Heterogeneously Integrated Lithium Niobate on Insulator Chip for Frequency Up-Conversion and Detection

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Lithium niobate on insulator (LNOI) has emerged as a promising candidate for next-generation integrated photonics and is moving toward the integration of multifunctional components on a single chip. In this letter, we demonstrate a multifunction LNOI photonic chip, which contains frequency up-conversion and photodetection. Efficient second harmonic generation, which converts the near-infrared to the visible, was realized by periodical poling of the x -cut LNOI, and the normalized conversion efficiency was 1350%W –1 cm –2 . Subsequent on-chip detection of the converted red light was made possible by heterogeneously integrating amorphous silicon with LNOI, which features a low dark current and a responsivity of 95 mA/W with a 4 V bias voltage. The results provide a proof of concept for on-chip frequency up-conversion and detection based on heterogeneous integration in the LNOI platform and will pave the way toward compact, reliable, and efficient classical and quantum information processing.