Nonlinear optical radiation of a lithium niobate microcavity

Abstract

The nonlinear optical radiation of an integrated lithium niobate microcavity is demonstrated, which has been neglected in previous studies of nonlinear photonic devices. We find that the nonlinear coupling between confined optical modes on the chip and continuum modes in free space can be greatly enhanced on the platform of integrated microcavity, with feasible relaxation of the phase-matching condition. With an infrared pump laser, we observe the vertical radiation of second-harmonic wave at the visible band, which indicates a robust phase-matching-free chip-to-free-space frequency converter and also unveils an extra energy dissipation channel for integrated devices. Such an unexpected coherent nonlinear interaction between the free-space beam and the confined mode is also validated by the different frequency generation. Furthermore, based on the phase-matching-free nature of the nonlinear radiation, we build an integrated atomic gas sensor to characterize Rb isotopes with a single telecom laser. The unveiled mechanism of nonlinear optical radiation is universal for all dielectric photonic integrated devices, and provides a simple and robust chip-to-free-space as well as visible-to-telecom interface.

7 Pages, 4 figures

References in corpus (6)

• Aluminum nitride as a new material for chip-scale optomechanics and nonlinear optics
• Efficient frequency conversion in a degenerate ${\chi }^{(2)}$ microresonator
• Cavity quantum electrodynamics and chiral quantum optics
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• Infrared Laser Locking to Rubidium Saturated Absorption Spectrum via a Photonic Chip Frequency Doubler
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Cited by in corpus (2)

• Subwavelength Photorefractive Grating in a Thin-Film Lithium Niobate Microcavity
• Manipulation of magnetic systems by quantized surface acoustic wave via piezomagnetic effect