Yang Hai-Bo, Wu Zheng-Mao, Tang Xi, Wu Jia-Gui, Xia Guang-Qiong. Influence of feedback strength on the characteristics of the random number sequence extracted from an external-cavity feedback semiconductor laserJ. Acta Physica Sinica, 2015, 64(8): 084204. DOI: 10.7498/aps.64.084204