Taylor K. Fryett

Low contrast dielectric metasurface optics

We demonstrate low contrast dielectric metasurface optical elements for operation at visible frequencies. Our devices show transmission efficiencies as high as 90% and focal spots on the order of the design wavelength.

Nanocavity Integrated van der Waals Heterostructure Light-Emitting Tunneling Diode

Developing a nanoscale, integrable, and electrically pumped single mode light source is an essential step toward on-chip optical information technologies and sensors. Here, we demonstrate nanocavity enhanced electroluminescence in van der Waals heterostructures (vdWhs) at room temperature. The vertically assembled light-emitting device uses graphene/boron nitride as top and bottom tunneling contacts and monolayer WSe2 as an active light emitter. By integrating a photonic crystal cavity on top of the vdWh, we observe the electroluminescence is locally enhanced (>4 times) by the nanocavity. The emission at the cavity resonance is single mode and highly linearly polarized (84%) along the cavity mode. By applying voltage pulses, we demonstrate direct modulation of this single mode electroluminescence at a speed of ∼1 MHz, which is faster than most of the planar optoelectronics based on transition metal chalcogenides (TMDCs). Our work shows that cavity integrated vdWhs present a promising nanoscale optoelectronic platform.

Silicon photonic crystal cavity enhanced second-harmonic generation from monolayer WSe2

Nano-resonators integrated with two-dimensional materials (e.g. transition metal dichalcogenides) have recently emerged as a promising nano-optoelectronic platform. Here we demonstrate resonator-enhanced second-harmonic generation (SHG) in tungsten diselenide using a silicon photonic crystal cavity. By pumping the device with ultrafast laser pulses near the cavity mode at the telecommunication wavelength, we observe a near visible SHG with a narrow linewidth and near unity linear polarization, originated from the coupling of the pump photon to the cavity mode. The observed SHG is enhanced by factor of ~200 compared to a bare monolayer on silicon. Our results imply the efficacy of cavity integrated monolayer materials for nonlinear optics and the potential of building a silicon-compatible second-order nonlinear integrated photonic platform.

Cavity enhanced nonlinear optics for few photon optical bistability

Weak material nonlinearity at optical frequencies poses a serious hurdle to realizing optical bistability at low optical powers, which is a critical component for digital optical computing. In this paper, we explore the cavity enhancement of the second-order optical nonlinearity in order to determine the feasibility of few photon optical bistability. Starting from a quantum optical formalism of a doubly resonant cavity (required to meet the condition of phase matching), we derive a dynamic classical model of a cavity that is bistable at the fundamental mode. We analyze the optical energy and the switching speed as a function of the cavity quality factors and mode volumes and identify the regime where only tens of photons are required to perform the switching. An unusual trend in the switching speed is also observed, where the speed monotonically decreases as the cavity linewidth increases. This is ascribed to the increase in the switching gain with increasing cavity linewidth.

Phase-matched nonlinear optics via patterning layered materials

The ease of integration and a large second-order nonlinear coefficient of atomically thin layered two-dimensional (2D) materials presents a unique opportunity to realize second-order nonlinearity in a silicon compatible integrated photonic system. However, the phase-matching requirement for second-order nonlinear optical processes makes the nanophotonic design difficult. We show that by nano-patterning the 2D material, quasi-phase-matching can be achieved. Such patterning-based quasi-phase-matching could potentially compensate for inevitable fabrication errors and significantly simplify the design process of the nonlinear nanophotonic devices.

Cavity nonlinear optics with layered materials

Abstract Unprecedented material compatibility and ease of integration, in addition to the unique and diverse optoelectronic properties of layered materials, have generated significant interest in their utilization in nanophotonic devices. While initial nanophotonic experiments with layered materials primarily focused on light sources, modulators, and detectors, recent efforts have included nonlinear optical devices. In this paper, we review the current state of cavity-enhanced nonlinear optics with layered materials. Along with conventional nonlinear optics related to harmonic generation, we report on emerging directions of nonlinear optics, where layered materials can potentially play a significant role.

Encapsulated Silicon Nitride Nanobeam Cavity for Hybrid Nanophotonics

The fragile nature of floating membrane resonators poses a serious problem for constructing a hybrid photonics platform. To overcome this challenge, we design and demonstrate encapsulated silicon nitride nanobeams and demonstrate coupling to layered materials.

Deterministic Positioning of Colloidal Quantum Dots on Silicon Nitride Nanobeam Cavities

We experimentally demonstrated deterministic positioning of solution processed colloidal quantum dots on a silicon nitride nanobeam resonator, with potential applications in nonlinear optics, multi-functional optical devices, and on-chip, solid-state quantum simulators.

Ultrathin van der Waals Metalenses

Ultrathin and flat optical lenses are essential for modern optical imaging, spectroscopy, and energy harvesting. Dielectric metasurfaces comprising nanoscale quasi-periodic resonator arrays are promising for such applications, as they can tailor the phase, amplitude, and polarization of light at subwavelength resolution, enabling multifunctional optical elements. To achieve 2π phase coverage, however, most dielectric metalenses need a thickness comparable to the wavelength, requiring the fabrication of high-aspect-ratio scattering elements. We report ultrathin dielectric metalenses made of van der Waals (vdW) materials, leveraging their high refractive indices and the incomplete phase design approach to achieve device thicknesses down to ∼λ/10, operating at infrared and visible wavelengths. These materials have generated strong interest in recent years due to their advantageous optoelectronic properties. Using vdW metalenses, we demonstrate near-diffraction-limited focusing and imaging and exploit their layered nature to transfer the fabricated metalenses onto flexible substrates to show strain-induced tunable focusing. Our work enables further downscaling of optical elements and opportunities for the integration of metasurface optics in ultraminiature optoelectronic systems.

Cavity integrated layered material devices

Layered materials have recently emerged as a promising class of optoelectronics material with high quantum efficiency of photo-emission, absorption and nonlinear optical properties. With significant progress in understanding the material science of these atomically thin materials, it is an opportune time to integrate these materials with existing optoelectronic platform to realize the full potential of the 2D materials. Integrating 2D material with nano-resonator could efficiently enhance the light-matter interaction and develop novel optoelectronics devices. Cavity-enhanced 2D material electro-optics modulation, nano-laser, and second order nonlinear devices has been demonstrated. In this paper, we report our recent progress on the cavity-integrated TMDC monolayer platform, including novel cavities for 2D material photonics and cavity nonlinear optics.