Light emitting device comprising wavelength converter

A light emitting device comprising:

• a substrate;
• a plurality of light sources arranged on said substrate and each having a light exit surface;
• a wavelength converter configured to convert light from a first wavelength to a second wavelength, said wavelength converter having a light exit surface and a light entrance surface extending in an angle different from zero to one another;
• and
• an optical coupling element, arranged between and in contact with said light exit surfaces of said plurality of light sources and said light entrance surface of said wavelength converter, and configured to couple light from said plurality of light sources to said wavelength converter;
• wherein at least a major portion of the surface of said wavelength converter, other than said light exit surface and said light entrance surface, has a surface roughness, RA, less than 100 nm.