Compact thin film lithium niobate folded intensity modulator using a waveguide crossing.

Area of Science:

• Photonics
• Materials Science
• Electrical Engineering

Background:

• Electro-optic modulators are vital for optical communications and analog photonic links.
• Integrating thin-film lithium niobate with photonic integrated circuit (PIC) compatible materials is essential for device miniaturization and performance enhancement.

Purpose of the Study:

• To develop a hybrid silicon nitride and lithium niobate folded electro-optic Mach Zehnder modulator (MZM).
• To achieve a small footprint, low voltage, and wide bandwidth modulator for high-performance photonic applications.

Main Methods:

• Fabrication of a hybrid MZM incorporating a waveguide crossing and multimode interference (MMI) couplers.
• Characterization of the modulator's DC half wave voltage, modulation efficiency, power extinction ratio, and frequency response.

Main Results:

• The modulator exhibits an effective interaction length of 10 mm.
• Achieved a DC half wave voltage of approximately 4.0 V (Vπ·L ≈ 4 V·cm).
• Demonstrated a power extinction ratio of approximately 23 dB and a 3-dB bandwidth of 37.5 GHz with low optical sideband power roll-off up to 110 GHz.

Conclusions:

• The hybrid silicon nitride and lithium niobate MZM offers a promising solution for high-performance, compact electro-optic modulation.
• The device's characteristics are suitable for demanding applications in optical communications and analog photonic links.