This paper presents a high pulse energy, narrow linewidth, mid-infrared (MIR) laser at 6.45 μm, based on a BaGa4Se7 (BGSe) crystal optical parametric oscillator (OPO) pumped by 1.064 μm laser. The maximum pulse energy at 6.45 μm was up to 1.23 mJ, with a pulse width of 24.3 ns and repetition rate of 10 Hz, corresponding to an optical–optical conversion efficiency of 2.1%, from pump light 1.064 μm to idler light 6.45 μm. The idler light linewidth was about 6.8 nm. Meanwhile, we accurately calculated the OPO phase-matching condition at BGSe crystal pumped by 1.064 μm laser, and a numerical simulation system was performed to analyze the input–output characteristics at 6.45 μm, as well as the effect of crystal length on the conversion efficiency. Good agreement was found between measurement and simulation. To the best of our knowledge, this is the highest pulse energy at 6.45 μm, with the narrowest linewidth for any all-solid-state MIR ns laser in BGSe-OPO pumped by simple 1.064 μm oscillator. This simple and compact 6.45 μm OPO system, with high pulse energy and narrow linewidth, can meet the requirements for tissue cutting and improve tissue ablation accuracy.

In the ever-increasing development of network storage technology, distributed RAID has been a hot topic for data reliability and availability. To solve the problem of distributed RAID technology, such as: parallel access difficulty, long rebuild time, small write update and strip alignment problem, we design and implement file level distributed RAID system (BW-FILERAID) based on Blue Whale File System (BWFS). Also we do the research on resource allocation strategy, page cache management with parity data, consistence maintenance, online extension of RAID group, error detect and rebuild and small write optimization in BW-FILERAID. According to the testing results, the writing performance of BW-FILERAID is better than Linux soft RAID about 5%~50%, and the reading performance is equivalent to the RAID0. And it also has excellent extensibility.