Integrated Lithium Niobate Intensity Modulator on a Silicon Handle With Slow-Wave Electrodes

Abstract

Segmented, or slow-wave electrodes have emerged as an index-matching solution to improve bandwidth of traveling-wave Mach Zehnder and phase modulators on the thin-film lithium niobate on insulator platform. However, these devices require the use of a quartz handle or substrate removal, adding cost and additional processing. In this work, a high-speed dual-output electro-optic intensity modulator in the thin-film silicon nitride and lithium niobate material system that uses segmented electrodes for RF and optical index matching is presented. The device uses a silicon handle and does not require substrate removal. A silicon handle allows the use of larger wafer sizes to increase yield, and lends itself to processing in established silicon foundries that may not have the capability to process a quartz or fused silica wafer. The modulator has an interaction region of 10 mm, shows a DC half wave voltage of 3.75 V, an ultra-high extinction ratio of roughly 45 dB consistent with previous work, and a fiber-to-fiber insertion loss of 7.47 dB with a 95 GHz 3 dB bandwidth.

High-Speed Optical Mode Switch in Lithium Niobate on Insulator

“…For example, when the length of modulation arms is designed to be 8 mm, the expected V π reduces to about 3.4 V. Table shows the comparison between our device and other reported works on the Si 3 N 4 -LNOI platform. It can be seen that the V π L of our device is lower than those in others’ works, − but slightly higher than that in our previous work . This is mainly due to the fact that, in this work, we design the gap between ground and signal electrodes to be 5.8 μm to reduce the loss introduced by electrodes.…”

“…The switching speed of the proposed device can be further improved by adopted sophisticated electrodes such as microstructured electrodes. 41,42…”

“…This shows that the modal switch has the potential to achieve similar switching speeds as the commonly used intensity modulators in the LNOI platform. The switching speed of the proposed device can be further improved by adopted sophisticated electrodes such as microstructured electrodes. , …”

Equivalent circuit model of the carrier-depletion-based push-pull silicon optical modulators with T-rail slow wave electrodes

“…"Dielectric quasi-TEM mode" is the propagation mode. In the slow-wave mode guided by a micron-sized electrode, quasi-TEM analysis is valid since the very small cross section of the transmission line ensures that the transverse fields are essentially quasi-stationary [23,[26][27][28]. As the circuit parameters generated during microwave propagation can be calculated by conformal mapping, partial capacitance method, and other methods, TSWE can be described by equivalent circuits.…”

“…The internal inductance can be calculated by Wheeler's incremental inductance rule [26]. Whether the transmission line is symmetrical or not, the internal inductance can be calculated by:…”