In this article, we rigorously analyze the effects of the dispersion forces (Casimir and van der ... more In this article, we rigorously analyze the effects of the dispersion forces (Casimir and van der Waals forces) on a nano-optomechanical device based on a silicon waveguide and a silicon dioxide substrate, surrounded by air and driven by optical forces. The dispersion forces are calculated using a modified Lifshitz theory, in order to take into account the device thickness and material s dielectric permittivities, which are obtained from experimental optical data and validated by means of a rigorous 3D FDTD simulation. We also take into account the mechanical nonlinearity of the waveguide, which is caused by its large deflection relative to its thickness, due to the nanoscale device dimensions. The nonlinear mechanical analytical model is also validated using a 3D FEM simulation. Our results show that, under appropriate design conditions, it is possible to attain a no pull in critical point due only to the optical force; therefore, in principle, it would be possible to control the de...
The energy-based methods as the Dispersion Relation (DR) and Response Theory of Optical Forces (R... more The energy-based methods as the Dispersion Relation (DR) and Response Theory of Optical Forces (RTOF) have been largely applied to obtain the optical forces in the nano-optomechanical devices, in contrast to the Maxwell Stress Tensor (MST). In this work, we apply first principles to show explicitly why these methods must agree with the MST formalism in linear lossless systems. We apply the RTOF multi-port, to show that the optical force expression on these devices can be extended to analyze multiple light sources, broadband sources, and multimode devices, with multiple degrees of freedom. We also show that the DR method, when expressed as a function of the derivative of the effective index performed at a fixed wave vector, may be misinterpreted and lead to overestimated results.
2018 SBFoton International Optics and Photonics Conference (SBFoton IOPC)
The effect of the material dispersion can be quantified either by the Abbe number or Group Veloci... more The effect of the material dispersion can be quantified either by the Abbe number or Group Velocity Dispersion (GVD). However, we show that these traditional techniques are not well suitable to quantify the materials dispersion effects on optical quantities in dielectric nanophotonic devices. Here, we apply classical electrodynamic theory to show that the complete description of materials dispersion properties leads to an additional term related to the materials’ group indexes. Based on that, we define a ratio factor capable of exactly quantifying the materials dispersion effects on any optical quantity at a specific wavelength. We also find that a conservative estimative can be done by the ratio between the highest-index material’ group index and its refractive index $\left( {n_{\text{g}}^{\text{M}}/{n_{\text{M}}}} \right)$ We believe that the results presented here may be useful during the modeling and simulation of nanophotonic devices.
We experimentally demonstrate waveguiding at the critical angle in a dielectric multi-layered str... more We experimentally demonstrate waveguiding at the critical angle in a dielectric multi-layered structure. At this exceptional point, the waveguide becomes scale invariant and the field is confined to the low-index region, with a spatially-uniform transverse profile
Stimulated Brillouin scattering (SBS) processes have been allowing important technological breakt... more Stimulated Brillouin scattering (SBS) processes have been allowing important technological breakthroughs in integrated photonics and nano-optomechanics, by exploiting light-sound (photon-phonon) interactions at the nanoscale. These nonlinear processes are created by two main effects: radiation pressure and electrostriction; however, the former is the predominant one in high-index-contrast nanowaveguides. In this letter, we derive a simple set of analytical expressions that can be used for optimizing the radiation pressure on the waveguide boundaries, for any optical mode, polarization, and wavelength. We observe a very strong influence of the waveguide geometric parameters on the optimal radiation pressure value. Furthermore, we explain how the existence of such optimal geometric dimensions is physically related to the minimization of the electromagnetic momentum flow in the propagation direction. This work provides a novel and robust method, yet simple, to optimize the radiation pr...
Stimulated Brillouin scattering (SBS) processes have been enabling important technological breakt... more Stimulated Brillouin scattering (SBS) processes have been enabling important technological breakthroughs in integrated photonics and nano-optomechanics by exploiting light-sound (photon-phonon) interactions at the nanoscale. These nonlinear processes are created by two main effects: radiation pressure and electrostriction; however, the former is the predominant one in high-index-contrast nanowaveguides. In this work, we derive a simple set of analytical expressions that can be used for optimizing the radiation pressure on the waveguide boundaries for any optical mode, polarization, and wavelength. We observe the very strong influence of waveguide geometric parameters on the optimal radiation pressure value. Furthermore, we explain how the existence of such optimal geometric dimensions is physically related to the minimization of the electromagnetic momentum flow in the propagation direction. This work provides a novel and robust yet simple method to optimize the radiation pressure in dielectric nanowaveguides, which may be of great relevance for designing integrated photonic-phononic devices.
Emerging nano-optofluidic devices have allowed a synergetic relation between photonic integrated ... more Emerging nano-optofluidic devices have allowed a synergetic relation between photonic integrated circuits and microfluidics, allowing manipulation and transport at the realm of nanoscale science. Simultaneously, optical gradient forces have allowed highly precise control of mechanical motion in nano-optomechanical devices. In this report, we show that the repulsive optical forces of the antisymmetric eigenmodes in an optomechanical device, based on a slot-waveguide structure, increases as the refraction index of the fluid medium increases. This effect provides a feasible way to tailor the repulsive optical forces when these nano-optomechanical devices are immersed in dielectric liquids. Furthermore, the total control of the attractive and repulsive optical forces inside liquids may be applied to design novel nanophotonic devices, containing both microfluidic and nanomechanical functionalities, which may find useful applications in several areas, such as biomedical sensors, manipulat...
Energy-based methods such as the dispersion relation (DR) and response theory of optical forces (... more Energy-based methods such as the dispersion relation (DR) and response theory of optical forces (RTOF) have been largely applied to obtain the optical forces in the nano-optomechanical devices, in contrast to the Maxwell stress tensor (MST). In this Letter, we apply first principles to show explicitly why these methods must agree with the MST formalism in linear lossless systems. We apply the RTOF multi-port to show that the optical force expression on these devices can be extended to analyze multiple light sources, broadband sources, and multimode devices, with multiple degrees of freedom. We also show that the DR method, when expressed as a function of the derivative of the effective index performed at a fixed wave vector, may be misinterpreted and lead to overestimated results.
Nano-optomechanical devices have enabled a lot of interesting scientific and technological applic... more Nano-optomechanical devices have enabled a lot of interesting scientific and technological applications. However, due to their nanoscale dimensions, they are vulnerable to the action of Casimir and van der Waals (dispersion) forces. This work presents a rigorous analysis of the dispersion forces on a nano-optomechanical device based on a silicon waveguide and a silicon dioxide substrate, surrounded by air and driven by optical forces. The dispersion forces are calculated using a modified Lifshitz theory with experimental optical data and validated by means of a rigorous 3D FDTD simulation. The mechanical nonlinearity of the nanowaveguide is taken into account and validated using a 3D FEM simulation. The results show that it is possible to attain a no pull-in critical point due to only the optical forces; however, the dispersion forces usually impose a pull-in critical point to the device and establish a minimal initial gap between the waveguide and the substrate. Furthermore, it is ...
Silicon Photonics and Photonic Integrated Circuits V, 2016
Abstract. In a conventional slot waveguide structure, light is strongly confined in the slot regi... more Abstract. In a conventional slot waveguide structure, light is strongly confined in the slot region only either for the quasi-transverse electric (TE) (in a vertically oriented slot) or for the quasi-transverse magnetic (TM) (in a horizontally oriented slot) fundamental eigenmode, which enhances the optical forces, thus decreasing the optical power necessary to control the displacement of the device, but only for one eigenmode polarization at a time. In this work, we analyzed the optical forces in a cross-slot waveguide, which is formed by four suspended silicon waveguides separated by two orthogonal air slots. Cross-slot waveguides can strongly confine light in both quasi-TE and quasi-TM polarizations, thus enhancing the optical force and reducing the optical power for both. Our simulation results show that by adjusting the optical power and the light polarization, it is possible to control the displacement of the waveguides in the vertical or in the horizontal direction almost individually, or in both directions simultaneously. The proposed nano-optomechanical device has potential applications in active photonic devices and novel mechanisms for nanosensors and nanoactuators, such as optical nanogrippers and nanotweezers.
The dynamic behavior of a capacitive micro-electro-mechanical (MEMS) accelerometer is evaluated b... more The dynamic behavior of a capacitive micro-electro-mechanical (MEMS) accelerometer is evaluated by using a theoretical approach which makes use of a squeeze film damping (SFD) model and ideal gas approach. The study investigates the performance of the device as a function of the temperature, from 228 K to 398 K, and pressure, from 20 to 1000 Pa, observing the damping gas trapped inside de mechanical transducer. Thermoelastic properties of the silicon bulk are considered for the entire range of temperature. The damping gases considered are Air, Helium and Argon. The global behavior of the system is evaluated considering the electro-mechanical sensitivity (SEM) as the main figure of merit in frequency domain. The results show the behavior of the main mechanism losses of SFD, as well as the dynamic sensitivity of the MEMS transducer system, and are in good agreement with experimental dynamic results behavior.
This work presents a rigorous analysis of optical forces between planar waveguides immersed in an... more This work presents a rigorous analysis of optical forces between planar waveguides immersed in an arbitrary background medium. This approach exploits the Minkowski stress tensor formulation, which is compared with a normalized version of the dispersion relation method, showing excellent results agreement for different dielectric fluid media. Due to slot-waveguide effect, optical forces from TM modes are more sensitive to changes in the fluid refractive index than the TE counterparts. Furthermore, the repulsive optical force from the antisymmetric TM1 mode becomes stronger for higher refractive indexes, whereas the attractive force of the symmetric TM0 mode becomes weaker. The methodology and results presented in this work provide a rigorous analysis of nano-optomechanical devices actuated by optical forces in a broad range of materials and applications. Therefore, this study may impact areas of light-induced interactions presenting novel optofluidic and optomechanical functionalities, thus finding applications in nanoscale transport, sensing and manipulation.
We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the... more We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the compressible-gas-film Reynolds equation, which relates pressure, density, viscosity and the surface velocity for the specific geometry of bounded film. This equation assumes that inertial forces are small compared to viscous forces, and that the gap is large compared to the mean free path of the gas. Assuming a small displacement of the moving electrode, small pressure variation around the ambient pressure and under the assumption of isothermal film, the analytical solution of the pressure is obtained. The pressure has two terms: one represents the damping and one represents the spring-like behavior of the gas. The integral of the pressure over the electrodes area lead directly to expressions for damping and air spring constant coefficients. The importance of compressible effects, represented by the spring constant coefficient, can be analyzed through of the squeeze number. For a very l...
We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the... more We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the compressible-gas-film Reynolds equation, which relates pressure, density, viscosity and the surface velocity for the specific geometry of bounded film. This equation assumes that inertial forces are small compared to viscous forces, and that the gap is large compared to the mean free path of the gas. Assuming a small displacement of the moving electrode, small pressure variation around the ambient pressure and under the assumption of isothermal film, the analytical solution of the pressure is obtained. The pressure has two terms: one represents the damping and one represents the spring-like behavior of the gas. The integral of the pressure over the electrodes area lead directly to expressions for damping and air spring constant coefficients. The importance of compressible effects, represented by the spring constant coefficient, can be analyzed through of the squeeze number. For a very l...
In this article, we rigorously analyze the effects of the dispersion forces (Casimir and van der ... more In this article, we rigorously analyze the effects of the dispersion forces (Casimir and van der Waals forces) on a nano-optomechanical device based on a silicon waveguide and a silicon dioxide substrate, surrounded by air and driven by optical forces. The dispersion forces are calculated using a modified Lifshitz theory, in order to take into account the device thickness and material s dielectric permittivities, which are obtained from experimental optical data and validated by means of a rigorous 3D FDTD simulation. We also take into account the mechanical nonlinearity of the waveguide, which is caused by its large deflection relative to its thickness, due to the nanoscale device dimensions. The nonlinear mechanical analytical model is also validated using a 3D FEM simulation. Our results show that, under appropriate design conditions, it is possible to attain a no pull in critical point due only to the optical force; therefore, in principle, it would be possible to control the de...
The energy-based methods as the Dispersion Relation (DR) and Response Theory of Optical Forces (R... more The energy-based methods as the Dispersion Relation (DR) and Response Theory of Optical Forces (RTOF) have been largely applied to obtain the optical forces in the nano-optomechanical devices, in contrast to the Maxwell Stress Tensor (MST). In this work, we apply first principles to show explicitly why these methods must agree with the MST formalism in linear lossless systems. We apply the RTOF multi-port, to show that the optical force expression on these devices can be extended to analyze multiple light sources, broadband sources, and multimode devices, with multiple degrees of freedom. We also show that the DR method, when expressed as a function of the derivative of the effective index performed at a fixed wave vector, may be misinterpreted and lead to overestimated results.
2018 SBFoton International Optics and Photonics Conference (SBFoton IOPC)
The effect of the material dispersion can be quantified either by the Abbe number or Group Veloci... more The effect of the material dispersion can be quantified either by the Abbe number or Group Velocity Dispersion (GVD). However, we show that these traditional techniques are not well suitable to quantify the materials dispersion effects on optical quantities in dielectric nanophotonic devices. Here, we apply classical electrodynamic theory to show that the complete description of materials dispersion properties leads to an additional term related to the materials’ group indexes. Based on that, we define a ratio factor capable of exactly quantifying the materials dispersion effects on any optical quantity at a specific wavelength. We also find that a conservative estimative can be done by the ratio between the highest-index material’ group index and its refractive index $\left( {n_{\text{g}}^{\text{M}}/{n_{\text{M}}}} \right)$ We believe that the results presented here may be useful during the modeling and simulation of nanophotonic devices.
We experimentally demonstrate waveguiding at the critical angle in a dielectric multi-layered str... more We experimentally demonstrate waveguiding at the critical angle in a dielectric multi-layered structure. At this exceptional point, the waveguide becomes scale invariant and the field is confined to the low-index region, with a spatially-uniform transverse profile
Stimulated Brillouin scattering (SBS) processes have been allowing important technological breakt... more Stimulated Brillouin scattering (SBS) processes have been allowing important technological breakthroughs in integrated photonics and nano-optomechanics, by exploiting light-sound (photon-phonon) interactions at the nanoscale. These nonlinear processes are created by two main effects: radiation pressure and electrostriction; however, the former is the predominant one in high-index-contrast nanowaveguides. In this letter, we derive a simple set of analytical expressions that can be used for optimizing the radiation pressure on the waveguide boundaries, for any optical mode, polarization, and wavelength. We observe a very strong influence of the waveguide geometric parameters on the optimal radiation pressure value. Furthermore, we explain how the existence of such optimal geometric dimensions is physically related to the minimization of the electromagnetic momentum flow in the propagation direction. This work provides a novel and robust method, yet simple, to optimize the radiation pr...
Stimulated Brillouin scattering (SBS) processes have been enabling important technological breakt... more Stimulated Brillouin scattering (SBS) processes have been enabling important technological breakthroughs in integrated photonics and nano-optomechanics by exploiting light-sound (photon-phonon) interactions at the nanoscale. These nonlinear processes are created by two main effects: radiation pressure and electrostriction; however, the former is the predominant one in high-index-contrast nanowaveguides. In this work, we derive a simple set of analytical expressions that can be used for optimizing the radiation pressure on the waveguide boundaries for any optical mode, polarization, and wavelength. We observe the very strong influence of waveguide geometric parameters on the optimal radiation pressure value. Furthermore, we explain how the existence of such optimal geometric dimensions is physically related to the minimization of the electromagnetic momentum flow in the propagation direction. This work provides a novel and robust yet simple method to optimize the radiation pressure in dielectric nanowaveguides, which may be of great relevance for designing integrated photonic-phononic devices.
Emerging nano-optofluidic devices have allowed a synergetic relation between photonic integrated ... more Emerging nano-optofluidic devices have allowed a synergetic relation between photonic integrated circuits and microfluidics, allowing manipulation and transport at the realm of nanoscale science. Simultaneously, optical gradient forces have allowed highly precise control of mechanical motion in nano-optomechanical devices. In this report, we show that the repulsive optical forces of the antisymmetric eigenmodes in an optomechanical device, based on a slot-waveguide structure, increases as the refraction index of the fluid medium increases. This effect provides a feasible way to tailor the repulsive optical forces when these nano-optomechanical devices are immersed in dielectric liquids. Furthermore, the total control of the attractive and repulsive optical forces inside liquids may be applied to design novel nanophotonic devices, containing both microfluidic and nanomechanical functionalities, which may find useful applications in several areas, such as biomedical sensors, manipulat...
Energy-based methods such as the dispersion relation (DR) and response theory of optical forces (... more Energy-based methods such as the dispersion relation (DR) and response theory of optical forces (RTOF) have been largely applied to obtain the optical forces in the nano-optomechanical devices, in contrast to the Maxwell stress tensor (MST). In this Letter, we apply first principles to show explicitly why these methods must agree with the MST formalism in linear lossless systems. We apply the RTOF multi-port to show that the optical force expression on these devices can be extended to analyze multiple light sources, broadband sources, and multimode devices, with multiple degrees of freedom. We also show that the DR method, when expressed as a function of the derivative of the effective index performed at a fixed wave vector, may be misinterpreted and lead to overestimated results.
Nano-optomechanical devices have enabled a lot of interesting scientific and technological applic... more Nano-optomechanical devices have enabled a lot of interesting scientific and technological applications. However, due to their nanoscale dimensions, they are vulnerable to the action of Casimir and van der Waals (dispersion) forces. This work presents a rigorous analysis of the dispersion forces on a nano-optomechanical device based on a silicon waveguide and a silicon dioxide substrate, surrounded by air and driven by optical forces. The dispersion forces are calculated using a modified Lifshitz theory with experimental optical data and validated by means of a rigorous 3D FDTD simulation. The mechanical nonlinearity of the nanowaveguide is taken into account and validated using a 3D FEM simulation. The results show that it is possible to attain a no pull-in critical point due to only the optical forces; however, the dispersion forces usually impose a pull-in critical point to the device and establish a minimal initial gap between the waveguide and the substrate. Furthermore, it is ...
Silicon Photonics and Photonic Integrated Circuits V, 2016
Abstract. In a conventional slot waveguide structure, light is strongly confined in the slot regi... more Abstract. In a conventional slot waveguide structure, light is strongly confined in the slot region only either for the quasi-transverse electric (TE) (in a vertically oriented slot) or for the quasi-transverse magnetic (TM) (in a horizontally oriented slot) fundamental eigenmode, which enhances the optical forces, thus decreasing the optical power necessary to control the displacement of the device, but only for one eigenmode polarization at a time. In this work, we analyzed the optical forces in a cross-slot waveguide, which is formed by four suspended silicon waveguides separated by two orthogonal air slots. Cross-slot waveguides can strongly confine light in both quasi-TE and quasi-TM polarizations, thus enhancing the optical force and reducing the optical power for both. Our simulation results show that by adjusting the optical power and the light polarization, it is possible to control the displacement of the waveguides in the vertical or in the horizontal direction almost individually, or in both directions simultaneously. The proposed nano-optomechanical device has potential applications in active photonic devices and novel mechanisms for nanosensors and nanoactuators, such as optical nanogrippers and nanotweezers.
The dynamic behavior of a capacitive micro-electro-mechanical (MEMS) accelerometer is evaluated b... more The dynamic behavior of a capacitive micro-electro-mechanical (MEMS) accelerometer is evaluated by using a theoretical approach which makes use of a squeeze film damping (SFD) model and ideal gas approach. The study investigates the performance of the device as a function of the temperature, from 228 K to 398 K, and pressure, from 20 to 1000 Pa, observing the damping gas trapped inside de mechanical transducer. Thermoelastic properties of the silicon bulk are considered for the entire range of temperature. The damping gases considered are Air, Helium and Argon. The global behavior of the system is evaluated considering the electro-mechanical sensitivity (SEM) as the main figure of merit in frequency domain. The results show the behavior of the main mechanism losses of SFD, as well as the dynamic sensitivity of the MEMS transducer system, and are in good agreement with experimental dynamic results behavior.
This work presents a rigorous analysis of optical forces between planar waveguides immersed in an... more This work presents a rigorous analysis of optical forces between planar waveguides immersed in an arbitrary background medium. This approach exploits the Minkowski stress tensor formulation, which is compared with a normalized version of the dispersion relation method, showing excellent results agreement for different dielectric fluid media. Due to slot-waveguide effect, optical forces from TM modes are more sensitive to changes in the fluid refractive index than the TE counterparts. Furthermore, the repulsive optical force from the antisymmetric TM1 mode becomes stronger for higher refractive indexes, whereas the attractive force of the symmetric TM0 mode becomes weaker. The methodology and results presented in this work provide a rigorous analysis of nano-optomechanical devices actuated by optical forces in a broad range of materials and applications. Therefore, this study may impact areas of light-induced interactions presenting novel optofluidic and optomechanical functionalities, thus finding applications in nanoscale transport, sensing and manipulation.
We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the... more We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the compressible-gas-film Reynolds equation, which relates pressure, density, viscosity and the surface velocity for the specific geometry of bounded film. This equation assumes that inertial forces are small compared to viscous forces, and that the gap is large compared to the mean free path of the gas. Assuming a small displacement of the moving electrode, small pressure variation around the ambient pressure and under the assumption of isothermal film, the analytical solution of the pressure is obtained. The pressure has two terms: one represents the damping and one represents the spring-like behavior of the gas. The integral of the pressure over the electrodes area lead directly to expressions for damping and air spring constant coefficients. The importance of compressible effects, represented by the spring constant coefficient, can be analyzed through of the squeeze number. For a very l...
We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the... more We describe the behavior of the gas between the electrodes of a capacitive accelerometer with the compressible-gas-film Reynolds equation, which relates pressure, density, viscosity and the surface velocity for the specific geometry of bounded film. This equation assumes that inertial forces are small compared to viscous forces, and that the gap is large compared to the mean free path of the gas. Assuming a small displacement of the moving electrode, small pressure variation around the ambient pressure and under the assumption of isothermal film, the analytical solution of the pressure is obtained. The pressure has two terms: one represents the damping and one represents the spring-like behavior of the gas. The integral of the pressure over the electrodes area lead directly to expressions for damping and air spring constant coefficients. The importance of compressible effects, represented by the spring constant coefficient, can be analyzed through of the squeeze number. For a very l...
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Papers by Janderson Rodrigues