Optimal geometry of nonlinear silicon slot waveguides accounting for the effect of waveguide losses (original) (raw)
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Optical properties of highly nonlinear silicon-organic hybrid (SOH) waveguide geometries
Optics Express, 2009
Geometry, nonlinearity, dispersion and two-photon absorption figure of merit of three basic silicon-organic hybrid waveguide designs are compared. Four-wave mixing and heterodyne pump-probe measurements show that all designs achieve high nonlinearities. The fundamental limitation of two-photon absorption in silicon is overcome using siliconorganic hybrid integration, with a five-fold improvement for the figure of merit (FOM). The value of FOM = 2.19 measured for silicon-compatible nonlinear slot waveguides is the highest value published.
Photonics Research, 2016
We investigate in this paper the influence of slow light on the balance between the Kerr and two-photon absorption (TPA) processes in silicon slotted hybrid nonlinear waveguides. Three typical silicon photonic waveguide geometries are studied to estimate the influence of the light slowdown factor on the mode field overlap with the silicon region, as well as on the complex effective nonlinear susceptibility. It is found that slotted photonic crystal modes tend to focalize in their hollow core with increasing group index (n G) values. Considering a hybrid integration of nonlinear polymers in such slotted waveguides, a relative decrease of the TPA process by more factor of 2 is predicted from n G 10 to n G 50. As a whole, this work shows that the relative influence of TPA decreases for slotted waveguides operating in the slow light regime, making them a suitable platform for third-order nonlinear optics.
Analytical predictions for nonlinear optical processes in silicon slot waveguides
Journal of Computational Electronics, 2018
Analytical expressions derived for dispersion relations and fields are used to obtain analytical predictions for the performance of modulators fabricated in second-order (χ 2) and third-order (χ 3) nonlinear materials filled into waveguide slot of siliconon-insulator waveguides. Analytical expressions are used to model the electron-optical modulation and Kerr effect on slot waveguides for the theoretical modeling. The results obtained for slot waveguides with second-order nonlinearities are compared with those obtained under the planar-waveguide approximations reported as in earlier work. Also, exhaustive solutions are obtained for third-order nonlinear slot waveguides. This work employs long standing and reliable mathematical methods to develop the computational modal of photonics integrated devices. Moreover, the present work allows one a new perspective on design of various optical devices based on low-index sub-wavelength nonlinear slot waveguides.
Optimized nonlinear SOI slot optical waveguides
fiber (PCF) Effective area (A eff) Silicon-on-insulator (SOI) Slot optical waveguide Finite element method (FEM) Group velocity dispersion (GVD) a b s t r a c t Nonlinear-optic (NLO) effects provide many device functions such as wavelength conversion and signal processing. The use of waveguides allows the implementation of efficient and compact devices. The importance of exploring nonlinear effects in Silicon-on-Insulator (SOI) slot optical waveguides is discernible from the facts that, it is CMOS technology compatible , thus ensuring low-cost large-scale integration, moreover, this structure of optical waveguides mingle the advantages of both silicon and silica to explore the promising non-linear interactions of light in the waveguides, such as rare-earth material doping to provide optical gain. In current research work, we have optimized nonlinear parameter () of the basic SOI slot optical waveguide by reducing the effective area (A eff). The effective area has been reduced by using Photonic Crystal Fiber (PCF) type cladding; where enough evidence is available that, SOI slot optical waveguide can be fabricated in a PCF type cladding. Wavelength dependent propagation constant values of slot optical waveguide are dominant over the band-gap effect (in case of PCF type cladding). Novelty lies in reducing the effective area (A eff) by a considerable amount, with respect to already established results. The results, besides opening further venues for researchers to find out nonlinear optimization techniques of slot optical waveguide structures can also help in enhancing lab on chip circuits, where in-built optical source is mandatory.
Optics Express, 2011
We describe a concept for second-order nonlinear optical processes in silicon photonics. A silicon-organic hybrid (SOH) double slot waveguide is dispersion-engineered for mode phase-matching (MPM). The proposed waveguide enables highly efficient nonlinear processes in the mid-IR range. With a cladding nonlinearity of χ (2) = 230 pm/V and 20 dBm pump power at a CW wavelength of 1550 nm, we predict a gain of 14.7 dB/cm for a 3100 nm signal. The suggested structure enables for the first time efficient second-order nonlinear optical mixing in silicon photonics with standard technology.
Flat and low dispersion in highly nonlinear slot waveguides
Optics express, 2010
We propose highly nonlinear slot waveguides with flat and low dispersion over a wide wavelength range. Si nano-crystal and chalcogenide glass are considered as slot materials. Over a 244-nm bandwidth, dispersion of 0+/-0.16 ps/(nmxm) is achieved in a silicon nano-crystal slot waveguide, with a nonlinear coefficient of 2874 /(Wm). The As(2)S(3) slot waveguide exhibits dispersion of 0+/-0.17 ps/(nmxm) over a bandwidth of 249 nm, with a nonlinear coefficient 16 times larger than that of As(2)S(3) rib waveguides and a nonlinear figure of merit three times larger than that of Si strip waveguides.
Nonlinear optical phenomena in silicon waveguides: modeling and applications
Optics Express, 2007
Several kinds of nonlinear optical effects have been observed in recent years using silicon waveguides, and their device applications are attracting considerable attention. In this review, we provide a unified theoretical platform that not only can be used for understanding the underlying physics but should also provide guidance toward new and useful applications. We begin with a description of the third-order nonlinearity of silicon and consider the tensorial nature of both the electronic and Raman contributions. The generation of free carriers through two-photon absorption and their impact on various nonlinear phenomena is included fully within the theory presented here. We derive a general propagation equation in the frequency domain and show how it leads to a generalized nonlinear Schrödinger equation when it is converted to the time domain. We use this equation to study propagation of ultrashort optical pulses in the presence of self-phase modulation and show the possibility of soliton formation and supercontinuum generation. The nonlinear phenomena of cross-phase modulation and stimulated Raman scattering are discussed next with emphasis on the impact of free carriers on Raman amplification and lasing. We also consider the four-wave mixing process for both continuous-wave and pulsed pumping and discuss the conditions under which parametric amplification and wavelength conversion can be realized with net gain in the telecommunication band.
Optics Letters, 2017
We derive from Maxwell's equations full-vectorial nonlinear propagation equations of four-wave mixing valid in straight semiconductor-on-insulator waveguides. Special attention is given to the resulting effective mode area, which takes a convenient form known from studies in photonic crystal fibers but has not been introduced in the context of integrated waveguides. We show that the difference between our full-vectorial effective mode area and the scalar equivalent often referred to in the literature may lead to mistakes when evaluating the nonlinear refractive index and optimizing designs of new waveguides. We verify the results of our derivation by comparing to experimental measurements in a silicon-on-insulator waveguide taking tolerances on fabrication parameters into account.