Microfluidic interferometer

We present a class of compact, fluid-based, interferometric, tunable optical components: the single-beam microfluidic Mach–Zender interferometer. Phase delay is achieved through light propagation across a fluid–air interface (meniscus). The effect of meniscus curvature on the device transmission is considered using the three-dimensional beam propagation method and shown to be an important device parameter. We engineer the meniscus curvature using monomer surface chemistry, rendering it flat, and find that the experimental response corresponds well with simulation. The device has a resonance at 1.3μm with a 25dB extinction ratio; the latter can be adjusted by shifting the meniscus position.