A tunable random laser with a bendable poly (dimethylsiloxane) (PDMS) substrate was described. The substrate is prepared based on soft lithography from lotus leaf, which have the similar surface structure with lotus leaf such as micropapilla. The micro-papilla on the surface of the substrate will provide efficient multiple scattering for the photon generated from gain medium, and the coherent random lasing is emerging because photon form closed-loop path among micropapilla via the scattering. The wavelength of the random laser emission spectrum can be tuned as wide as 26.0 nm by changing the pump position due to the diverse distribution of the micro-scale features on the soft substrate. The random laser provides a promising solution toward the realization of many laser based applications such as integrating optical biosensors on chips, probing micro-scale structural alterations and developing a multi-color even white random laser.
This paper reports the simultaneous output of 358.7nm and 420.3nm laser generated by two-photon excitation (52 S1/2→62 D5/2, TPE) and four-wave mixing effect (FWM) in rubidium system for the first time. Unlike some fluorescent signals, this four-wave mixing beam has a high monochromaticity and extreme directivity and can be used as a laser source. In this study, we also measured the fluorescence lines in the range of 300-820 nm under 52 S1/2→62 D5/2 TPE, and studied other transitions that may occur. The experimental results show that the blue-violet laser produced by this alkali metal rubidium four-wave mixing can provide a new laser source for underwater laser communication, display technology, fluorescence excitation, Raman spectroscopy, marine resource detection, laser biomedicine, lithography, high density information storage and other fields.
The kinetic behaviors of 6p[1/2]0, 6p[3/2]2 ,and 6p[5/2]2 were examined under the ultrahigh pumped power. These processes were detected by the way of time-resolved fluorescence and ASE spectra. A theory of energy-pooling is presented under the focused condition. There are three types of energy-pooling processes. The first type is energy-pooling ionization. The obvious ionization can be observed whenever the laser prepared state is the 6p[1/2]0, 6p[3/2]2, or 6p[5/2]2 state. The second type is energy-pooling with big energy difference. The energy-pooling collision between the two 6p[1/2]0 atoms can produce one 5d[3/2]1 atom and one 6s’[1/2]0 atom when the prepared state is 6p[1/2]0. The third type is energy-pooling with small energy difference. The way of generation of five secondary 6p states is energy-pooling instead of collision relaxation.
A blue random laser based on solid waveguide gain films with silver nanoparticles (NPs) and SiO2 NPs is demonstrated. Located surface plasmon resonance (LSPR) property and multiple scattering are proven playing an important role simultaneously.
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