In this paper the most important properties of lithium niobate crystals for photonic applications are reviewed. We will summarize how acting on the stoichiometry, sample structure, doping and domain structure of the crystals, these properties are governed, and can be taylored for each specific application. Finally we present a review of photonic applications in a wide spectrum of fields as lasers and non-linear optics, optical communications, optical memories, and diffractive optics.

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Optical and optoelectronic techniques for micro-and nano-object manipulation are becoming essential tools in nano-and bio-technology. A remarkable optoelectronic technique that has experimented a strong development in the last few years is the so called photovoltaic optoelectronic tweezers. It is based on the light-induced electric fields generated by the bulk photovoltaic effect in certain ferroelectrics such as LiNbO3. The technique is simple and versatile, enabling a successful manipulation of a large variety of micro-and nano-objects with only optical control, without the need of electrodes or power supplies. However, it is still a challenge for this tool, to handle objects immersed in aqueous solution due to the electric screening effects of polar liquids. This has hindered their application in biotechnology and biomedicine where most processes develop in aqueous solution. In this work, a new efficient route to overcome this problem has been proposed and demonstrated. It uses photovoltaic optoelectronic tweezers to manipulate aqueous droplets, immersed in a non-polar oil liquid, but hanging at the interface air-oil. In this singular configuration, the high electric fields generated in the photovoltaic substrate allow a simple and flexible manipulation of aqueous droplets controlled by the light. Droplet guiding, trapping, merging and splitting have been achieved and efficient operation with water and a variety of biodroplets (DNA, sperm, and PBS solutions) have been demonstrated. The reported results overcome a main limitation of these tweezers to handle bio-materials and promises a high potential for biotechnological and biochemistry applications including their implementation in optofluidic devices.

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O/)licrrl iirtciferoi~~ctiy is used to stz~lly the film thickness of pccrses, colrl of soap srcspeiuioiu and of their base oils in point or lii,e cwrloct. 111 mze cllse, sa?tiples were taken born a grease-lubriccrtc(l p111.i~~c-Occiring test c$/.er 5%-and 25-million revolutions. The effcc/I'~~c ~~i.scosity of (1 pease t~itder the very high shear rates of the order i f 1/2 X lo-" S-I e i z c o z~~z l~~~e d in rolling conlack can be cc1./c11ln/ccl.