Thin-fIlm Lithium Niobate Integrated Photonics on Silicon for Electro- and Nonlinear-optic Applications

In order to overcome the drawbacks associated with conventional bulk lithium niobate photonic, thin-film lithium-niobate-on-silicon has been pursued recently. This work presents contributions made to electro-, and nonlinear-optic applications of this technology. For electrooptic applications, detailed modeling and design guidelines of optical and radio-frequency parameters of ultracompact modulators are developed and their accuracy in predicting the high-speed performance of such devices have been verified by comparison with experimental results. Novel design techniques and pathways for ultrahigh-speed (sub-terahertz) operation of such modulators, achieving up to 400 GHz modulation bandwidth, are also presented. For optical interconnect applications, novel structures for ultralow-power consumption modulators are designed and fabricated. Coherent modulation schemes, such as quadrature phase shift keying, is also pursued on the same thin-film platform for advanced optical communication systems. For nonlinear-optic applications, fabrication integrability of thin-film lithium niobate and chalcogenide glass waveguides on a single silicon chip for future directions, such as on-chip self-referenced optical frequency comb generation, is experimentally demonstrated. That is a pathway for both second- and third-order optical nonlinearity occurring on lithium niobate and chalcogenide, respectively, is designed and presented. An innovative and robust foundry-compatible back-end-of-line integration method is also proposed, in order to integrate thin-film lithium niobate devices with silicon or silicon-nitride photonic circuitry. Overall, this work extends the capabilities of the thin-film lithium niobate technology for novel electro- and nonlinear-optic applications. Finally, extensions of the aforementioned results suitable for future work are discussed

High-Speed Modeling Of Thin-Film Lithium-Niobate-On-Silicon Electrooptic Modulators

A model is developed for frequency-dependent response of compact high-speed thin-film lithium-niobate-on-silicon electrooptic modulators. The model predicts potential for \u3e 100 GHz modulation bandwidth

Performance Predictions For Compact Lithium Niobate Mach-Zehnder Electrooptic Modulators

A model for the frequency-dependent response of compact thin-film lithium-niobate electrooptic modulators is developed and verified by comparison with measurements. Device designs with significant improvement in the attainable modulation bandwidth are also presented

High-Speed Modeling Of Ultracompact Electrooptic Modulators

The technology for compact thin-film lithium niobate electrooptic modulators has made significant advances recently. With achieving high levels of maturity for such platforms, a model is now required in order to accurately design the devices and reliably predict their performance limits. In this paper, a general transmission-line model is developed for predicting the frequency-dependent response of the compact modulators. The main radio frequency (RF) parameters of the modulators, such as characteristic impedance, effective index, and attenuation constant are calculated as a function of the coplanar waveguide dimensions, and validated by using numerical simulations. The accuracy of the model in predicting the 3-dB modulation bandwidth of the devices is verified by comparison with experimental results. Finally, guidelines for device design with significant improvement in the attainable modulation bandwidth are also presented by optimization of RF and optical parameters, predicting \u3e 100 GHz modulation bandwidth. The presented model is not limited to emerging thin-film lithium niobate devices, and is applicable to any type of ultracompact electrooptic modulator

Cascaded Integration Of Optical Waveguides With Third-Order Nonlinearity With Lithium Niobate Waveguides On Silicon Substrates

The cascaded integration of optical waveguides with third-order optical nonlinearity (χ(3) susceptibilitiy) with lithium niobate (LiNbO3) waveguides is demonstrated on the same chip. Thin-film (LiNbO3) and chalcogenide (ChG) glass (Ge23Sb7S70) waveguides are integrated on silicon (Si) substrates. An optical mode transition between the two waveguides is achieved through low-loss mode-converting tapers, with a measured loss of ∼1.5 dB for transverse-electric and ∼1.75 dB for transverse-magnetic input polarizations. For nonlinear characterization, wavelength conversion via four-wave mixing is demonstrated on the ChG-LN waveguides. This platform provides an efficient method for the utilization of second- and third-order optical nonlinearities on the same chip, rendering it ideal for nonlinear applications such as stabilized octave-spanning optical frequency comb generation

High-Performance And Linear Thin-Film Lithium Niobate Mach Zehnder Modulators On Silicon Up To 50 Ghz

Compact electro-optical modulators are demonstrated on thin films of lithium niobate on silicon operating up to 50 GHz. The half-wave voltage length product of the high-performance devices is 3.1 V.cm at DC and less than 6.5 V.cm up to 50 GHz. The 3 dB electrical bandwidth is 33 GHz, with an 18 dB extinction ratio. The third-order intermodulation distortion spurious free dynamic range is 97.3 dBHz2/3 at 1 GHz and 92.6 dBHz2/3 at 10 GHz. The performance demonstrated by the thin-film modulators is on par with conventional lithium niobate modulators but with lower drive voltages, smaller device footprints, and potential compatibility for integration with large-scale silicon photonics

Thin-Film Lithium Niobate On Silicon Mach-Zehnder Electrooptic Modulators Up To 50 Ghz

Compact electrooptical modulators are demonstrated on thin-film lithium niobate on silicon with half-wave voltage-length product of 3.1 to 6.5 V.cm (from DC up to 50 GHz), 18 dB extinction ratio, and 33-GHz3-dB electrical bandwidth

Thin-Film Lithium Niobate On Silicon Mach-Zehnder Electrooptic Modulators Up To 50 Ghz

Compact electrooptical modulators are demonstrated on thin-film lithium niobate on silicon with half-wave voltage-length product of 3.1 to 6.5 V.cm (from DC up to 50 GHz), 18 dB extinction ratio, and 33-GHz 3-dB electrical bandwidth

Second-Harmonic Generation In Periodicallypoled Thin Film Lithium Niobate Wafer-Bonded On Silicon

Second-order optical nonlinear effects (second-harmonic and sum-frequency generation) are demonstrated in the telecommunication band by periodic poling of thin films of lithium niobate wafer-bonded on silicon substrates and rib-loaded with silicon nitride channels to attain ridge waveguide with cross-sections of ∼2 μm2. A nonlinear conversion of 8% is obtained with a pulsed input in 4 mm long waveguides. The choice of silicon substrate makes the platform potentially compatible with silicon photonics, and therefore may pave the path towards on-chip nonlinear and quantum-optic applications