Long Low-Loss-Litium Niobate on Insulator Waveguides with Sub-Nanometer Surface Roughness

Rongbo Wu; Min Wang; Jian Xu; Jia Qi; Wei Chu; Zhiwei Fang; Jianhao Zhang; Junxia Zhou; Lingling Qiao; Zhifang Chai; Jintian Lin; Ya Cheng

doi:10.3390/nano8110910

Long Low-Loss-Litium Niobate on Insulator Waveguides with Sub-Nanometer Surface Roughness

Nanomaterials (Basel). 2018 Nov 6;8(11):910. doi: 10.3390/nano8110910.

Authors

Rongbo Wu^{1

2}, Min Wang^{3

4}, Jian Xu^{5

6}, Jia Qi^{7

8}, Wei Chu^{9

10}, Zhiwei Fang^{11

12}, Jianhao Zhang^{13

14}, Junxia Zhou^{15

16}, Lingling Qiao¹⁷, Zhifang Chai^{18

19}, Jintian Lin²⁰, Ya Cheng^{21

22

23

24}

Affiliations

¹ State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. rbwu@siom.ac.cn.
² University of Chinese Academy of Sciences, Beijing 100049, China. rbwu@siom.ac.cn.
³ State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China. mwang@phy.ecnu.edu.cn.
⁴ XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China. mwang@phy.ecnu.edu.cn.
⁵ State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China. jxu@phy.ecnu.edu.cn.
⁶ XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China. jxu@phy.ecnu.edu.cn.
⁷ State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. qijia@siom.ac.cn.
⁸ University of Chinese Academy of Sciences, Beijing 100049, China. qijia@siom.ac.cn.
⁹ State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. chuwei@siom.ac.cn.
¹⁰ XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China. chuwei@siom.ac.cn.
¹¹ State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China. zwfang@phy.ecnu.edu.cn.
¹² XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China. zwfang@phy.ecnu.edu.cn.
¹³ State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. jhzhang@siom.ac.cn.
¹⁴ University of Chinese Academy of Sciences, Beijing 100049, China. jhzhang@siom.ac.cn.
¹⁵ State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China. 52180920026@stu.ecnu.edu.cn.
¹⁶ XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China. 52180920026@stu.ecnu.edu.cn.
¹⁷ State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. qiaolingling@siom.ac.cn.
¹⁸ State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China. zfchai@phy.ecnu.edu.cn.
¹⁹ XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China. zfchai@phy.ecnu.edu.cn.
²⁰ State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. jintianlin@siom.ac.cn.
²¹ State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. ya.cheng@siom.ac.cn.
²² State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China. ya.cheng@siom.ac.cn.
²³ XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China. ya.cheng@siom.ac.cn.
²⁴ Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, Shanxi, China. ya.cheng@siom.ac.cn.

Abstract

In this paper, we develop a technique for realizing multi-centimeter-long lithium niobate on insulator (LNOI) waveguides with a propagation loss as low as 0.027 dB/cm. Our technique relies on patterning a chromium thin film coated on the top surface of LNOI into a hard mask with a femtosecond laser followed by chemo-mechanical polishing for structuring the LNOI into the waveguides. The surface roughness on the waveguides was determined with an atomic force microscope to be 0.452 nm. The approach is compatible with other surface patterning technologies, such as optical and electron beam lithographies or laser direct writing, enabling high-throughput manufacturing of large-scale LNOI-based photonic integrated circuits.

Keywords: chemo-mechanical polishing; lithium niobate; optical lithography; photonic integrated circuit; propagation loss; waveguide.

Grants and funding

11734009, 11874375, 61590934, 61635009, 61327902, 61505231, 11604351, 11674340, 61575211, 61675220, 61761136006/National Natural Science Foundation of China