{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T23:22:38Z","timestamp":1772234558643,"version":"3.50.1"},"posted":{"date-parts":[[2024,7,9]]},"group-title":"Physical Sciences","reference-count":0,"publisher":"MDPI AG","license":[{"start":{"date-parts":[[2024,7,9]],"date-time":"2024-07-09T00:00:00Z","timestamp":1720483200000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2024,7,8]]},"abstract":"<jats:p>Photonic circuits find applications in biomedicine, manufacturing, quantum computing and communications. Photonic waveguides are crucial components, typically having cross-sections orders of magnitude inferior compared with other photonic components (e. g. optical fibers, light sources and photodetectors). Several light coupling methods exist, consisting of either on-plane (e. g. adiabatic and end-fire coupling) or off-plane methods (e. g. grating and vertical couplers). The grating coupler is a versatile light transference technique which can be tested at wafer level, not requiring specific fiber terminations or additional optical components, like lenses, polarizers or prisms. This study focuses on fully-etched grating couplers without bottom reflector, made from hydrogenated amorphous silicon (a-Si:H), deposited over a silica substrate. Different coupler designs were tested, of these we highlight two: superimposition of two lithographic masks with different periods and an offset between them to create a random distribution and a technique based on the quadratic refractive index variation along the device&amp;rsquo;s length. Results were obtained by 2D-FDTD simulation. The designed grating couplers achieve coupling efficiencies for the TE-like mode over -8 dB (mask overlap) and -3 dB (quadratic variation), at a wavelength of 1550 nm. The coupling scheme considers a 220 nm a-Si:H waveguide and an SMF-28 optical fiber.<\/jats:p>","DOI":"10.20944\/preprints202407.0689.v1","type":"posted-content","created":{"date-parts":[[2024,7,10]],"date-time":"2024-07-10T15:34:13Z","timestamp":1720625653000},"source":"Crossref","is-referenced-by-count":1,"title":["Grating Coupler Design for Low-Cost Fabrication in Amorphous Silicon Photonic Integrated Circuits"],"prefix":"10.20944","author":[{"given":"Daniel","family":"Almeida","sequence":"first","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8785-445X","authenticated-orcid":false,"given":"Paulo","family":"Lourenco","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9938-0351","authenticated-orcid":false,"given":"Alessandro","family":"Fantoni","sequence":"additional","affiliation":[]},{"given":"Jo\u00e3o","family":"Costa","sequence":"additional","affiliation":[]},{"given":"Manuela","family":"Vieira","sequence":"additional","affiliation":[]}],"member":"1968","container-title":[],"original-title":[],"deposited":{"date-parts":[[2024,8,30]],"date-time":"2024-08-30T00:41:17Z","timestamp":1724978477000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.preprints.org\/manuscript\/202407.0689\/v1"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,7,9]]},"references-count":0,"URL":"https:\/\/doi.org\/10.20944\/preprints202407.0689.v1","relation":{"is-preprint-of":[{"id-type":"doi","id":"10.3390\/photonics11090783","asserted-by":"subject"}]},"subject":[],"published":{"date-parts":[[2024,7,9]]},"subtype":"preprint"}}