Isroel M. Mandel

Theory and Design of a Novel Integrated Polarimetric Sensor Utilizing a Light Sorting Metamaterial Grating

An integrated polarimetric detector using a polarization-dependent light sorting metamaterial grating is proposed and its theoretical principles of operation are discussed. This polarimeter implements a metamaterial grating in a focal plane array situated atop of a gallium arsenide substrate. The metamaterial serves three purposes in this design. The first function of the metamaterial is to split and selectively channel TM and TE polarized light through different parts of the grating using resonant waveguide modes. The second function is to transmit the localized light into the semiconductor substrate. The third function of the metamaterial is to serve as an electrical contact array for current collection of the photogenerated carriers in the GaAs substrate. By biasing the contacts with different leads, one can separate the current collected from each polarization. Optical and electrical simulation methods are used to obtain the optical transmission, electrical crosstalk, and responsivity of the device. Using the developed theoretical model, it is shown that the device is capable of determining the Stokes parameters of incident light from the separated currents.

Dispersion engineering of surface plasmons

In this work, it is shown how the shapes of surface plasmon dispersion curves can be engineered by manipulating the distribution of the electromagnetic fields in multilayer structures, which themselves are controlled by the free electron density in metal-like materials, such as doped semiconductors in the THz spectral range. By having a nonuniform free electron density profile, reduced relative to that in typical bulk metals, the electromagnetic fields of surface plasmons are distributed in different metallic materials that have different complex dielectric permittivities. As the in-plane component of surface plasmons wave-vector increases, they become more confined to a particular layer of the multilayer structure and have energies that are predictable by considering the permittivity of the layer in which the fields are most concentrated. Unusual and arbitrary shapes of surface plasmon dispersion curves can be designed, including stair steps and dovetails shapes.

Photon sorting in the near field using subwavelength cavity arrays in the near-infrared

A frequency selective metasurface capable of sorting photons in the near-infrared spectral range is designed, fabricated, and characterized. The metasurface, a periodic array of dielectric cylindrical cavities in a gold film, localizes and transmits light of two spectral frequency bands into spatially separated cavities, resulting in near-field light splitting. The design and fabrication methodologies of the metasurface are discussed. The transmittance and photon sorting properties of the designed structure is simulated numerically and the measured transmission is presented.

Surface plasmon sorting and engineered dispersion curves using multilayer doped semiconductors

A method to engineer complex shapes into the dispersion curves (DCs) of surface plasmon (SP) in flat multilayer structures composed of doped semiconductors is shown analytically and numerically. It is shown that the shapes of SP DCs in multilayer structures can be engineered by controlling not only the free electron density in each layer, as has been well described in past literature on the subject, but also by controlling the spatial profiles of the electromagnetic fields associated with surface plasmons. It is the ability to impart complex shapes in the SP DCs that is new and described in this paper—and not just raising or lowering the surface plasmon energies as a function of free electron concentration. DCs with stair-step or dove-tail shapes are possible. In this work, a method to design structures that support SPs with DCs of arbitrary shapes is described. An analytical description of the design methodology is developed, and the resulting structures are numerically modeled using continuous wave excitation and time-dependent pulsed excitation. Time domain studies of the creation and decay in which the SPs are performed, along with spatial sorting of the SPs, yield results in agreement with the predictions of the analytic model.

Measurement of Photon Sorting at Microwave Frequencies in a Cavity Array Metasurface

We present experimental results demonstrating the spatial sorting of incoming radiation in two spectral ranges. A metasurface composed of a periodically patterned metal of subwavelength thickness with dielectric inclusions concentrates and localizes electromagnetic fields near the surface. Light of the separate spectral bands is channeled into different geometrically tuned cavities within each spatially repeating unit cell. Excitation of cavity modes facilitates this simultaneous spatial- and spectral-selective absorption. The measured reflection and field profiles are presented and the spectral and spatial selectivity are shown. A method to apply these concepts to split radiation into three spectral bands is also proposed.

Stokes parameter sensor using an integrated cavity array metasurface

Polarimetric sensing has been shown to have numerous applications in imaging such as enhancing the contrast of an image and the shape of the source object. There is increasing interest in developing a sensor that is able to measure all the Stokes parameters of an incident beam without a reduction in image resolution. We propose a cavity array metasurface polarization sensor capable of determining the complete elliptical polarization state of an incident beam allowing for the Stokes parameters to be calculated within a single pixel. The metasurface consists of a metal lm with periodically patterned cavities lled with an absorbing dielectric. Each unit cell of the periodic array contains three di erent cavities with each cavity interacting in a di erent manner with the incoming beam, absorbing the radiation. The absorption in each of the three cavities depends on the incident polarization state and phase of the incident beam. An isolated measurement of the absorption in each cavity within the unit cell is possible with separate collection of photogenerated carriers. This will enable the elliptical polarization state of an incident beam to be measured. In this work, we describe the elements of the metasurface sensor and numerically characterize its optical response to elliptically polarized light.

Full device analysis of novel metamaterial coated PN and MIS solar cells using numerical methods

In this work we describe how to model the efficiency of solar cells with novel metamaterial coatings optimized for light harvesting. Full device modeling is implemented using optical and electrical simulations. As a proof of concept, we simulate the operation of a metamaterial contact on a first generation monocrystalline silicon solar cell. We compare device characteristics and efficiencies to standard antireflective coatings applied to a grid contact cell. The effects of the metamaterial contact on silicon solar cell efficiencies is discussed for PN junction and metal-insulator-semiconductor cell structures. It is found that the metal-insulator-semiconductor solar cell designed performs better than the PN junction cell.