OPTICAL APPARATUS WHICH USES A VIRTUALLY IMAGED PHASED ARRAY TO PRODUCE CHROMATIC DISPERSION

An apparatus which adds "opposite dispersion" to light, to compensate for chromatic dispersion of the light caused by travelling through an optical fiber. The apparatus includes a virtually imaged phased array (VIPA), and a light returning device. The VIPA provides angular dispersion to the light, and the light returning device returns the light back to the VIPA to undergo multiple reflection inside the VIPA. The light returning device is typically a mirror. In this case, the mirror can be shaped so that the apparatus adds a constant dispersion to the light. Moreover, a lens can be positioned between the VIPA and the light returning device so that (a) the light travels from the VIPA to the light returning device by travelling from the VIPA to the lens and then being focused by the lens to the light returning device, (b) the light returns from the light returning device to the VIPA by travelling from the light returning device to the lens and then being directed by the lens to the VIPA, and (c) the light travelling from the VIPA to the lens is parallel with the returned light travelling from the lens to the VIPA.