An investigation was made of the spectral composition of the spontaneous radiation, superradiance, and laser radiation emitted by a pulsed copper vapor laser. The time resolution was about 3 nsec. It was found that the observed spectral structure of the laser radiation and superradiance was governed by the hyperfine and isotopic splitting of the active levels of the copper atom. In the absence of saturation of the active medium a narrowing of the spectral line profiles was observed during a superradiance pulse. When saturation was achieved for superradiance and lasing, the line profiles broadened to the width of the spontaneous emission line during a radiation pulse. It was found that the temperature of the gas in the copper vapor laser did not exceed 2500°K.
A steady-state superradiant laser can be used to generate ultranarrow-linewidth light, and thus has important applications in the fields of quantum information and precision metrology. However, the light produced by such a laser is still essentially classical. Here, we show that the introduction of a Rydberg medium into a cavity containing atoms with a narrow optical transition can lead to the steady-state superradiant emission of ultranarrow-linewidth
nonclassical light. The cavity nonlinearity induced by the Rydberg medium strongly modifies the superradiance threshold, and leads to a Mollow triplet in the cavity output spectrum
−this behavior can be understood as an unusual analogue of resonance fluorescence. The cavity output spectrum has an extremely sharp central peak, with a linewidth that can be far narrower than that of a classical superradiant laser. This unprecedented spectral sharpness, together with the nonclassical nature of the light, could lead to new applications in which spectrally pure
quantum light is desired.
A detailed investigation is made of the spectral properties of several superfluorescence operations in Nd-doped and Er-doped silica fibres pumped by a 514.5 nm Ar ion laser. The study demonstrates the spectral narrowing processes in the operations of superfluorescence. In Nd-doped fibre, the higher gain at 1080 nm suppresses the emission at about 910 nm, but the authors have still realized, for the first time, superfluorescence in this wavelength band, and a 0.4 mW output was achieved in a double-pass configuration. Also, the process of change from superfluorescence to lasing was recorded and analysed.