Ultra-compact organic vertical-cavity laser with high-contrast grating feedback for gas detection

Abstract

The miniaturization of optical sensors is a key step towards the development of highly integrated optical sensing techniques and devices. The present work proposes an ultra-compact organic vertical-cavity microlaser based on an active micro-pillar design, and explores its potential applications as a highly integrated gas sensor. The vertical-cavity is realized by embedding an organic Rhodamine 6G doped SiO2 gain layer inside one small cavity which is formed by distributed bragg reflectors and a high contrast grating thin layer. The hybrid structure of top reflector of cavity enables part of the field to interact with the medium surrounding the cavity, while maintaining a high confinement factor, low lasing threshold, and single-mode operation around 570 nm. In particular, the vertical microlaser can be used as a convenient and versatile wavelength-interrogation sensing architecture, whereby variations of the laser spectral line can be correlated to small changes in the gas concentration. Through using full-wave electromagnetic simulations, we obtain a significantly improved figure of merit (441 RIU−1) for the bulk sensitivity. The vertical architecture and small design of the proposed micro-laser-based sensor render it attractive for highly integrated remote sensing of gases.