Design optimization of bowtie nanoantenna for high-efficiency thermophotovoltaics

Abstract

A novel matching technique and the field enhancement at the terminals of a bowtie nanoantenna are utilized to develop compact, highly efficient, and flexible thermophotovoltaic (TPV) cells. The bowtie antenna is designed for maximum power transfer to a near infrared band (1 μm to 2.2 μm) of a TPV cell using Indium Gallium Arsenide Antimonide (InGaAsSb). A nano-meter size block of InGaAsSb with a low bandgap energy of 0.52 eV is mounted at the terminals of the antenna. Such a load presents a frequency dependent impedance with a high resistance and capacitance at the desired frequency (180 THz). For maximum power transfer, a high impedance bowtie antenna operating at the anti-resonance mode in conjunction with an inductive stub is realized. The plasmonic behavior of the metal that tends to reduce the antenna size is partially compensated by the extra length needed to achieve the anti-resonance condition. At the desired band, the proposed nanoantenna loaded with InGaAsSb block shows an electric field intensity at the antenna terminals, which is approximately 23.5 times higher than the incident electric field intensity. This feature allows for development of efficient TPV cell and sensitive IR detectors. The infinite array of the bowtie antennas backed by a metallic reflector located at a quarter-wave behind the array is shown to absorb ∼95% of the incident power, which is more than 50% higher than the bulk InGaAsSb TPV cell. A novel configuration of the bowtie nanoantenna array is also presented that allows for collection of DC currents through an almost arbitrary parallel or series configuration of TPV cells without adversely affecting the IR performance of the individual antennas. In this scheme, elements can be arranged to be polarization dependent or independent.

Plasmonic cross-junction ring antenna implementation for field enhancement

“…Also, gap structures are noticed for this aim and different models are presented [19]. In addition, array arrangement of nano antenna is shown as a way to improve detection enhancement and bowtie and dipole antenna are suitable for this aim [20][21].…”

Nanoscale plasmonic antenna difference formation implementation effect on field enhancement

“…Different forms of Antennas such as dipole for = 814 nm with each branch 20 nm × 200 nm base on Green function for scattering field [8], bowtie have been studied for 500-1600 nm with size of 100 nm × 120 nm [9], also photoemission electron microscope (PEEM) feeding for f = 300-450 THz (corresponding to = 1000-660 nm) has been used for field enhancement [10] and ring structure is noticed for multi resonance application [11] have become conventional for bio sensing with nano antenna because of easy feeding with laser [12] and array arrangement [13,14]. Nearfield scanning optical microscopy (NSOM) subwavelength aperture probe is one of the earliest methods for optical imaging and recently gold gap nano antennas with picoseconds laser pulses are applied for higher accuracy in detection [15].…”

Bowtie Nanoantenna Array Integrated With Artificial Impedance Surfaces for Realizing High Field Enhancement and Perfect Absorption Simultaneously

“…To improve the field enhancement of the nanoantennas, researchers have been actively utilizing three methods: 1) in-plane coupling between two metallic arms of the nanoantenna [15], [16], 2) out-of-plane coupling between the nanoantenna and its image using a dielectric spacer with a metallic reflector or film [17], and 3) coupling between nanoantenna elements using nanoantenna array structures [18]- [20]. Using the grounded spacer and the array structure, optimum geometric conditions such as spacer thickness and distance between nanoantennas in the array (array pitch) to maximize the field enhancement have been studied [21]- [23].…”