Coating for optimising output coupling of em radiation
AssigneeUniversity Court of the University of St Andrews
InventorsMalcolm Dunn, Cameron F. Rae, Tom J. Edwards, David J. M. Stothard, David Walsh
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Abstract
A coating between a nonlinear crystal and a silicon prism coupler, prevents transmission of radiation scattered within the crystal by filtering out frequencies outside the silicon bandgap to avoid free carrier absorption, but transmits THz frequencies that correspond to the bandgap.
Claims10
A device comprising a first medium for propagation of an em-wave, a semi- insulator material for coupling the em-wave from the first medium into a second medium of lower refractive index than the first medium, and a filter for filtering out radiation that has a frequency greater than the frequency that corresponds to the semi-insulator band gap but allows the em-wave to pass into the semi-insulator material, wherein the filter is between the first medium and the semi-insulator material.
A method comprising:
- providing a filter in a device having a first medium for propagation of an em-wave and a semi-insulator material for coupling the em-wave from the first medium into a second medium of lower refractive index than the first medium wherein the filter is provided between the first medium and the semi-insulator material, and
- employing the filter to filter out radiation that has a frequency greater than the frequency that corresponds to the semi-insulator band gap but allowing the em-wave to pass into the semi-insulator material.
Dependencies are inferred from the claim text.