Low threshold polymeric integrated optofluidic microlaser

A low threshold optofluidic microlaser have been achieved using only polymeric materials and lamination process. The resonator is fabricated by two commercially available (3M) plane parallel Bragg mirrors composed of hundred layers with alternating high- and low-index layers of polyester and acrylic polymer with a high reflectivity (R>96%). The cavity, the mirrors and the substrates are assembled by a cold lamination process. This approach simplifies the fabrication procedure while retaining high optical surface quality, resulting in a compact, low-cost disposable device. As gain medium a water solution of Rhodamine B with a concentration of 0.9mM has been employed. A pulsed laser (557 nm wavelength, 5 ns pulse width, 10 Hz repetition rate) normally incident into the FP microcavity through a lens with a focal spot size of 140 μm has been used for the measurements. The device shows a threshold of 1 μJ/mm2 with emission peaks centered at around λ =632 nm.