On-chip mode converter based on two cascaded Bragg gratings

Xiao, Rulei; Shi, Yuechun; Li, Jia; Dai, Pan; Zhao, Yong; Li, Lianyan; Lu, Jun; Chen, Xiangfei

doi:10.1364/oe.27.001941

Cited by 48 publications

(14 citation statements)

References 39 publications

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“…Up to now, various mode converters have been proposed. Three methods are usually utilized for mode conversions: (1) phase matching; (2) beam shaping; and (3) coherent scattering [13]- [16]. Based on these methods, mode conversions that are realized by gradual index change or lowcontrast index modulation such as tapers and Bragg gratings, cannot well address the challenges like the large device footprint, limited operation bandwidth and robustness, lack of scalability for more mode order conversion.…”

Section: Introductionmentioning

confidence: 99%

Efficient TE-Polarized Mode-Order Converter Based on High-Index-Contrast Polygonal Slot in a Silicon-on-Insulator Waveguide

Hao¹,

Xiao²,

Shi³

et al. 2019

IEEE Photonics J.

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We proposed a new type of transverse electric (TE) polarized mode-order converter based on a deeply-etched polygonal slot on a silicon-on-insulator waveguide. Along the transverse direction of the waveguide, two irregular boundary surfaces of the slot can introduce high-contrast index modulation on guided modes, leading to multimode interference in the slot. Therefore, when the slot is optimized, we can achieve efficient mode conversions based on the multimode interference. As examples, mode converters from the fundamental TE mode (TE 0 ) to the first-order TE mode (TE 1 ) and to the second-order TE mode (TE 2 ) have both been demonstrated with a short device length (<24.0 μm), a high mode conversion efficiency (>97.6%), and a low modal crosstalk (< −20.0 dB) over a broad wavelength range from 1500 to 1600 nm (∼100 nm). In addition, based on different polygonal slots, other types of mode conversions such as from TE 1 to TE 3 and from TE 2 to TE 1 have be realized. Fabrication tolerance of the proposed structure is analyzed. Owing to the high efficiency and compact size, the proposed structure could be applied to on-chip mode division multiplexing systems for high-density integration.

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Section: Introductionmentioning

confidence: 99%

Efficient TE-Polarized Mode-Order Converter Based on High-Index-Contrast Polygonal Slot in a Silicon-on-Insulator Waveguide

Hao¹,

Xiao²,

Shi³

et al. 2019

IEEE Photonics J.

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“…Figure 3 shows the calculated mode CE and CT of the proposed TM 0 -to-TM 3 mode-order converter as functions of the length L 3 (L 6 ), width W 3 (W 6 ), and relative distance W s (W m ) of slot 3 (6). Note that for the mode-order converter, high mode CE was a paramount evaluation index which reflected well its pivotal mode conversion performance [11][12][13][14][15][19][20][21][22]. Meanwhile, we also employed CT between the required mode (TM 3 mode) and other modes at the output port to characterize the mode purity for the mode conversion process.…”

Section: Resultsmentioning

confidence: 95%

“…Some prevailing optimization methods (e.g., deep learning and topology optimization [16][17][18]) have also been used to find the optimal structure pattern at the cost of quite time-consuming iterative calculations and complex patterns for the device fabrication. Compared with these latest reports, some classical structures such as Mach−Zehnder interferometers (MZI) [19,20] and Bragg gratings [21,22] are still employed to realize the mode-order conversion due to their simple structures, high performance and clear working mechanisms. However, the main issue of these typical schemes are their device lengths (>50 µm).…”

Section: Introductionmentioning

confidence: 99%

Silicon-Based TM0-to-TM3 Mode-Order Converter Using On-Chip Shallowly Etched Slot Metasurface

Zhu

Kang

et al. 2021

Photonics

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Mode-order converters drive the on-chip applications of multimode silicon photonics. Here, we propose a TM0-to-TM3 mode-order converter by leveraging a shallowly etched slot metasurface pattern atop the silicon waveguide, rather than as some previously reported TE-polarized ones. With a shallowly etched pattern on the silicon waveguide, the whole waveguide refractive index distribution and the corresponding field evolution will be changed. Through further analyses, we have found the required slot metasurface pattern for generating the TM3 mode with high conversion efficiency of 92.9% and low modal crosstalk <−19 dB in a length of 17.73 μm. Moreover, the device’s working bandwidth and the fabrication tolerance of the key structural parameters are analyzed in detail. With these features, such devices would be beneficial for the on-chip multimode applications such as mode-division multiplexing transmission.

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“…Numerical results show that the conversion efficiencies of TE 0 -to-TE 1 , TE 0 -to-TE 2 , and TE 0 -to-TE 3 mode-order converters are larger than 94.4%, 95.7%, and 83.7% in the wavelength range from 1.5 to 1.6 μm, with corresponding device lengths of 8.72, 4.98, and 14.54 μm, respectively. Recently, TE 1 -to-TE 2 mode conversion was achieved via two cascaded SWGs, which shows the potential for realizing arbitrary mode-order converters by cascading multiple SWGs [59]. Another type of mode handling device is the mode blocking filter, which suppresses undesired modes without affecting others.…”

Section: Subwavelength Structured Mode Handling Devicesmentioning

confidence: 99%

Subwavelength structured silicon waveguides and photonic devices

Sun

Zhang

et al. 2020

Nanophotonics

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AbstractSubwavelength structures such as subwavelength gratings (SWGs) and subwavelength metamaterials are capable of tailoring the optical properties of materials and controlling the flow of light at the nanoscale. The effective indices of the subwavelength structured strip and slab waveguides can be changed in a wide range by choosing an appropriate duty cycle or a filling factor of silicon, which provides an effective method to manipulate the optical field and achieve effective index matching for functional devices. Recent advances in nanofabrication techniques have made it possible to implement subwavelength structures in silicon strip and slab waveguides. Here we review various approaches used to design subwavelength structures and achieve exotic optical responses and discuss how these structures can be used to realize high-performance silicon photonic devices. Both one-dimensional SWG devices and two-dimensional subwavelength metamaterial devices are covered in this review, including subwavelength structure–based polarization handling devices, mode manipulation devices, and building blocks for integrated optical interconnects. Perspectives on subwavelength structured silicon photonic devices are also discussed.

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On-chip mode converter based on two cascaded Bragg gratings

Cited by 48 publications

References 39 publications

Efficient TE-Polarized Mode-Order Converter Based on High-Index-Contrast Polygonal Slot in a Silicon-on-Insulator Waveguide

Efficient TE-Polarized Mode-Order Converter Based on High-Index-Contrast Polygonal Slot in a Silicon-on-Insulator Waveguide

Silicon-Based TM0-to-TM3 Mode-Order Converter Using On-Chip Shallowly Etched Slot Metasurface

Subwavelength structured silicon waveguides and photonic devices

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