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Abstract High-power terahertz (THz) quantum cascade laser, as an emerging THz solid-state radiation source, is attracting attention for numerous applications including medicine, sensing, and communication. However, due to the sub-wavelength confinement of the waveguide structure, direct beam brightness upscaling with device area remains elusive due to several mode competition and external optical lens is normally used to enhance the THz beam brightness. Here, we propose a metallic THz photonic crystal resonator with a phase-engineered design for single mode surface emission over a broad area. The quantum cascade surface-emitting laser is capable of delivering an output peak power over 185 mW with a narrow beam divergence of 4.4° × 4.4° at 3.88 THz. A high beam brightness of 1.6 × 107 W sr−1m−2 with near-diffraction-limited M2 factors of 1.4 in both vertical and lateral directions is achieved from a large device area of 1.6 × 1.6 mm2 without using any optical lenses. The adjustable phase shift between the lattices enables a stable and high-intensity surface emission over a broad device area, which makes it an ideal light extractor for large-scale THz emitters. Our research paves the way to high brightness solid-state THz lasers and facilitates new applications in standoff THz imaging, detection, and diagnosis.

Abstract Topological lasers (TLs) have attracted widespread attention due to their mode robustness against perturbations or defects. Among them, electrically pumped TLs have gained extensive research interest due to their advantages of compact size and easy integration. Nevertheless, limited studies on electrically pumped TLs have been reported in the terahertz (THz) and telecom wavelength ranges with relatively low output powers, causing a wide gap between practical applications. Here, we introduce a surface metallic Dirac-vortex cavity (SMDC) design to solve the difficulty of increasing power for electrically pumped TLs in the THz spectral range. Due to the strong coupling between the SMDC and the active region, robust 2D topological defect lasing modes are obtained. More importantly, enough gain and large radiative efficiency provided by the SMDC bring in the increase of the output power to a maximum peak power of 150 mW which demonstrates the practical application potential of electrically pumped TLs.

The photonic crystal surface-emitting laser (PCSEL) has attracted much attention due to the advantages of a small far-field divergence angle and high output power. Here, we report a high-power terahertz (THz) photonic crystal laser with high beam quality through the optimization of the absorption boundary condition and the introduction of the symmetrically distributed electrodes. Single-mode surface emission at 3.4 THz with the maximum peak output power of 50 mW is demonstrated. Meanwhile, a high symmetric far-field pattern with C6 symmetry and a small divergence angle is achieved. In this device, the integration of the stable single-mode operation, high beam quality and high output power is realized, which may have great significance for practical applications.

Quantum light sources that generate single photons and entangled photons have important applications in the fields of secure quantum communication and linear optical quantum computing. Self-assembled semiconductor quantum dots, also known as “artificial atoms”, have discrete energy-level structures due to electronic confinement in all three spatial dimensions. It has the advantages of high stability, high brightness, deterministic, and tunable emission wavelength, and is easy to integrate into an optical microcavity with a high-quality factor, which can realize a high-performance quantum light source. In this paper, we first introduce the generation principles, properties, and applications of single-photon sources in the field of quantum information and then present implementations and development of quantum light sources in self-assembled semiconductor quantum dot materials. Finally, we conclude with an outlook on the future development of semiconductor quantum dot quantum light sources.

A rapid and effective polymerase chain reaction (PCR) test, specific for the detection of Mycobacterium bovis and Mycobacterium avium subsp. paratuberculosis in invasive flies, was developed. This duplex PCR technique was specifically designed to amplify the sequences of IS6110 of M. bovis and IS900 of M. avium subsp. paratuberculosis. The results of the interference test, simulated contamination test, and several other experiments indicated that this technique had high stability, specificity, and sensitivity with detection limits at 92.98 pg of M. bovis and 110.27 pg of M. avium subsp. paratuberculosis. Therefore, this duplex PCR test is a rapid and effective technique to simultaneously detect M. bovis and M. avium subsp. paratuberculosis. [ABSTRACT FROM AUTHOR]