Multi-Channel Parallel Silicon Mode-Order Converter for Multimode On-Chip Optical Switching

Jia, Hao; Chen, Haoxiang; Wang, Tao; Xiao, Huifu; Ren, Guanghui; Mitchell, Arnan; Yang, Jianhong; Tian, Yonghui

doi:10.1109/jstqe.2019.2958997

Cited by 14 publications

(13 citation statements)

References 26 publications

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“…Previously, little progress was made on multi‐mode conversion from multiple low‐order modes to high‐order modes except a recent demonstration with two particular pairs of modes using an inverse design. [ 32 ] The key challenge of realizing multi‐mode conversion is to achieve equally high conversion efficiencies for multiple mode pairs. Due to the significant discrepancy of the phase matching conditions between different pairs of modes, multi‐mode conversion is difficult to realize using conventional phase matching techniques based on periodic perturbations.…”

Section: Figurementioning

confidence: 99%

“…We also verify the scalability of the device with more mode pairs by simulations. The proposed method shows several advantages: 1) the design is computationally efficient relative to other approaches, for example, inverse design, which may take tens of hours; [ 32,33 ] 2) the insertion loss of the device is low by using shallow etching of optimized 2D patterns on the surface of the silicon waveguide; 3) the device is tolerant to fabrication errors as the device performance is insensitive to certain structural parameter changes; 4) the design methodology is scalable toward higher‐order modes and more mode pairs.…”

Section: Figurementioning

confidence: 99%

“…The optimization process using two Xeon Gold 6128 processors consumes about 15 min. Table S1, Supporting Information compares the computation time of our method with other algorithms used to optimize similar objectives, such as two‐modes conversion [ 32 ] and two‐modes exchange. [ 33 ] It clearly indicates that our proposed method is computationally efficient.…”

Section: Figurementioning

confidence: 99%

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On‐Chip Multi‐Mode Manipulation via 2D Refractive‐Index Perturbation on a Waveguide

Yao

Wang

et al. 2020

Advanced Optical Materials

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illustrate our design methodology. Previously, little progress was made on multimode conversion from multiple low-order modes to high-order modes except a recent demonstration with two particular pairs of modes using an inverse design. [32] The key challenge of realizing multi-mode conversion is to achieve equally high conversion efficiencies for multiple mode pairs. Due to the significant discrepancy of the phase matching conditions between different pairs of modes, multi-mode conversion is difficult to realize using conventional phase matching techniques based on periodic perturbations. [16-18] In the following, we demonstrate a scalable and computationally efficient method for low-loss multi-mode conversion using a quasi 2D metastructure on a silicon waveguide. Shallow hexagonal trenches etched on the silicon waveguide provide sufficient refractive-index perturbations and introduce low excess losses. A segmented index profile in the transverse direction is designed based on coupled mode theory to maximize target mode coupling coefficients, while a quasi-periodic refractiveindex variation along the propagation direction is optimized by particle swarm optimization (PSO) algorithm to achieve approximately equal conversion efficiencies for multiple pairs of modes. As a proof-of-concept experiment, we demonstrate a multi-mode converter that can realize the simultaneous conversion processes from TE i modes to TE i+3 (i = 0, 1, and 2) modes. The length of the multi-mode converter is 16.2 µm. For the TE 0to-TE 3 , TE 1-to-TE 4 , and TE 2-to-TE 5 mode conversion processes, the measured insertion losses are 0.4, 1.0, and 0.5 dB, respectively, and the corresponding crosstalk values are below −15.5, −16.5, and −14.1 dB, respectively, at 1538 nm. We also verify the scalability of the device with more mode pairs by simulations. The proposed method shows several advantages: 1) the design is computationally efficient relative to other approaches, for example, inverse design, which may take tens of hours; [32,33] 2) the insertion loss of the device is low by using shallow etching of optimized 2D patterns on the surface of the silicon waveguide; 3) the device is tolerant to fabrication errors as the device performance is insensitive to certain structural parameter changes; 4) the design methodology is scalable toward higherorder modes and more mode pairs. The propagation of optical field in a perturbed dielectric structure can be approximately described by the coupled mode theory. Attributed to the index perturbations on a silicon multimode waveguide, energy can be coupled from one waveguide mode to other modes, and the amplitude of each mode along Generation and manipulation of optical modes are of general interest to the photonics community. Mode conversion is an essential requirement in modedivision multiplexed systems. In this paper, a scalable method to simultaneously manipulate multiple waveguide modes on chip is proposed. As one experimental demonstration, simultaneous multi-mode conversion processes have been achieved o...

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Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

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On‐Chip Multi‐Mode Manipulation via 2D Refractive‐Index Perturbation on a Waveguide

Yao

Wang

et al. 2020

Advanced Optical Materials

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“…Under this condition, we require the waveguide to be able to generate more higher-order eigenmodes on-chip. In order to solve this issue, high-performance mode-order converters which can change the input fundamental mode into the higherorder mode are the pivotal components for the on-chip MDM applications [6,[8][9][10].…”

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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“…Traditionally, multimode interference (MMI) couplers [36][37][38], photonic crystal waveguides [39,40] or cascaded tapers [41] are employed. Moreover, several computer-generated nanostructures based on inverse-design algorithms have also been demonstrated [42][43][44][45]. (iii) Beam forming technique: The concept follows that the th N ( ≥ N 1 ) order TE mode can be treated as a combination of N+1 antiphase adjacent TE 0 -like modes.…”

Section: Introductionmentioning

confidence: 99%

Scalable Metasurface Building Blocks for Arbitrary On-chip High-order Mode Manipulation

Xiang

Tao

Zhao

et al. 2020

2020 European Conference on Optical Communications (ECOC)

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On-chip integrated mode-division multiplexing (MDM) has been emerging as a promising technology to further improve the link capacity and satisfy the continuously increasing bandwidth demand in data communications. One of the most important components in MDM and multimode photonics is a mode converter. While several configurations have been developed to realize on-chip mode converters, it is still very challenging to achieve versatile high-order mode converters with high performance in a generic way to reduce the R&D and prototyping costs. Here we initiate a breakthrough utilizing a simple yet universal generic building block concept with metasurface structures to implement programmable arbitrary highorder mode converters with competitive performance, high reliability and compact footprints. The building block, i.e., the TE0-TE2 mode converter is first introduced to illustrate the generic concept, which exhibits low insertion loss of 0.3 dB, low crosstalk of -10 dB across broad wavelength band of 250 nm with a footprint of 2.7×1.3 µ 2 m . All even-order and odd-order mode converters can be realized by directly programming multiple parallel basic building blocks and coarsely engineering the waveguide widths simply in a universal approach. The proposed mode converter building blocks for high-order mode conversion highlight features of uniform performance with broad bandwidth, low insertion loss, compact footprints and good fabrication tolerance, plus the uniquely simple and scalable generic fashion, making them extremely attractive for on-chip multimode optical interconnections.

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Multi-Channel Parallel Silicon Mode-Order Converter for Multimode On-Chip Optical Switching

Cited by 14 publications

References 26 publications

On‐Chip Multi‐Mode Manipulation via 2D Refractive‐Index Perturbation on a Waveguide

On‐Chip Multi‐Mode Manipulation via 2D Refractive‐Index Perturbation on a Waveguide

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

Scalable Metasurface Building Blocks for Arbitrary On-chip High-order Mode Manipulation

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