Optimizing Graphene Ring Modulators: A Comparative Study of Straight, Bent, and Racetrack Geometries
Graphene-based micro-ring modulators are promising candidates for next-generation optical interconnects, offering compact footprints, broadband operation, and CMOS compatibility. However, most demonstrations to date have relied on conventional straight bus coupling geometries, which limit design fle...
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| Format: | Article |
| Language: | English |
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MDPI AG
2025-07-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/15/15/1158 |
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| author | Pawan Kumar Dubey Ashraful Islam Raju Rasuole Lukose Christian Wenger Mindaugas Lukosius |
| author_facet | Pawan Kumar Dubey Ashraful Islam Raju Rasuole Lukose Christian Wenger Mindaugas Lukosius |
| author_sort | Pawan Kumar Dubey |
| collection | DOAJ |
| description | Graphene-based micro-ring modulators are promising candidates for next-generation optical interconnects, offering compact footprints, broadband operation, and CMOS compatibility. However, most demonstrations to date have relied on conventional straight bus coupling geometries, which limit design flexibility and require extremely small coupling gaps to reach critical coupling. This work presents a comprehensive comparative analysis of straight, bent, and racetrack bus geometries in graphene-on-silicon nitride (Si<sub>3</sub>N<sub>4</sub>) micro-ring modulators operating near 1.31 µm. Based on finite-difference time-domain simulation results, a proposed racetrack-based modulator structure demonstrates that extending the coupling region enables critical coupling at larger gaps—up to 300 nm—while preserving high modulation efficiency. With only 6–12% graphene coverage, this geometry achieves extinction ratios of up to 28 dB and supports electrical bandwidths approaching 90 GHz. Findings from this work highlight a new co-design framework for coupling geometry and graphene coverage, offering a pathway to high-speed and high-modulation-depth graphene photonic modulators suitable for scalable integration in next-generation photonic interconnects devices. |
| format | Article |
| id | doaj-art-cb19429ea65e4cf39157c67c7075ed33 |
| institution | Kabale University |
| issn | 2079-4991 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj-art-cb19429ea65e4cf39157c67c7075ed332025-08-20T03:36:22ZengMDPI AGNanomaterials2079-49912025-07-011515115810.3390/nano15151158Optimizing Graphene Ring Modulators: A Comparative Study of Straight, Bent, and Racetrack GeometriesPawan Kumar Dubey0Ashraful Islam Raju1Rasuole Lukose2Christian Wenger3Mindaugas Lukosius4IHP-Leibniz Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), GermanyIHP-Leibniz Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), GermanyIHP-Leibniz Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), GermanyIHP-Leibniz Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), GermanyIHP-Leibniz Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), GermanyGraphene-based micro-ring modulators are promising candidates for next-generation optical interconnects, offering compact footprints, broadband operation, and CMOS compatibility. However, most demonstrations to date have relied on conventional straight bus coupling geometries, which limit design flexibility and require extremely small coupling gaps to reach critical coupling. This work presents a comprehensive comparative analysis of straight, bent, and racetrack bus geometries in graphene-on-silicon nitride (Si<sub>3</sub>N<sub>4</sub>) micro-ring modulators operating near 1.31 µm. Based on finite-difference time-domain simulation results, a proposed racetrack-based modulator structure demonstrates that extending the coupling region enables critical coupling at larger gaps—up to 300 nm—while preserving high modulation efficiency. With only 6–12% graphene coverage, this geometry achieves extinction ratios of up to 28 dB and supports electrical bandwidths approaching 90 GHz. Findings from this work highlight a new co-design framework for coupling geometry and graphene coverage, offering a pathway to high-speed and high-modulation-depth graphene photonic modulators suitable for scalable integration in next-generation photonic interconnects devices.https://www.mdpi.com/2079-4991/15/15/1158graphene electro-absorption modulatorring resonatorsilicon nitride waveguidefinite-difference time-domain (FDTD) simulationcritical coupling |
| spellingShingle | Pawan Kumar Dubey Ashraful Islam Raju Rasuole Lukose Christian Wenger Mindaugas Lukosius Optimizing Graphene Ring Modulators: A Comparative Study of Straight, Bent, and Racetrack Geometries Nanomaterials graphene electro-absorption modulator ring resonator silicon nitride waveguide finite-difference time-domain (FDTD) simulation critical coupling |
| title | Optimizing Graphene Ring Modulators: A Comparative Study of Straight, Bent, and Racetrack Geometries |
| title_full | Optimizing Graphene Ring Modulators: A Comparative Study of Straight, Bent, and Racetrack Geometries |
| title_fullStr | Optimizing Graphene Ring Modulators: A Comparative Study of Straight, Bent, and Racetrack Geometries |
| title_full_unstemmed | Optimizing Graphene Ring Modulators: A Comparative Study of Straight, Bent, and Racetrack Geometries |
| title_short | Optimizing Graphene Ring Modulators: A Comparative Study of Straight, Bent, and Racetrack Geometries |
| title_sort | optimizing graphene ring modulators a comparative study of straight bent and racetrack geometries |
| topic | graphene electro-absorption modulator ring resonator silicon nitride waveguide finite-difference time-domain (FDTD) simulation critical coupling |
| url | https://www.mdpi.com/2079-4991/15/15/1158 |
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