Femtosecond mode-locked fiber laser employing a hollow optical fiber filled with carbon nanotube dispersion as saturable absorber

Abstract

We propose a novel in-line saturable absorber incorporating a hollow optical fiber (HOF) filled with single-walled carbon nanotube (SWCNT) dispersion. The evanescent field of the propagating light in the ring core interacts with the SWCNT/polymer composite distributed over the whole length of the HOF. The proposed saturable absorber with all-fiber format offers the robust and long nonlinear interaction along the waveguide direction expecting the increase of the threshold for optical and thermal damages with simple fabrication process. Low concentration SWCNT/polymer composite exhibiting very broadband resonant absorption around 1.5 microm with low scattering loss is prepared and based on this, we successfully demonstrate the passively mode-locked fiber laser including the SWCNT-filled HOF where the spectral bandwidth and the pulse duration of the laser output are 5.5 nm and 490 fs, respectively, with a repetition rate of 18.5 MHz.

Carbon nanotubes for ultrafast fibre lasers

“…The same method of evanescent field interaction is utilised in SA based on photonic crystal or hollow optical fibre filled with carbon nanotube dispersion [67]. An aqueous suspension of individual SWNTs filled the fibre under a gas pressure about 10 atm (Figure 14).…”

“…There are numerous reports in the literature [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67] on the use of SWNTs as mode lockers and Q-switches for ultrafast lasers in the broad wavelength band, which are summarised in Table 1. One of the main advantages of SWNT-based SAs, apart from ultrashort relaxation time and high nonlinearity, is the ease of their fabrication and implementation into the laser setup.…”

Carbon Nanotube-Based Photonic Devices: Applications in Nonlinear Optics

“…Hence, such nonlinearity can be enhanced by increasing the length of interaction between the CNTs and the propagating optical field. Numerous approaches have been considered for this purpose by employing devices such as D-Shape fibers tapered fibers (Kieu et al, 2009), hollow core fibers (Choi et al, 2009), micro-slot fiber devices (Martinez et al, 2010) and planar waveguides (Kashiwagi et al, 2007). These approaches involve evanescent coupling, where the CNTs are placed adjacent to the optical waveguide.…”

Passive mode-locked lasing by injecting a carbon nanotube-solution in the core of an optical fiber

“…By embedding the CNTs into a polymer, there are also protected from the mechanical damage and degradation suffered when free standing on air. Therefore, most of the current research employs devices based on a variation of polymer embedded CNTs [8][9][10][11][12][13][14]. Our current research is focusing on implementing SAs and nonlinear devices with good quality CNT dispersion, low losses, resistance to thermal damage and increased nonlinearity and interaction lengths for the realization of high power fiber lasers.…”