Fig. 3: Integrated electro-optic phase modulator characterization on X-cut thin-film lithium niobate.

Integrated electro-optic phase modulator characterization on X-cut thin-film lithium niobate. a EO frequency combs generated by a 2 cm-long, integrated EO phase modulator at pump frequencies of 183.9, 193.4, 201.2, 212.6, and 221.2 THz (equivalent wavelengths of 1630, 1550, 1490, 1410, and 1355 nm). The modulation frequency is 29.158 GHz, and the electrical power is estimated to be 4.47 W (36.5 dBm). b Half-wave voltage (\({V}_{\pi }\)) at different modulation frequencies (blue curve) and the \(\sqrt{2}\)-scaled \({V}_{\pi }\) referenced to the 6 GHz \({V}_{\pi }\) (gray dashed line, corresponding modulation frequency is the 3 dB EO bandwidth), at three select optical frequencies. c Optical frequency dependence of the 6 GHz \({V}_{\pi }\) and d the 3 dB EO bandwidth. The 6 GHz \({V}_{\pi }\) and 3 dB EO bandwidth variation (blue shaded region enclosed by black dashed lines) over ~30 THz optical bandwidth is about 1.4 V and 8 GHz, respectively. Points near 215 and 219 THz (red dots) are affected by mode-crossings and have relatively higher 6 GHz \({V}_{\pi }\) and lower 3 dB EO bandwidth