Al-free cladding-layer blue laser diodes with a low aspect ratio in far-field beam pattern *Project supported by the National Key R&D Program (Nos. 2017YFB0403100, 2017YFB0403101), the National Natural Science Foundation of China (Nos. 61534007, 61404156, 61522407, 61604168, 61775230), the Key Frontier Scientific Research Program of the Chinese Academy of Sciences (No. QYZDB-SSW-JSC014), the Science and Technology Service Network Initiative of the Chinese Academy of Sciences, the Key R&D Program of Jiangsu Province (No. BE2017079), the Natural Science Foundation of Jiangsu Province (No. BK20160401), and the China Postdoctoral Science Foundation (No. 2016M591944). Project was also supported by the Open Fund of the State Key Laboratory of Luminescence and Applications (No. SKLA-2016-01), the Open Fund of the State Key Laboratory on Integrated Optoelectronics (Nos. IOSKL2016KF04, IOSKL2016KF07), and the Seed Fund from SINANO, CAS (No. Y5AAQ51001). Project also supported technically by Nano Fabrication Facility, Platform for Characterization & Test, Nano-X of SINANO, CAS. (August 2018)