Design for tunable optofluidic optical coupler with large dynamic range

A novel scheme for tunable optofluidic optical coupler is proposed, by using directional coupling waveguide structure and microfluidic channel with two tapers at end points. The normalized optical power at two output ports can be dynamically manipulated by controlling the refractive index of liquid mixture in microfluidic channel. The optical performance of the designed device is numerically investigated by employing the beam propagation method (BPM). The simulated results demonstrate that large dynamic range and low optical loss for both TE and TM mode can be easily achieved, and furthermore the dependence of polarization states and operation wavelength is very low in our designed device. In addition, the tunable optofluidic coupler has advantages including simple structure and large fabrication tolerance. Accordingly, our proposed device offers a new approach for manipulation of optical power output, which has wide potential application in optofluidic systems.