Real-Time Tunable Optofluidic Splitter via Two Laminar Flow Streams in a Microchannel

This paper reports a tunable optofluidic splitter in which the incident light is split via refraction and reflection at the interface between two laminar flows in a microchannel but with different refractive indices. A Y-junction microchannel is used to demonstrate the continuous tuning of the splitting ratio of optical power by smooth adjustment of the ratio of two flow rates. In addition, it has achieved the tuning of split angle from 5° to 19° by the control of the refractive index contrast. The dynamic response gives a fastest switching frequency of 1.67 Hz between the "wave-guiding" and "splitting" status.