Light emission from color centers in diamond is being extensively investigated for developing, among other quantum devices, single-photon sources operating at room temperature. By doping diamond with phosphorus, one obtains an n-type semiconductor, which can be exploited for the electrical excitation of color centers. Here, we discuss the optical properties of color centers in phosphorus-doped diamond, especially the silicon-vacancy center, presenting the single-photon emission characteristics and the temperature dependence aiming for electroluminescent single-photon emitting devices.

Optoelectronic tunability in van der Waals heterostructures is essential for their optoelectronic applications. In this work, tunable photoconductive properties were investigated in the heterostructures of WSe2 and monolayer graphene with different stacking orders on SiO2/Si substrates. Here, we demonstrated the effect of the material thickness of WSe2 and graphene on the interfacial charge transport, light absorption, and photoresponses. The results showed that the WSe2/graphene heterostructure exhibited positive photoconductivity after photoexcitation, while negative photoconductivity was observed in the graphene/WSe2 heterostructures. The tunable photoconductive behaviors provide promising potential applications of van der Waals heterostructures in optoelectronics. This work has guiding significance for the realization of stacking engineering in van der Waals heterostructures.

We present a new planarized waveguide geometry for THz quantum cascade laser frequency combs with improved waveguide losses, RF and thermal dissipation properties. Ridge devices display broadband free-running comb states, and the THz emission can be further broadened by RF injection. Tapered waveguide devices feature a strong field-enhancement effect, which results in an improved comb performance. This includes free-running comb states with strong single beatnotes up to nearly -30 dBm at 90 K, almost three orders of magnitude stronger than for ridge devices. Improved comb operation is maintained also for high operating temperatures, up to 115 K.

Metasurfaces are versatile tools for controlling the behaviour of light through the exact control of light scattering at an interface. Here, we adopt the metasurface technology for optical manipulation applications, using their form factor and light-momentum engineering ability to enable new form of light-matter interactions. The resulting lab-on-chip platform offers unique advantages for biophotonic applications, including single molecule force spectroscopy and biological imaging.