Quantum dots (QDs) of semiconductors are promising materials for light emission applications due to their size-tunable optoelectronic properties. We present results of direct quantum dot (QD) formation from precursors inside a polymer matrix using laser irradiation. The method is important because it provides a simple means of patterning nanocomposite material within selected regions of a polymer, as required for device design. Several combinations of polymer/precursors films were treated with a picosecond laser at wavelength of 266 nm in order to verify the formation of the QDs inside the polymeric matrix. Precursors for CdS and CdSe QDs were used in experiments. The structural studies of laser-irradiated samples carried out by means of transmission electron microscopy (TEM) showed the QD formation. The size of QDs and the clusters depended on the laser irradiation dose transferred to the film. The QDs were collected to clusters including 10-60 QDs of different size. The mean size of QDs was less than 10nm. The optical analysis carried out by means of UV-VIS and optical microscopy confirmed the formation of the QDs after laser processing. The time-resolved photoluminescence revealed the energy transfer from the organic host to QDs. However, the charge separation was present due to a certain energy level alignment. Modification of the polymer/precursor blends is still required to prevent imbalance of carrier injection to QDs. Photo-luminescent spectroscopy and fluorescence microscopy have revealed that even if the QDs are not emissive, in certain polymer/QDs combinations the PL emission of the polymer is restored after laser treatment.
An application of mechanically created long-period fiber gratings as sensitive bend sensors in structures and other areas is suggested. A resonance splitting of about 10 nm is observed under a maximum bend curvature of 0.4 m–1, producing a bend sensitivity of 25 nm/m–1. The design features of the experimental setup developed for the realization of mechanically created long-period fiber gratings and measurement of their output spectrum under different bend curvatures are discussed.