Efficient photoinduced second-harmonic generation in silicon nitride photonics

Second Harmonic Generation in Polymer Photonic Integrated Circuits

“…The most promising way to increase the conversion efficiency is the development of a resonant or double resonant cavity design. Even for moderate pump powers and small crystal lengths high conversion efficiencies have been demonstrated with this approach in bulk optics [17] and in microring resonators demonstrated in thinfilm lithium niobate and silicon nitride platforms [18][19][20]. Development of a stable resonant cavity with the on-chip integrated GRIN lenses is possible by applying high reflective coatings to the waveguide oriented facets of the GRIN lenses or waveguide inscribed Bragg-gratings at the input and output waveguides and is currently under investigation.…”

“…A shorter crystal would also reduce the gap between recently reported values of 50 % conversion efficiency in nanophotonic ppLN waveguides [21] and this work. The advantage of the nonlinear waveguides described in [18][19][20][21] is the required low pump power for SHG and small footprint compared to ppLN bulk crystals. In principle it should also be possible to integrate ppLN waveguides into dedicated and precisely etched U-grooves, with butt coupling of the ppLN to polymer waveguide.…”

Integrated photon-pair sources with nonlinear optics

“…There are some significant differences that limit their compatibility with different material platforms. First of all, SPDC requires that the nonlinear medium shows second-order nonlinearity, either naturally in non-centrosymmetric crystals or induced by strain 30 and photo-galvanic effect 31 or by tuning the structure orientation of 2D crystals 32 . As a result, SFWM is more widely applicable, since all materials exhibit odd order nonlinearities.…”

Anomalously Strong Second‐Harmonic Generation in GaAs Nanowires via Crystal‐Structure Engineering

“…Nonlinear optical processes in semiconductor nanostructures can be utilized in a wide range of classical and quantum applications, including on‐chip integrated nano‐photonic systems, [ 1–5 ] nonlinear optical microscopy, [ 6–8 ] and sensing. [ 9,10 ] The lowest‐order nonlinear optical process is second‐harmonic generation (SHG) or frequency doubling, where two incident photons of the same frequency, ω, are converted into a new photon with the frequency, 2ω.…”

“…[ 9,10 ] The lowest‐order nonlinear optical process is second‐harmonic generation (SHG) or frequency doubling, where two incident photons of the same frequency, ω, are converted into a new photon with the frequency, 2ω. It offers an efficient and convenient approach for the realization of next‐generation frequency references and combs, [ 2–4 ] as well as for infrared‐to‐visible light conversion that can be used in tunable nanoscale light sources [ 10,11 ] and for infra‐red light visualization. [ 12 ]…”