Patent ID: RE38809

Claim:
An index-switched optical variable delay device for varying a path length of an optical beam, comprising: A slab of birefringent crystal having a first birefringent axis and a second birefringent axis, a first array of corner reflectors being placed at a first side of said slab, a second array of corner reflectors being placed at an opposite side of said slab, and a multiple of polarization rotators each independently operable to rotate a first polarization state of an input light beam to a second polarization state which is substantially orthogonal to the first polarization state when being activated and leave the first polarization state unaffected when being de-activated; said two corner reflector arrays being such arranged that the optical beam entering from the first side of the slab towards the opposite side is reflected back by a first corner reflector on the opposite side towards a second corner reflector at the first side; the beam being reflected again by the second corner reflector towards a third corner reflector on the opposite side, and continuing being reflected back and forth across the slab by successive corner reflectors until exiting; the polarization rotators each being placed between the slab and a selected corner reflector.