Ultra-Wideband Tunable Microwave Photonic Filter Based on Thin Film Lithium Niobate

Abstract

In signal processing of the growing semaphore, a microwave photonic filter (MPF) is capable of dealing with high-frequency signals, offering the advantages of high bandwidth, easy tuning, and more. This paper presents an efficient tunable microwave photonic filter that features a wideband tuning capability and narrow-band filtering effect based on the lithium niobate on insulator (LNOI) material platform. A multi-mode waveguide race-track type microring resonator has been designed, along with a thermal electrode that utilizes the thermo-optical effect of lithium niobate to adjust the microring resonator. The packaged device has been tested, with a wideband tunable range of 4.7~38.2 GHz achieved. This allows for cross-band continuous tuning across the C-band to Ka-band range. When supplied with 29.1 mW of electric power, the thermal tuning efficiency reaches 9.2 pm/mW, enabling high-frequency tuning of up to 38.2 GHz. The filter possesses a high resolution, exhibiting a 3 dB bandwidth of 662 MHz.