In this project we propose and fabricate a hyperbolic metamaterials-based narrowband notch filter for the infrared regime with a center wavelength that remains fixed as the angle of incidence changes from 0 to 30 degrees for TM polarization. This novel device modifies a conventional Bragg reflector by including a middle resonance layer that opens up a narrow, highly transmissive band. To achieve angular independence, a subwavelength sized array of silver wires are inserted in a vertical orientation and permeate all 7 Si and SiO2 layers of the structure.
In this work the theoretical underpinnings are explored using Maxwell-Garnett Theory, and simulated with 3D finite element full wave electromagnetic modeling software. Simulations demonstrate that the device is capable of up to 60% transmission at a fixed center wavelength for TM polarization in the infrared.
The device is fabricated using typical microfabrication techniques. The silver nanowires are fabricated via DC electrodeposition. The angle and polarization dependent transmission, reflection and absorption of the device are experimentally measured, and scanning electron microscopy images of the structure are shown.
Though the experimental validation of this device is performed for the infrared regime, scaling the structural sizes can extend the operating regime to higher and lower wavelengths. Whether used as a stand-alone filter, or integrated into a hyperspectral array, the angle-independent response of this filter has many uses in remote sensing applications.
In this project we develop a handheld, portable, highly selective and sensitive chem/biosensor that has potential applications in both airborne and water-based environmental sensing. The device relies on a plasmonic chip of subwavelength-scale periodic gold rods engineered to resonate in the near infrared. The chip is functionalized with a novel class of proteins that exhibit large conformational changes upon binding to a specific target analyte. The subsequent change in local refractive index near the surface of the gold is one to two orders of magnitude greater than current conventional methods, which produces a readily measurable 5 to 10 percent difference in light transmission. This allows us to forgo traditional, bulky tabletop setups in favor of a compact form factor. Using commercially available optics to construct a transmission-based optical train, measured changes in bulk refractive index are presented here. While synthesis of binding protein efforts are focused on heme as analyte for proof of concept validation, the functionalized protein can be engineered to pair with a wide variety of analytes with minimal alterations to the plasmonic chip or device design. Such flexibility allows for this device to potentially meet the needs of first responders and health care professionals in a multitude of scenarios.
For vortex fiber multiplexing to reach practical commercial viability, simple silicon photonic interfaces with vortex fiber will be required. These interfaces must support multiplexing. Toward this goal, an efficient singlefed multimode Forked Grating Coupler (FGC) for coupling two different optical vortex OAM charges to or from the TE0 and TE1 rectangular waveguide modes has been developed. A simple, apodized device implemented with e-beam lithography and a conventional dual-etch processing on SOI wafer exhibits low crosstalk and reasonable mode match. Advanced designs using this concept are expected to further improve performance.
The forked grating coupler (FGC) is a novel low-profile device compatible with silicon photonics that is capable of sensitive detection or efficient radiation of Optical Vortex (OV) light beams conveying orbital optical angular momentum (OAM). The FGC device combines the idea of a Bragg coupler with the forked hologram to create an integrated optics device that can selectively and efficiently couple selected optical vortex modes at near-normal incidence into planar confined dielectric waveguide modes of a photonic IC. FGCs retain many of the advantages of Bragg couplers, including convenience of placement and fabrication, reasonable bandwidth, small size, and CMOS process compatibility. In this work, prototype designs of FGC structures for 1550 nm wavelength have been developed for implementation on silicon on insulator (SOI) substrate. Fully vectorial three-dimensional (3D) electromagnetic simulation has allowed performance to be optimized over a range of structural parameters. Results have been evaluated against optical performance metrics including overall efficiency, mode match efficiency, and crosstalk between OV modes. Candidate FGC devices have been fabricated on SOI with e-beam lithography and tested optically. Tolerance to etch depth error has been evaluated.
We present research results centered on development of a highly sensitive handheld chem/biosensor device using a novel class of engineered proteins, designed to undergo extreme conformational changes upon binding their target, which in turn cause extreme changes in refractive index in the protein layer. These proteins are attached to a detector chip with a structured metasurface, to translate the refractive index change into an enhanced shift in surface plasmon resonances (SPR), thereby improving the sensitivity of the overall detector relatively to current commercially available SPR systems. Theoretical calculations have demonstrated the potential of the conformational changes in the engineered proteins to provide the desired change in refractive index. A plasmonic chip with a simple grating metasurface structure was designed to maximize the SPR shift. A prototype chip and a prototype for the overall device housing were fabricated with the inclusion of all other required (commercially available) optical components. The proposed device holds considerable promise as a low-cost, highly sensitive, field-deployable detection system for chemical and biological toxins.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.