Recent progress of second harmonic generation based on thin film lithium niobate [Invited]

Yang Li; Zhijin Huang; Wentao Qiu; Jiangli Dong; Heyuan Guan; Huihui Lu

doi:10.3788/COL202119.060012

Journals >Chinese Optics Letters >Volume 19 >Issue 6 >Page 060012 > Article

Chinese Optics Letters
Vol. 19, Issue 6, 060012 (2021)

Recent progress of second harmonic generation based on thin film lithium niobate [Invited]

Yang Li¹, Zhijin Huang¹, Wentao Qiu¹, Jiangli Dong², Heyuan Guan^2、*, and Huihui Lu^1、**

Author Affiliations

¹Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Jinan University, Guangzhou 510632, China

²Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, China

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DOI: 10.3788/COL202119.060012 Cite this Article Set citation alerts

Yang Li, Zhijin Huang, Wentao Qiu, Jiangli Dong, Heyuan Guan, Huihui Lu. Recent progress of second harmonic generation based on thin film lithium niobate [Invited][J]. Chinese Optics Letters, 2021, 19(6): 060012 Copy Citation Text

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Fig. 1. Summary of different approaches of SHG based on TFLN technology.

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(a) Schematic and false-color SEM image of a periodically poled nanophotonic waveguide[39]; Copyright 2018, Optical Society of America. (b) SH confocal microscopy of the PPLN thin film fabricated by microelectrode poling and the cross section of the LNOI ridge waveguide[40]; Copyright 2020, AIP Publishing. (c) Schematic of the cascading EO coupling and SHG process in the PPLN ridge waveguide[41]; Copyright 2019, Optical Society of America. (d) Schematic illustration of the PPLN waveguide with poling electrodes[42]; Copyright 2019, Optical Society of America.

Fig. 2. (a) Schematic and false-color SEM image of a periodically poled nanophotonic waveguide^[39]; Copyright 2018, Optical Society of America. (b) SH confocal microscopy of the PPLN thin film fabricated by microelectrode poling and the cross section of the LNOI ridge waveguide^[40]; Copyright 2020, AIP Publishing. (c) Schematic of the cascading EO coupling and SHG process in the PPLN ridge waveguide^[41]; Copyright 2019, Optical Society of America. (d) Schematic illustration of the PPLN waveguide with poling electrodes^[42]; Copyright 2019, Optical Society of America.

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Fig. 3. (a) Demonstration of efficient SHG in PPLN microring resonators^[46]; Copyright 2019, Optical Society of America. (b) Schematic of the periodically grooved structure of an LN waveguide and cross-section image of the X-cut LNOI waveguide^[44]; Copyright 2017, Optical Society of America. (c) Schematic and working principle of the metasurface-assisted LN nanophotonic waveguide^[47]; Copyright 2017, Springer Nature. (d) Schematic of a rib-loaded GA-QPM waveguide with a sinusoidal modulation of the width along with the optical mode profiles of the fundamental and SH TE modes at a grating width of 1095 nm^[45]; Copyright 2017, AIP Publishing.

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Fig. 4. (a) Schematic of the LN powder to form the cavity behavior in the SH emission at a certain pump intensity^[50]; Copyright 2019, American Physical Society. (b) SEM images of single LN nanocubes to obtain the maximal SHG^[51]; Copyright 2019, American Chemical Society.

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Fig. 5. (a) Images of SHG in an LN metasurface and SHG power depending on average power of the fundamental harmonic (FH) beam^[52]; Copyright 2020, American Chemical Society. (b) Schematic of LN nonlinear metasurfaces fabricated on an X-cut LN film residing on a fused quartz substrate. Left inset gives a typical SEM image of the cross section of the metasurface, and the right inset presents the measured second-order susceptibility of the LN film used in this study^[53]; Copyright 2021, John Wiley and Sons.

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Fig. 6. (a) SEM images showing the mask for ion-beam-enhanced etching (IBEE) (Cr/SiO₂ pillars) and measured SH enhancement factor and linear reflection spectrum of the fabricated sample^[59]; Copyright 2015, American Chemical Society. (b) Schematic of the experiment mounted using index matching oil in a typical Kretschmann geometry^[70]; Copyright 2018, Optical Society of America.

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Fig. 7. (a) Scanning-electron micrograph of LN microresonators to achieve modal dispersion^[75]; Copyright 2017, Optical Society of America. (b) SEM images of the LN microdisk PM^[77]; Copyright 2020, IOP Publishing. (c) SEM image of the X-cut LN microdisk and spectra of the pump light, the second-harmonic wave, and the third-harmonic wave. SHG conversion efficiency as a function of the in-coupled power^[78]; Copyright 2019, American Physical Society. (d) Schematic depiction of the proposed nanostructure for generating SH and nonlinear simulations^[82]; Copyright 2020, De Gruyter.

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Year	TFLN Structure	Poled/Coupling Region Length L (mm)	FF Power ( $λ_{FF}$ )	Coupling Loss (dB/facet)	Waveguide Propagation Loss (dB/cm)	$η_{SH}$ ( $% W^{- 1} {cm}^{- 2}$ )	Institute
2011	Plasmonic waveguide^[60]	1	1 W (1550 nm)	–	–	1.3%	Nanjing University
2015	Nanoscale LN waveguides^[61]	0.9	737 µW (1411 nm)	–	61	6.9	Friedrich Schiller Universität Jena
2017	PE channel waveguide^[36]	3.2	1 mW (1385 nm)	–	2.5	48	Shandong University
2016	Rib-loaded SiN-PPLN^[22]	4.8	0.5 mW (1530 nm)	∼6.8	$0.3 \pm 0.2$	160	University of California
2017	Metasurface-assisted PM LN waveguide^[47]	0.019	10⁹ V/m/20 mW (1640 nm)	–	–	1660	Harvard University
2017	GA-QPM LN ridge waveguide^[45]	4.9	84 mW (1568 nm)	6.5	1	0.8	University of Central Florida
2017	Integrated TFLN waveguide^[44]	3	18.3 µW (1550 nm)	4.8	$3 \pm 0.2$	41	Harvard University
2016	Diced ridge PPLN waveguides^[62]	5.8	6.6 mW (1550 nm)	–	0.57	77.9	Shandong University
2018	PPLN on silicon^[63]	20	10 mW (1547 nm)	–	0.2	1230	University of Central Florida
2018	Nanostructured PPLN waveguide^[39]	4	220 mW (1550 nm)	∼10	–	2600	Harvard University
2018	LN nanophotonic waveguide^[64]	8	∼1 mW (1540 nm)	5	0.54	22.2	University of Rochester
2019	PPLN microrings^[46]	–	115 µW (1617 nm)	–	–	250,000%/W	Yale University
2019	PPLNOI ridge waveguide^[41]	10	10 mW (1590 nm)	–	–	0.04	Shanghai Jiao Tong University
2019	Dry-etched^[65]	0.6	1 mW (1540 nm)	6	3	4600	University of Central Florida
2019	Dry-etched^[21]	4	2.95 mW (1550 nm)	4.3	0.3	2200	Stevens Institute of Technology
2020	Z-cut PPLNOI waveguide^[66]	1	–(1550 nm)	$5.4 \pm 0.3$	$< 0.03$	2400	Stevens Institute of Technology
2020	Dry-etched PPLN^[67]	5	0.1 mW (1570 nm)	$- 7$	$- 0.54$	2000	University of California
2020	PPLNOI ridge waveguide^[40]	6	397 µW (1470 nm)	–	–	3061	Nanjing University+Sun Yat-sen University
2020	Birefringent phase-matching LN waveguide^[68]	10	4500 W (1064 nm)	–	0.58	0.87%	Shandong University
2020	Shallow-etched TFLN waveguides^[42]	5	10 mW (1560 nm)	7.7	1	3757	University of California
2020	PPLN waveguide^[69]	6	60 fJ (2050 nm)	–	$< 0.1$	1000	Stanford University
2020	LN slab waveguides by grating metasurfaces^[48]	0.05	25 mW (1064 nm)	–	–	$4.6 \times 10^{- 7}$	Nanjing University

Table 1. Comparisons of SHG Conversion Efficiency of Different TF-PPLN Waveguides

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Year	Structure	Mechanism	Structure Parameter (Radius R, Diameter D, Height H, Thickness T)	Peak Pump Intensity/Power ( $λ_{FF}$ )	Q Factor ( $λ$ )	$η_{SH}$	$η_{\dim}^{SH}$ ( $W^{- 1}$ )/Unstructured LN	Institute
2012–2013	Embedded Ag-LN^[83,84]	Fabry–Perot resonance	Coaxial aperture (R_inner $= 65 nm$ , R_outer $= 135 nm$ , H = 120 nm)	–1550 nm	–	–	$\sim 27 times$	FEMTO-ST, CNRS
2014	LN microdisk resonators^[85]	Cavity resonance	LN microdisk (D = 28 µm, T = ∼300 nm)	1.8 mW (1546 nm)	$1.02 \times 10^{5}$ (1507 nm)	–	0.109	Harvard University
2015	High-Q LN microresonator^[76]	Femtosecond laser micromachining	LN microdisk (D = ∼82 µm, T = ∼670 nm)	54.6 µW (1550 nm)	$2.45 \times 10^{6}$ (1550 nm)	–	$2.30 \times 10^{- 3}$	Shanghai Institute of Optics and Fine Mechanics
2015	LN-filled gold nanorings^[59]	Plasmonic resonance	Ring R_inner $= 80 nm$ , R_outer $= 120 nm$ , H = 100 nm)	$4 GW / {cm}^{2}$ (820 nm)	–	–	$\sim 20 times$	Friedrich Schiller University Jena
2017	LN microdisk resonator^[75]	Broadband SPDC	LN microdisk (R = 45 µm, T = 300 nm)	115 µW (1549.32 nm)	$1.2 \times 10^{5}$ (1549.32 nm)	–	$3.6 \times 10^{- 3}$	University of Rochester
2018	PPLN microcavity^[74]	Whispering gallery mode (WGM)	PPLN microdisk (D = ∼80 µm, T = 700 nm)	1.1 mW (1550 nm)	$6.7 \times 10^{5}$	–	$2.2 \times 10^{- 3}$	Nankai University
2018	Gold deposited on TFLN^[70]	Plasmonic SHG	Gold film (T = ∼30 nm)	$60 MW / {cm}^{2}$ (1240 nm)	–	$2 \times 10^{- 13}$	–	Macquarie University
2018	LN nanodisks on an Al substrate^[81]	Anapole resonances	LN nanodisk (D = 256 nm, H = 70 nm)	$5.31 GW / {cm}^{2}$ (351.3 nm)	–	$1.1528 \times 10^{- 5}$	–	Institute of Lasers, State Academy of Sciences
2019	On-chip monocrystalline TFLN microdisk resonator^[78]	QPM	LN microdisk (D = ∼30 µm, T = 600 nm)	0.25 mW (1547.8 nm)	$9.61 \times 10^{6}$ (1547.8 nm)	–	9.9%/mW	Shanghai Institute of Optics and Fine Mechanics
2019	LNO nanocubes^[51]	Mie resonances	Nanocube (200 nm)	$1.7 GW / {cm}^{2}$ (720 nm)	–	–	$7.6 \times 10^{- 7}$	ETH Zürich
2019	Periodic LN bar and LN disk^[24]	Fano resonances	Bar and disk (D = 700 nm, T = 340 nm, L = 1100 nm)	$3.2 GW / {cm}^{2}$ (1605 nm)	2350 (1605 nm)	$3.165 \times 10^{- 4}$	–	Jinan University
2019	Superfine LN powder^[50]	Cavity-enhanced SHG	–	$1.58 GW / {cm}^{2}$ (793.5 nm)	–	–	–	Shanghai Jiao Tong University
2020	BPPLN microcavities^[49]	Multiple reciprocal vectors	Minimum domain unit (width = 100 nm)	0.02 mW (1550 nm)	$1.43 \times 10^{5}$	–	$5.1 \times 10^{- 1}$	Nankai University
2020	LNOI wafer^[86]	Fabry–Perot resonance	LN film (H = 196.8 nm)	$4.05 GW / {cm}^{2}$ (840 nm)	–	$1.6 \times 10^{- 5}$	–	Nankai University
2020	Nanostructured LN^[82]	Anapole resonances	LN nanodisk (D = 432 nm, H = 104 nm)	$5.31 GW / {cm}^{2}$ (565.4 nm)	–	$5.1371 \times 10^{- 5}$	0.1711	Jinan University
2020	LN metasurface^[52]	ED and MD Mie resonances	Nanocube (period = 870 nm, length = 700 nm)	$4.3 GW / {cm}^{2}$ (1550 nm)	–	$\sim 10^{- 6}$	$1.14 \times 10^{- 3}$	Friedrich Schiller University Jena
2021	LN nanograting metasurfaces^[83]	Mie resonance	Metasurface (period D = 600 nm, H = 235 nm)	$2.05 GW / {cm}^{2}$ (820 nm)	–	$4.2 \times 10^{- 6}$	$\sim 2 times$	Nankai University
2021	Integrated LN microresonators^[87]	Ultrahigh Q performance	LN microdisk (D = 1030 µm)	5 µW (1550 nm)	$1.56 \times 10^{8}$ ( $\sim 1551.52 nm$ )	–	602%/mW	Shanghai Institute of Optics and Fine Mechanics