A transmissive optical element is fabricated by filling a mold with molten liquid that includes a transparent plastic and a phosphor additive, and allowing the molten liquid to solidify to produce the transmissive optical element having phosphor dispersed therein. Accordingly, a separate phosphor coating or phosphor-containing encapsulant need not be used. Transmissive optical elements include a shell made of transparent plastic with a phosphor dispersed therein. The phosphor may be uniformly and/or nonuniformly dispersed in the shell.