US Patent 8455903 Non-radiatively pumped wavelength converter

A light source comprises an electroluminescent device that generates pump light and a wavelength converter that includes an absorbing element for absorbing at least some of the pump light. A first layer of light emitting elements is positioned proximate the absorbing element for non-radiative transfer of energy from the absorbing element to the light emitting elements. At least some of the light emitting elements are capable of emitting light having a wavelength longer than the wavelength of the pump light. In some embodiments the electroluminescent device is a light emitting diode (LED) that has a doped semiconductor layer positioned between the LED's active layer and the light emitting elements. The first doped semiconductor layer may have a thickness in excess of 20 nm. A second layer of light emitting elements may be positioned for non-radiative energy transfer from the first layer of light emitting elements.