Ultra-Compact Band-Pass and Band-Stop Tunable Filters Based on Loop-Cascaded Nanobeam Structure

We propose an ultra-compact band-pass and band-stop filter with bandwidth tunability based on the loop-cascaded nanobeam structure in simulation, with a small coupling region of 41×1 μm
²
. It features low insertion loss, large bandwidth tunable range and high sidelobe suppression ratio. By two-stage cascading, the bandwidth of the band-pass filter can be adjusted in the range of 6 nm-24 nm. We also experimentally demonstrate the loop-cascaded nanobeam band-pass and band-stop filter with a coupling region of only 17.5×1 μm
²
.