Cheng Z, Chen X, Wong CY, Xu K, Fung CKY, Chen YM, Tsang HK. Focusing subwavelength grating coupler for mid-infrared suspended membrane waveguide.
Opt Lett 2012;
37:1217-1219. [PMID:
22466200 DOI:
10.1364/ol.37.001217]
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Abstract
A mid-infrared (mid-IR)-focusing subwavelength grating (SWG) coupler and suspended membrane waveguide (SMW) on a silicon-on-insulator wafer are studied. For a transverse-electric mode uniform SWG, finite-difference time-domain simulation predicts 44.2% coupling efficiency with 1 dB bandwidth of about 220 nm and backreflection of 0.78% at 2.75 μm. Then the uniform SWG is curved to a focusing SWG using a phase-matching formula. The SMWs are analyzed by the finite element method and fabricated. An Er3+-Pr3+ co-doped mid-IR fiber laser is used for device characterization. The fabricated mid-IR SWG coupler has 24.7% coupling efficiency.
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