Design of narrow band-pass filters based on the resonant-tunneling phenomenon in multicore photonic crystal fibers

The objective of the present paper is to introduce and numerically demonstrate the operation of a novel band-pass filter based on the phenomenon of resonant tunneling in multi-core photonic crystal fibers (PCFs). The proposed PCF consists of two identical cores separated by a third one which acts as a resonator. With a fine adjustment of the design parameters associated with the resonant-core, phase matching at a single wavelength can be achieved, thus enabling very narrow-band resonant directional coupling between the input and the output cores. The validation of the design is ensured with an accurate PCF analysis based on finite element and beam propagation algorithms. The proposed narrow band-pass filter can be employed in various applications such as all fiber bandpass/bandstop filtering.