An optically pumped GaN-based vertical cavity surface emitting laser (VCSEL) is demonstrated. Laser emission near 363 nm is observed at room temperature from the surface of a VCSEL structure optically pumped along a cleaved sample edge by focused light from a nitrogen laser. The VCSEL structure, which was grown on a sapphire substrate by metalorganic vapor phase epitaxy, consists of a 10 μm GaN active region sandwiched between 30-period Al0.40Ga0.60N–Al0.12Ga0.88N Bragg reflectors. At optical pump intensities above ∼2.0 MW/cm2, a narrow (<5 Å) laser mode at 363.5 nm emerges from the GaN photoluminescence spectrum. This mode becomes the dominant feature of the spectrum at higher pump powers, and additional modes appear ∼1.3 nm above and below this mode at 362.1 nm and 364.8 nm. The ∼1.3 nm mode spacing corresponds closely with the 1.1 nm spacing predicted from an electromagnetics model of the VCSEL structure.

We previously demonstrated that the expression of the argininosuccinate synthetase (ASS) gene, a key step in nitric oxide production, is stimulated either by interleukin‐1β[Brasse‐Lagnel et al. (2005) Biochimie 87, 403–9] or by glutamine in Caco‐2 cells [Brasse‐Lagnel et al. (2003) J. Biol. Chem. 278, 52504–10], through the activation of transcription factors nuclear factor‐κB and Sp1, respectively. In these cells, the fact that glutamine stimulated the expression of a gene induced by pro‐inflammatory factors appeared paradoxical as the amino acid is known to exert anti‐inflammatory properties in intestinal cells. We therefore investigated the effect of simultaneous addition of both glutamine and interleukin‐1β on ASS gene expression in Caco‐2 cells. In the presence of both compounds for 4 h, the increases in ASS activity, protein amount and mRNA level were almost totally inhibited, implying a reciprocal inhibition between the amino acid and the cytokine. The inhibition was exerted at the level of the transcription factors Sp1 and nuclear‐κB: (a) interleukin‐1β inhibited the glutamine‐stimulated DNA‐binding of Sp1, which might be related to a decrease of its glutamine‐induced O‐glycosylation, and (b) glutamine induced per se a decrease in the amount of nuclear p65 protein without affecting the stimulating effect of interleukin‐1β on nuclear factor‐κB, which might be related to the metabolism of glutamine into glutamate. The present results constitute the first demonstration of a reciprocal inhibition between the effects of an amino acid and a cytokine on gene expression, and provide a molecular basis for the protective role of glutamine against inflammation in the intestine.

Green lasers with high efficiency are keystone components for mobile projectors. We demonstrate a miniature device (<0.7 cc volume) that utilizes adaptive optics for operation over a 50 °C temperature range without requiring a thermo‐electric cooler. The use of adaptive optics also helps in reducing the cost of the laser assembly.

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Abstract— Efficient and very‐compact projectors embedded into mobile consumer‐electronic devices, such as handsets, media players, gaming consoles, and GPS units, will enable new consumer use and industry business models. A keystone component for such projectors is a green laser that is commensurately efficient and compact. A synthetic green‐laser architecture is described that can achieve efficiencies of 15%. The architecture consists of an infrared distributed Bragg reflector laser coupled into a second‐harmonic‐generation device for conversion to green.