Electrical generation of terahertz blackbody radiation from graphene

Far-infrared and terahertz emitting diodes based on graphene/black-P and graphene/MoS2 heterostructures

We propose the far-infrared and terahertz emitting diodes (FIR-EDs and THz-EDs) based on the graphene-layer/black phosphorus (GL/b-P) and graphene-layer/MoS₂ (GL/MoS₂) heterostructures with the lateral hole and vertical electron injection and develop their device models. In these EDs, the GL serves as an active region emitting the FIR and THz photons. Depending on the material of the electron injector, the carriers in the GL can be either cooled or heated dictated by the interplay of the vertical electron injection and optical phonon recombination. The proposed EDs based on GL/b-P heterostructures can be efficient sources of the FIP and THz radiation operating at room temperature.

Fluorescent incandescent light sources from individual quadrilateral ZnO microwire via Ga-incorporation

By means of nanophotonics principle, the thermal radiation can be tailored, thus, traditional tungsten lamp light source can glow the vitality and the vigor due to the low-efficiency approaching to commercial fluorescent or light-emitting diode bulbs. However, too far by demanding exacting terms, such as high-temperature thermal radiation (∼ 3000 K), high-vacuum encapsulation technology, restricted spectrally controllable source and so on, tungsten-based incandescent lamp filament has greatly limited the application in lighting, diagnosis and treatment, communication, imaging, etc. Herein, individual Ga-doped ZnO microwires (ZnO:Ga MWs) were successfully synthesized, which can be utilized to construct typical incandescent sources. By adjusting the Ga-incorporation, lighting colors are tuned in the visible spectral band. Especially, by incorporating Au quasiparticle nanofilms, the incandescent lighting features can further be modulated, such as the emission peaks, the modulation of lighting regions. Therefore, individual ZnO:Ga MWs based incandescent emitters can undertake a new function of the oldest, affordable and easily prepared light sources. While preliminary, individual ZnO:Ga MWs being treated as efficient incandescent light sources, can also open up intriguing scientific questions, and possible applications of linear, transparent, flexible displays and optical interconnects with electronic circuits.

Optical properties of surface states in two-dimensional topological insulators

We present a simple and tractable approach to investigate the optical properties of surface states in two-dimensional (2D) topological insulators (TIs). The analytic expression of optical conductivity of surface states in 2D TIs are obtained based on the kinetic equations. It is found that universal optical conductance can be observed in the high frequency region, which does not depend on the temperature, the chemical potential, or the bandgap of the systems. This universal optical conductance is similar to that in graphene. However, the optical absorption edge of such surface states strongly depend on the chemical potential and the bandgap of the systems. There are obvious optical absorption peaks at low temperature in the low frequency region, which are very different from that in graphene. The bandgaps in surface states can be accurately experimentally measured by the optical absorption edges or the peaks. We expect that our theoretical results offer transparent understandings for the experimental results and applications of 2D TIs.