Generation of ultra-fast laser pulses using nanotube mode-lockers

The non-linear optical properties of SWNTs are at the centre of an expanding area of research. SWNTs are good saturable absorbers with an ultrafast recovery time, i.e. they are pass-high filters for light, becoming transparent for sufficiently high incident power [1, 2]. This makes them ideal components for a wide range of photonic devices, such as all-optical switches, pulse compressors, noise regenerative filters, etc. Many key applications of carbon nanotubes in electronic devices require individual tubes with given chirality for their optimum performance. However, precise chirality control is not necessary if we want to exploit their electronic properties to build ultra-fast optoelectronic devices. The main requirement is to control the average diameter distribution to match the wavelength of interest. Furthermore SWNTs can be easily processed in film or polymer composites. They also have very good radiation and thermal stability. These makes them very competitive when compared to existing passive mode-locking technology, based on semiconductor saturable absorber mirrors, which are molecular beam epitaxy grown multiple quantum wells requiring expensive packaging [3]. Here we report the generation of ultrashort laser pulses in erbium doped fiber lasers by using SWNTsPVA saturable absorber films. The SWNTs-PVA composite does not show laser or environmental damage after continuous operation in the laser cavity.