A heterogeneously integrated lithium niobate-on-silicon nitride photonic platform

Abstract

The availability of thin-film lithium niobate on insulator (LNOI) and advances in processing have led to the emergence of fully integrated LiNbO3 electro-optic devices, including low-voltage, high-speed modulators, electro-optic frequency combs, and microwave-optical transducers. Yet to date, LiNbO3 photonic integrated circuits (PICs) have mostly been fabricated using non-standard etching techniques that lack the reproducibility routinely achieved in silicon photonics. Widespread future application of thin-film LiNbO3 requires a reliable and scalable solution using standard processing and precise lithographic control. Here we demonstrate a heterogeneously integrated LiNbO3 photonic platform that overcomes the abovementioned challenges by employing wafer-scale bonding of thin-film LiNbO3 to planarized low-loss silicon nitride (Si3N4) photonic integrated circuits, a mature foundry-grade integrated photonic platform. The resulting devices combine the substantial Pockels effect of LiNbO3 with the scalability, high-yield, and complexity of the underlying Si3N4 PICs. Importantly, the platform maintains the low propagation loss (<0.1 dB/cm) and efficient fiber-to-chip coupling (<2.5 dB per facet) of the Si3N4 waveguides. We find that ten transitions between a mode confined in the Si3N4 PIC and the hybrid LiNbO${}_3$ mode produce less than 0.8 dB additional loss, corresponding to a loss per transition not exceeding 0.1 dB. These nearly lossless adiabatic transitions thus link the low-loss passive Si3N4 photonic structures with electro-optic components. We demonstrate high-Q microresonators, optical splitters, electrically tunable photonic dimers, electro-optic frequency combs, and carrier-envelope phase detection of a femtosecond laser on the same platform, thus providing a reliable and foundry-ready solution to low-loss and complex LiNbO3 integrated photonic circuits.

References in corpus (8)

• Integrated Photonic Quantum Technologies
• Monolithic Ultrahigh-Q Lithium Niobate Microring Resonator
• Ultra-low loss integrated visible photonics using thin-film lithium niobate
• Low-loss fiber-to-chip interface for lithium niobate photonic integrated circuits
• Wafer-scale low-loss lithium niobate photonic integrated circuits
• Coherent two-octave-spanning supercontinuum generation in lithium-niobate waveguides
• Nonreciprocal Transmission of Microwave Acoustic Waves in Nonlinear Parity-Time Symmetric Resonators
• Electrically driven linear optical isolation through phonon mediated Autler-Townes splitting

Cited by in corpus (13)

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• Programmable access to microresonator solitons with modulational sideband heating
• A 3.584 Tbps coherent receiver chip on InP-LiNbO3 wafer-level integration platform
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• Low-power, agile electro-optic frequency comb spectrometer for integrated sensors
• Bound-state-in-continuum guided modes in a multilayer electro-optically active photonic integrated circuit platform
• Colossal terahertz emission with ultrafast tunability based on van der Waals ferroelectric NbOI${}_2$
• Absorption loss and Kerr nonlinearity in barium titanate waveguides
• Heterogeneous integration of amorphous silicon carbide on thin film lithium niobate
• Broadband acousto-optic modulators on Silicon Nitride
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