Invited Article: Acousto-optic finite-difference frequency-domain algorithm for first-principles simulations of on-chip acousto-optic devices

Shi, Yu; Cerjan, Alexander; Fan, Shanhui

doi:10.1063/1.4975002

Cited by 3 publications

(1 citation statement)

References 53 publications

(129 reference statements)

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“…Notably, the use of 2 + 1D mode solvers in both optical and acoustic domains allows for accurate and efficient calculation of propagation parameters and coupling terms, which can be used as inputs to coupled mode theory or acousto-optic simulations 40 , 41 for accuracy comparable to full 3D simulations but with orders of magnitude faster simulation times. Such fast simulation enables design approaches that are not practical with full 3D simulations, such as large parameter sweeps and optimizations.…”

Section: Introductionmentioning

confidence: 99%

Acoustic Waveguide Eigenmode Solver Based on a Staggered-Grid Finite-Difference Method

Dostart

Liu

Popović

2017

Sci Rep

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A numerical method of solving for the elastic wave eigenmodes in acoustic waveguides of arbitrary cross-section is presented. Operating under the assumptions of linear, isotropic materials, it utilizes a finite-difference method on a staggered grid to solve for the acoustic eigenmodes (field and frequency) of the vector-field elastic wave equation with a given propagation constant. Free, fixed, symmetry, and anti-symmetry boundary conditions are implemented, enabling efficient simulation of acoustic structures with geometrical symmetries and terminations. Perfectly matched layers are also implemented, allowing for the simulation of radiative (leaky) modes. The method is analogous to that in eigenmode solvers ubiquitously employed in electromagnetics to find waveguide modes, and enables design of acoustic waveguides as well as seamless integration with electromagnetic solvers for optomechanical device design. The accuracy of the solver is demonstrated by calculating eigenfrequencies and mode shapes for common acoustic modes across four orders of magnitude in frequency in several simple geometries and comparing the results to analytical solutions where available or to numerical solvers based on more computationally expensive methods. The solver is utilized to demonstrate a novel type of leaky-guided acoustic wave that couples simultaneously to two independent radiation channels (directions) with different polarizations – a ‘bi-leaky’ mode.

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Section: Introductionmentioning

confidence: 99%

Acoustic Waveguide Eigenmode Solver Based on a Staggered-Grid Finite-Difference Method

Dostart

Liu

Popović

2017

Sci Rep

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Surface acoustic waves for acousto-optic modulation in buried silicon nitride waveguides

2019

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We theoretically investigate the use of Rayleigh surface acoustic waves (SAWs) for refractive index modulation in optical waveguides consisting of amorphous dielectrics. Considering low-loss Si 3 N 4 waveguides with a standard core cross-section of 4.4×0.03 µm 2 size, buried 8-µm deep in a SiO 2 cladding, we compare surface acoustic wave generation in various different geometries via a piezo-active, lead zirconate titanate film placed on top of the surface and driven via an interdigitized transducer (IDT). Using numerical solutions of the acoustic and optical wave equations, we determine the strain distribution of the SAW under resonant excitation. From the overlap of the acoustic strain field with the optical mode field, we calculate and maximize the attainable amplitude of index modulation in the waveguide. For the example of a near-infrared wavelength of 840 nm, a maximum shift in relative effective refractive index of 0.7x10 −3 was obtained for TE polarized light, using an IDT period of 30-35 µm, a film thickness of 2.5-3.5 µm, and an IDT voltage of 10 V. For these parameters, the resonant frequency is in the range of 70-85 MHz. The maximum shift increases to 1.2x10 −3 , with a corresponding resonant frequency of 87 MHz, when the height of the cladding above the core is reduced to 3 µm. The relative index change is about 300 times higher than in previous work based on non-resonant proximity piezo-actuation, and the modulation frequency is about 200 times higher. Exploiting the maximum relative index change of 1.2×10 −3 in a low-loss, balanced Mach-Zehnder modulator should allow full-contrast modulation in devices as short as 120 µm (half-wave voltage length product = 0.24 Vcm).

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Rigorous space-time coupled-wave analysis for patterned surfaces with temporal permittivity modulation [Invited]

Inampudi

Salary

Jafar‐Zanjani

et al. 2018

Opt. Mater. Express

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Invited Article: Acousto-optic finite-difference frequency-domain algorithm for first-principles simulations of on-chip acousto-optic devices

Cited by 3 publications

References 53 publications

Acoustic Waveguide Eigenmode Solver Based on a Staggered-Grid Finite-Difference Method

Acoustic Waveguide Eigenmode Solver Based on a Staggered-Grid Finite-Difference Method

Surface acoustic waves for acousto-optic modulation in buried silicon nitride waveguides

Rigorous space-time coupled-wave analysis for patterned surfaces with temporal permittivity modulation [Invited]

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