On-Chip Fabry–Perot Bragg Grating Cavity Enhanced Four-Wave Mixing

Abstract

Optical microcavity based four-wave mixing (FWM) and its various applications, such as entangled photon pair generation, have been intensively studied in the past few years. Compared to the microring cavities that most researchers have been focusing on, here, we report the generation of FWM photons with Fabry−Perot Bragg grating cavities (FPBG) using the Si 3 N 4 / SiO 2 platform. By leveraging the large, nonuniform and symmetrical dispersion and tunability of our grating cavity, a unique strategy is established to compensate the strong normal dispersion of the waveguide and phase matching condition is achieved on a thin Si 3 N 4 film, which is critical for efficient wavelength conversion.We develop an analytical model to optimize the nonlinear conversion efficiency of FWM, and we also introduce tapered grating in the FPBG to reduce the grating loss from 3.5 dB/cm to 0.36 dB/cm. With a 5.3 dBm pump power, the nonlinear conversion efficiency is characterized to be −37.7 dB. Our work demonstrates that FPBG is a promising on-chip platform for entangled photon pair generation and quantum communication applications.

Tunable Ultranarrowband Grating Filters in Thin-Film Lithium Niobate

“…These results hold promise for further applications of integrated LNOI photonic circuits to electro-optic switching and modulation in telecommunication systems as well as efficient photon manipulation in integrated quantum photonics. Moreover, they pave the way to the implementation of more advanced functionalities for spectral shaping and tuning, such as superstructured gratings for dispersion engineering and χ (2) nonlinearity enhancement for novel frequency comb or quantum sources. , The small footprints and low-voltage operation achieved with these devices and the scalability of their fabrication process might also be advantageously exploited toward developments of microwave photonics and programmable nanophotonics for, for example, multispectral sensing, neuromorphic, and quantum computing. ,− …”

“…In the most general case one can write , The factor Q α depends only on the intrinsic losses of the cavity. In our case, the latter are quantified by the waveguide propagation loss coefficient α (cm –1 ) and are essentially determined by sidewall scattering. , The term Q κ expresses the extra loss associated with coupling light into and out of the cavity, which in our case occurs by transmission through Bragg grating mirrors of length (Figure b). The transmission of the mirrors depends on κ, hence, Q κ is parametrized in terms of the latter.…”

“…It also decreases the cavity free spectral range (FSR) and may introduce multiple resonances. The ensuing multiwavelength response and the spectral engineering capabilities afforded by long-cavity PSBG devices can on the other hand be appealing for advanced manipulation in several classical and quantum optics applications. ,, A theoretical analysis of the trade-offs and optimization of PSBG devices is provided in the Supporting Information, section S3. In what follows, we deal with these aspects from an experimental perspective (see also Supporting Information, section S5).…”

“…Integrated optical filters are essential components for a wide variety of applications, , encompassing photonic and microwave signal processing, , lasers, , telecom systems, − sensing, , and quantum optics . Electrical tunability is an additional attractive feature, typically achieved by means of thermal, strain or carrier injection in optical fibers or silicon photonic circuits. , However, these approaches may suffer from high power consumption and introduce additional optical losses, motivating alternative solutions based on materials with a strong Pockels electro-optic response, such as lithium niobate (LN).…”

Impact of nonlocal response in plasmonic metasurfaces on four-wave mixing

“…In order to overcome the weak nature of third-order optical nonlinearity of materials, various optical resonators are designed to boost the FWM process by confining or slowing the light in extreme small volumes. For example, dispersion engineered waveguides [8,9], photonic crystal waveguides [10,11], waveguides integrated with 2D materials [12,13], micro-ring resonators [14,15], Fabry-Perot cavity [16], and various plasmonic nanostructures [17][18][19][20]. Among these methods, the plasmonic nanostructures have attracted enormous attention since the electromagnetic waves can be extremely confined into deep subwavelength volumes, and thus the local field can be dramatically enhanced to strength the light-matter interaction [17].…”