Abstract: A photonic device includes a substrate and a tantala ring resonator on the substrate. The tantala ring resonator has at least one of (i) a quality factor exceeding three million and (ii) a threshold power less than one hundred milliwatts. A frequency-comb generation method includes sweeping the output frequency of a laser coupled to a tantala ring resonator that has at least one of (i) a quality factor exceeding three million and (ii) a threshold power less than one hundred milliwatts.

Abstract: A millimeter-wave frequency synthesizer generates a millimeter wave by photomixing two Kerr-soliton microcombs. A single-frequency laser beam is modulated to create first and second pump components having first and second pump frequencies. The first pump component excites a first microresonator to create a first microcomb while the second pump component excites a second microresonator to generate a second microcomb. A pair of comb lines from the two microcombs is detected to generate a low-frequency beat note that is phase-locked by identically tuning the pump frequencies. Another pair of comb lines is detected with a high-speed photodiode to generate the millimeter wave. The frequency of the millimeter wave is based on (i) the difference between the pump frequencies, (ii) the difference between the repetition rates, and (iii) the index of the comb lines that are photomixed to generate the millimeter wave.

Abstract: A monolithic photonic resonator includes a bulk optic with first and second superpolished facets, and a high-reflectivity coating applied to each of the first and second superpolished facets. The superpolished facets form an optical resonator. The bulk optic is a single piece of an optical material that is solid, i.e., has no internal holes, gaps, or pockets. The bulk optic therefore serves as an intraresonator optical medium while still supporting a finesse of 10,000 or more. The superpolished facets may be counterfacing to form a Fabry-Perot cavity. Alternatively, the bulk optic may include forms one or more additional facets off of which light inside the bulk optic undergoes total internal reflection. The monolithic photonic resonator may be mounted in a support structure that minimizes the overall vibration sensitivity of the resonator's resonance frequency.

Abstract: A tantala ring resonator includes a tantala ring resonator formed by ion-beam sputtering of tantalum pentoxide and exhibiting an optical quality factor in excess of 3×106, and a substrate to which the tantala ring resonator is attached. A method for fabricating nonlinear photonic devices includes depositing tantalum pentoxide with ion-beam sputtering to form a tantala layer onto a substrate, annealing the tantala layer, and etching the tantala layer to form a photonic device.

Abstract: A dual-comb optical-frequency comb generator includes a tunable comb-generating laser, a coarse-comb generator, a fine-comb generator, a second harmonic generator, a coarse-comb offset photodetector, a dual-comb offset photodetector, and a fine-comb photodetector. The coarse comb is self-referencing and coupled to the fine comb so as to enable absolute determination of the frequencies of the fine comb.

Abstract: A dual-comb optical-frequency comb generator includes a tunable comb-generating laser, a coarse-comb generator, a fine-comb generator, a second harmonic generator, a coarse-comb offset photodetector, a dual-comb offset photodetector, and a fine-comb photodetector. The coarse comb is self-referencing and coupled to the fine comb so as to enable absolute determination of the frequencies of the fine comb.