Systematic Investigation of Millimeter-Wave Optic Modulation Performance in Thin-Film Lithium Niobate

TL;DR

This paper systematically investigates the performance of thin-film lithium niobate mmWave-optic modulators up to 325 GHz, providing models, measurements, and design guidelines for future high-frequency photonic systems.

Contribution

It offers a comprehensive analysis combining theoretical modeling, experimental verification, and measurement of mmWave-optic modulators at ultrahigh frequencies.

Findings

Achieved a 3-dB bandwidth of 170 GHz and 6-dB bandwidth of 295 GHz.

Measured a low RF half-wave voltage of 7.3 V at 250 GHz.

Provided design guidelines for mmWave-optic modulators.

Abstract

Millimeter-wave (mmWave) band (30 - 300 GHz) is an emerging spectrum range for wireless communication, short-range radar and sensor applications. mmWave-optic modulators that could efficiently convert mmWave signals into optical domain are crucial components for long-haul transmission of mmWave signals through optical networks. At these ultrahigh frequencies, however, the modulation performances are highly sensitive to the transmission line loss as well as the velocity- and impedance-matching conditions, while precise measurements and modeling of these parameters are often non-trivial. Here we present a systematic investigation of the mmWave-optic modulation performances of thin-film lithium niobate modulators through theoretical modeling, electrical verifications and electro-optic measurements at frequencies up to 325 GHz. Based on our experimentally verified model, we demonstrate thin-film lithium niobate mmWave-optic modulators with a measured 3-dB electro-optic bandwidth of 170 GHz and a 6-dB bandwidth of 295 GHz. The device also shows a low RF half-wave voltage of 7.3 V measured at an ultrahigh modulation frequency of 250 GHz. This work provides a comprehensive guideline for the design and characterization of mmWave-optic modulators and paves the way toward future integrated mmWave photonic systems for beyond-5G communication and radar applications.