Investigation on optical integration between LED Mid-IR light sources and Si-based waveguides for sensing applications

Research on mid-IR silicon-based waveguides has recently received strong interest. Particularly, this paper focuses on one of the critical issues in micron-scale photonic integrated circuits, which is to efficiently couple a mid-IR LED (light emitting diode) light source to an external micron-scale waveguide. The optical coupling scheme is crucial for the exploitation of LED light sources in waveguide-based spectroscopic sensing applications. This paper reports optical coupling scheme between an LED mid-IR light source and a silicon rich silicon nitride (SiN) waveguide that could enable the use of LED-based light sources. Finally, the detection limit of the investigated device for carbon dioxide gas detection is calculated.

Local Environments of Low-redshift Supernovae

We characterize the local (2 kpc sized) environments of Type Ia, II, and Ib/c supernovae (SNe) that have recently occurred in nearby (d ≲ 50 Mpc) galaxies. Using ultraviolet (UV; from Galaxy Evolution Explorer) and infrared (IR; from Wide-field Infrared Survey Explorer) maps of 359 galaxies and a sample of 472 SNe, we measure the star formation rate surface density (ΣSFR) and stellar mass surface density (Σ⋆) in a 2 kpc beam centered on each SN site. We show that core-collapse SNe are preferentially located along the resolved galactic star-forming main sequence, whereas Type Ia SNe are extended to lower values of ΣSFR at fixed Σ⋆, indicative of locations inside quiescent galaxies or quiescent regions of galaxies. We also test how well the radial distribution of each SN type matches the radial distributions of UV and IR light in each host galaxy. We find that, to first order, the distributions of all types of SNe mirror those of both near-IR light (3.4 and 4.5 μm, tracing the stellar mass distribution) and mid-IR light (12 and 22 μm, tracing emission from hot, small grains), and also resemble our best-estimate ΣSFR. All types of SNe appear more radially concentrated than the UV emission of their host galaxies. In more detail, the distributions of Type II SNe show small statistical differences from those of near-IR light. We attribute this overall structural uniformity to the fact that within any individual galaxy, ΣSFR and Σ⋆ track one another well, with variations in ΣSFR/Σ⋆ most visible when comparing between galaxies.

Discovery of a 310 Day Period from the Enshrouded Massive System NaSt1 (WR 122)

We present optical and infrared (IR) light curves of NaSt1, also known as Wolf–Rayet 122, with observations from Palomar Gattini-IR (PGIR), the Zwicky Transient Facility (ZTF), the Katzman Automatic Imaging Telescope, the Asteroid Terrestrial-impact Last Alert System, and the All-Sky Automated Survey for Supernovae (ASAS-SN). We identify a P = 309.7 ± 0.7 day photometric period from the optical and IR light curves that reveal periodic, sinusoidal variability between 2014 July and 2021 July. We also present historical IR light curves taken between 1983 July and 1989 May, which show variability consistent with the period of the present-day light curves. In the past, NaSt1 was brighter in the J band with larger variability amplitudes than the present-day PGIR values, suggesting that NaSt1 exhibits variability on longer (≳decade) timescales. Sinusoidal fits to the recent optical and IR light curves show that the amplitude of NaSt1's variability differs at various wavelengths and also reveal significant phase offsets of 17.0 ± 2.5 day between the ZTF r and PGIR J light curves. We interpret the 310 day photometric period from NaSt1 as the orbital period of an enshrouded massive binary. We suggest that the photometric variability of NaSt1 may arise from variations in the line-of-sight optical depth toward circumstellar optical/IR-emitting regions throughout its orbit due to colliding-wind dust formation. We speculate that past mass transfer in NaSt1 may have been triggered by Roche-lobe overflow (RLOF) during an eruptive phase of an Ofpe/WN9 star. Lastly, we argue that NaSt1 is no longer undergoing RLOF mass transfer.

INTERPRETATION OF OPTICAL AND IR LIGHT CURVES FOR TRANSITIONAL DISK CANDIDATES IN NGC 2264 USING THE EXTINCTED STELLAR RADIATION AND THE EMISSION OF OPTICALLY THIN DUST INSIDE THE HOLE

In the stellar forming region NGC 2264 there are objects catalogued as hosting a transitional disk according to spectrum modeling. Four members of this set have optical and infrared light curves coming from the CoRoT and Spitzer telescopes. In this work, we try to simultaneously explain the light curves using the extinction of the stellar radiation and the emission of the dust inside the hole of a transitional disk. For the object Mon-296, we were successful. However, for Mon-314, and Mon-433 our evidence suggests that they host a pre-transitional disk. For Mon-1308 a new spectrum fitting using the 3D radiative transfer code Hyperion allows us to conclude that this object hosts a full disk instead of a transitional disk. This is in accord to previous work on Mon-1308 and with the fact that we cannot find a fit for the light curves using only the contribution of the dust inside the hole of a transitional disk.

Using plasmons to harness infrared solar light

Using plasmons to harness infrared solar light The PLASMIONICO project aims to advance the sustainable production of electricity by harnessing infrared (IR) solar light, which is typically wasted in conventional solar cells. The key concept is to allow IR light to be absorbed at nanostructured metal cathodes to launch surface plasmons (rapid oscillations of electronic charge analogous to sound waves in liquids) to generate a photocurrent. Our strategy uses inverted silicon pyramid arrays covered with thin gold films, manufactured employing low-cost and scalable methods. After optimising the infrared absorption performance, we are set to improve photocurrent delivery with promising results.

PULSE OXIMETER USAGE IN PATIENT COVID-19 TREATMENT : AT A GLANCE

Background: The end of 2019, Wuhan experienced an insurgence of coronavirus within two months of this prolong pandemic. Patients with Covid-19 have chance in suffering a serious damage of respiratory system, which then lead to hypoxemia. The harmful of silent hypoxemia is that either the patients are remain untreated or they will not seek any treatment at all, though their blood oxygen levels (SpO2 levels) slowly decrease. Especially those who isolated at home. Pulse oximeter is a mini device that evaluate the level of arterial blood saturation. Purpose: This article gives a short review about the principle, application, advantage, and disadvantage of pulse oximetry in maintaining the Covid-19 patients with hypoxemia. Review: Two basic principles of pulse oximetry that are important: (a) to differentiate the oxyhemoglobin (HbO2 ) and deoxyhemoglobin (HHb), (b) to get the value of SpO2 from arterial compartment blood. How pulse oximeter detects SpO2 is based on the amount of red and IR light absorbed. Pulse oximeter can detect an abnormality of respiratory system in Covid-19 patients that may cannot be detected earlier. Pulse oximeter also helps diagnosing some severe pneumonia cases. It also can be realiable to diagnose an ARDS (Acute Respiratory Distress Syndroms) if the devices are found limited (WHO, 2020). Beside the advantages of pulse oximeter, there are some erroneous of readings. Conclusion: Pulse oximeter is a mini device which offers many advantages over its limitations. Limitation of pulse oximeter can be early detected and overcame with an introduction evaluation of clinical conditions of each patients.