Blue laserA blue laser emits electromagnetic radiation with a wavelength between 400 and 500 nanometers, which the human eye sees in the visible spectrum as blue or violet. Blue lasers can be produced by direct, inorganic diode semiconductor lasers based on quantum wells of gallium(III) nitride at 380-417nm or indium gallium nitride at 450nm diode-pumped solid-state infrared lasers with frequency-doubling to 405nm upconversion of direct diode semiconductor lasers via thullium or paraseodyium doped fibers at 480nm metal vapor, ionized gas lasers of helium-cadmium at 442 nm and 10-200 mW argon-ion lasers at 458 and 488 nm Lasers emitting wavelengths below 445 nm appear violet, but are called blue lasers.
WaveguideA waveguide is a structure that guides waves, such as sound (acoustic waveguide), light (optical waveguide), radio waves (radio-frequency waveguide) or other electromagnetic waves, with minimal loss of energy by restricting the transmission of energy to one direction. Without the physical constraint of a waveguide, wave intensities decrease according to the inverse square law as they expand into three-dimensional space. There are different types of waveguides for different types of waves.
Condensat de Bose-EinsteinUn condensat de Bose-Einstein est un état de la matière apparent au niveau macroscopique, formé de bosons identiques (typiquement des atomes se comportant comme des bosons), tel qu'un grand nombre de ces particules, à une température suffisamment basse, occupent un unique état quantique de plus basse énergie (état fondamental) lui donnant des propriétés spécifiques. Ce phénomène a été prédit en 1925 par Albert Einstein, qui a généralisé au cas des atomes les travaux de Satyendranath Bose sur les statistiques quantiques des photons (travaux ouvrant la voie vers les lasers).
