in whispering gallery mode microlasers with spiral cavity design. These microlasers with suspended cavity design are not only useful in reducing the lasing threshold but also have significance in 3D photonic integrated circuits.