The present invention discloses an LED lamp which has a light guide with a total internal reflection (TIR) surface. A light modification layer comprising either a pure component or a mixture of the component selected from a group consisted of a yellow phosphor, a red phosphor, a green phosphor, a blue phosphor, and a reflective material is optionally adopted. The light beam is modified by the light modification layer before going out of the lamp. A blue light is one of the candidates which can be adopted as the light source.