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• Chinese Optics Letters
• Vol. 20, Issue 11, 111902 (2022)
Zhenzhong Hao1, Li Zhang1, Jie Wang1, Fang Bo1、2、*, Feng Gao1、2, Guoquan Zhang1、2、**, and Jingjun Xu1、2、***
Author Affiliations
• 1MOE Key Laboratory of Weak-Light Nonlinear Photonics, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin 300457, China
• 2Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
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Zhenzhong Hao, Li Zhang, Jie Wang, Fang Bo, Feng Gao, Guoquan Zhang, Jingjun Xu. Sum-frequency generation of a laser and its background in an on-chip lithium-niobate microdisk[J]. Chinese Optics Letters, 2022, 20(11): 111902 Copy Citation Text show less
Fig. 1. Schematic of the experimental setup to measure sum-frequency signals. An arbitrary function generator (AFG) is used to precisely control the output wavelength of the pump laser and to trigger the oscilloscope. The pump light passes through a fiber polarization controller (PC) and a beam splitter, and then couples into the LN WGM microcavity via a tapered fiber. The transmission of the pump is monitored by a photodetector connected to an oscilloscope. The tapered fiber that is used to couple the pump collects the nonlinear optical signals as well. The nonlinear optical signals are detected by a spectrometer.
Fig. 2. Nonlinear optical signals. Peak 1, marked in red, corresponding to the second harmonic generation (SHG) of the pump laser at 1521.36 nm. Peaks 2–9 in blue are the sum-frequency generation (SFG) signals of the pump laser and its background.
Fig. 3. Transmission spectra of the pump laser and its background. (a) A typical broad transmission spectrum of an LN WGM microcavity coupled to a tapered fiber. (b) The enlarged view of the yellow highlighted part of (a) showing the pump laser background in detail. The peaks marked in blue represent the WGMs associated with the sum-frequency processes.
Fig. 4. Dependence of the conversion efficiency of the typical nonlinear optical signals on that of the pump laser. (a) and (b) show the data for the second harmonic signal and that for the sum-frequency signal marked as Peak 7, respectively.
Peak Number$λSFG$ (nm)$λCal$ (nm)$λMeas$ (nm)$λMeas−λCal$ (nm)
2769.7801558.1961558.416$+0.220$
3770.8531562.6021562.463$−0.139$
4772.0751567.6301567.545$−0.085$
5775.1561580.3861580.290$−0.096$
6775.7821582.9881583.006$+0.018$
7776.4141585.6211585.675$+0.054$
8777.7191591.0751591.075$+0.000$
9779.5791598.8791598.763$−0.116$
Table 1. Wavelengths of Light Associated with the Sum-Frequency Processes
Zhenzhong Hao, Li Zhang, Jie Wang, Fang Bo, Feng Gao, Guoquan Zhang, Jingjun Xu. Sum-frequency generation of a laser and its background in an on-chip lithium-niobate microdisk[J]. Chinese Optics Letters, 2022, 20(11): 111902