Rectangular glass micro-capillaries for biophotonic applications

In this work, we report the characterization of 5-cm-long glass micro-capillaries with 20 μm × 200 μm and 50 μm × 500 μm (nominal values) inner dimensions of the rectangular channel. Optical low-coherence reflectometry enables detection of the optical distance between in-depth interfaces of the glass micro-capillary also in presence of fluids inserted into the channel just by capillary action. Thus, group refractive index of the filling solution can be easily recovered.