Tunable CWDM by utilizing ordered structures in magnetic fluid films

With the demand of the development in high-speed telecommunication, the WDM technologies become important and attract lots of interests of scientists and engineers. In this report, we explore a new method to fabricate coarse WDM (CWDM) by utilizing the ordered structure in the magnetic fluid films under external magnetic fields. It was found that the first-order interference lights of two incident visible lights with a difference of 20 nm in wavelength can be absolutely separated. This separation was further observed to increase as the incident angle of the light incident into the magnetic fluid film was raised, whereas the transmittance became lower. Due to the tunability of the ordered structure in the magnetic fluid film by adjusting the external field strength, the magnetic-fluid-based CWDM is tunable and the 4-channel tunable CWDM is demonstrated in this work.