Low-cost fabrication of microlasers based on polymeric micropedestals

Our current work exploits direct laser writing (DLW) and low one-photon absorption (LOPA) in a low-cost three-dimensional optical fabrication system designed to print micrometric polymeric structures. Micropedestals were obtained by focusing a laser beam on a photoresist layer deposited on a silica glass substrate. Subsequent coating with rhodamine 6G dye allows these pedestals to function as microlasers upon optical excitation at 532 nm. Our microlasers, with a diameter of similar to 53 mu m and a height of similar to 40 mu m, exhibit a broad fluorescence peak in the spectral range 540-600 nm, in addition to narrow lasing peaks, exhibiting quality factors Q exceeding 2000 and a lasing threshold of similar to 5 mu Jcm(-2). The observed free spectral range associated with the lasing peaks of similar to 3 nm is consistent with simulations, which we include in this paper. In addition, we present simulations for the longitudinal shift of the patterning laser spot, which occurs particularly for relatively thick photoresist layers, coupled with a large index contrast at the photoresist top surface. Such a shift could introduce errors in the resulting microfabricated structures if left unaccounted for. We hope that our work will contribute to the development of microlasers for various photonic applications, particularly if dimensions can be reduced, for on-chip optical communications and data processing. (C) 2021 Optical Society of America

Automated summary

The research utilizes direct laser writing and low one-photon absorption to print micrometric polymeric structures in a low-cost three-dimensional optical fabrication system, resulting in microlasers with broad fluorescence peaks and narrow lasing peaks. The observed narrow lasing peaks exhibit quality factors exceeding 2000 and a lasing threshold of approximately 5 μJcm(-2). The free spectral range associated with the lasing peaks of approximately 3 nm is consistent with simulations presented in the paper.