Switchable and tunable triple-channel bandpass filter

Abstract

In this paper, a triple-channel bandpass filter with switchable and tunable functions is proposed, which is based on a triple-mode cross resonator. The varactors and switching diodes are loaded at the end of the resonator. Because of the use of switches, resonators have four working states: conventional single-mode, two dual-mode and one triple-mode. The varactor makes the channel independently adjustable. Finally, a triple-channel bandpass filter with switchable and tunable functions is designed by using two identical triple-mode resonator coupling structures. To solve the problem of whether each channel in the multichannel filter is independently adjustable, this paper gives a simple and rigorous judgment method, namely rank criterion, which is a necessary and sufficient condition for each channel to be independently adjustable. The design method of EVCM (element variable coupling matrix) is adopted, which can not only obtain the desired frequency response through adjustable elements but also help to select resonators and coupling modes in the actual circuit design. The final circuit size of the designed filter is 0.29 λg × 0.26 λg. The measured results are in good agreement with the simulation results.

Frequency-tunable single-photon router based on a microresonator containing a driven three-level emitter

“…One feasible way to address the problem is to adopt the frequencymodulation technology to match the targeted frequencies with good tuning controllability, which has been applied in tunable frequency optical combs, [26,27] single-photon diode, [28] and tunable bandpass filters. [29][30][31][32][33][34][35] Motivated by these considerations, we propose a novel frequency-tunable router of single photons based on a doublewaveguide structure connected by a whispering-gallery-mode resonator with a driven three-level system. To the best of our knowledge, few studies on frequency-tunable routing for single photons have been carried out.…”