In-line Saturable Absorber Research Articles

All-polarization-maintaining Er-doped dual comb fiber laser using single-wall carbon nanotubes.

We demonstrated a bi-directional, Er-doped dual comb fiber laser consisting of all-polarization-maintaining fiber devices. Polyimide films in which single-wall carbon nanotubes (SWNTs) were dispersed were used as the in-line saturable absorber. In order to avoid synchronization of the two combs and associated damage to the SWNT film, a two-branch configuration with two SWNT films was employed. Soliton pulses with almost the same optical spectra were generated stably in each direction, and dual comb beats were observed simply by overlapping the two outputs. The repetition frequency was 28 MHz, and the frequency difference was 105-140 Hz. Thanks to the small frequency difference, dual comb beats corresponding to the whole optical spectrum were observed without any overlapping. Fourier transform spectroscopy using the developed dual comb source was examined, and the characteristics of an optical filter were successfully obtained.

Mode-Locked All-Fiber Lasers at Both Anomalous and Normal Dispersion Regimes Based on Spin-Coated <named-content content-type="math" xlink:type="simple"> <inline-formula> <tex-math notation="TeX">$\hbox{MoS}_{2}$</tex-math></inline-formula></named-content> Nano-Sheets on a Side-Polished Fiber

We demonstrate an all-fiberized mode-locked laser by employing Molybdenum Disulfide (MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) spin-coated onto a side-polished fiber (SPF) as an in-line saturable absorber. Single crystal MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> has been exfoliated via the Li intercalation method and then dispersed with large population of few-layer MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nano-sheets in ethanol. Subsequently, a saturable absorber has been prepared using a relatively simple method: spin-coating the uniform MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> solution on the fabricated SPF without using any polymer or toxic procedure. Power-dependent transmission property of the prepared MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nano-sheets on the SPF was experimentally analyzed, providing the feasibility to apply it as an efficient in-line saturable absorption behavior. By deploying the MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> SPF into a fiber laser cavity with finely tuned laser pump power and cavity dispersion, mode-locked pulses were obtained at anomalous and normal dispersion of the laser cavity. The self-started soliton pulses at the anomalous dispersion regime were generated with a spectral bandwidth of 9.96 nm at 1584 nm and a pulse duration of 521 fs. Moreover, by managing the dispersion to the normal regime, stable pulses at net-normal intra-cavity dispersion with 11.9 ps pulse duration were obtained with a spectral bandwidth of 18.2 nm at 1570 nm. The results prove the effectiveness of developing MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> saturable absorbers and applications for pulsed laser operation.

Graphene-filled hollow optical fiber saturable absorber for efficient soliton fiber laser mode-locking

We demonstrate a novel in-line saturable absorber based on hollow optical fiber (HOF) filled with graphene composite for high power operation of mode-locked fiber laser. Evanescent field of guided mode propagating in few centimeter-long HOF interacts with the graphene/polyvinyl acetate (PVAc) composite, which enables robust and efficient nonlinear absorption leading to stable passive mode-locking. The mode-locked fiber laser generates soliton pulses with 5.9-nm spectral bandwidth and its maximum output power is measured up to 80 mW. We also observe passive harmonic mode-locking of soliton laser delivering stable pulses with a repetition rate of 506.9 MHz at 33rd harmonics.

Mode-locked fiber laser using an SU8/SWCNT saturable absorber

We report the fabrication of a saturable absorber based on SU8 single wall carbon nanotube (SWCNT) composite material. Thin films with a controllable thickness can be fabricated using a simple and reliable process. These films can be inserted between two FC/APC connectors in order to have an inline saturable absorber. A passive mode-locked laser was built by interleaving the fiberized saturable absorber in an erbium-doped fiber (L-band) ring cavity laser. The laser produces 871 fs pulses with a repetition rate of 21.27 MHz and a maximum average power of 1 mW.

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

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.

Autosolitons in dispersion-managed systems with in-line saturable absorbers

We study the formation of stable solitonlike pulses in dispersion-managed fiber transmission systems using an in-line fast saturable absorber. Operational regimes suitable for 40-Gbit/s channel rate transmission are demonstrated.

In-line saturable absorber in transmission systems with cascaded semiconductor optical amplifiers

A significant improvement of high bit-rate RZ transmission system performance was demonstrated by employing an in-line saturable absorber. The basic features of such a system are discussed. Error free 5-Gb/s single channel transmission over 30000 km has been obtained at 1.3-/spl mu/m in a fiber loop setup. The saturable absorber was fabricated directly in the semiconductor optical amplifier by ion-implantation.