Broadband Tunable Add/Drop Filters Based on Dielectric Double-Disk Microcavities

Herein, we present a spectrally tunable add/drop filter based on a dielectric double-disk microcavity. Numerical simulation shows that a whispering gallery mode of this filter has a very large wavelength tuning range of 103 nm for a 20 nm change of an air slot between the double disks. Based on this mechanism, broadband wavelength tuning and on/off switching are demonstrated in this paper. Under the resonance condition, drop power and through power at gap size of 10 nm were obtained as 0.87 and 0.0036, while the on/off ratios of the signal at the through port and the drop port were 35:1 and 105:1, respectively.