We designed and fabricated a suspended SiC-based membrane high contrast grating (HCG) reflectors. The rigorous
coupled-wave analysis (RCWA) was employed to verify the structural parameters including grating periods, grating
height, filling factors and air-gap height. From the optimized simulation results, the designed SiC-based membrane HCG
has a wide reflection stopband (reflectivity (R) <90%) of 135 nm for the TE polarization, which centered at 480 nm. The
suspended SiC-based membrane HCG reflectors were fabricated by nanoimprint lithography and two-step etching
technique. The corresponding reflectivity was measured by using a micro-reflectivity spectrometer. The experimental
results show a high reflectivity (R<90%), which is in good agreement with simulation results. This achievement should
have an impact on numerous III-N based photonic devices operating in the blue wavelength or even ultraviolet region.
We report on the numerical analysis of the electrical and optical properties of current-injected III-N based vertical-cavity surface-emitting lasers (VCSELs) with three types of current confinement schemes: the conventional planar-Indium Tin Oxide (ITO) type, the AlN-buried type without ITO, and the hybrid type. The proposed hybrid structure, which combines an ITO layer and an intracavity AlN aperture, exhibits not only a uniform current distribution but also an enhanced lateral optical confinement. Thus, the hybrid type design shows a remarkably better performance including lower threshold current and series resistance compared with the planar-ITO type and the AlN-buried type. Furthermore, the multi-transverse mode lasing behavior induced by strong index guiding of the AlN aperture is suppressed to single transverse mode operation by reducing the aperture size. Such design provides a powerful solution for the high performance III-N based VCSELs and is also viable by using current state of the art processing techniques.
The characteristics of exciton-polaritons in ZnO-based microcavities (MCs) are demonstrated with a large vacuum Rabi
splitting due to large exciton binding energy and oscillator strength. The lower polariton branches (LPBs) can be clearly
observed. For low temperature and large negative detuning conditions, a clear polariton relaxation bottleneck in bulk
ZnO-based MCs has been observed in angle-resolved photoluminescence measurements from 100 to 353 K at different
cavity-exciton detunings. The bottleneck is strongly suppressed with increasing the temperature and pumping power and
reducing detuning. This observed results supposed to be due to more efficient phonon-assisted relaxation and a longer
radiative lifetime of the polaritons. In addition, the linewidth broadening, blue-shift of the emission peak, and
polarization of polariton lasing from below threshold to up threshold are also discussed.
Here we report the first realization of a current injection microcavity GaN exciton-polariton light emitting diode (LED)
operating under room temperature (RT). The hybrid microcavity structure consists of InGaN/GaN quantum wells
sandwiched between bottom epitaxial DBR and top dielectric DBR. The anti-crossing behavior of polariton LED
denotes a clear signature of the strong interaction between excitons and cavity photons.