Reconfigurable Narrowband Optical Filter on Thin-Film Lithium Tantalate

Abstract

Narrowband optical filters with flexible tunability are key components for integrated reconfigurable wavelength division multiplexing and microwave photonic systems to cope with diverse signals and interference. However, providing reconfigurability while preserving ultra-narrow bandwidth remains challenging. Here we present a Mach-Zehnder interferometer (MZI)-coupled microring filter based on thin-film lithium tantalate (TFLT), showing the ability to control bandwidth, extinction ratio (ER) and resonance wavelength. After electrode integration, the device maintains a minimum bandwidth of 63 MHz. The filter supports continuous bandwidth tuning from 63 MHz to 1.4 GHz and ER control from 0 to 20 dB. In addition, it performs wavelength tuning ability with an efficiency of 1.29 pm/mW, making it suitable for handling interference signals within a wide frequency range. This device is promising for reconfigurable optical communications, dynamic channel management, and on-chip narrowband optical microwave filtering and interference mitigation.