Broadband High-Sensitivity Thin-Film LiNbO3 Based E-Field Sensor With LF-Shaped Electrode

A novel broadband high-sensitivity optical E-field sensor is proposed in this letter. To solve the problem of bandwidth sensitivity, thin-film LiNbO3 (TFLN) is employed to fabricate the photonic device. Herein, the inductively coupled plasma (ICP) etching methodology using a mixture of Ar and $\text{C}_{{4}}\text{F}_{{8}}$ is first introduced, which is more effective in etching and helps to sharpen the lateral angle of the LN ridge waveguide. The LF-shaped electrode is designed to improve the performance of the sensor with a bandwidth of 1 MHz to 20 GHz and a sensitivity of 1 mV/m. The volume of the sensor with the package is only ${20}\times {5} \times 5$ mm, which can be utilized in narrow spaces of the weak electromagnetic signal in the wideband frequency range.

I. Introduction

For many years, E-field sensors have been used to measure electromagnetic field signals inside and outside devices or in free space [1]. Electronic E-field sensors (D-dot sensors) are usually based on a dipole antenna and are well suited for measuring transient electromagnetic pulse signals due to their sharp rise times. However, the main challenge in the development of an electric E-field sensor is the design of its antenna, which limits the bandwidth of the sensor (0.4 GHz~10 GHz) [2], [3], [4].