{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,20]],"date-time":"2026-08-20T04:25:51Z","timestamp":1787199951934,"version":"build-2736575974"},"reference-count":24,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T00:00:00Z","timestamp":1787011200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"MSIT\/IITP","award":["2019-0-00002"],"award-info":[{"award-number":["2019-0-00002"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nanomaterials"],"abstract":"<jats:p>Spectrally flat-topped and polarization-insensitive coarse wavelength division multiplexing (CWDM)-targeted optical demultiplexers based on distributed multimode-interference (MMI) phase compensations are analytically calculated and experimentally demonstrated. The proposed device for use in a CWDM optical receiver consists of a polarization splitter-rotator (PSR) and two identical silicon-nanowire multiple delayed interferometric (MDI) demultiplexers. The broadband operating nature of MMI couplers is highly suitable for applying the proposed device to &gt;60 nm wide CWDM applications. Moreover, by properly adjusting the relative output phase relations of MMI couplers according to their optical splitting ratios, we experimentally validated a flat-topped CWDM spectral response within the O-band spectral range. Concurrently, stable optical demultiplexing operations were maintained regardless of the input signal polarization states via the monolithically integrated PSR. Fabricated using a silicon photonics foundry process based on ArF-dry lithography technology, the devices exhibited a 1 dB flat bandwidth of &gt;12 nm, a polarization-dependent loss of &lt;1.0 dB, an adjacent-channel isolation of &gt;10 dB, and a polarization crosstalk of &lt;\u221220 dB across the measured output channels. Although the current spectral crosstalk is ~\u221210 dB, it can be further suppressed to the \u221220 dB level through fabrication process optimization to minimize random phase fluctuations, or by incorporating a double-filtering scheme. This distributed MMI phase compensation strategy can be broadly applied to scalable WDM architectures in datacom applications.<\/jats:p>","DOI":"10.3390\/nano16161024","type":"journal-article","created":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T13:11:57Z","timestamp":1787058717000},"page":"1024","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Spectrally Flat and Polarization-Diversified Silicon-Nanowire Coarse WDM Demultiplexers Based on Distributed Multimode-Interference Phase Compensations"],"prefix":"10.3390","volume":"16","author":[{"given":"Seok-Hwan","family":"Jeong","sequence":"first","affiliation":[{"name":"Department of Semiconductor Engineering, The University of Suwon, Hwaseong 18323, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Heuk","family":"Park","sequence":"additional","affiliation":[{"name":"Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joon Ki","family":"Lee","sequence":"additional","affiliation":[{"name":"Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"5706","DOI":"10.1364\/OE.373454","article-title":"4-channel 200 Gb\/s WDM O-band silicon photonic transceiver sub-assembly","volume":"28","author":"Pitris","year":"2020","journal-title":"Opt. 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