Design of a Single-Feed Dual-Band Dual-Polarized Printed Microstrip Antenna Using a Boolean Particle Swarm Optimization

A novel dual-frequency dual-linear-polarization printed antenna element benefiting from a single-feed single-layer structure is introduced in this paper. The Boolean particle swarm optimization algorithm in conjunction with the method of moments (MoM) is employed to optimize the geometry of the antenna after considering three objectives: cross polarization, return loss, and boresight direction in both bands. A fuzzy-logic based ordered weighted averaging operator allows us to efficiently implement the multi-objective optimization technique. Prototypes of the optimized designs have been fabricated and tested. The measured results show excellent performance with more than 15 dB of return loss and 10 dB of cross polarization in both frequency bands of operation, i.e., 12 and 14 GHz. A gain of 4.8 dBi has been measured for both frequency bands

Design of a Single-Feed Dual-Band Dual-Polarized Printed Microstrip Antenna Using a Boolean Particle Swarm Optimization

A novel dual-frequency dual-linear-polarization printed antenna element benefiting from a single-feed single-layer structure is introduced in this paper. The Boolean particle swarm optimization algorithm in conjunction with the method of moments (MoM) is employed to optimize the geometry of the antenna after considering three objectives: cross polarization, return loss, and boresight direction in both bands. A fuzzy-logic based ordered weighted averaging operator allows us to efficiently implement the multi-objective optimization technique. Prototypes of the optimized designs have been fabricated and tested. The measured results show excellent performance with more than 15 dB of return loss and 10 dB of cross polarization in both frequency bands of operation, i.e., 12 and 14 GHz. A gain of 4.8 dBi has been measured for both frequency bands

Proposal for Compact Optical Filters Using Large Index Step Binary Supergratings

Compact optical filters are proposed using an aperiodic grating of fixed element size [i.e., a binary supergrating (BSG)] with a large refractive index step. These filters allow for almost arbitrary wavelength filtering, yet they are more compact than previous demonstrations of BSG. The filters are designed using a combination of Boolean particle swarm optimization (B-PSO) and a one-dimensional transfer matrix method. To demonstrate the compact device size, several 50-mum-long single-wavelength transmission filters are demonstrated theoretically, each having a different wavelength while using the same structural parameters. A multiwavelength filter is also proposed in an 80-mum-long structure to show the versatility of the large refractive index step BSG. A genetic algorithm is substituted for the B-PSO; however, B-PSO shows better performance here. This work may be applied to produce compact optical filters for intrachip optical networks and compact tunable lasers, while using existing single-step photolithography processes

Proposal for Compact Optical Filters Using Large Index Step Binary Supergratings

Compact optical filters are proposed using an aperiodic grating of fixed element size [i.e., a binary supergrating (BSG)] with a large refractive index step. These filters allow for almost arbitrary wavelength filtering, yet they are more compact than previous demonstrations of BSG. The filters are designed using a combination of Boolean particle swarm optimization (B-PSO) and a one-dimensional transfer matrix method. To demonstrate the compact device size, several 50-mum-long single-wavelength transmission filters are demonstrated theoretically, each having a different wavelength while using the same structural parameters. A multiwavelength filter is also proposed in an 80-mum-long structure to show the versatility of the large refractive index step BSG. A genetic algorithm is substituted for the B-PSO; however, B-PSO shows better performance here. This work may be applied to produce compact optical filters for intrachip optical networks and compact tunable lasers, while using existing single-step photolithography processes

Broadband Linear-Dichroic Photodetector in a Black Phosphorus Vertical p-n Junction

The ability to detect light over a broad spectral range is central for practical optoelectronic applications, and has been successfully demonstrated with photodetectors of two-dimensional layered crystals such as graphene and MoS2. However, polarization sensitivity within such a photodetector remains elusive. Here we demonstrate a linear-dichroic broadband photodetector with layered black phosphorus transistors, using the strong intrinsic linear dichroism arising from the in-plane optical anisotropy with respect to the atom-buckled direction, which is polarization sensitive over a broad bandwidth from 400 nm to 3750 nm. Especially, a perpendicular build-in electric field induced by gating in black phosphorus transistors can spatially separate the photo-generated electrons and holes in the channel, effectively reducing their recombination rate, and thus enhancing the efficiency and performance for linear dichroism photodetection. This provides new functionality using anisotropic layered black phosphorus, thereby enabling novel optical and optoelectronic device applications.Comment: 18 pages, 5 figures in Nature Nanotechnology 201

Intelligent Particle Swarm Optimization Using Q-Learning

Abstract- The particle swarm algorithm is a relatively new approach to optimization, drawing inspiration from group behavior and the establishment of social norms. It is gaining popularity, especially because of the speed of convergence and the fact that it is easy to use. In this paper a novel adaptive particle swarm optimization method is introduced, in which, granting an extra facility of intelligence via Q-Learning to each agent helps the method to avoid being trapped in local optima. Named Intelligent PSO, the proposed method has been tested on several test functions and the results show the ability of the method in finding global or near-global optimums and better performance than the existing algorithms reported recently in the literature. I

Transparent Metallic Fractal Electrodes for Semiconductor Devices

Nanostructured metallic films have the potential to replace metal oxide films as transparent electrodes in optoelectronic devices. An ideal transparent electrode should possess a high, broadband, and polarization-independent transmittance. Conventional metallic gratings and grids with wavelength-scale periodicities, however, do not have all of these qualities. Furthermore, the transmission properties of a nanostructured electrode need to be assessed in the actual dielectric environment provided by a device, where a high-index semiconductor layer can reflect a substantial fraction of the incident light. Here we propose nanostructured aluminum electrodes with space-filling fractal geometries as alternatives to gratings and grids and experimentally demonstrate their superior optoelectronic performance through integration with Si photodetectors. As shown by polarization and spectrally resolved photocurrent measurements, devices with fractal electrodes exhibit both a broadband transmission and a flat polarization response that outperforms both square grids and linear gratings. Finally, we show the benefits of adding a thin silicon nitride film to the nanostructured electrodes to further reduce reflection

Scalable fabrication of nano-architected materials using 3D interference lithography with metasurfaces at visible wavelengths (Conference Presentation)

Nano-architected materials have the potential to be adopted in several areas including photonic devices and structural materials. We present a 3D interference lithography technique with dielectric metasurfaces at visible wavelengths that allows patterning of thick epoxide films over areas on the order of 10 cm^2 with 100 nm resolution. By leveraging the ability of the metasurface to control the amplitude and phase of a wavefront, complex near-field 3D interference patterns can be designed. Pyrolysis of 3D patterned SU-8 produces a carbon-based material with sub-100 nm features and enhanced mechanical properties

Scalable fabrication of nano-architected materials using 3D interference lithography with metasurfaces at visible wavelengths (Conference Presentation)

Nano-architected materials have the potential to be adopted in several areas including photonic devices and structural materials. We present a 3D interference lithography technique with dielectric metasurfaces at visible wavelengths that allows patterning of thick epoxide films over areas on the order of 10 cm^2 with 100 nm resolution. By leveraging the ability of the metasurface to control the amplitude and phase of a wavefront, complex near-field 3D interference patterns can be designed. Pyrolysis of 3D patterned SU-8 produces a carbon-based material with sub-100 nm features and enhanced mechanical properties

Transparent Metallic Fractal Electrodes for Semiconductor Devices

Nanostructured metallic films have the potential to replace metal oxide films as transparent electrodes in optoelectronic devices. An ideal transparent electrode should possess a high, broadband, and polarization-independent transmittance. Conventional metallic gratings and grids with wavelength-scale periodicities, however, do not have all of these qualities. Furthermore, the transmission properties of a nanostructured electrode need to be assessed in the actual dielectric environment provided by a device, where a high-index semiconductor layer can reflect a substantial fraction of the incident light. Here we propose nanostructured aluminum electrodes with space-filling fractal geometries as alternatives to gratings and grids and experimentally demonstrate their superior optoelectronic performance through integration with Si photodetectors. As shown by polarization and spectrally resolved photocurrent measurements, devices with fractal electrodes exhibit both a broadband transmission and a flat polarization response that outperforms both square grids and linear gratings. Finally, we show the benefits of adding a thin silicon nitride film to the nanostructured electrodes to further reduce reflection