Broadband millimeter-wave frequency mixer based on thin-film lithium niobate photonics

TL;DR

This paper presents a novel integrated photonic millimeter-wave mixer using thin-film lithium niobate, achieving broad bandwidth frequency conversion with high efficiency and reconfigurability for advanced wireless and radar systems.

Contribution

The work introduces a high-performance, reconfigurable millimeter-wave mixer based on TFLN photonics, overcoming previous limitations in bandwidth and efficiency at high frequencies.

Findings

Demonstrated frequency down-conversion from 20 GHz to 67 GHz

Achieved up-conversion to frequencies up to 110 GHz

Showed improved bandwidth and conversion efficiency

Abstract

Frequency mixers are fundamental components in modern wireless communication and radar systems, responsible for up- and down-conversion of target radio-frequency (RF) signals. Recently, photonic-assisted RF mixers have shown unique advantages over traditional electronic counterparts, including broad operational bandwidth, flat frequency response, and immunity to electromagnetic interference. However, current integrated photonic mixers face significant challenges in achieving efficient conversion at high frequencies, especially in millimeter-wave bands, due to the limitations of existing electro-optic (EO) modulators. Additionally, high-frequency local oscillators in the millimeter-wave range are often difficult to obtain and expensive, leading to unsatisfactory cost and restricted operational bandwidth in practice. In this paper, we harness the exceptional EO property and scalability of thin-film lithium niobate (TFLN) photonic platform to implement a high-performance harmonic reconfigurable millimeter-wave mixer. The TFLN photonic circuit integrates a broadband EO modulator that allows for extensive frequency coverage, and an EO frequency comb source that significantly reduces the required carrier frequency of the local oscillator. We experimentally demonstrate fully reconfigurable frequency down-conversion across a broad operational bandwidth ranging from 20 GHz to 67 GHz, with a large intermediate frequency of 20 GHz, as well as up-conversion to frequencies of up to 110 GHz. Our integrated photonic mixing system shows dramatically improved bandwidth performance, along with competitive indicators of frequency conversion efficiency and spurious suppression ratio, positioning it as a promising solution for future millimeter-wave transceivers in next-generation communication and sensing systems.