Fiber Optofluidic Microlaser With Lateral Single Mode Emission

We report a low threshold fiber optofluidic microlaser, based on a microstructured optical fiber (MOF). The particular MOF structure is used not only as the microfluidic channel for sampling the liquid gain, but also as a spectral filter to achieve the single mode emission. Lateral laser emission from the MOF is observed when 1 mM Rhodamine 6G in ethanol is sucked into the MOF by the capillary force and pumped with a pulsed laser. It requires a low volume, ∼470 pL, of the gain materials. Single mode emission with a full width at half-maximum (FWHM) of 53 pm is obtained with a threshold of 13.2 μJ/mm
²
. The filtering effect is investigated both experimentally and theoretically by the interference within the cavity. The dependence of the number of modes on the lateral position of the pump with respect to the MOF is also discussed By using the single mode emission, it is promising for the multiplexing of optofluidic lasers in the spectral domain.