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We fabricated polyvinyl alcohol (PVA) nanofibers doped with Rhodamine 6G laser dyes via an electrospinning technique, which were then excited by a pulsed laser for laser emission. The laser was observed at a low threshold of several µJ and the intensity increased with the dye concentration. A single peak with a full width at half maximum (FWHM) of 4 nm was detected for a fiber of 300 nm diameter and multi-peaks with an FWHM of 2 nm were recorded as the diameter was increased to 800 nm. However, the multi-peaks tended to saturate to one laser peak with an intensive incident laser. The lasing mode was closely related to the diameters of the PVA fibers. Simulating results indicated that the single and multiple modes were closely related to the pump wavelength. The nanofiber as a network forming a random laser is expected to be used as a waveguide in communications and the multi-modes have potential application in cryptology.

The controlled colour generation and colour erasing phenomena of alkylammonium polyoxomolybdate complexes were first observed in the trans-(1R,2R)-1,2-bis(undecylcarbonylamino)cyclohexane organogel system using the sol-gel phase transition.

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Accurate mathematical models called one-line calibration and parameter fitting are presented for wavelength calibration of a flat-field grating spectrometer. The models precisely establish the relationship between wavelength and pixel position of the detector, since geometry parameters and the grating equation of the spectrometer are taken into account. Compared with the commonly used polynomial fitting, the models presented here provide more reliable calibration results, especially in the extended region away from the calibration points. In addition to the high precision of calibration, the parameter fitting procedure provides a helpful way to obtain the actual parameters of the spectrometer.