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An ultra‐compact multimode interference coupler with a subwavelength grating slot
Author(s) -
OrtegaMoñux Alejandro,
AlonsoRamos Carlos,
MaeseNovo Alejandro,
Halir Robert,
ZavargoPeche Luis,
PérezGalacho Diego,
MolinaFernández Iñigo,
WangüemertPérez J. Gonzalo,
Cheben Pavel,
Schmid Jens H.,
Lapointe Jean,
Xu Danxia,
Janz Siegfried
Publication year - 2013
Publication title -
laser and photonics reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.778
H-Index - 116
eISSN - 1863-8899
pISSN - 1863-8880
DOI - 10.1002/lpor.201200106
Subject(s) - cladding (metalworking) , materials science , silicon on insulator , grating , extinction ratio , fabrication , optoelectronics , power dividers and directional couplers , photonics , optics , electronic circuit , silicon , physics , electrical engineering , engineering , wavelength , medicine , alternative medicine , pathology , metallurgy
Multimode interference couplers (MMIs) are fundamental building blocks in photonic integrated circuits. Here it is experimentally demonstrated, for the first time, a two‐fold length reduction in an MMI coupler without any penalty on device performance. The design is based on a slotted 2 × 2 MMI fabricated on a commercial silicon‐on‐insulator (SOI) substrate. The slot is implemented with a subwavelength grating (SWG) comprising holes fully etched down to the oxide cladding, thereby allowing single etch step fabrication. The device has been designed using an in‐house tool based on the Fourier Eigenmode Expansion Method. It has a footprint of only 3.5 μm x 23 μm and it exhibits a measured extinction ratio better than 15 dB within the full C‐band (1530 nm‒1570 nm). SWG engineered slots thus offer excellent perspectives for the practical realization of MMIs couplers with substantially reduced footprint yet with outstanding performance.