Birefringence and optical power confinement in horizontal multi-slot waveguides made of Si and SiO2.
ABSTRACT Through simulations and measurements, we show that in multi-slot thin film waveguides, the TM polarized modes can be confined mostly in the low refractive index layers of the waveguide. The structure consisted of alternating layers of a-Si and SiO(2), in the thickness range between 3 and 40 nm, for which the slots were the SiO(2) layers. Simulations were performed using the transfer matrix method and experiments using the m-line technique at 1.55 mum. The dependence of the birefringence and of the power confinement in the slots was studied as a function of the waveguide thickness, the Si and SiO(2) layer thicknesses, and the SiO(2) / Si layer thickness ratio. We find a large birefringence-a refractive index difference between TE and TM modes-as large as 0.8. For TM polarized modes, up to ~ 85% of the total power in the fundamental mode can be confined in the slots.
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ABSTRACT: Free carrier absorption (FCA) in silicon is the major obstacle toward achieving optical gain in Si nanostructure systems. In this Letter, we present experimental results of pump-induced loss for TE and TM polarization in multislot SiO<sub>2</sub>/nc-Si waveguides. Continuous wavelength and ultrafast studies of carriers excited in the nc-Si multilayers reveal strong suppression of transmission loss related to FCA in Si nanostructures for TM-polarized probe light. We demonstrate theoretically and experimentally that FCA may be reduced under TM polarization as much as 9 times compared to TE polarization.Optics Letters 11/2013; 38(22):4849-52. · 3.39 Impact Factor
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ABSTRACT: Bending efficiency of three-dimensional (3-D) horizontal single- and multiple-slot waveguide microrings are analyzed using a combination of effective-index and modified transfer-matrix methods. The effects of waveguide parameters, low-index material, high-index material, asymmetric structure, and asymmetric slots on the bending loss are studied. We show that the bending efficiency can be enhanced by applying asymmetric structures and asymmetric slots. In addition, it is demonstrated that the bending loss increases with increasing the number of slots. However, by using proper thicknesses for different high-index layers of horizontal multiple-slot waveguide, it is possible that horizontal multipleslot waveguide can provide a lower bending loss than the single-slot one.Proceedings of SPIE - The International Society for Optical Engineering 08/2010; · 0.20 Impact Factor
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ABSTRACT: In this paper, we propose a new dual slot based on rib-like structure, which exhibits a flat and near-zero dispersion over a 198 nm wide wavelength range. Chromatic dispersion of dual-slot silicon (Si) waveguide is mainly determined by waveguide dispersion due to the manipulating mode effective area rather than by the material dispersion. Moreover, the nonlinear coefficient and effective mode area of the waveguide are also explored in detail. A nonlinear coefficient of 1460/m/W at 1550 nm is achieved, which is 10 times larger than that of the Si rib waveguide. By changing different waveguide variables, both the dispersion and nonlinear coefficient can be tailored, thus enabling the potential for a highly nonlinear waveguide with uniform dispersion over a wide wavelength range, which could benefit the performance of broadband optical signal systems.Applied Optics 09/2014; 53(27). · 1.69 Impact Factor