Compact slow-light waveguide and modulator on thin-film lithium niobate platform

Area of Science:

• Photonics
• Materials Science
• Electrical Engineering

Background:

• Compact and fast electro-optic modulators are crucial for advanced optical interconnects.
• Thin-film lithium niobate (TFLN) is a promising platform for integrated photonics.

Purpose of the Study:

• To demonstrate the slow-light (SL) effect on a TFLN platform.
• To construct an ultra-compact SL Mach-Zehnder modulator (SL-MZM) with enhanced electro-optic (EO) performance.
• To achieve high-speed optical data transmission.

Main Methods:

• Fabrication of SL waveguides using a coupled Bragg resonator structure on TFLN.
• Construction of an ultra-compact SL-MZM (L ≈ 370 μm).
• Characterization of optical and EO properties, including passband width, insertion loss, group index, and EO bandwidth.
• High-speed On-Off Keying (OOK) transmission experiments.

Main Results:

• Achieved a large optical passband width of ~8 nm and a maximal optical group index of 7.50 (3.4x that of regular TFLN rib waveguides).
• Demonstrated an ultra-compact SL-MZM with an EO bandwidth exceeding 50 GHz over an ~8 nm wavelength band.
• Successfully performed high-speed OOK transmissions at 64 Gbit/s and 80 Gbit/s.

Conclusions:

• This work presents the first monolithic TFLN SL waveguides and compact SL-MZMs with >50 GHz EO bandwidth.
• The developed SL-MZM technology offers significant potential for next-generation optical interconnect systems.
• The achieved performance highlights the viability of SL effects for enhancing EO modulator capabilities on the TFLN platform.