초록 ▼

The invention relates to a frequency converter comprising a guide and a non-linear medium (NLM) in which the condition of phase matching between non-linear polarization and created waves is satisfied locally. The object of the invention resides in an additional layer C lying on the medium (NLM), the

The invention relates to a frequency converter comprising a guide and a non-linear medium (NLM) in which the condition of phase matching between non-linear polarization and created waves is satisfied locally. The object of the invention resides in an additional layer C lying on the medium (NLM), the refractive index of which is such that it increases the conversion yield, for conversion of the incident waves to the waves created within the guide. This layer may be a symmetrization layer whose index is close to the index of the medium (NLM). The conversion yield may be further increased by means of an intermediate layer C.sub.ex, which lies between the layer C and the medium (NLM) and the index of which is close to that of the guide.

대표청구항 ▼

[ We claim:] [1.] Frequency converter comprising a guide of refractive index n.sub.g, supplied by one or more light waves of frequency .omega..sub.n, also comprising a non-linear medium (NLM) of index n.sub.s (less than n.sub.g) in which the condition for phase matching between non-linear polarizati

[ We claim:] [1.] Frequency converter comprising a guide of refractive index n.sub.g, supplied by one or more light waves of frequency .omega..sub.n, also comprising a non-linear medium (NLM) of index n.sub.s (less than n.sub.g) in which the condition for phase matching between non-linear polarization generated by incident waves and created waves at frequencies .omega..sub.em is satisfied over a depth D of the non-linear medium by periodic modulation of a parameter involved in the non-linear interaction, said depth being defined in a plane perpendicular to an axis of propagation of the incident and created waves, said waves being confined in the two directions perpendicular to their axis of propagation, and said waves having spatial overlap in the plane perpendicular to the axis of propagation of said waves, on the one hand of a non-linear polarization generated by the k.sub.i th-order guided modes of the incident waves and on the other hand of the l.sub.j th-order guided modes of the created waves, characterized in that:the converter comprises a layer C.sub.ex lying at the surface of the non-linear medium, said layer C.sub.ex having an index n.sub.eg close to the index n.sub.g of the guide, and a second layer C.sub.1 of refractive index N lying above the layer C.sub.ex, wherein the layer C.sub.1 is a symmetrization layer of refractive index less than n.sub.g and close to n.sub.s so as to increase the spatial overlap of the non-linear polarization in a region lying above the depth D of the medium (NLM) generated by the fundamental modes of the incident waves and the fundamental modes of the created waves.