M. Tsuzuki, L. Jin, M. Yamanaka, V. Sonnenchein, H. Tomita, A. Sato, T. Ohara, Y. Sakakibara, E. Omoda, H. Kataura, T. Iguchi, N. Nishizawa. Midinfrared optical frequency comb based on difference frequency generation using high repetition rate Er-doped fiber laser with single wall carbon nanotube film[J]. Photonics Research, 2016, 4(6): 313