Nonlinear photonics in carbon nanotubes and graphenes

First nonlinear photonic application of these nano-carbons was use of saturable absorption in CNT as a mode locker for fiber lasers in 2003. The absorption in CNT is saturable, and its recovery time is fast, <;lps, due to the relaxation though metallic CNTs. Tube diameter of ~1.2nm gives absorption at wavelength around 1.55μm. Since the first proposal, CNT saturable absorbers (SAs) have been used in a variety of laser systems for mode locking and also Q-switching, because of many advantages over existing mode lockers such as semiconductor based one (SESAM), or a fiber-nonlinearity-based one, such as inherently fast recovery time, easy fabrication, robust, wavelength tunable, low loss, small size and compatibility to optical fiber. It is applicable to any laser configurations, such as ring- and linear-cavity lasers.