On-chip photonic ultra-short-pulse synthesizer

An integrated photonic chip comprising a photonic integrated circuit comprising:

• an input coupler comprising a first waveguide comprising a first cross-section to receive input pulses from a free-space beam, optical fiber, or another waveguide;
• at least one second waveguide comprising a nonlinear waveguide with a second cross-section that supports an electromagnetic mode which has more than 90% of its energy confined in an area smaller than 5 microns by 5 microns and that comprises a second-order nonlinearity configured to modify the spectrum and/or the temporal shape of the input pulses, which involves generation of new spectral content to output pulses from the input pulses;
• and
• one or multiple outputs of the chip outputting the output pulses in response to the input pulses which are shorter than 1 nanosecond and longer than 3 fs at their full width at half maximum and
• wherein the output pulses have different spectral and/or temporal shapes than the input pulses;
• and
• wherein the input coupler further comprises at least one of a mode converter, waveguide taper, inverse waveguide taper, or a mode filter configured for efficiently routing the radiation in one or a plurality of the modes of the first waveguide to one or a plurality of modes in the second waveguide.