Optical switch, multiplexer, and demultiplexer

An optical interconnection apparatus, comprising:

• a free space region of predetermined geometry;
• a first array of waveguides radially directed toward a first focal point located a predetermined distance outside the free space region so as to reduce phase errors caused by mutual coupling between the waveguides in the first array;
• a second array of waveguides radially directed toward a second focal point located a predetermined distance outside the free space region so as to reduce phase errors caused by mutual coupling between the waveguides in the second array;
• and
• an optical grating connected to the second array of waveguides and having a plurality of optical waveguides each having a predetermined length which differs from the predetermined lengths of the other waveguides in the grating, the length difference between two adjacent waveguides in the grating not being constant throughout the grating and the lengths of the waveguides in the grating being such that residual phase errors are reduced.

An optical transmission system, comprising:

• a plurality of input ports at least one of which receives optical communication signals;
• a plurality of output ports at least one of which transmits optical communication signals;
• a first plurality of input waveguides radially directed from the plurality of input ports toward a first focal point;
• a first star coupler having an input connected to the plurality of input waveguides;
• a first plurality of output waveguides radially directed to a second focal point and connected to an output of the first star coupler;
• an optical grating comprising a plurality of unequal length waveguides having inputs connected to the first plurality of output waveguides;
• a second plurality of input waveguides radially directed to a third focal point and connected to outputs of the optical grating;
• a second star coupler having an input connected to an output of the second plurality of input waveguides;
• and
• a second plurality of output waveguides radially directed from the plurality of output ports toward a fourth focal point and connected to an output of the second star coupler;
• the first and second focal points being located predetermined distances from the first star coupler and the third and fourth focal points being located predetermined distances from the second star coupler so as to reduce phase errors caused by mutual coupling between the waveguides in the array of input and output waveguides.