Ultra-Compact Vertical Optical Coupler Based on Subwavelength Grating

Fig. 1. Schematics of designed vertical optical coupler. (a) 3D diagram; (b) cross-sectional view; (c) top view; (d) 3D diagram of SWG and tapered waveguide

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$Effective refractive index versus equivalent refractive index of SWG$

Fig. 2. Effective refractive index versus equivalent refractive index of SWG

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Fig. 3. Coupling ratio versus number of periods of subwavelength grating

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Fig. 4. Coupling ratio versus wavelength for vertical coupler

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Fig. 5. Normalized electric field intensity of light field. (a) Top view; (b) side view; (c) cross-sectional light field distribution at A; (d) cross-sectional light field distribution at B; (e) cross-sectional light field distribution at C

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Fig. 6. Fabrication process

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Fig. 7. Tolerance analysis of process errors. (a)Coupling ratio versus duty cycle; (b) coupling ratio versus tip width of tapered waveguide; (c) coupling ratio versus misalignment, and position of coupler relative to LN waveguide indicated in inset

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Table 1. Material parameters and structural parameters of designed vertical optical coupler waveguide

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Table 1. Material parameters and structural parameters of designed vertical optical coupler waveguide

Parameter	Value
Wavelength λ /nm	1550
Thickness of Si ${O_{2}}_{}$ /μm	3
Thickness of Si /nm	220
Width of Si waveguide /nm	400
Height of BCB /nm	300
Refractive index of BCB	1.54
Height of LN waveguide /nm	600
${W_{1}}_{}$ /μm	1
${W_{2}}_{}$ /μm	1.4
Height of LN ridge waveguide h /nm	180
Refractive index of LN	2.14
Width of SWG ${W_{g}}_{}$ /nm	400
Width of taper tip ${W_{t}}_{}$ /nm	80

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Ran Zhao, Chonglei Sun, Xiao Xu, Jia Zhao. Ultra-Compact Vertical Optical Coupler Based on Subwavelength Grating[J]. Acta Optica Sinica, 2020, 40(14): 1405002

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Paper Information

Category: Diffraction and Gratings

Received: Feb. 10, 2020

Accepted: Apr. 13, 2020

Published Online: Jul. 23, 2020

The Author Email: Zhao Jia (zhaojia@sdu.edu.cn)

DOI:10.3788/AOS202040.1405002

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology