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We present an efficient segmented-stepwise method to design a short and low-loss mode-size converter. A silicon-on-insulator platform-based converter with 20 μm length and 95.2% conversion efficiency is acquired by taking only 10 optimization generations using 2D-FDTD method. A 3D-FDTD simulation is performed to verify the calculated results, returning an efficiency of 92.1%. The proposed device can be used to connect a 12-μm-wide waveguide and a 0.5-μm-wide single-mode waveguide, with comparable performance of a regular scheme using 150-μm-long linear taper. For demonstration, the converter was fabricated by electron-beam-lithography and inductively-coupled-plasma etching. A conversion loss of -0.62±0.02 dB at 1550 nm was experimentally measured.
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http://dx.doi.org/10.1364/OL.39.006273 | DOI Listing |
We demonstrate efficient edge couplers by fabricating a 3D mode size converter on a lithium niobate-on-insulator photonic platform. The 3D mode size converter is fabricated using an etching process that employs a Si external mask to provide height variation and adjust the width variation through tapering patterns via lithography. The measured edge coupling efficiency with a 3D mode size converter was approximately 1.
View Article and Find Full Text PDFNanophotonics
September 2024
State Key Laboratory for Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Center for Optical & Electromagnetic Research, International Research Center for Advanced Photonics, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
Efficient coupling between optical fibers and on-chip photonic waveguides has long been a crucial issue for photonic chips used in various applications. Edge couplers (ECs) based on an inverse taper have seen widespread utilization due to their intrinsic broadband operation. However, it still remains a big challenge to realize polarization-insensitive low-loss ECs working at the O-band (1,260-1,360 nm), mainly due to the strong polarization dependence of the mode coupling/conversion and the difficulty to fabricate the taper tip with an ultra-small feature size.
View Article and Find Full Text PDFThis paper demonstrates the benefits of leveraging free-space optics concepts in the design of certain integrated photonic components, leading to a footprint reduction without compromising on performance. Specifically, we present ultra-short, highly efficient and fabrication-friendly mode-size converters based on metamaterial Fresnel lens-assisted tapers. This is achieved using a parameterized inverse-design approach, where the metamaterial phase shifters are realized using fabrication-friendly Manhattan geometries, by optimizing the width, length, and position of the phase shifters.
View Article and Find Full Text PDFIn this Letter, we propose and demonstrate an integrated mode-size converter (MSC) with a compact footprint, low losses, and a broad bandwidth. By exploiting a parabolic mirror, the divergent light from a narrow waveguide (450 nm) is collimated to match the mode size of a wide waveguide (10 µm). The measured insertion loss (IL) is ≈ 0.
View Article and Find Full Text PDFOpt Express
October 2021
Fiber couplers usually take a lot of space on photonic integrated circuits due to the large mode-size mismatch between the waveguide and fiber, especially when a fiber with larger core is utilized, such as a few-mode fiber. We demonstrate experimentally that such challenge can be overcome by an ultra-compact mode-size converter with a footprint of only 10 µm. Our device expands TE and TE waveguide modes simultaneously from a 1-µm wide strip waveguide to an 18-µm wide slab on a 220-nm thick silicon-on-insulator, with calculated losses of 0.
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