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The mechanisms contributing to experimental quality factors of short wavelength ($\ensuremath{\lambda}=440--480$ nm) III-nitride on silicon one-dimensional photonic crystal cavities were quantified. Fluctuations in fundamental and first-order cavity mode wavelength and quality factor were compared over sets of nominally identical cavities. Unlike at $\ensuremath{\lambda}=1.5\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{m}$, experimental quality factors were not limited by fabrication disorder modeled as smooth, normally distributed hole size and position variations; after ruling out absorption losses, additional scattering losses were found to predominate at short wavelengths. Experimental quality factors were sensitive to conformal deposition of few nanometer thin films on the photonic crystal surface, suggesting that the additional scattering losses were linked to the surface.

An exciton-polariton is a hybrid quasiparticle, a photon plus an electron-hole pair in a semiconductor, that combines propagation at nearly the speed of light with strong interactions. The authors give experimental proof of principle for the guided motion of polaritons through $I\phantom{\rule{0}{0ex}}I\phantom{\rule{0}{0ex}}I$-nitride heterostructures, which could lead to active all-optical devices operating in the strong-coupling regime $a\phantom{\rule{0}{0ex}}t$ $r\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}m$ $t\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}e$. As such, this study is a promising step toward the practical realization of integrated polaritonic circuits.

We study the carrier-density-dependent recombination dynamics in $m$-plane InGaN/GaN multiple quantum wells in the presence of $n$-type background doping by time-resolved photoluminescence. Based on Fermi's golden rule and Saha's equation, we decompose the radiative recombination channel into an excitonic and an electron-hole pair contribution, and extract the injected carrier-density-dependent bimolecular recombination coefficients. Contrary to the standard electron-hole picture, our results confirm the strong influence of excitons even at room temperature. Indeed, at 300 K, excitons represent up to 63 \ifmmode\pm\else\textpm\fi{} 6% of the photoexcited carriers. In addition, following the Shockley-Read-Hall model, we extract the electron and hole capture rates by deep levels and demonstrate that the increase in the effective lifetime with injected carrier density is due to asymmetric capture rates in presence of an $n$-type background doping. Thanks to the proper determination of the density-dependent recombination coefficients up to high injection densities, our method provides a way to evaluate the importance of Auger recombination.

Applying four-wave mixing spectroscopy to a high-quality GaN/AlGaN single quantum well, we report on the experimental determination of excitonic dephasing times at different temperatures and exciton densities in III-nitride heterostructures. By comparing the evolution with the temperature of the dephasing and the spin-relaxation rate, we conclude that both processes are related to the rate of excitonic collisions. When spin relaxation occurs in the motional-narrowing regime, it remains constant over a large temperature range as the spin-precession frequency increases linearly with temperature, hence compensating for the observed decrease in the dephasing time. From those measurements, a value of the electron-hole exchange interaction strength of 0.45 meV at $T=10\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ is inferred.

We study the relative intensity noise (RIN) per unit bandwidth in polariton laser diodes (LDs) for two pumping geometries, namely, the direct electrical and the intracavity ones as originally described in I. Iorsh et al. [Phys. Rev. B 86, 125308 (2012)], by using rate equations including Langevin noise sources that are adapted from equations employed to describe conventional semiconductor LDs. The obtained expressions for the RIN, which can be used for all inorganic semiconductor polariton LDs, are specifically applied to the case of III-nitride devices. It is highlighted that for frequencies larger than the relaxation resonance frequency the expected minimum RIN of polariton LDs-whatever the pumping geometry-is equal to the standard quantum limit (2h nu/P-0). The general RIN line shape as a function of frequency and optical output power is discussed for the two geometries and simplified expressions for the RIN are given. Then a comprehensive account of the expected evolution of the linewidth of III-nitride polariton LDs upon increasing pumping strength is also given by considering the most advanced theories available to date. The modified Schawlow-Townes linewidth is estimated from the effective ground-state polariton lifetime at threshold, leading to a predicted linewidth as narrow as similar to 15 MHz at room temperature for the two pumping geometries when using a consistent set of parameters for III-nitride polariton LDs.