Tunable dual-channel filter based on the photonic crystal with air defects.

We propose a tuning filter containing two channels by inserting a defect layer (Air/Si/Air/Si/Air) into a one-dimensional photonic crystal of Si/SiO2, which is on the symmetry of the defect. Two transmission peaks (1528.98 and 1564.74 nm) appear in the optical communication S-band and C-band, and the transmittance of these two channels is up to 100%. In addition, this design realizes multi-channel filtering to process large dynamic range or multiple independent signals in the near-infrared band by changing the structure. The tuning range will be enlarged, and the channels can be moved in this range through the easy control of air thickness and incident angle.