Patent ID: 6867902

Claim:
Device for performing a parametric process according to which a pump radiation at frequency ω p generates a radiation at frequency ω g interacting with at least one signal radiation at frequency ω s different from ω p , comprising: a substantially periodic photonic crystal structure comprising a plurality of unitary cells that follow one other along a predetermined direction, each unitary cell comprising a first layer having a first refractive index n 1 and a first length L 1 , a second layer having a second refractive index n 2 , with n 1 different from n 2 , and a second length L 2 ; an input for sending said at least one signal radiation at frequency ω s along said substantially periodic structure; an input for providing said pump radiation at frequency ω p to said substantially periodic structure; and an output suitable to extract from the device said generated radiation at frequency ω g ; characterised in that each unitary cell also comprises a third layer having a third refractive index n 3 , with n 3 different from n 2 , and a third length L 3 and a fourth layer having a fourth refractive index n 4 , with n 4 different from n 1 and from n 3 , and a fourth length L 4 , the periodical alternance of the first, second, third and fourth layer forming said substantially periodic photonic crystal structure; at least one among the first, the second, the third and the fourth layers has a non-linearity of the χ 2 or χ 3 type; at least one of the following conditions is met: a) n 1 is different from n 3 ; b) n 2 is different from n 4 ; c) L 1 is different from L 3 ; d) L 2 is different from L 4 ; and in that n 1 , n 2 , n 3 , n 4 , L 1 , L 2 , L 3 , L 4 are selected so as to perform the parametric process in phase matching conditions.