COMPENSATION OF THE WAVELENGTH DEPENDENCE IN DIFFRACTIVE STAR COUPLERS

Optical systems are described that compensate for the wavelength dispe rsion that arises in a diffractive fan-out star coupler. Two approache s are investigated, a space-variant one and a space-invariant one. In the space-variant approach an array of diffractive optical elements co rrects the wave fronts. In the space-invariant approach a combination of refractive and diffractive lenses compensates for the chromatic foc us shifts that are caused by the fan-out element. Examples for such co mpensating optical systems are presented, along with simulated results . The detailed design for an optimized space-invariant system is descr ibed.