Ultracompact, polarization-independent, and highly scalable optical power splitting model employing fan-out bending metamaterials

Zhenzhao Guo; Jinbiao Xiao; Shengbao Wu

doi:10.1364/PRJ.470827

Journals >Photonics Research >Volume 10 >Issue 11 >Page 2448 > Article

Photonics Research
Vol. 10, Issue 11, 2448 (2022)

Ultracompact, polarization-independent, and highly scalable optical power splitting model employing fan-out bending metamaterials | Editors' Pick

Zhenzhao Guo^1、2, Jinbiao Xiao^2、3、*, and Shengbao Wu^1、4、*

Author Affiliations

¹Photonics Information Innovation Center, Hebei Provincial Center for Optical Sensing Innovations, College of Physics Science and Technology, Hebei University, Baoding 071002, China

²National Research Center for Optical Sensing/Communications Integrated Networking, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China

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DOI: 10.1364/PRJ.470827 Cite this Article Set citation alerts

Zhenzhao Guo, Jinbiao Xiao, Shengbao Wu. Ultracompact, polarization-independent, and highly scalable optical power splitting model employing fan-out bending metamaterials[J]. Photonics Research, 2022, 10(11): 2448 Copy Citation Text

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A 3D schematic of the proposed power splitting scheme: (a) the 1×4 power splitter with enlarged views of light propagation profiles for TE and TM modes, respectively; (b) the top view of the input taper, angled output tapers, and FBSWGs, which are shown separately to facilitate the understanding; the designed (c) 1×2 power splitter, (d) 1×3 power splitter, and (e) 1×5 power splitter. All devices are covered by up-SiO2 claddings, which are not shown here for clarity. (f) Working principle of power splitters using FBSWGs, the optical path from the center point to the arbitrary point of the mth bending grating line is noRm, resulting in curved wavefronts, and such curved wavefronts are matched with that of angled output tapers. Comparisons of (g) conventional straight SWGs and (h) a bending silicon waveguide with the proposed FBSWG scheme. Distributions of electric-fields Ex and Ey for TE and TM modes are also simulated by the 3D-FDTD method and displayed in (f)–(h).

Fig. 1. A 3D schematic of the proposed power splitting scheme: (a) the 1×4 power splitter with enlarged views of light propagation profiles for TE and TM modes, respectively; (b) the top view of the input taper, angled output tapers, and FBSWGs, which are shown separately to facilitate the understanding; the designed (c) 1×2 power splitter, (d) 1×3 power splitter, and (e) 1×5 power splitter. All devices are covered by up-SiO2 claddings, which are not shown here for clarity. (f) Working principle of power splitters using FBSWGs, the optical path from the center point to the arbitrary point of the mth bending grating line is noRm, resulting in curved wavefronts, and such curved wavefronts are matched with that of angled output tapers. Comparisons of (g) conventional straight SWGs and (h) a bending silicon waveguide with the proposed FBSWG scheme. Distributions of electric-fields Ex and Ey for TE and TM modes are also simulated by the 3D-FDTD method and displayed in (f)–(h).

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Calculated PSDs, respectively, for (a) the TE mode and (b) TM mode as θO1/θO4 and θO2/θO3 vary in Step I, for (c) the TE mode and (d) TM mode as w1/w4 and w2/w3 vary in Step II, for (e) the TE mode and (f) TM mode as L1/L4 and L2/L3 vary in Step III, and for (g) the TE mode and (h) TM mode as LO1/LO4 and LO2/LO3 vary in Step IV.

Fig. 2. Calculated PSDs, respectively, for (a) the TE mode and (b) TM mode as θO1/θO4 and θO2/θO3 vary in Step I, for (c) the TE mode and (d) TM mode as w1/w4 and w2/w3 vary in Step II, for (e) the TE mode and (f) TM mode as L1/L4 and L2/L3 vary in Step III, and for (g) the TE mode and (h) TM mode as LO1/LO4 and LO2/LO3 vary in Step IV.

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Fig. 3. Calculated light propagation profiles as the fundamental TE/TM mode is injected for the (a) and (b) 1×2 power splitter, (c) and (d) 1×3 power splitter, (e) and (f) 1×4 power splitter, and (g) and (h) 1×5 power splitter, respectively.

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Fig. 4. Calculated ILs and OUs for the (a) 1×3 power splitter, (b) 1×4 power splitter, and (c) 1×5 power splitter with a deviated duty cycle for both TE and TM modes. The calculated wavelength dependence of the ILs and OUs for the (d) 1×3 power splitter, (e) 1×4 power splitter, and (f) 1×5 power splitter for TE and TM polarizations.

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Fig. 5. (a) Microscope image of the reference TE and TM waveguides. (b) Microscope image of the three-stage cascaded measure scheme for the fabricated 1×3 power splitters and (c) and (d) corresponding scanning electron microscope (SEM) images of fabricated 1×3 power splitters. Microscope image of the three-stage cascaded measure scheme for the fabricated (e) 1×4 power splitters and (f) 1×5 power splitters. Pseudocolor SEM images of (g) the 1×4 and (h) the 1×5 power splitting elements.

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Fig. 6. Measured and normalized transmittance Tchannel i spectra of the 1×3 power splitter for the input (a) TE and (b) TM modes, the 1×4 power splitter for the input (c) TE and (d) TM modes, and the 1×5 power splitter for the input (e) TE and (f) TM modes, respectively.

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OPS	$M_{12}$	$θ_{SWG}$	$L_{1}$	$L_{2}$	$w_{1}$	$w_{2}$	$θ_{1}$	$θ_{2}$	$L_{O 1}$	$L_{O 2}$	$R_{0}$
$1 \times 2$	17	33	1.3	1.3	0.25	0.25	8	8	2.4	2.4	0.98
$1 \times 3$	$M_{13}$	$θ_{SWG}$	$L_{1}$	$L_{2}$	$L_{3}$	$w_{1}$	$w_{2}$	$w_{3}$	$θ_{1}$	$θ_{2}$	$θ_{3}$
	19	48	1.69	2.25	1.69	0.4	0	0.4	15.75	0	15.75
	$L_{O 1}$	$L_{O 2}$	$L_{O 3}$	$R_{0}$
	2.2	1.95	2.2	0.76
$1 \times 4$	$M_{14}$	$θ_{SWG}$	$L_{1}$	$L_{2}$	$L_{3}$	$L_{4}$	$w_{1}$	$w_{2}$	$w_{3}$	$w_{4}$	$θ_{1}$
	18	56	1.048	2	2	1.048	0.244	0.281	0.281	0.244	25
	$θ_{2}$	$θ_{3}$	$θ_{4}$	$L_{O 1}$	$L_{O 2}$	$L_{O 3}$	$L_{O 4}$	$R_{0}$
	9.5	9.5	25	2	1.8	1.8	2	0.76
$1 \times 5$	$M_{15}$	$θ_{SWG}$	$L_{1}$	$L_{2}$	$L_{3}$	$L_{4}$	$L_{5}$	$w_{1}$	$w_{2}$	$w_{3}$	$w_{4}$
	19	56	1.05	1.923	2.25	1.923	1.05	0.246	0.193	0	0.193
	$w_{5}$	$θ_{1}$	$θ_{2}$	$θ_{3}$	$θ_{4}$	$θ_{5}$	$L_{O 1}$	$L_{O 2}$	$L_{O 3}$	$L_{O 4}$	$L_{O 5}$
	0.246	24.5	16.5	0	16.5	25.5	2	1.95	2	1.95	2
	$R_{0}$
	0.76
SPC^b	$w_{I}$	$w_{O}$	$w_{t}$	$L_{s}$	$L_{I}$	$a$	$Λ$
SPC^b	0.5	0.5	0.1	0.6	1.82	0.12	0.22

Table 1. Optimized Parameters of the 1×2, 1×3, 1×4, and 1×5 Power Splitters^a

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Structure	Function	Length (µm)	IL (dB)		OU (dB)		Bandwidth (nm)^c
Structure	Function	Length (µm)	Sim^a	Exp^b	Sim	Exp	Sim	Exp
Y-branch [11]	$1 \times 4$ at TE	4000	0.26	$< 1.2$	–	$< 2.2$	100 ( $IL < 1$ )	100 ( $IL < 1.2$ , $OU < 2.2$ )
Y-branch [11]	$1 \times 4$ at TM	4000	–	$< 1.8$	–	$< 2.2$	100 ( $IL < 1.3$ )	100 ( $IL < 1.8$ , $OU < 2.2$ )
Tapers [17]	$1 \times 4$ at TE	12.5	0.18	$< 0.4$	–	$< 0.68$	100 ( $IL < 0.22$ )	40 ( $IL < 0.4$ , $OU < 0.68$ )
MMI [20]	$1 \times 4$ at TE	36	$\sim 0.1$	0.42	$\sim 0.08$	0.61	150 ( $IL < 0.59$ , $OU < 0.34$ )	104 ( $IL < 0.89$ , $OU < 0.62$ )
DCs [22]	$1 \times 3$ at TE	7.3	0.016	0.068	0.058	$< 1$	111 ( $IL < 0.031$ , $OU < 1$ )	50 ( $IL < 0.82$ , $OU < 1$ )
DCs [22]	$1 \times 3$ at TM	7.3	0.065	0.62	0.021	$< 1$	90 ( $IL < 0.17$ , $OU < 1$ )	54 ( $IL < 1.5$ , $OU < 1$ )
This work	$1 \times 3$ at TE	4.24	0.43	0.75	0.023	0.64	180 ( $IL < 0.6$ , $OU < 1$ )	54 ( $IL < 1.2$ , $OU < 0.9$ )
	$1 \times 3$ at TM	4.24	0.24	0.58	0.015	0.32	180 ( $IL < 0.6$ , $OU < 1$ )	54 ( $IL < 1.2$ , $OU < 0.9$ )
	$1 \times 4$ at TE	4.02	0.33	1.16	0.066	0.8	190 ( $IL < 0.6$ , $OU < 1$ )	49 ( $IL < 1.35$ , $OU < 1$ )
	$1 \times 4$ at TM	4.02	0.18	0.66	0.0005	0.43	190 ( $IL < 0.6$ , $OU < 1$ )	49 ( $IL < 1.35$ , $OU < 1$ )