Optofluidic microring dye laser embedded in polydimenthylsiloxane with reduced threshold

Abstract

We demonstrate an integrated optofluidic microring dye laser with a relatively low threshold on a polydimenthylsiloxane (PDMS) chip. The chip was fabricated through conventional soft lithography. It consists of a liquid waveguide with microring structure providing the feedback. A reduced threshold is realized due to the unique design of the bus waveguide across the center of the microring structure, which results in a great reduction in the cavity losses. Laser dye rhodamine 6G (R6G) dissolved in benzyl alcohol was injected into the microfluidic channel as the gain medium. When the dye laser was pumped with a pulsed laser at 532 nm, the dye laser oscillation was achieved with a threshold of only 4–5 μJ mm−2. The convenience in fabrication and operation makes the optofluidic microring dye laser a promising underlying photonic component in the integrated optofluidic systems.