Frequency-comb source and generation and method
A method for generating an optical frequency comb includes generating a first optical frequency comb spanning a first optical bandwidth and including a first plurality of frequency tones spaced by a free-spectral range. The method also includes generating an additional optical frequency comb from a first frequency tone of the first plurality of frequency tones.
1 . An optical frequency-comb source comprising:
an optical resonator including a feed waveguide and a closed-loop waveguide evanescently coupled to the feed waveguide;
a first active-region waveguide, formed of a first gain medium, and optically coupled to an entrance port of the feed waveguide; and
a second active-region waveguide, formed of a second gain medium, and optically coupled to an exit port of the feed waveguide;
wherein an end of the first active-region waveguide faces the entrance port of the feed waveguide.
2 . The optical frequency-comb source of claim 1 , the closed-loop waveguide being formed at least in part of a third-order nonlinear optical material.
3 . The optical frequency-comb source of claim 1 , further comprising an optical amplifier that includes the first active-region waveguide.
4 . The optical frequency-comb source of claim 3 , the optical amplifier being a semiconductor optical amplifier.
5 . The optical frequency-comb source of claim 3 , the optical amplifier being one of an erbium-doped fiber amplifier and a Raman amplifier.
6 . The optical frequency-comb source of claim 1 , further comprising an optical amplifier that includes the second active-region waveguide.
7 . The optical frequency-comb source of claim 1 , further comprising an electro-optic frequency-comb source optically coupled to the second active-region waveguide.
8 . The optical frequency-comb source of claim 7 , the electro-optic frequency-comb source including a phase modulator optically coupled to an intensity modulator, the phase modulator including an input port optically coupled to the second active-region waveguide, and an output port coupled to the intensity modulator.
9 . The optical frequency-comb source of claim 8 , the intensity modulator including one of a Mach-Zehnder interferometer and a ring modulator.
10 . The optical frequency-comb source of claim 1 , further comprising:
a substrate formed of an electrical insulator and having a substrate top-surface, at least one of the optical resonator, the first active-region waveguide, and the second active-region waveguide being formed on the substrate top-surface.
11 . The optical frequency-comb source of claim 1 , the optical resonator being one of a Fabry-Perot resonator and a microring resonator.
12 . An optical frequency-comb source comprising:
a substrate formed of an electrical insulator;
an optical resonator including a feed waveguide and a closed-loop waveguide evanescently coupled to the feed waveguide;
a first active-region waveguide, formed of a first gain medium, and optically coupled to an entrance port of the feed waveguide; and
a second active-region waveguide, formed of a second gain medium, and optically coupled to an exit port of the feed waveguide;
the first active-region waveguide and the feed waveguide being coplanar in a plane parallel to a top surface of the substrate.
13 . An optical frequency-comb source comprising:
an optical resonator including a feed waveguide and a closed-loop waveguide evanescently coupled to the feed waveguide;
a first active-region waveguide, formed of a first gain medium and optically coupled to an entrance port of the feed waveguide via a taper/inverted-taper geometry; and
a second active-region waveguide, formed of a second gain medium, and optically coupled to an exit port of the feed waveguide.