N×N switching arrangement of two planar arrays without waveguide crossings
View Patent ↗An N×N crossconnect switch is implemented without the use of waveguide crossings. In one embodiment, the N×N crossconnect switch uses two non-parallel planar arrays of 1×2 and 2×1 switching elements combined with a cylindrical reflector. In another embodiment, the N×N crossconnect switch includes an input planar array and output planar array implemented on a single wafer both having a refractive index n>1 separated by a central region having a refractive index n 0 =1.
1. An N×N optical interconnection arrangement, where N is an integer greater than one, comprising a first and second planar array,
the first array including N planar imaging elements, each imaging element having N planar input waveguides coupled thereto,
the second array including N planar imaging elements, each imaging element having N planar output waveguides coupled thereto and wherein
each input waveguide of a particular imaging element of the first array is coupled to a unique output waveguide of a corresponding imaging element of the second array.
2. The N×N optical interconnection arrangement of claim 1 wherein the two planar arrays are implemented on a single wafer separated by a central region and wherein the central region has a refractive index n 0 and the two planar arrays have index n>n 0 .
3. The N×N optical interconnection arrangement of claim 2 wherein each of the imaging elements of the two arrays has a refracting curve with suitable focal length.
4. The N×N optical interconnection arrangement of claim 3 wherein the aperture of each output waveguide is essentially the image of the aperture of the corresponding input waveguide and the phase center of the output waveguide is essentially the image of the phase center of the input waveguide, so as to realize a broadband match between the two waveguides according to the laws of imaging.
5. The N×N optical interconnection arrangement of claim 3 wherein the locations of each pair of corresponding waveguides are optimized so as to maximize power transfer between the two waveguides.
6. The N×N optical interconnection arrangement of claim 3 wherein the location of each input waveguide is properly chosen so that the phase front produced after refraction by the first refractive element has its center of curvature essentially located at the second refractive element.
7. An N×N optical interconnection arrangement, where N is an integer greater than one, comprising a first and second planar array,
the first array including N planar imaging elements, each imaging element having N planar input waveguides coupled thereto,
the second array including N planar imaging elements, each imaging element having N planar output waveguides coupled thereto,
wherein each input waveguide of a particular imaging element of the first array is coupled to a unique output waveguide of a corresponding imaging element of the second array, and
wherein a particular imaging element of the first array is coupled to the corresponding imaging element of the second array using a cylindrical reflector.
8. The N×N optical interconnection arrangement of claim 7 wherein each imaging element of either array is realized on a planar wafer and it comprises
a diffractive element formed by a curved cylindrical edge of the wafer and
a core layer formed in the vicinity of the cylindrical edge,
wherein the edge of the core layer and the cylindrical edge have different profiles arranged so that
radiation from the first array emanates from a virtual focal line that is a straight line common to all imaging elements of the first array, and
the second array is similarly arranged so that it is characterized by a straight focal line if the sense of transmission is reversed.
9. The N×N optical interconnection arrangement of claim 8 wherein either focal line is transformed by the cylindrical reflector into an image produced at the other focal line.
10. The N×N optical interconnection arrangement of claim 1 further comprising
N optical 1×N switch arrays, each 1×N switch array connected to a different transmitting element of the first array, each 1×N switch array having an input for receiving an optical signal and N outputs, where each of the N output connect to a different input of the same transmitting element of the first array and
N optical N×1 switch arrays, each N×1 switch array connected to a different receiving element of the second array, each N×1 switch array having N inputs for receiving optical signals and an output for outputting an optical signal, where each of the N inputs connect to a different output of the same receiving element of the second array.
11. The N×N optical interconnection arrangement of claim 10 wherein one or both of the 1×N and N×1 switch arrays are formed using a switch array implemented using (1) 1×2 and/or 2×1 switching elements, (2) wavelength routers, or (3) a combination of 1×2 and/or 2×1 switching elements and/or wavelength routers.