Phase-matched third-harmonic UV generation using low-order modes in a glass micro-fiber

Fundamental-mode third harmonic generation in microfibers by pulse-induced quasi-phase matching

“…When the cost of backward pump energy is taken into account, conversion efficiency of the fundamental-mode THG could ideally be enhanced by about six orders of magnitude in this quasi-phase-matching way. If the SPM and XPM effects are not effectively corrected for, the expected enhancement factor would be reduced by one or two orders; however, even in this situation, the third harmonic could still be generated in the fundamental mode at an efficiency of ∼ 10 −6 , which is the typical level reported in experiments employing intermodal phase matching technique where only higher-order mode THG is possible [12,13].…”

“…Microfibers make possible simple devices capable of performing sensing at the nanoscale and integrate fiberized sources with nonlinear waveguides [10], and they have initiated a lot of works in the past years, including THG [11][12][13][14] where intermodal phase matching schemes were also used, such as between the fundamental pump mode HE 11 (ω) and the higher-order third harmonic mode HE 12 (3ω). In such schemes, perfect phase matching could be achieved theoretically by choosing a suitable microfiber diameter, but in practice intrinsic surface roughness from the microfiber fabrication process may greatly reduce the conversion efficiency [15].…”

Optical microfibers and nanofibers

“…Owing to the miniaturized mode area [11,18] and engineerable dispersion [11,16,211], MNFs exhibit enhanced nonlinear effects such as supercontinuum generation [9,15,17,112,113,118,119,182], third-harmonic generation [183][184][185][186][187][188], bistability [46,160], two-photon absorption [189,190] with relatively low optical power. To obtain higher optical nonlinearity, many other materials with high nonlinearities (e.g., leadsilicate, bismuth-silicate, As 2 Se 3 chalcogenide) have been drawn into MNFs for various purposes [82,191].…”

Optical microfiber passive components

“…(n 2 and A eff are the material nonlinear refractive index and the beam effective area, respectively) and allows for the prompt observation of nonlinear effects like supercontinuum generation [24][25][26][27][28][29][30][31][32][33][34], third-harmonic generation [21,35], slow and fast light [36] and bistability [37,38] [34]. Highly nonlinear glasses usually are transparent far into the infrared region, thus they can be exploited for the generation of supercontinuum in spectral regions where silica is not transparent [29].…”