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In an effort to realize a compact and integrated ultrafast fiber laser system, we propose a fiber component serving as a wavelength division multiplexer (WDM), output coupler (OC), and mode-locker by a magnetron-sputtering saturable absorber (SA) on a laboratory-tapered coupler. With the function-integrated coupler, an Er-doped mode-locked fiber laser with 112 MHz repetition rate, 286 fs pulse width, and 87 dB signal-to-noise ratio (SNR) is demonstrated. The noise feature of the mode-locked laser is also characterized. To the best of our knowledge, this is the first demonstration of a mode-locked fiber laser based on a WDM/OC/SA integrated device.

We report, for the first time, the nonlinear absorption at the 2 µm waveband of three Sb-related materials including two Sb compounds, GaSb and InSb, and one Sb alloy, Ge8Sb92. These saturable absorbers (SAs) were coated on tapered single mode fibers by the magnetron-sputtering deposition method. By incorporating these SAs into Tm-doped fiber lasers, ultrafast mode-locked solitons could be readily obtained. Stable pulse trains with 922 fs/753 fs/1005 fs pulse durations, 31.35 mW/37.70 mW/16.60 mW output powers, 93 dB/80 dB/92 dB signal-to-noise ratios were achieved with GaSb/InSb/Ge8Sb92, respectively. Our findings demonstrate that these materials can be widely used for photonic devices in the 2 µm waveband where ultrafast optical switching and modulating are desired.

Multi-pulse dynamic patterns have been experimentally observed in an Ytterbium-doped fiber laser passively mode locked by a topological insulator (TI) Bi 2 Te 3 saturable absorber (SA). The fundamental mode-locking operation with a repetition rate of ~1.10 MHz was achieved under a pump power of ~160 mW with an appropriate setting of the polarization controller (PC). It was found that through either changing the pump power or rotating the orientation of intra-cavity PC, several characteristic modes have been experimentally observed, including disordered multi-pulses, bunch of pulses, and soliton rains. Simultaneously, quasi-square pulses have also been observed in the laser cavity. Our systematic study clearly demonstrated that TI could be developed as an effective SA for the generation of different pulse operation states in a passively mode-locked all-normal-dispersion Ytterbium-doped fiber laser.

The influence of Bragg fiber design parameters on photonic bandgap was discussed via the finite element method.The theoretical results show that the bandgap move to long wavelength when the thickness or the refractive index of the Ge-doped layers increases.A novel W-shape-core Bragg fiber was firstly proposed by introducing a F-doped low index layer adjacent of fiber core.The calculation demonstrates the W-shape-core Bragg fiber can reduce the confinement loss and improve the bending-resistant ability effectively.A W-shape-core Bragg fiber was designed with a core diameter of 30 μm,which has a loss of 0.1 dB/km at wavelength of 1.06 μm and is proved single mode propagation theoretically.

We investigate on a multi-wavelength operation erbium-doped fiber laser Q-switched by a graphene-based saturable absorber. Stable pulses were generated with the widths from 6.9 to 1.5 μs, energies from 40.4 to 130.2 nJ and repetition rates from 68.32 to 132.9 kHz, when the pump power increased from 142.32 to 441.86 mW. A fiber Bragg grating with five reflective peaks was inserted into the fiber ring through an optical circulator, resulting in a stable output of five- lasing-wavelength output. The laser can perform as a low-cost and easy-built all fiber light source, and has potential applications in the fields where pulses at multi-wavelength operation are needed, i.e., temperature or strain fiber sensors. © 2012 Society of Photo-Optical Instrumentation Engineers

A 145-m long microstructured optical fiber taper was fabricated on the industry drawing tower. The fiber taper had good uniformity of structure as the outer diameter decreased from 110 to 80 μm. Its optical attenuation was measured 52 dB/km at 1060 nm, and the zero dispersion wavelengths along the slow axis were calculated decreasing from 1000 to 915 nm. Watt-level supercontinuum spanning from 430 to 2050 nm was obtained as the fiber taper pumped by a 1064 nm picosecond laser source. The nonlinear mechanism of spectral broadening is carefully investigated with the support of numerical simulations.