Integrated Nonlinear Optical Frequency Conversion

Dear Colleagues,

Integrated photonic platforms have recently made great strides in nonlinear-optic applications, particularly frequency conversion. Example demonstrations comprise second-harmonic and difference-frequency generations and other parametric effects based on second-order nonlinearity, four-wave mixing, cross-phase modulation and supercontinuum generation based on third-order electronic nonlinearity, as well as stimulated Raman and Brillouin inelastic nonlinearities. The targeted applications span short- and long-wavelength optical sources, stabilized frequency combs, microwave photonics, quantum optics, etc. Although pump wavelengths in the visible to the near-infrared regimes may still be more accessible, pumping at the ultraviolet, mid-infrared and terahertz ranges have been emerging too. The list of promising active materials has also been rapidly expanding and includes several crystalline, polycrystalline, and amorphous dielectrics, semiconductors, glasses, and polymers. These host solid materials are usually formed on substrates like silicon or quartz, for consequent or concurrent microfabrication processes in order to develop novel nonlinear photonic devices and circuits. The devices are typically based on planar optical waveguides with the host nonlinear material as the core or cladding. However, managing additional features, requirements and constraints like group-velocity dispersion, propagation loss, phase mismatch, pulse compression, modal and polarization properties, as well as cascading nonlinear functionalities have become important for advanced applications. Hence, sophisticated engineering techniques that employ integrated gratings, microrings and cavities, interferometers, modal- and polarization-controllers, material poling, optoelectronic components and heterogeneous integration of multiple materials in sometimes unconventional and z-variant waveguide structures are being pursued. Challenges of integrating the nonlinear devices with sources, photodetectors, and passive devices such as mode-size converters and wavelength-manipulators are also important considerations for compactness of the final products.

This Special Issue covers original review and contributed articles on experimental and theoretical works in the broad areas outlined above. Solutions and demonstrations based on novel design, fabrication, characterization and modeling methods to further advance the field are considered.

Prof. Sasan Fathpour
Guest Editor

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• Nonlinear frequency conversion
• Nonlinear integrated optics
• Integrated photonics
• Photonic integrated circuits
• Optical waveguides