We demonstrate a high-efficiency intermodal four-wave-mixing process in an all-fiber system, comprising a picosecond fiber laser and a high-order-mode (HOM) fiber. Two pump photons in the LP01 mode of the fiber can generate an anti-Stokes photon in the LP01 mode and a Stokes photon in the LP02 mode. The wavelength dependent mode profiles of the HOM fiber produce significant spatial overlap between the modes involved. The anti-Stokes wave at 941 nm is generated with 20% conversion efficiency with input pulse energy of 20 nJ. The guidance of the anti-Stokes and Stokes waves in the HOM fiber enhances system stability.
Cheng, J., Pedersen, M. E. V., Charan, K., Wang, K., Xu, C., Grüner-Nielsen, L. E., & Jakobsen, D. (2012). Intermodal four-wave mixing in a higher-order-mode fiber. Applied Physics Letters, 101, 161106. https://doi.org/10.1063/1.4759038