Volume: 19 Issue 6
17 Article(s)

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Research Articles
Special Issue on Lithium Niobate Based Photonic Devices
Editorial for special issue on lithium niobate based photonic devices
Feng Chen, and Yuping Chen
Lithium niobate (LiNbO3), so-called “Silicon in Photonics,” is a multifunctional crystal with a combination of a number of excellent physical properties. In optics and photonics, the LiNbO3-based devices, such as modulators, wavelength converters, waveguide amplifiers, and quantum photonic chips, have been realized and widely applied in various areas. In addition to the traditional waveguides, the LiNbO3 on insulators (LNOI) technology enables fabrication of large-scale, high-quality LiNbO3 thin film wafers, boosting the development of thin film LiNbO3-based devices; consequently, versatile applications have been realized to satisfy the small footprint for photonic integrated circuits (PICs). Aiming to present the impressive progresses in this field, Chinese Optics Letters publishes this special issue focusing on the fabrication of new LNOI wafers, new design of LNOI-based structures, and the intriguing applications of LNOI-based devices in selected active topics.
Chinese Optics Letters
  • Publication Date: Jun. 28, 2021
  • Vol.19 Issue, 6 060001 (2021)
Efficient second harmonic generation in silicon covered lithium niobate waveguides
Bin Fang, Shenglun Gao, Zhizhang Wang, Shining Zhu, and Tao Li
Chinese Optics Letters
  • Publication Date: Mar. 26, 2021
  • Vol.19 Issue, 6 060004 (2021)
Polarization diversity two-dimensional grating coupler on x-cut lithium niobate on insulator
Renyou Ge, Hao Li, Ya Han, Lifeng Chen, Jian Xu, Meiyan Wu, Yongqing Li, Yannong Luo, and Xinlun Cai
We propose and demonstrate a polarization diversity two-dimensional grating coupler based on the lithium niobate on insulator platform, for the first time, to the best of our knowledge. The optimization design, performance characteristics, and fabrication tolerance of the two-dimensional grating coupler are thoroughly analyzed utilizing the three-dimensional finite-difference time-domain method. Experimentally, -7.2 dB of coupling efficiency is achieved with 1 dB bandwidth of 64 nm. The polarization-dependent loss is about 0.4 dB around 1550 nm. Our work provides new polarization multiplexing approaches for the lithium niobate on insulator platform, paving the way for critical applications such as high-speed polarization multiplexed electro-optical modulators.
Chinese Optics Letters
  • Publication Date: Apr. 12, 2021
  • Vol.19 Issue, 6 060006 (2021)
Locally periodically poled LNOI ridge waveguide for second harmonic generation [Invited]
Biao Mu, Xianfang Wu, Yunfei Niu, Yan Chen, Xinlun Cai, Yanxiao Gong, Zhenda Xie, Xiaopeng Hu, and Shining Zhu
Chinese Optics Letters
  • Publication Date: Apr. 27, 2021
  • Vol.19 Issue, 6 060007 (2021)
On-chip erbium-doped lithium niobate waveguide amplifiers [Invited]
Qiang Luo, Chen Yang, Zhenzhong Hao, Ru Zhang, Dahuai Zheng, Fang Bo, Yongfa Kong, Guoquan Zhang, and Jingjun Xu
Chinese Optics Letters
  • Publication Date: May. 08, 2021
  • Vol.19 Issue, 6 060008 (2021)
High-Q lithium niobate microring resonators using lift-off metallic masks [Invited]
Ke Zhang, Zhaoxi Chen, Hanke Feng, Wing-Han Wong, Edwin Yue-Bun Pun, and Cheng Wang
High-Q lithium niobate (LN) optical micro-resonators are an excellent platform for future applications in optical communications, nonlinear optics, and quantum optics. To date, high-Q factors are typically achieved in LN using either dielectric masks or femtosecond laser ablation, while the more standard and commonly available lift-off metallic masks are often believed to lead to rough sidewalls and lowered Q factors. Here, we show that LN microring resonators with strong light confinement and intrinsic Q factors over 1 million can be fabricated using optimized lift-off metallic masks and dry etching processes, corresponding to a waveguide propagation loss of ~0.3 dB/cm. The entire process is fully compatible with wafer-scale production and could be transferred to other photonic materials.
Chinese Optics Letters
  • Publication Date: May. 13, 2021
  • Vol.19 Issue, 6 060010 (2021)
Nonlinear Talbot self-healing in periodically poled LiNbO3 crystal [Invited] | On the Cover
Bingxia Wang, Shan Liu, Tianxiang Xu, Ruwei Zhao, Peixiang Lu, Wieslaw Krolikowski, and Yan Sheng
The nonlinear Talbot effect is a near-field nonlinear diffraction phenomenon in which the self-imaging of periodic objects is formed by the second harmonics of the incident laser beam. We demonstrate the first, to the best of our knowledge, example of nonlinear Talbot self-healing, i.e., the capability of creating defect-free images from faulty nonlinear optical structures. In particular, we employ the tightly focused femtosecond infrared optical pulses to fabricate LiNbO3 nonlinear photonic crystals and show that the defects in the form of the missing points of two-dimensional square and hexagonal periodic structures are restored in the second harmonic images at the first nonlinear Talbot plane. The observed nonlinear Talbot self-healing opens up new possibilities for defect-tolerant optical lithography and printing.
Chinese Optics Letters
  • Publication Date: May. 08, 2021
  • Vol.19 Issue, 6 060011 (2021)
Recent progress of second harmonic generation based on thin film lithium niobate [Invited]
Yang Li, Zhijin Huang, Wentao Qiu, Jiangli Dong, Heyuan Guan, and Huihui Lu
Recently, nonlinear photonics has attracted considerable interest. Among the nonlinear effects, second harmonic generation (SHG) remains a hot research topic. The recent development of thin film lithium niobate (TFLN) technology has superior performances to the conventional counterparts. Herein, this review article reveals the recent progress of SHG based on TFLN and its integrated photonics. We mainly discuss and compare the different techniques of TFLN-based structures to boost the nonlinear performances assisted by localizing light in nanostructures and structured waveguides. Moreover, our conclusions and perspectives indicate that more efficient methods need to be further explored for higher SHG conversion efficiency on the TFLN platform.
Chinese Optics Letters
  • Publication Date: May. 25, 2021
  • Vol.19 Issue, 6 060012 (2021)
Surface lattice resonances in dielectric metasurfaces for enhanced light-matter interaction [Invited]
Yuechen Jia, Yingying Ren, Xingjuan Zhao, and Feng Chen
Lithium niobate (LiNbO3) is a versatile crystalline material for various photonic applications. With the recent advances in LiNbO3-on-insulator (LNOI) thin film technology, LiNbO3 has been regarded as one of the most promising platforms for multi-functional integrated photonics. In this work, we present the field enhancement due to collective resonances in arrayed LiNbO3 nanoantennas. These resonances arise from the enhanced radiative coupling of localized Mie resonances in the individual nanoparticles and Rayleigh anomalies due to in-plane diffraction orders of the lattice. We describe the pronounced differences in field enhancement and field distributions for electric and magnetic dipoles, offering valuable information for the design and optimization of high-quality-factor optical metasurfaces based on LiNbO3.
Chinese Optics Letters
  • Publication Date: Jun. 16, 2021
  • Vol.19 Issue, 6 060013 (2021)
Broadband and lossless lithium niobate valley photonic crystal waveguide [Invited] | Editors' Pick
Rui Ge, Xiongshuo Yan, Yuping Chen, and Xianfeng Chen
We investigate the influences of structure parameters and interface shapes on the bandwidth of the edge state of lithium niobate valley photonic crystals. By increasing the size difference of two air holes in the same unit cell, we find that the bandwidth of the lossless nontrivial edge state possesses a peak value of 0.0201(a/λ), which can be used to construct broadband valley photonic crystal waveguides. Mode field distributions verify that the waveguide is robust against sharp bends and exhibits chirality. When the unit cell is arranged in a bearded interface with the top and bottom components showing negative and positive valley Chern numbers, respectively, we find that the lithium niobate valley photonic crystal is more likely to exhibit a lossless edge state, which is difficult to be realized in valley waveguides with low refractive index materials. This work can provide guidance on the design of the high-performance topological waveguide.
Chinese Optics Letters
  • Publication Date: Jun. 16, 2021
  • Vol.19 Issue, 6 060014 (2021)
Effect of dimension variation for second-harmonic generation in lithium niobate on insulator waveguide [Invited]
Xiao-Hui Tian, Wei Zhou, Kun-Qian Ren, Chi Zhang, Xiaoyue Liu, Guang-Tai Xue, Jia-Chen Duan, Xinlun Cai, Xiaopeng Hu, Yan-Xiao Gong, Zhenda Xie, and Shi-Ning Zhu
Chinese Optics Letters
  • Publication Date: Jun. 21, 2021
  • Vol.19 Issue, 6 060015 (2021)
Wideband thin-film lithium niobate modulator with low half-wave-voltage length product
Xuecheng Liu, Bing Xiong, Changzheng Sun, Jian Wang, Zhibiao Hao, Lai Wang, Yanjun Han, Hongtao Li, Jiadong Yu, and Yi Luo
Chinese Optics Letters
  • Publication Date: Jun. 28, 2021
  • Vol.19 Issue, 6 060016 (2021)
Hybrid mono-crystalline silicon and lithium niobate thin films [Invited] | Editors' Pick
Houbin Zhu, Qingyun Li, Huangpu Han, Zhenyu Li, Xiuquan Zhang, Honghu Zhang, and Hui Hu
The heterogeneous integration of silicon thin film and lithium niobate (LN) thin film combines both the advantages of the excellent electronics properties and mature micro-processing technology of Si and the excellent optical properties of LN, comprising a potentially promising material platform for photonic integrated circuits. Based on ion-implantation and wafer-bonding technologies, a 3 inch wafer-scale hybrid mono-crystalline Si/LN thin film was fabricated. A high-resolution transmission electron microscope was used to investigate the crystal-lattice arrangement of each layer and the interfaces. Only the H-atom-concentration distribution was investigated using secondary-ion mass spectroscopy. High-resolution X-ray-diffraction ω–2θ scanning was used to study the lattice properties of the Si/LN thin films. Raman measurements were performed to investigate the bulk Si and the Si thin films. Si strip-loaded straight waveguides were fabricated, and the optical propagation loss of a 5-μm-width waveguide was 6 dB/cm for the quasi-TE mode at 1550 nm. The characterization results provide useful information regarding this hybrid material.
Chinese Optics Letters
  • Publication Date: Jun. 21, 2021
  • Vol.19 Issue, 6 060017 (2021)

About the Cover

Nonlinear Talbot self-healing: the capability of creating defect-free images from faulty nonlinear photonic structures by the second harmonic of the incident laser beam.