Analysis of scattering loss due to sidewall roughness in slot waveguides by variation of mode effective index

Sidewall-roughness scattering loss is generally severe in slot waveguides manufactured by lithography process. A suitable model is absent for evaluating this scattering loss in slot waveguides. In this paper, basing on the mechanism of sidewall-roughness scattering, we analyze the relative extent of the scattering loss in slot waveguides by the variation of mode effective refractive index induced by the sidewall roughness, i.e. the derivative of the effective refractive index with respect to the width of the waveguide's high-index strips. Effects of waveguide structure on this derivative are obtained and their rationality is discussed. The characteristics of the sidewall-roughness scattering loss in slot waveguides are extrapolated. We demonstrate that this model is feasible for estimating the relative extent of the scattering loss in slot waveguides and the influence of waveguide parameters on it. In addition, referring to the same model for solid-core strip waveguides, the proportionality factor relating attenuation coefficient and the effective index derivative is provided. Comparison between calculation results and measured loss further verifies the applicability of this model to slot waveguides.

[1]  B. Garrido,et al.  Toward a 1.54 $\mu$m Electrically Driven Erbium-Doped Silicon Slot Waveguide and Optical Amplifier , 2013, Journal of Lightwave Technology.

[2]  K. Cui,et al.  Designing low transmission loss silicon slot waveguide at wavelength band of high material absorption , 2013 .

[3]  A. Melloni,et al.  Roughness induced backscattering in optical silicon waveguides. , 2010, Physical review letters.

[4]  Y. Fainman,et al.  Compact and integrated TM-pass waveguide polarizer. , 2005, Optics express.

[5]  C. Ciminelli,et al.  Fully three-dimensional accurate modeling of scattering loss in optical waveguides , 2009 .

[6]  Qianfan Xu,et al.  Guiding and confining light in void nanostructure. , 2004, Optics letters.

[7]  F. Payne,et al.  A theoretical analysis of scattering loss from planar optical waveguides , 1994 .

[8]  W Freude,et al.  Reduced propagation loss in silicon strip and slot waveguides coated by atomic layer deposition. , 2011, Optics express.

[9]  Fang Liu,et al.  Silicon Slot Waveguides With Low Transmission and Bending Losses at 1064 nm , 2016, IEEE Photonics Technology Letters.

[10]  Daniele Melati,et al.  A unified approach for radiative losses and backscattering in optical waveguides , 2014 .

[11]  Carlos Angulo Barrios,et al.  Optical Slot-Waveguide Based Biochemical Sensors , 2009, Sensors.

[12]  G. Lo,et al.  Low-loss silicon slot waveguides and couplers fabricated with optical lithography and atomic layer deposition. , 2011, Optics express.

[13]  T. Barwicz,et al.  Three-dimensional analysis of scattering losses due to sidewall roughness in microphotonic waveguides , 2005, Journal of Lightwave Technology.

[14]  Xu Liu,et al.  Design of a Compact Polarization Splitter in Horizontal Multiple-Slotted Waveguide Structures , 2008 .

[15]  Michael Hochberg,et al.  High-Q Optical Resonators in Silicon-on-Insulator-Based Slot Waveguides , 2005 .

[16]  Vittorio M. N. Passaro,et al.  Efficient Chemical Sensing by Coupled Slot SOI Waveguides , 2009, Sensors.

[17]  Maryse Fournier,et al.  Low-loss strip-loaded slot waveguides in silicon-on-insulator. , 2010, Optics express.

[18]  Fang Liu,et al.  Experimental demonstration of silicon slot waveguide with low transmission loss at 1064 nm , 2014 .

[19]  Michael Hochberg,et al.  Design and Fabrication of Segmented, Slotted Waveguides for Electro-Optic Modulation , 2007 .

[20]  Antao Chen,et al.  Reduction of scattering loss of silicon slot waveguides by RCA smoothing. , 2012, Optics letters.