  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 microns 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
micro-Joule/square-milimeter. 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.
