Ultra-High Extinction Dual-Output Thin-Film Lithium Niobate Intensity Modulator

Abstract

A low voltage, wide bandwidth compact electro-optic modulator is a key building block in the realization of tomorrow's communication and networking needs. Recent advances in the fabrication and application of thin-film lithium niobate, and its integration with photonic integrated circuits based in silicon make it an ideal platform for such a device. In this work, a high-extinction dual-output folded electro-optic Mach Zehnder modulator in the silicon nitride and thin-film lithium niobate material system is presented. This modulator has an interaction region length of 11 mm and a physical length of 7.8 mm. The device demonstrates a fiber-to-fiber loss of roughly 12 dB using on-chip fiber couplers and DC half wave voltage (Vπ) of less than 3.0 V, or a modulation efficiency (Vπ•L) of 3.3 V•cm. The device shows a 3 dB bandwidth of roughly 30 GHz. Notably, the device demonstrates a power extinction ratio over 45 dB at each output port without the use of cascaded directional couplers or additional control circuitry; roughly 31 times better than previously reported devices. Paired with a balanced photo-diode receiver, this modulator can be used in various photonic communication systems. Such a detecting scheme is compatible with complex modulation formats such as differential phase shift keying and differential quadrature phase shift keying, where a dualoutput, ultra-high extinction device is fundamentally paramount to low-noise operation of the system.

Ultra Wideband Dual-Output Thin Film Lithium Niobate Intensity Modulator

“…In contrast, 2×2 MMI as a combiner will force the output power couple into the other port under null bias condition. Dual-output MZM with a SiN/LN platforms have been demonstrated with similar concepts as in our previous research [24].…”

Compact and Efficient Thin‐Film Lithium Niobate Modulators

“…Table 1 and 2 summarize the progress of different TFLN modulators with the MZI structure. [ 5,6,12,15,26–107 ] Figure summarizes the half‐wave voltage, device length, and bandwidth of etched and non‐etched TFLN modulators. Both these two kinds of modulators can realize a very high bandwidth.…”

Compact thin-film lithium niobate modulators using slotted coplanar waveguide electrode suitable for high-volume fabrication

“…In order to be compatible with compact transceiver packages [27], such as quad small form factor pluggable double density, various studies on folded TFLN modulators with reduced modulator length have been reported [7][8][9][10][11][12] and the performance comparison of these folded TFLN modulators are shown in table 1. In [7,8], the modulators were fabricated on a quartz-based TFLN platform or heterogeneous LN/silicon-on-insulator (SOI) platform.…”

“…For example, in [8][9][10], instead of edge coupling, the coupling between the modulator and fibers is through a grating coupler, which results in a large coupling loss and wavelength sensitivity, and therefore cannot be used in a practical environment. In [11,12], the modulators used edge coupling but the insertion loss is still relatively large, reaching 12 dB and 21 dB, respectively.…”