This issue of the Photonics Letters of Poland contains seven papers that are related to: experimental investigations on high-power Er:ZBLAN fiber laser operating at around 2.8µm; synthesis and characterization of LVLVPM material in the form of an amino acid derivative crystal with potential applications in nonlinear optics; morphology and structure characterization of SnO₂ nanowires produced with use of a hybrid electrospinning method combined with a heat treatment process at the temperature of 600oC; verification of the usefulness of commercially available granulates of PMMA and PS for the production of polymer optical fibers by extrusion method; numerical investigations on a metamaterial narrowband perfect absorber (with the maximum absorbance of 95.7%) formed by the periodic array of silicon meta-atoms placed on 80-nm-thick gold layer; numerical studies on a miniaturized design of the plasmonic Bragg grating filter based on metal-insulator-metal waveguide deposited on a quartz substrate operating in near-infrared wavelength range; numerical studies on C-band pass one-dimensional photonic crystal strip waveguide based on silicon-on-insulator platform to be easily realized with use of standard CMOS technology.