Multi-mode multi-pass delay

A method comprising:

• coupling a first waveguide, comprising a first input waveguide, and a second waveguide, comprising a second input waveguide, in a first plurality of waveguides to a multimode waveguide delay device comprising a spiral delay line, the first waveguide and the second waveguide being coupled to a first end of the multimode waveguide delay device, the multimode waveguide delay device comprising a second end that is opposite of the first end,
• the first waveguide being coupled to a first optical mode in the multimode waveguide delay device for coupling light from the first waveguide into the multimode waveguide delay device, and
• the second waveguide being coupled to a second optical mode in the multimode waveguide delay device for coupling light from the second waveguide into the multimode waveguide delay device,
• the second optical mode being different than the first optical mode,
• coupling, at the second end of the multimode waveguide delay device, the first optical mode and the second optical mode from the multimode waveguide delay device to a second plurality of waveguides,
• the first optical mode being coupled to a third waveguide, comprising a first output waveguide, of the second plurality of waveguides, and
• the second optical mode being coupled to a fourth waveguide, comprising a second output waveguide, of the second plurality of waveguides, wherein the multimode waveguide delay device is configured to provide a uniform optical delay between the first end of the multimode waveguide delay device and the second end of the multimode waveguide delay device.