Stimulated emission spectra of powders of double sodium and lanthanum tetramolybdate

Abstract

Readout noise is a critical parameter for characterizing the performance of charge-coupled devices (CCDs), which can be greatly reduced by the correlated double sampling (CDS) circuit. However, a conventional CDS circuit inevitably introduces new noise since it consists of several active analog components such as operational amplifiers. This paper proposes a digital CDS circuit technique, which transforms the pre-amplified CCD signal into a train of digital presentations by a high-speed data acquisition card directly without the noisy CDS circuit, then implements the digital CDS algorithm through a numerical method. A readout noise of 3.3 e − and an energy resolution of 121 eV@5.9 keV can be achieved via the digital CDS technique.

Sharp intense line in the bioluminescence emission of the firefly

“…Large variation in the intensity ratio F591/F562 also points towards a mechanism like this. It could be mentioned here that in random lasers, for the particle size much larger than the emission wavelength a single particle could serve as the resonator [26,27] while for the particle size less than the wavelength laser resonators are formed by recurrent scattering [28]. In the present case, we speculate that the emission peak becomes narrower due to the preferential amplification at 591 nm within the FWHM.…”

Modeling of photon density dynamics in random lasers

“…After their first theoretical prediction [1,2] and experimental observation [3,4], a variety of random lasers has been reported in the literature. This includes random lasers based on highly scattering dielectrics materials doped with Nd 3+ [5][6][7][8][9], Pr 3+ [10], Ti 3+ [11] and other ions, ZnO random lasers [4,12,13], random lasers based on scattering polymers [14][15][16], etc. Due to the easy manufacturing, low price, small size, and robustness in operation, random lasers are very attractive for potential applications, which include express testing of novel laser materials [5], markers [17,18], high brightness laser displays [19], etc.…”

Random Laser Action in Semiconductor Powder

“…According to the random laser theory [3,19], the gain length at the onset of lasing is l g ϳ V 2͞3 ͞l ϳ 2.8 mm. Experimentally, at the lasing threshold pump intensity (763 kW͞cm 2 ), the gain coefficient was measured to be ϳ20 cm 21 . The corresponding gain length is ϳ1 mm.…”