Micro-joule level visible supercontinuum generation in seven-core photonic crystal fibers pumped by a 515 nm laser.

Abstract

A visible supercontinuum (SC) with high energy is of vital importance to applications in remote sensing and hyperspectral light detection and ranging. A fiber laser with a wavelength of 1030nm is frequency doubled through a LBO (LiB3O5) crystal, and a high-energy 515nm laser is obtained after wavelength conversion. Two kinds of seven-core photonic crystal fibers (PCFs) are used in this Letter. One is a uniform seven-core PCF (USC-PCF), and the other is a tapered seven-core PCF (TSC-PCF). Pumped by a 515nm laser with a pulse width in nanosecond level, an SC covering 400 to 900nm is efficiently generated in both PCFs. A maximum energy of 4.24μJ is obtained in a USC-PCF. To prevent fiber damage of the coupling fiber end, the TSC-PCF which contains a transition fiber and a meters-long small core fiber is fabricated. One end of the transition fiber possesses a larger core diameter, and the pump laser can be coupled into the TSC-PCF without fiber damage. The meters-long small core fiber has the same core size with a USC-PCF and is utilized as the nonlinear medium to generate an SC. The dispersive wave in the short wavelength band is excited when more energy is shed into a fiber anomalous dispersion region. Up to 15th-order Raman peaks are observed during the SC evolution process.