Michael Ian Lapsley

We introduce an optofluidic based variable optical attenuator with high stability, high reliability, simple and inexpensive fabrication, and an attenuation performance comparable to commercial devices. A standard soft lithography process produces a single-layered polydimethylsiloxane (PDMS) microfluidic device integrated with optical fibers. By altering the refractive index of the fluid within the microchannel, we can control the reflectivity of the fluid/PDMS interface and thus achieve variable attenuation. Theoretical calculations are conducted based on Snell’s law of refraction and the Fresnel equations of reflection, and the calculated attenuation response matches well with experimental data.


Figure: A schematic of the optical attenuator device. Altering the flow rates Q1 and Q2 changes the reflected power (R) of the incident beam (I).