Compact Polarization-Insensitive 2 × 2 3 dB Quasi-Adiabatic Coupler Based on Shape Optimization

Su, Guangchen; Chen, Hongliang; Fu, Xin; Yang, Lin

doi:10.3390/photonics12030208

Open AccessArticle

Compact Polarization-Insensitive 2 × 2 3 dB Quasi-Adiabatic Coupler Based on Shape Optimization

¹

Key Laboratory of Optoelectronic Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China

²

Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

^*

Author to whom correspondence should be addressed.

Photonics 2025, 12(3), 208; https://doi.org/10.3390/photonics12030208

Submission received: 17 January 2025 / Revised: 14 February 2025 / Accepted: 26 February 2025 / Published: 27 February 2025

(This article belongs to the Special Issue Recent Advancement in Microwave Photonics)

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Abstract

In this study, we designed and experimentally demonstrated a compact polarization-insensitive 2 × 2 3 dB quasi-adiabatic coupler based on B-spline curves and shape optimization. By using the supermode to enable the segmented shape optimization of the coupler, we significantly reduced the computational cost of the optimization process. The numerical simulation results exhibited a power imbalance below ±0.46 dB and an insert loss (IL) of less than 0.09 dB over a broad bandwidth of 140 nm, ranging from 1490 nm to 1630 nm for both the TE and TM polarizations, with a compact coupling length of 12 µm. The experimental results showed a power splitting ratio within 3 ± 0.46 dB over the range of 1525 nm–1600 nm for the TM mode and 1576 nm–1610 nm for the TE mode. This broadband and low-loss 3 dB coupler is suitable for microwave photonic (MPW) applications, enabling efficient polarization-independent signal processing in integrated photonic systems.

Keywords: quasi-adiabatic coupler; inverse design; shape optimization; silicon photonics; waveguide devices

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MDPI and ACS Style

Su, G.; Chen, H.; Fu, X.; Yang, L. Compact Polarization-Insensitive 2 × 2 3 dB Quasi-Adiabatic Coupler Based on Shape Optimization. Photonics 2025, 12, 208. https://doi.org/10.3390/photonics12030208

AMA Style

Su G, Chen H, Fu X, Yang L. Compact Polarization-Insensitive 2 × 2 3 dB Quasi-Adiabatic Coupler Based on Shape Optimization. Photonics. 2025; 12(3):208. https://doi.org/10.3390/photonics12030208

Chicago/Turabian Style

Su, Guangchen, Hongliang Chen, Xin Fu, and Lin Yang. 2025. "Compact Polarization-Insensitive 2 × 2 3 dB Quasi-Adiabatic Coupler Based on Shape Optimization" Photonics 12, no. 3: 208. https://doi.org/10.3390/photonics12030208

APA Style

Su, G., Chen, H., Fu, X., & Yang, L. (2025). Compact Polarization-Insensitive 2 × 2 3 dB Quasi-Adiabatic Coupler Based on Shape Optimization. Photonics, 12(3), 208. https://doi.org/10.3390/photonics12030208

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Compact Polarization-Insensitive 2 × 2 3 dB Quasi-Adiabatic Coupler Based on Shape Optimization

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