Parametric interaction of laser cavity-solitons with an external CW pump.

We study the interaction of a laser cavity-soliton microcomb with an externally coupled, co-propagating tunable CW pump, observing parametric Kerr interactions which lead to the formation of both a cross-phase modulation and a four-wave mixing replica of the laser cavity-soliton. We compare and explain the dependence of the microcomb spectra from both the cavity-soliton and pump parameters, demonstrating the ability to adjust the microcomb externally without breaking or interfering with the soliton state. The parametric nature of the process agrees with numerical simulations.

Dual-polarization RF channelizer based on microcombs.

We report a dual-polarization radio frequency (RF) channelizer based on microcombs. Two high-Q micro-ring resonators (MRRs) with slightly different free spectral ranges (FSRs) are used: one MRR is pumped to yield soliton crystal microcombs ("active"), and the other MRR is used as a "passive" periodic optical filter supporting dual-polarization operation to slice the RF spectrum. With the tailored mismatch between the FSRs of the active and passive MRRs, wideband RF spectra can be channelized into multiple segments featuring digital-compatible bandwidths via the Vernier effect.

Thermo-Optic Response and Optical Bistablility of Integrated High-Index Doped Silica Ring Resonators.

The engineering of thermo-optic effects has found broad applications in integrated photonic devices, facilitating efficient light manipulation to achieve various functionalities. Here, we perform both an experimental characterization and a theoretical analysis of these effects in integrated microring resonators made from high-index doped silica, which have had many applications in integrated photonics and nonlinear optics. By fitting the experimental results with theory, we obtain fundamental parameters that characterize their thermo-optic performance, including the thermo-optic coefficient, the efficiency of the optically induced thermo-optic process, and the thermal conductivity.

Second-harmonic generation in a high-index doped silica micro-ring resonator.

We report the first, to the best of our knowledge, observation of second-harmonic generation (SHG) in a high-index doped silica micro-ring resonator, due to the symmetry-breaking-induced χ at the core and cladding interface of the waveguide. The generated SH power is shown to have quadratic dependence on the in-cavity power of the fundamental pump at around 1550 nm. The pumping wavelength sweep method is adopted to fulfill the phase-matching condition for maximum conversion efficiency of SHG.

Ultralarge anti-Stokes lasing through tandem upconversion.

Coherent ultraviolet light is important for applications in environmental and life sciences. However, direct ultraviolet lasing is constrained by the fabrication challenge and operation cost. Herein, we present a strategy for the indirect generation of deep-ultraviolet lasing through a tandem upconversion process.

All-optical RF spectrum analyzer with a 5 THz bandwidth based on CMOS-compatible high-index doped silica waveguides.

We report an all-optical radio-frequency (RF) spectrum analyzer with a bandwidth greater than 5 THz, based on a 50 cm long spiral waveguide in a CMOS-compatible high-index doped silica platform. By carefully mapping out the dispersion profile of the waveguides for different thicknesses, we identify the optimal design to achieve near-zero dispersion in the C-band. To demonstrate the capability of the RF spectrum analyzer, we measure the optical output of a femtosecond fiber laser with an ultrafast optical RF spectrum in the terahertz regime.

Third-harmonic generation in CMOS-compatible highly doped silica micro-ring resonator.

We present the first demonstration of visible emission from highly doped silica glass micro-ring resonators (MRRs) through a third-harmonic generation (THG) nonlinear process. We obtain green light conversion efficiency of 2.7×10 W in a MRR with loaded Q-factor of 1.

Integrating temporal and spatial control of electronic transitions for bright multiphoton upconversion.

The applications of lanthanide-doped upconversion nanomaterials are limited by unsatisfactory brightness currently. Herein, a general strategy is proposed for boosting the upconversion efficiency in Er ions, based on combined use of a core-shell nanostructured host and an integrated optical waveguide circuit excitation platform. A NaErF@NaYF core-shell nanoparticle is constructed to host the upconversion process for minimizing non-radiative dissipation of excitation energy by surface quenchers.

Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals.

We propose a novel solar cell structure with photonic nanocrystals coupled to quantum dots (QDs) for advanced management of photons and carriers. The photonic nanocrystals at the surface create an extra interaction between the photons and the QDs, which promotes light trapping. Photo-generated carriers can be efficiently transported by preparing vertically aligned QDs with electronic coupling.

Coupling-loss reduction of a vertically coupled microring resonator filter by spot-size-matched busline waveguides.

To improve the input-output coupling loss of a vertically coupled microring resonator filter, we fabricated microring resonators on an antiresonant reflecting optical waveguide (ARROW) with a large spot size and on the rectangular busline waveguide with a spot-size transformer. The spot size and the tapered structure were optimally designed from the viewpoint of spot-size matching to single-mode fibers and the reduction of radiation loss. Clear dropping responses were demonstrated for the ARROW-based microring resonator filters, and the coupling loss was successfully reduced by 22 dB.