Tunable optical transmission of magnetic microsphere colloids

摘要

We demonstrate the tunable transmission of core-shell magnetic microsphere colloids (MMC) and report its modeling by effective medium approximation (EMA). Transmission from the MMC was measured experimentally at various filling factors. Using the EMA, the relations between transmission of the colloids, their filling factor, and the applied magnetic field are quantified. Using an electromagnetic actuator, it was shown that the transmission can be reproducibly tuned by controlling the duration as well as the strength of the applied magnetic field. By choosing proper values of applied magnetic field strength, application duration, and optical path length, dynamic properties of the tunable optical switch are studied. These results are useful to the design of tunable optical switches and windows based on magnetic colloids. (C) 2018 Optical Society of America