Microchannels in conventional single-mode fibers.

Microchannels are fabricated into conventional single-mode fibers by femtosecond laser processing and chemical etching. Fabrication limitations imposed by the fiber geometry are highlighted and resolved through a simple technique without compromising fabrication flexibility. A microfluidic fiber device consisting of a 4 microm wide microchannel that intersects the fiber core for refractive index sensing is further demonstrated.