Semiconductor amplifier or laser having integrated lens

An optical device includes a semiconductor optical amplifier and a lens for receiving optical energy from the optical amplifier. The lens and the optical amplifier are monolithically integrated on a common substrate. The optical amplifier may be of the type having a tapered active region. Rather than an optical amplifier, a semiconductor laser may be integrated with the lens. The lens may be formed by changing the refractive index of the waveguide core which is formed in the semiconductor material. This refractive index change may be produced by changing the thickness of a portion of the waveguide core layer.