No abstract

A platform for the realization of tightly-confined lithium niobate photonic devices and circuits on silicon substrates is reported based on wafer bonding and selective oxidation of refractory metals. The heterogeneous photonic platform is employed to demonstrate high-performance lithium niobate microring optical resonators and Mach-Zehnder optical modulators. A quality factor of ~7.2 × 10⁴ is measured in the microresonators, and a half-wave voltage-length product of 4 V.cm and an extinction ratio of 20 dB is measured in the modulators.

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  dBHz^2/3 at 1 GHz and 92.6  dBHz^2/3 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.

LiNbO 3 thin film crystals have been produced using crystal ion slicing and wafer bonding. Films with a thickness of 680nm are produced on a thin layer of SiO2, which is deposited on a substrate with electrodes. The crystalline and optical qualities of the fabricated thin films are investigated and are comparable to bulk LiNbO3 single crystals. The effect of thermal annealing is studied using Rutherford backscattering. The refractive indices and the electro-optical (EO) coefficient of the fabricated films are measured using prism coupling dark line spectroscopy and modified attenuated total reflection. The EO coefficient is equal to r33=31pm∕V at λ=633nm.

No abstract

Thin films of lithium niobate are wafer bonded onto silicon substrates and rib-loaded with a chalcogenide glass, Ge(23)Sb(7)S(70), to demonstrate strongly confined single-mode submicron waveguides, microring modulators, and Mach-Zehnder modulators in the telecom C band. The 200 μm radii microring modulators present 1.2 dB/cm waveguide propagation loss, 1.2 × 10(5) quality factor, 0.4 GHz/V tuning rate, and 13 dB extinction ratio. The 6 mm long Mach-Zehnder modulators have a half-wave voltage-length product of 3.8 V.cm and an extinction ratio of 15 dB. The demonstrated work is a key step towards enabling wafer scale dense on-chip integration of high performance lithium niobate electro-optical devices on silicon for short reach optical interconnects and higher order advanced modulation schemes.

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 µm 2 . The compactness of the waveguides results in efficient second-order nonlinear devices. 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. References and Links

Ridge waveguides are fabricated using submicron thin films of lithium niobate prepared by crystal ion slicing and wafer bonding (“smart guide”). The waveguides are made by physical etching the lithium niobate thin film using ion beam milling. The waveguides are low loss. An electro-optic polarization modulator with VπL of 15Vcm at λ=1.55μm is demonstrated using the waveguides.