Intense supercontinuum generation in the near-ultraviolet range from a 400-nm femtosecond laser filament array in fused silica**Project supported by the National Basic Research Program of China (Grant No. 2013CB922404), the National Natural Science Foundation of China (Grant Nos. 11274053, 11474039, 11474040, and 11004240), the Science and Technology Department of Jilin Province, China (Grant No. 20170519018JH), and the Innovation Fund of

Abstract

An intense supercontinuum (SC) in the near-ultraviolet range is generated from filamentation by focusing a 400-nm laser into fused silica with a microlens array (MLA). The spectrum of the SC is shown to be sensitive to the distance between the MLA and fused silica. In our optimal conditions, the near-ultraviolet SC can cover a range of 350–600 nm, where a bandwidth of approximately 55 nm above the 1μ J/nm spectral energy density and 20 nm bandwidth with tens of μJ/nm are achieved. In addition, the energy conversion efficiency of the 400 nm laser for SC generation is further analyzed. A maximum conversion efficiency of 66% is obtained when the entrance face of fused silica is set around the focus of the MLA.