Inverse-Designed Narrow-Band and Flat-Top Bragg Grating Filter

Chen, Yu; He, An; Yao, Junjie; Zhong, Meilin; Li, Zhihao; Zhang, Leyuan; Cao, Wei; Sun, Xu; Shen, Gangxiang; Liu, Ning

doi:10.3390/photonics12111049

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Inverse-Designed Narrow-Band and Flat-Top Bragg Grating Filter

by

Yu Chen

¹

,

An He

¹,

Junjie Yao

¹,

Meilin Zhong

¹,

Zhihao Li

¹,

Leyuan Zhang

¹,

Wei Cao

²

,

Xu Sun

²,

Gangxiang Shen

¹ and

Ning Liu

^1,*

¹

School of Electronic and Information Engineering, Soochow University, Suzhou 215006, China

²

Silicon Photonics R&D Center, CreaLights Technology Co., Ltd., Suzhou 215124, China

^*

Author to whom correspondence should be addressed.

Photonics 2025, 12(11), 1049; https://doi.org/10.3390/photonics12111049

Submission received: 10 September 2025 / Revised: 16 October 2025 / Accepted: 21 October 2025 / Published: 23 October 2025

(This article belongs to the Special Issue Silicon Photonics: From Fundamentals to Future Directions)

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Abstract

Integrated optical filters are fundamental and indispensable components of silicon photonics, which enhance the data throughput of high-demand communication networks. Grating-assisted filters have been widely used due to the merits they offer: flat top, low crosstalk, and no FSR. In this paper, we report an inverse-designed narrow-band silicon Bragg grating filter that unites lateral-misalignment apodization with cooperative particle swarm optimization (CPSO). The initial coupling-coefficient profile of the filter is first yielded by a layer-peeling algorithm (LPA). Subsequently, the final structure is designed by CPSO to approach the desired spectral response. The filter is fabricated on a 220 nm silicon-on-insulator platform. The measured results exhibit 3.39 nm bandwidth, 19.34 dB side lobe suppression ratio (SLSR), and 1.75 dB insertion loss. The proposed design method effectively solves the problem of excessively high side lobes in uniform gratings and LPA-designed gratings when designing narrow-bandwidth filters.

Keywords: inverse design; Bragg-grating filter; silicon photonics; cooperative particle swarm optimization

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MDPI and ACS Style

Chen, Y.; He, A.; Yao, J.; Zhong, M.; Li, Z.; Zhang, L.; Cao, W.; Sun, X.; Shen, G.; Liu, N. Inverse-Designed Narrow-Band and Flat-Top Bragg Grating Filter. Photonics 2025, 12, 1049. https://doi.org/10.3390/photonics12111049

AMA Style

Chen Y, He A, Yao J, Zhong M, Li Z, Zhang L, Cao W, Sun X, Shen G, Liu N. Inverse-Designed Narrow-Band and Flat-Top Bragg Grating Filter. Photonics. 2025; 12(11):1049. https://doi.org/10.3390/photonics12111049

Chicago/Turabian Style

Chen, Yu, An He, Junjie Yao, Meilin Zhong, Zhihao Li, Leyuan Zhang, Wei Cao, Xu Sun, Gangxiang Shen, and Ning Liu. 2025. "Inverse-Designed Narrow-Band and Flat-Top Bragg Grating Filter" Photonics 12, no. 11: 1049. https://doi.org/10.3390/photonics12111049

APA Style

Chen, Y., He, A., Yao, J., Zhong, M., Li, Z., Zhang, L., Cao, W., Sun, X., Shen, G., & Liu, N. (2025). Inverse-Designed Narrow-Band and Flat-Top Bragg Grating Filter. Photonics, 12(11), 1049. https://doi.org/10.3390/photonics12111049

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