Solar energy is harvested, traditionally, either through photovoltaic technology or through the ingestion of crops. Since the two functions are utilized in distinct areas of human lives, it is assumed the two cannot coexist. This paper proposes a design for the integration of photovoltaic technology and plant physiology. The Solis Flores is an autonomous solar panel powered system that is intercropped within agricultural fields. This plant inspired photovoltaic system is synchronized with the agricultural crop fields by monitoring their health statuses. The Solis Flores surveys soil moisture levels and pH levels to manage and improve the agricultural plant health without competing for land. Through the inspiration of plant anatomy and function, the Solis Flores utilizes solar energy as its source energy, and rooted sensors to analysis possible health contingencies then communicate to the user the status of the field. The Solis Flores' solar panels, resembling the leaves and flowers of a plant, is designed to sun track and optimize the collection of solar energy. The circuitry is protected by a housing unit resembling a pot which also host the internal battery storage powering the complete system. The Solis Flores implements a wireless ad hoc network or WANET and a sensor based plant health monitoring system to an autonomous solar panel system. The ZigBee XBee platform is the WANET system chosen due to its range capacity and power efficiency. In addition, the XBee is designed to enable a security authentication allowing additional units to join or leave the network. Each Solis Flores has a master microcontroller which will monitor the soil moisture and pH level. Under stressful situations the microcontroller will be alerted and the message will be broadcasted across the network. The user as coordinator of the network can access the status of the field and monitor the crop health. This data can be logged in an external storage for seasonal evaluation and tracking. Through the successful implementation, the union between plant physiology and the technological expansion can be further explored.

We demonstrate a two-contact, bi-directional, dual color light emitting diode with superlattice active regions operated at wavelengths near 4 gm and 8 gm. The operational wavelength of the device is controlled by the bias polarity. A modification of the long wavelength superlattice facilitated hole transport into the corresponding active region and lead to a more than fourfold increase in output optical power. (C) 2016 Elsevier Ltd. All rights reserved.

Next-generation Infrared Focal Plane Arrays (IRFPAs) are demonstrating ever increasing frame rates, dynamic range, and format size, while moving to smaller pitch arrays.1 These improvements in IRFPA performance and array format have challenged the IRFPA test community to accurately and reliably test them in a Hardware-In-the-Loop environment utilizing Infrared Scene Projector (IRSP) systems. The rapidly-evolving IR seeker and sensor technology has, in some cases, surpassed the capabilities of existing IRSP technology. To meet the demands of future IRFPA testing, Santa Barbara Infrared Inc. is developing an Infrared Light Emitting Diode IRSP system. Design goals of the system include a peak radiance >2.0W/cm2/sr within the 3.0-5.0μm waveband, maximum frame rates >240Hz, and >4million pixels within a form factor supported by pixel pitches ≤32μm. This paper provides an overview of our current phase of development, system design considerations, and future development work.

The effect of hole transport on the performance of infrared light emitting diodes (LED) was investigated. The active area of the LEDs comprised two type-II superlattices with different periods and widths connected in series. Electroluminescence spectra of the devices with different positions of long wave and mid wave superlattice sections were mostly contributed by the superlattice closest to the p-contact. The experimental results indicate that due to suppressed vertical hole transport, the recombination of electrically injected electrons and holes in a type II superlattice LED active region takes place within a few superlattice periods near p-barrier. Possible reason for the effect is reduction of hole diffusion coefficient in an active area of a superlattice LED under bias.

Bulk unrelaxed InAsSb alloys with Sb compositions up to 65% were grown on compositionally graded GaInSb and AlInSb buffers on GaSb substrates by molecular beam epitaxy. The minimum energy gap for these materials at T = 77 K was estimated to be 90 meV. Benchmark material parameters were measured for barrier photodetector heterostructures with 1- μ m-thick InAs 0.6 Sb 0.4 absorbers. A minority hole lifetime of 185 ns and a diffusion length of 9 μ m at T = 77 K were determined from the transient response of barrier heterostructures. The data imply a hole mobility of 10 3 cm 2 /Vs, which was confirmed with frequency response measurements. A 100- μ m square mesa contact nBn heterostructure demonstrated a −3 dB frequency response bandwidth of 50 MHz.

Radiative recombination of InAs/GaSb superlattice (SL) n - i - p light emitting diodes (LED) was studied theoretically and experimentally. It is shown that recombination takes place not uniformly in the whole SL i region but in a very close vicinity of the p contact. The physics behind this is the formation of high electric field and high carrier concentration domains in a biased device near SL interfaces with the contacts. As a result, in narrow hole miniband the hole vertical diffusion coefficient falling off with the electric field is so small that holes are confined very close to the p contact. This reduces the effective recombination area to 1-2 periods of the SL.

Temperature related inconveniences such as heat stroke, heat rash, frostbite, hypothermia and others, have been a persistent problem for people throughout history. Some of these conditions, when left unchecked, have led to unfortunate deaths. What is even more common is the unsatisfaction that people have with the weather at various points of the year. People often complain that it is either too hot or too cold. The current technological solutions made to keep people thermally comfortable such as air conditioning and heating units have come a long way and have been successful in helping people obtain comfort in their dwellings (e.g. home or car), but are not personal mobility solutions. What if one has to be out in the weather? The addition or subtraction of layers with coats and jackets or beach wear, are popular solutions to that problem, but do not always yield upmost satisfaction, for layers become cold over time and sunburn is a serious problem. This is why a heating/cooling suit is a very beneficial product for the masses. Such a suit allows the user to control and monitor the internal temperature of the suit from high temperatures to low temperatures, depending on the season. Creating the most comfortable thermal environment for the user within an enclosed space of small proximity while providing comfort, practicality and mobility is the objective of this suit. With the use of the thermoelectric effect, microcontroller technology and a bit of ingenuity, this suit can be realized.

Light-emitting diodes emitting near 2 mu m producing quasi-continuous wave optical power of >10 mW at room temperature have been demonstrated. The combination of a strain-engineered quantum well active region and a cascaded injection scheme made it possible to achieve an internal efficiency of 120%. The higher wall plug efficiency of the two-cascade devices indicates that Auger recombination is primarily responsible for the efficiency drop at high injection levels.

Light-emitting diodes emitting near 2 μm producing quasi-continuous wave optical power of at room temperature have been demonstrated. The combination of a strain-engineered quantum well active region and a cascaded injection scheme made it possible to achieve an internal efficiency of 120%. The higher wall plug efficiency of the two-cascade devices indicates that Auger recombination is primarily responsible for the efficiency drop at high injection levels.

In the past decade, there have been close to 350,000 fatal crashes in the United States [1]. With various improvements in traffic and vehicle safety, the number of such crashes is decreasing every year. One of the ways to reduce vehicle crashes is to prevent excessive speeding in the roads and highways. The paper aims to outline the design of an embedded system that will automatically control the speed of a motor vehicle based on its location determined by a GPS device. The embedded system will make use of an AVR ATMega128 microcontroller connected to an EM-406A GPS receiver. The large amount of location input data justifies the use of an ATMega128 microcontroller which has 128KB of programmable flash memory as well as 4KB SRAM, and a 4KB EEPROM Memory [2]. The output of the ATMega128 will be a DOGMI63W-A LCD module which will display information of the current and the set-point speed of the vehicle at the current position. A discrete indicator LED will flash at a pre-determined frequency when the speed of the vehicle has exceeded the recommended speed limit. Finally, the system will have outputs that will communicate with the Engine Control Unit (ECU) of the vehicle. For the limited scope of this project, the ECU is simulated as an external device with two inputs that will acknowledge pulse-trains of particular frequencies to limit the speed of a vehicle. The speed control system will be programmed using mixed language C and Assembly with the latter in use for some pre-written subroutines to drive the LCD module. The GPS module will transmit National Marine Electronics Association (NMEA) data strings to the microcontroller (MCU) using Serial Peripheral Interface (SPI). The MCU will use the location coordinates (latitude and longitude) and the speed from the NMEA RMC output string. The current speed is then compared against the recommended speed for the vehicle's location. The memory locations in the ATMega128 can be used to store set-point speed values against a particular set of location co-ordinates. Apart from its implementation in human operated vehicles, the project can be used to control speed of autonomous cars and to implement the idea of a variable speed limit on roads introduced by the Department of Transportation [3].

Metamorphic heterostructures containing bulk InAs1−xSbx layers and AlInAsSb barriers were grown on GaSb substrates. The lattice mismatch (up to 2.1%) between the GaSb substrates and the InAsSb layers was accommodated by the growth of GaInSb linearly graded buffers. The 1 μm thick InAsSb0.44 layer with an absorption edge above 9 μm exhibited an in-plane residual strain of about 0.08%. InAs1−xSbx structures with x = 0.2 and x = 0.44 operated as light emitting diodes at 80 K demonstrated output powers of 90 μW and 8 μW at 5 μm and 8 μm, respectively.

Light-emitting diodes emitting near 2 μm producing quasi-continuous wave optical power of at room temperature have been demonstrated. The combination of a strain-engineered quantum well active region and a cascaded injection scheme made it possible to achieve an internal efficiency of 120%. The higher wall plug efficiency of the two-cascade devices indicates that Auger recombination is primarily responsible for the efficiency drop at high injection levels.

This work reports on progress in development of the metamorphic GaSb-based laser heterostructures and fabrication of the diffraction limited laser diodes.

GaSb-based type I InGaAsSb quantum well mid-infrared (mid-IR) light-emitting diodes (LEDs) operated at wavelengths up to 3.66 µm are demonstrated. The application of quinternary AlGaInAsSb barriers improved hole confinement in the quantum wells and enabled an LED radiant excitance of 1.3 W cm−2 (λ = 3.66 µm) at 100 K which corresponds to the emittance of a blackbody at 1350 K. High-contrast individually addressed 512 × 512 LED arrays were designed and fabricated using wet etching. An accurate characterization technique for mid-IR LEDs has been developed.

High-power 2.2-μm diode lasers and their arrays were designed and fabricated. Laser heterostructures were grown using solid-source molecular beam epitaxy on GaSb substrates. The device active regions contained two 1.5% compressively strained GaInAsSb quantum wells. Heavy compressive strain in the active region ensured strong carrier confinement and high differential gain. A broadened waveguide design approach was utilized to obtain an internal optical loss below 4 cm -1 and a threshold current density below 100 A/cm 2 . Individual high-power lasers produced 1.6 W of continuous-wave (CW) multimode power at room temperature from a single 100-μm-wide aperture. Linear laser arrays generated more than 25 W of quasi-continuous wave output power. The device power conversion efficiencies were better than 20% in peak and above 10% at maximum output power level.

Recent progress and state of GaSb based type-I lasers emitting in spectral range from 2 to 3.5 μm is reviewed. For lasers emitting near 2 μm an optimization of waveguide core width and asymmetry allowed reduction of far field divergence angle down to 40-50 degrees which is important for improving coupling efficiency to optical fiber. As emission wavelength increases laser characteristics degrade due to insufficient hole confinement, increased Auger recombination and deteriorated transport through the waveguide layer. While Auger recombination is thought to be an ultimate limiting factor to the performance of these narrow bandgap interband lasers we demonstrate that continuous improvements in laser characteristics are still possible by increasing hole confinement and optimizing transport properties of the waveguide layer. We achieved 190, 170 and 50 mW of maximum CW power at 3.1, 3.2 and 3.32 μm wavelengths respectively. These are the highest CW powers reported to date in this spectral range and constitute 2.5-fold improvement compared to previously reported devices.

We have designed and developed dual wavelength type I quantum well light emitting diodes (LEDs) operating at 2 μm and 3–3.4 μm wavelengths with independently controlled intensities. The room temperature quasicontinuous wave output power was 2.8 mW at 2 μm and 0.14 mW at 3 μm. The design of the dual wavelength structure allows for monolithically integrating LED pixels with different wavelengths opening the way for the fabrication of multiwavelength LED arrays for multispectral and hyperspectral imaging applications.

Recent progress and state of GaSb based type-I lasers emitting in spectral range from 2 to 3.5 mu m is reviewed. For lasers emitting near 2 mu m an optimization of waveguide core width and asymmetry allowed reduction of far field divergence angle down to 40-50 degrees which is important for improving coupling efficiency to optical fiber. As emission wavelength increases laser characteristics degrade due to insufficient hole confinement, increased Auger recombination and deteriorated transport through the waveguide layer. While Auger recombination is thought to be an ultimate limiting factor to the performance of these narrow bandgap interband lasers we demonstrate that continuous improvements in laser characteristics are still possible by increasing hole confinement and optimizing transport properties of the waveguide layer. We achieved 190, 170 and 50 mW of maximum CW power at 3.1, 3.2 and 3.32 mu m wavelengths respectively. These are the highest CW powers reported to date in this spectral range and constitute 2.5-fold improvement compared to previously reported devices.