Photonic Integrated Circuit

A device, comprising:

• a photonic integrated circuit, comprising:
• a first waveguide on a first waveguide substrate,
• a second waveguide on a second waveguide substrate,
• a resonator device, comprising:
• a first mirror, comprising a first layered structure on a first mirror substrate, wherein the first mirror substrate is provided by or fixed to the first waveguide substrate or the second waveguide substrate,
• a second mirror, comprising a second layered structure on a second mirror substrate, wherein the second mirror substrate is provided by or fixed to the first waveguide substrate or the second waveguide substrate, wherein
• the first mirror and the second mirror form end mirrors of an optical resonator, and wherein at least a portion of the first waveguide is within the optical resonator, wherein
• the first waveguide substrate is continuous with the second waveguide substrate, and wherein
• a first end of the first waveguide is aligned with a second end of the second waveguide;
• the device comprising an optical parametric oscillator, a cavity-enhanced photon-pair source, a second-harmonic generator, a difference-frequency generator, or a sum-frequency generator, or wherein
• the device is adapted for frequency-comb generation, frequency-comb spectroscopy, squeezed-light generation, squeezed-state encoding, quantum key distribution, quantum computing, generation of single frequency modes of ultra-narrow bandwidth, wavelength-division multiplexing, sensing, light ranging and detection (LIDAR), spectroscopy, or mid-infrared spectroscopy.

A method for producing a photonic integrated circuit, the method comprising:

• providing a first waveguide substrate,
• providing a second waveguide substrate,
• providing a first mirror comprising a first layered structure on a first mirror substrate,
• providing a second mirror comprising a second layered structure on a second mirror substrate,
• forming a first waveguide on the first waveguide substrate,
• forming a second waveguide on the second waveguide substrate,
• positioning the first mirror with respect to the first waveguide substrate or the second waveguide substrate, and
• fixing the first mirror to the first waveguide substrate or the second waveguide substrate, wherein
• the first mirror and the second mirror form end mirrors of an optical resonator,
• at least a portion of the first waveguide is within the optical resonator,
• the first waveguide substrate is continuous with the second waveguide substrate, and
• a first end of the first waveguide is aligned with a second end of the second waveguide.