Femtosecond phase-coherent two-dimensional (2D) spectroscopy has been experimentally demonstrated as the direct optical analog of 2D nuclear magnetic resonance. An acousto-optic pulse shaper created a collinear three-pulse sequence with well-controlled and variable interpulse delays and phases,which interacted with a model atomic system of rubidium vapor. The desired nonlinear polarization was selected by phase cycling (coadding experimental results obtained with different interpulse phases). This method may enhance our ability to probe the femtosecond structural dynamics of macromolecules.

The laser emission of YAIO3:Er at 1.663 pm was investigated in order to find the best conditions with respect to crystal orientation, Er concentration. and output coupling. Using ten different laser rods the following optimised data have been obtained: b axis laser rod(Pnmanotation),1.25%Erdoping,and857~outputmirrorreflectivity.Thetemperature dependence of laser threshold and efficiency was measured between -50" and 50 "C. At room temperature we obtained34 J thresholdenergy and0.07% slope efficiency. In addition laser emission of LiYFJ:Ho, Er, Tm at 2.065 pm was investigated. The slope efficiency was 0.22%. Laser emission of YA103:Ho, Er, Tm at 2.12 pm is briefly mentioned.

We have developed a wideband tunable optical filter that uses a long-period fiber grating (LPFG) in which both resonance wavelength and its signal attenuation can be adjusted. We create the grating mechanically by pressing a spring coil to an optical fiber. We achieve continuous fine tuning of wavelength and attenuation by varying the temperature of the LPFG. The adjustable ranges of the LPFG are more than 200 nm in resonance wavelength and more than 10 dB in signal attenuation.

A new experimental technique is developed for producing a high-performance single-crystalline Ag nanostructure on transparent and flexible amorphous substrates for use in plasmonic sensors and circuit components. This technique is based on the epitaxial growth of Ag on a (001)-oriented single-crystalline NaCl substrate, which is subsequently dissolved in ultrapure water to allow the Ag film to be transferred onto a wide range of different substrates. Focused ion beam milling is then used to create an Ag nanoarray structure consisting of 200 cuboid nanoparticles with a side length of 160 nm and sharp, precise edges. This array exhibits a strong signal and a sharp peak in plasmonic properties and Raman intensity when compared with a polycrystalline Ag nanoarray.

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