All-fiber based devices for third harmonic generation in the ultraviolet range are highly desirable. Using a fundamental wavelength of 1.06 mu m as an example, we show numerically how the phase-matching condition for third harmonic generation can be achieved between an index-guided fundamental HE11 mode for the infrared source and a bandgap-guided higher-order HE12 mode for the ultraviolet radiation in all-solid photonic crystal fibers. The fiber parameters are first determined by an analytical effective index model and then improved by numerical calculations.
Bai, J. X., Xing, W. Q., Yang, C., Li, Y. F., & Bird, D. M. (2012). Strategy to achieve phase matching condition for third harmonic generation in all-solid photonic crystal fibers. IEEE Photonics Technology Letters, 24(5), 389-391. https://doi.org/10.1109/lpt.2011.2179798