An illumination apparatus includes a linear array of light emitting diode (LED) chips disposed on a support. A linear reflector assembly has a light coupling reflector portion and a one dimensional light collimation or focusing portion. The linear reflector assembly is secured to the support parallel with the linear array of LED chips. An encapsulant is disposed in the light coupling reflector portion of the linear reflector assembly and pots the LED chips. An elongate phosphor element is disposed over the encapsulant such that the light coupling reflector portion and the encapsulant enhance light coupling between the LED chips and the elongate phosphor element, and the one-dimensional light collimation or focusing portion one-dimensionally collimates or focuses light emitted by the combination of the LED chips and the elongate phosphor element.