A solid state illumination device includes a semiconductor light emitter mounted on a base and surrounded by sidewalls, e.g., in a circular, elliptical, triangular, rectangular or other appropriate arrangement, to define a chamber. A top element, which may be reflective, may be coupled to the sidewalls to further define the chamber. The light produced by the semiconductor light emitter is emitted through the sidewalls of the chamber. The sidewalls and/or top element may include wavelength converting material, for example, as a plurality of dots on the surfaces. An adjustable wavelength converting element may be used within the chamber, with the adjustable wavelength converting element being configured to adjust the surface area that is exposed to the light emitted by the semiconductor light emitter in the chamber to alter an optical property of the chamber.