Compact non-blocking non-dilated optical switch using mode conversion

A mode selective optical switching circuit comprising:

• a plurality of input waveguides having signal inputs thereto;
• a plurality of mode selective couplers in a staggered array of rows and columns, each of said couplers having first and second inputs and first and second outputs;
• each of said input waveguides being connected to one of said inputs of one of said mode selective couplers;
• a mode converter in each input waveguide between said signal input and the input to said one of said mode selective couplers;
• and
• a plurality of outputs, each connected to an output of one of said mode selective couplers by means of an output waveguide.

A method for optical switching, comprising the steps of:

• introducing optical signals along any of a plurality of optical paths having a plurality of optical inputs and a plurality of optical output destination paths;
• routing said optical signals along said plurality of paths to any of a plurality of mode selective optical circuits optically coupled to said plurality of paths between said plurality of optical inputs and said plurality of optical outputs wherein said mode selective optical circuits are arranged in a staggered diagonal configuration creating a plurality of layers and columns and are controlled so that all optical signals have a pathway to the destination path;
• converting said optical signals to be switched between paths from a fundamental mode to a higher mode wherein only said higher mode optical signals continuously cross couple between said plurality of layers;
• converting said higher mode optical signals back to said fundamental mode at the destination path;
• and
• removing any non-mode converted energy remaining on any of said plurality of waveguides.