Reconstruction of extraordinary refractive index profile of O2+ ion-implanted LiNbO3 single-mode channel waveguide based on beam propagation method and image processing

2007 ◽  
Vol 274 (1) ◽  
pp. 80-84 ◽  
Author(s):  
Xiangzhi Liu ◽  
Fei Lu ◽  
Feng Chen ◽  
Ruifeng Zhang ◽  
Hanping Liu ◽  
...  
2019 ◽  
Vol 9 (20) ◽  
pp. 4362 ◽  
Author(s):  
Adel Shaaban ◽  
Yi-Chun Du ◽  
Lotfy Rabeh Gomaa

We adapted a fast Fourier transform-based Beam Propagation Method (FFT-BPM) to investigate waveguide discontinuities in plasmonic waveguides. The adaptation of the FFT-BPM to treat transverse magnetic (TM) fields requires the circumvention of two major difficulties: the mixed derivatives of the magnetic field and waveguide refractive index profile in the TM wave equation and the step-like index change at the transverse metal-dielectric boundary of the plasmonic guide and the transverse boundaries of the dielectric waveguide as well. An equivalent-index method is adopted to transform TM fields to transverse electric (TE) ones, thus enabling the benefit of the full power and simplicity of the FFT-BPM. Moreover, an appropriate smoothing function is used to approximate the step-like refractive index profile in the transverse direction. At the junction plane, we used an accurate combined spatial-spectral reflection operator to calculate the reflected field. To validate our proposed scheme, we investigated the modal propagation in a silicon waveguide terminated by air (like a laser facet in two cases: with and without a coating layer). Then we considered a subwavelength plasmonic waveguide (metal-insulator-metal MIM) butt-coupled with a dielectric waveguide, where the power transmission efficiency has been calculated and compared with other numerical methods. The comparison reveals good agreement.


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