Carrier saturation in multiple quantum well metallo-dielectric semiconductor nanolaser: is bulk material a better choice for gain media?

Although multi quantum well (MQW) structure is frequently suggested as the appropriate medium for providing optical gain in nanolasers with low threshold current, we demonstrate that in general bulk gain medium can be a better choice. We show that the high threshold gain required for nanolasers demands high threshold carrier concentrations and therefore a highly degenerate condition in which the barriers between the quantum wells are heavily pumped. As a result, there occurs spontaneous emission from the barrier in very dissipative low Q modes or undesired confined higher Q modes with resonance wavelengths close to the barrier bandgap.

Spectroscopic determination of protein concentrations from proteinase K digests.

A method to determine protein concentrations and absorptivities based on absorbance measurements of proteinase K digests has been developed. Molar absorptivities of proteinase K digests at 56 degrees C can be predicted by using the following equation: epsilon (M)(280)=5318 x (No.of Trp) + 1227 x (No.