An Integrated Adjustable-Bandwidth Rectangular Filter Based on Cascading Ring-Assisted Mach-Zehnder Interferometers

We propose a narrowband rectangular optical filter based on cascading ring-assisted Mach-Zehnder interferometers with spectrum tailoring. Just by reasonably arranging the temperatures of different micro heaters on each stage, the center wavelength and bandwidth of filter can be tuned simply. We fabricated the device and measured the performance to prove that the bandwidth could be adjusted from 14 GHz to 4 GHz maintaining rectangular response. The filter shows potential in practical applications due to its flexibility and reconfigurability.