High-performance thin-film lithium niobate electro-optic modulator on a thick silica buffering layer

High-speed thin-film lithium niobate (TFLN) electro-optic modulators are essential for next-generation photonic integrated circuits. We demonstrate a high-performance TFLN Mach-Zehnder modulator on a thick silica buried layer using periodic capacitively loaded traveling-wave electrodes. Our design simplifies fabrication compared to undercut silicon or quartz substrates while enhancing modulation efficiency. The fabricated device achieves a modulation efficiency of 1.25 V·cm in the C-band with only 1.3 dB roll-off at 67 GHz, successfully overcoming the voltage-bandwidth trade-off. This work provides a streamlined, scalable approach for high-performance TFLN modulators, supporting advanced optical communications and signal processing.