Ultra‐Efficient 0. 1 V cm Lithium Niobate Modulator with > 200 GHz Bandwidth Using a High‐Permittivity Bragg Waveguide

Lithium niobate on insulator platforms is the best candidate for future chip‐scale electro‐optic modulators due to its superior performance characteristics. A high‐performance modulator should have a low driving voltage, a short length, and a wide bandwidth. Compared to other modulator types, these structures exhibit a higher voltage‐length product (). A lower has the potential to enable the development of low‐voltage, compact, and broadband modulators through optimized electrode designs. In this study, three innovative lithium niobate Mach–Zehnder modulators are introduced, in which a high permittivity material (i.e., lead zirconate titanate (PZT) with a relative permittivity close to 2000) has been used around a lithium niobate Bragg grating waveguide to reduce the values. The proposed modulators achieved values of 0.258, 0.176, and 0.105 V cm, representing the lowest values among lithium niobate Mach–Zehnder modulators developed to date. Furthermore, these modulators demonstrated large electro‐optic 3‐dB bandwidths of 190, 104, and 235 GHz, with short modulation lengths of 0.520, 1.7, and 1 mm at the DC voltages of 4.96, 1, and 1 V, respectively. These structures, thus, serve as promising candidates for low‐voltage, high‐bandwidth, and short‐length modulators.