Numerical Study on Fabrication Tolerance of Half-Ridge InP Polarization Converters

Masaru ZAITSU  Takuo TANEMURA  Yoshiaki NAKANO  

IEICE TRANSACTIONS on Electronics   Vol.E97-C   No.7   pp.731-735
Publication Date: 2014/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E97.C.731
Type of Manuscript: INVITED PAPER (Special Section on Opto-electronics and Communications for Future Optical Network)
Polarization converters,  fabrication tolerances,  monolithic integration,  polarization-multiplexing,  photonic integrated circuits,  

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Integrated InP polarization converters based on half-ridge structure are studied numerically. We demonstrate that the fabrication tolerance of the half-ridge structure can be extended significantly by introducing a slope at the ridge side and optimizing the thickness of the residual InGaAsP layer. High polarization conversion over 90% is achieved with the broad range of the waveguide width from 705 to 915 nm, corresponding to a factor-of-two or larger improvement in the fabrication tolerance compared with that of the conventional polarization converters. Finally we present a simple fabrication procedure of this newly proposed structure, where the thickness of the residual InGaAsP layer is controlled precisely by using a thin etch-stop layer.