Freeform thin-film lithium niobate mode converter for photon-pair generation

Thin-film lithium niobate (TFLN) has emerged as a promising platform for integrated photonics due to its exceptional material properties. The application of freeform topology optimization to TFLN devices enables the realization of compact designs with complex functionalities and high efficiency. How...

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Main Authors: Kim Changhyun, Bae Munseong, Choi Minho, Lee Sangbin, Lee Myunghoo, Kim Chihyeon, Jung Hojoong, Chung Haejun, Kwon Hyounghan
Format: Article
Language:English
Published: De Gruyter 2025-02-01
Series:Nanophotonics
Subjects:
Online Access:https://doi.org/10.1515/nanoph-2024-0515
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author Kim Changhyun
Bae Munseong
Choi Minho
Lee Sangbin
Lee Myunghoo
Kim Chihyeon
Jung Hojoong
Chung Haejun
Kwon Hyounghan
author_facet Kim Changhyun
Bae Munseong
Choi Minho
Lee Sangbin
Lee Myunghoo
Kim Chihyeon
Jung Hojoong
Chung Haejun
Kwon Hyounghan
author_sort Kim Changhyun
collection DOAJ
description Thin-film lithium niobate (TFLN) has emerged as a promising platform for integrated photonics due to its exceptional material properties. The application of freeform topology optimization to TFLN devices enables the realization of compact designs with complex functionalities and high efficiency. However, the stringent fabrication constraints of TFLN present significant challenges for optimization, particularly in nonlinear photonic devices. In this work, we propose an inverse design methodology that successfully addresses these challenges and demonstrates the development of an efficient freeform TFLN mode converter. The numerically optimized mode converter achieves a transmission efficiency of 67.60 % and a mode purity of 84.58 %. Experimental validation through nonlinear processes, including second harmonic generation and spontaneous parametric down-conversion, shows that the fabricated devices improve the efficiency of these processes by factors of two and three, respectively, compared to devices without freeform designs. The proposed inverse design framework provides a powerful tool for advancing the development of TFLN-based devices, with broad applicability to nonlinear and quantum photonics.
format Article
id doaj-art-77d7f063ddcd4cc8991a472593cff492
institution DOAJ
issn 2192-8614
language English
publishDate 2025-02-01
publisher De Gruyter
record_format Article
series Nanophotonics
spelling doaj-art-77d7f063ddcd4cc8991a472593cff4922025-08-20T02:40:18ZengDe GruyterNanophotonics2192-86142025-02-0114111949196010.1515/nanoph-2024-0515Freeform thin-film lithium niobate mode converter for photon-pair generationKim Changhyun0Bae Munseong1Choi Minho2Lee Sangbin3Lee Myunghoo4Kim Chihyeon5Jung Hojoong6Chung Haejun7Kwon Hyounghan8Center for Quantum Technology, 58975Korea Institute of Science and Technology (KIST), Seoul02792, South KoreaDepartment of Electronic Engineering, Hanyang University, Seoul, 04763, South KoreaCenter for Quantum Technology, 58975Korea Institute of Science and Technology (KIST), Seoul02792, South KoreaDepartment of Artificial Intelligence Semiconductor Engineering, Hanyang University, Seoul, 04763, South KoreaDepartment of Electrical and Computer Engineering, University of Washington, Seattle, WA, 98195, USADepartment of Electronic Engineering, Hanyang University, Seoul, 04763, South KoreaCenter for Quantum Technology, 58975Korea Institute of Science and Technology (KIST), Seoul02792, South KoreaDepartment of Electronic Engineering, Department of Artificial Intelligence, and Department of Artificial Intelligence Semiconductor Engineering, Hanyang University, Seoul, 04763, South KoreaCenter for Quantum Technology, 58975Korea Institute of Science and Technology (KIST), Seoul02792, South KoreaThin-film lithium niobate (TFLN) has emerged as a promising platform for integrated photonics due to its exceptional material properties. The application of freeform topology optimization to TFLN devices enables the realization of compact designs with complex functionalities and high efficiency. However, the stringent fabrication constraints of TFLN present significant challenges for optimization, particularly in nonlinear photonic devices. In this work, we propose an inverse design methodology that successfully addresses these challenges and demonstrates the development of an efficient freeform TFLN mode converter. The numerically optimized mode converter achieves a transmission efficiency of 67.60 % and a mode purity of 84.58 %. Experimental validation through nonlinear processes, including second harmonic generation and spontaneous parametric down-conversion, shows that the fabricated devices improve the efficiency of these processes by factors of two and three, respectively, compared to devices without freeform designs. The proposed inverse design framework provides a powerful tool for advancing the development of TFLN-based devices, with broad applicability to nonlinear and quantum photonics.https://doi.org/10.1515/nanoph-2024-0515lithium niobatemode converterinverse designtopology optimizationspontaneous parametric down conversion
spellingShingle Kim Changhyun
Bae Munseong
Choi Minho
Lee Sangbin
Lee Myunghoo
Kim Chihyeon
Jung Hojoong
Chung Haejun
Kwon Hyounghan
Freeform thin-film lithium niobate mode converter for photon-pair generation
Nanophotonics
lithium niobate
mode converter
inverse design
topology optimization
spontaneous parametric down conversion
title Freeform thin-film lithium niobate mode converter for photon-pair generation
title_full Freeform thin-film lithium niobate mode converter for photon-pair generation
title_fullStr Freeform thin-film lithium niobate mode converter for photon-pair generation
title_full_unstemmed Freeform thin-film lithium niobate mode converter for photon-pair generation
title_short Freeform thin-film lithium niobate mode converter for photon-pair generation
title_sort freeform thin film lithium niobate mode converter for photon pair generation
topic lithium niobate
mode converter
inverse design
topology optimization
spontaneous parametric down conversion
url https://doi.org/10.1515/nanoph-2024-0515
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