Frequency converter, with very high efficiency, in guided optics
First Claim
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1. Frequency converter comprising a guide of refractive index ng, supplied by one or more light waves of frequency ω
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n, also comprising a non-linear medium (NLM) of index ns (less than ng) in which the condition for phase matching between non-linear polarization generated by incident waves and created waves at frequencies ω
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 ki th-order guided modes of the incident waves and on the other hand of the lj th-order guided modes of the created waves, characterized in that;
the converter comprises a layer Cex lying at the surface of the non-linear medium, said layer Cex having an index neg close to the index ng of the guide, and a second layer C1 of refractive index N lying above the layer Cex, wherein the layer C1 is a symmetrization layer of refractive index less than ng and close to ns 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.
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Abstract
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 Cex, which lies between the layer C and the medium (NLM) and the index of which is close to that of the guide.
37 Citations
10 Claims
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1. Frequency converter comprising a guide of refractive index ng, supplied by one or more light waves of frequency ω
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n, also comprising a non-linear medium (NLM) of index ns (less than ng) in which the condition for phase matching between non-linear polarization generated by incident waves and created waves at frequencies ω
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 ki th-order guided modes of the incident waves and on the other hand of the lj th-order guided modes of the created waves, characterized in that;the converter comprises a layer Cex lying at the surface of the non-linear medium, said layer Cex having an index neg close to the index ng of the guide, and a second layer C1 of refractive index N lying above the layer Cex, wherein the layer C1 is a symmetrization layer of refractive index less than ng and close to ns 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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n, also comprising a non-linear medium (NLM) of index ns (less than ng) in which the condition for phase matching between non-linear polarization generated by incident waves and created waves at frequencies ω
Specification
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Current AssigneeThomson-CSF
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Original AssigneeThomson-CSF
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InventorsPapuchon, Michel, Delacourt, Dominique, Papillon, Dominique, Truffer, Jean-Patrick
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Primary Examiner(s)Lee, John D.
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Application NumberUS08/693,221Time in Patent Office622 DaysField of Search385/122, 359/326, 359/328, 359/332US Class Current359/332CPC Class CodesG02F 1/377 in an optical waveguide str...G02F 1/395 in optical waveguides
