We investigate the tunability of optofluidic distributed feedback (DFB) dye lasers. The lasers rely on light-confinement in a nano-structured polymer film where an array of nanofluidic channels constitutes a third order Bragg grating DFB laser resonator with a central phase-shift. The lasers are operated by filling the DFB laser resonator with a dye solution by capillary action and optical pumping with a frequency doubled Nd:YAG laser. The low reflection order of the DFB laser resonator yields low out-of-plane scattering losses as well as a large free spectral range (FSR), and low threshold fluences down to ~7 microJ/mm2 are observed. The large FSR facilitates wavelength tuning over the full gain spectrum of the chosen laser dye and we demonstrate 45 nm tunability using a single laser dye by changing the grating period and dye solution refractive index. The lasers are straight-forward to integrate on lab-on-a-chip microsystems, e.g. for novel sensor concepts, where coherent light in the visible range is desired.

This letter describes the design and operation of a polymer-based third order distributed feed-back (DFB) microfluidic dye laser. The device relies on light-confinement in a nano-structured polymer film where an array of nanofluidic channels is filled by capillary action with a liquid dye solution which has a refractive index lower than that of the polymer. In combination with a third order DFB grating, formed by the array of nanofluidic channels, this yields a low threshold for lasing. The laser is straight-forward to integrate on Lab-on-a-Chip micro-systems where coherent, tunable light in the visible range is desired.

We present a laterally emitting, coupled cavity micro fluidic dye ring laser, suitable for integration into lab-on-a-chip micro systems. The micro-fluidic laser has been successfully designed, fabricated, characterized and modelled. The resonator is formed by a micro-fluidic channel bounded by two isosceles triangle mirrors. The micro-fluidic laser structure is defined using photo lithography in 10 µm thick SU-8 polymer on a glass substrate. The micro fluidic channel is sealed by a glass lid, using PMMA adhesive bonding. The laser is characterized using the laser dye Rhodamine 6G dissolved in ethanol or ethylene glycol as the active gain medium, which is pumped through the micro-fluidic channel and laser resonator. The dye laser is optically pumped normal to the chip plane at 532 nm by a pulsed, frequency doubled Nd:YAG laser and lasing is observed with a threshold pump pulse energy flux of around 55 µJ/mm 2 . The lasing is multi-mode, and the laser has switchable output coupling into an integrated polymer planar waveguide. Tuning of the lasing wavelength is feasible by changing the dye/solvent properties.