Clearing a path for light through non-Hermitian media.

The performance of all active photonic devices today is greatly limited by loss. Here, we show that one can engineer a low loss path in a metal-clad lossy multi-mode waveguide while simultaneously achieving high-performance active photonic devices. We leverage non-Hermitian systems operating beyond the exceptional point to enable the redistribution of losses in a multi-mode photonic waveguide.

Shape optimization for high efficiency metasurfaces: theory and implementation.

Complex non-local behavior makes designing high efficiency and multifunctional metasurfaces a significant challenge. While using libraries of meta-atoms provide a simple and fast implementation methodology, pillar to pillar interaction often imposes performance limitations. On the other extreme, inverse design based on topology optimization leverages non-local coupling to achieve high efficiency, but leads to complex and difficult to fabricate structures.

All-dielectric scale invariant waveguide.

Total internal reflection (TIR) governs the guiding mechanisms of almost all dielectric waveguides and therefore constrains most of the light in the material with the highest refractive index. The few options available to access the properties of lower-index materials include designs that are either lossy, periodic, exhibit limited optical bandwidth or are restricted to subwavelength modal volumes. Here, we propose and demonstrate a guiding mechanism that leverages symmetry in multilayer dielectric waveguides as well as evanescent fields to strongly confine light in low-index materials.

Rigorous analysis of Casimir and van der Waals forces on a silicon nano-optomechanical device actuated by optical forces.

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.

Optical forces through the effective refractive index.

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.

Tailoring Optical Forces Behavior in Nano-optomechanical Devices Immersed in Fluid Media.

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.