Fully reconfigurable optomechanical add-drop filters

TL;DR

This paper demonstrates a fully reconfigurable optomechanical add-drop filter with high efficiency and a broad tuning range, achieved through tunable coupling in a double-disk cavity system controlled by a piezoelectric nanostage.

Contribution

The work introduces a broadly tunable, fully reconfigurable add-drop filter based on a double-disk cavity with optimized coupling, enabling dynamic wavelength selection in optical communication.

Findings

Achieved 89% drop efficiency and 1.9% transmission.

Realized an 8 nm tuning range exceeding one FSR.

Demonstrated control of resonance with 7 V voltage via piezoelectric actuation.

Abstract

Fully reconfigurable add-drop filters (ADFs) have important applications in optical communication and information processing. Here we demonstrate a broadly tunable add-drop filter based on a double-disk cavity optomechanical system, side-coupled with a pair of tapered fiber waveguides. By varying the coupling rates between the cavity and the two waveguides, we investigate the dependence of the through (drop) efficiency on the coupling rates, which agrees well with the theoretical results. By optimizing the cavity-waveguide coupling rates, a drop efficiency of 89% and a transmission of 1.9% have been achieved. Benefiting from the large optomechanical coupling coefficient of the double-disk microcavity, a tuning range of 8 nm has been realized, which is more than one free spectral range (FSR) of the cavity. This is realized by changing the air gap of the double disk using a fiber tip, which is controlled by a piezoelectrical nanostage, with a required voltage of 7 V. As a result, both the through and drop signals can be resonant with any wavelength within the transparent window of the cavity material, which indicates that the ADF is fully reconfigurable.