A power converting device for converting optical power into electrical power adapted for optical wireless power transmission using a laser beam , said power converting device comprising: a photovoltaic cell (81a/b) having a plurality of conductors (83a/b) on a surface adapted to receive said laser beam, said photovoltaic cell having at least one junction having a bandgap energy between 0.75eV and 1.2 eV; and a cover layer disposed upon said photovoltaic cell, said cover layer comprising a material adapted to restrict transmission, by either absorption or reflection, of illumination having wavelengths outside of the range of the wavelength of said laser beam, and to transmit said laser beam towards said photovoltaic cell; wherein: said laser beam has a wavelength falling in a first range between 700nm and 1500nm; the transmission of said cover layer for said wavelength of said laser beam is at least 50% higher than its transmission for wavelengths within a second range of 550nm to 700nm, such that said power converting device has an efficiency of conversion to electrical power at said wavelength of said laser beam at least 2.5 times higher than its efficiency at a wavelength of 550nm; and said cover layer being further configured to absorb or reflect at least a third wavelength between 300nm and 550nm, so that at least 50% of the power of said third wavelength is absorbed before reaching said at least one junction, when illuminated through said external layer from any direction between ±20° to the normal to the surface of said external layer, and said power converting device conversion efficiency for said third wavelength being less than 10%; said power converting device being characterized in that it has a conversion efficiency of below 5% for a fourth wavelength between 1500nm and 2000nm. a photovoltaic cell (81a/b) having a plurality of conductors (83a/b) on a surface adapted to receive said laser beam, said photovoltaic cell having at least one junction having a bandgap energy between 0.75eV and 1.2 eV; and a cover layer disposed upon said photovoltaic cell, said cover layer comprising a material adapted to restrict transmission, by either absorption or reflection, of illumination having wavelengths outside of the range of the wavelength of said laser beam, and to transmit said laser beam towards said photovoltaic cell; said laser beam has a wavelength falling in a first range between 700nm and 1500nm; the transmission of said cover layer for said wavelength of said laser beam is at least 50% higher than its transmission for wavelengths within a second range of 550nm to 700nm, such that said power converting device has an efficiency of conversion to electrical power at said wavelength of said laser beam at least 2.5 times higher than its efficiency at a wavelength of 550nm; and said cover layer being further configured to absorb or reflect at least a third wavelength between 300nm and 550nm, so that at least 50% of the power of said third wavelength is absorbed before reaching said at least one junction, when illuminated through said external layer from any direction between ±20° to the normal to the surface of said external layer, and said power converting device conversion efficiency for said third wavelength being less than 10%; said power converting device being characterized in that it has a conversion efficiency of below 5% for a fourth wavelength between 1500nm and 2000nm. <EOS>