GaAs Mid-IR Electrically Tunable Metasurfaces

In this work, we explore III-V based metal-semiconductor-metal structures for tunable metasurfaces. We use an epitaxial transfer technique to transfer a III-V thin film directly on metallic surfaces, realizing III-V metal-semiconductor-metal (MSM) structures without heavily doped semiconductors as substitutes for metal layers. The device platform consists of gold metal layers with a p-i-n GaAs junction. The target resonance wavelength can be tuned by modifying the geometry of the top metal grating on the GaAs, while systematic resonance tunability has been shown through the modulation of various carrier concentration injections in the mid-IR range. Electrically tunable metasurfaces with multilevel biasing can serve as a fundamental building block for electrically tunable metasurfaces. We believe that our demonstration can contribute to understanding the optical tuning of III-V under various biased conditions, inducing changes in metasurfaces.

Monolithic III-V on Metal for Thermal Metasurfaces

It has been proposed that metal-semiconductor-metal (MSM) structures can be used to tune the absorptivity of a metasurface at infrared wavelengths. Indium arsenide (InAs) is a low-band-gap, high-electron-mobility semiconductor that may enable rapid index tuning for dynamic control over the infrared spectrum. However, direct growth of III-V thin films on top of metals has typically resulted in small-grain, polycrystalline materials that are not amenable to high-quality devices. Previously, epitaxial wafers were used for this purpose. However, the epitaxial constraints required that InAs be used for both the tuning layer and the bottom "metallic" layer, limiting the range of accessible designs. In this work, we show a demonstration of direct growth of single-crystalline InAs on metal to build tunable absorbers/emitters in the infrared regime. The growth was carried out at a temperature of 300 °C by the low temperature templated liquid phase (LT-TLP) method. The size of InAs single-crystalline mesas is ∼2500 μm², enabling the desired device sizes. The proposed growth and device enable scalable and tunable infrared devices for various thermal-photonic applications.

Consecutive intravenous infusions: simulation of two compartment pharmacokinetic drugs

A program is presented to simulate the blood concentrations which result from multiple, consecutive, constant rate intravenous infusions of drugs displaying two compartment kinetics. The program utilizes the principle of superposition and was developed for a Hewlett-Packard model 97 programmable calculator. The program can handle form 1-8 consecutive infusions, each with its own infusion rate and duration. Post-infusion blood concentrations can also be readily obtained A modification of the main program is also presented which enables the stimulation of blood concentration--time data pairs without operator assistance. A desired increment of time specified, and the program will provide concentration--time data pairs between specified starting and ending times.