Currently, different competing waveguide and resonator concepts exist for terahertz quantum-cascade lasers (THz QCLs). We examine the continuous-wave (cw) performance of THz QCLs with single-plasmon (SP) and metal-metal (MM) waveguides fabricated from the same wafer. While SP QCLs are superior in terms of output power, the maximum operating temperature for MM QCLs is typically much higher. For SP QCLs, we observed cw operation up to 73 K as compared to 129 K for narrow (≤ 15 μm) MM QCLs. In the latter case, single-mode operation and a narrow beam profile were achieved by applying third-order distributed-feedback gratings and contact pads which are optically insulated from the intended resonators. We present a quantitative analytic model for the beam profile, which is based on experimentally accessible parameters.

Local oscillators in terahertz heterodyne spectrometers have to be operated in continuous-wave mode at precisely defined target frequencies. In particular, for advanced airborne instruments, several specifications such as operating temperature and cooling requirements are necessary to be considered. We have developed a quantum-cascade laser (QCL) applicable as a local oscillator for heterodyne spectroscopy of the OI line at 4.745 THz, which is of particular interest for astronomy. We demonstrate a distributed-feedback QCL operating in continuous-wave mode up to about 60 K, which can be tuned precisely to the target frequency when operated in a mechanical cooler.

With the increasing levels of digital transformation, focus on digital identities of individuals is increasingly getting prominence. It is the information captured as part of the identity surrounding the citizens which decides what services and products one is entitled to and can access. At present, there are still around 1.1 billion people in the world without any official identity. To address this concern, United Nations through its 16th Sustainable Development Goals (SDGs) recommended governments to provide their citizens with unique identities by 2030. India's Aadhaar is one significant step in this direction as it has already reached over 1 billion enrolments in India. However establishing a national digital identity program successfully requires expertise, time, and huge financial commitments. This paper takes Aadhaar as a case study and uses Design Theory (DT) and Critical Success Factor theory (CSF) as a theoretical lens and attempts to evaluate design and execution choices made during the tenure of the project. The study also identifies and prioritizes primary goals of Aadhaar based on the secondary data, expert opinion through a Focus Group Discussion (FGD) and subsequently systematic prioritization using mixed research methodologies.The expert opinion from the FGD was analyzed using the Best-Worst method (BWM), followed by the Total Interpretive Structural Modeling (TISM) method and Matrix of Cross Impact Multiplications Applied to Classification (MICMAC) analysis. The study identified uniqueness, security and privacy as the top priority goals in an identity system and is 11 times more crucial than scalability which is identified to be of lesser priority. These findings from this study could be considered as a reference for other countries that aim to develop and implement digital identity for its citizens.

Compounds with polarizable π systems that are susceptible to attack with nucleophiles at C-Hal (Hal = Cl, Br) bonds react with Pd(PPh3)4 to yield net oxidative addition. X-ray structures show that the resulting Pd(PPh3)2Hal groups greatly reduce intermolecular π-π interactions. The Pd-functionalized dyes generally exhibit solution-like absorption spectra in films, whereas their Hal analogues exhibit features attributable to aggregation.

Ternary mixed crystal effect on electron mobility in a strained wurtzite AlN/GaN/AlN quantum well with an InxGa1−xN nanogroove