Zhao Junqing

Graphene-Oxide-Based Q-Switched Fiber Laser with Stable Five-Wavelength Operation

We demonstrate an erbium-doped ring-cavity fiber laser Q-switched by a graphene oxide-based saturable absorber (GOSA). The GOSA was fabricated by vertically evaporating GO-polyvinylalcohol (GO/PVA) composite dispersion, and has a good performance under room temperature. Utilizing a specially fabricated fiber Bragg grating (FBG), stable five-wavelength lasing is realized and stabilized at different pump powers under any polarization state. When the pump power increases from 78.4 mW to 379.3 mW, the output power ranging from 1.9 mW to 16.6 mW could be obtained, with pulse duration from 6.8 μs to 2.72 μs, single pulse energy from 123.73 nJ to 229.74 nJ, and pulse repetition rate from 15.36 kHz to 72.25 kHz. To the best of our knowledge, it is the first simultaneous realization of five-wavelength operation and pulse output in a GO Q-switched all fiber laser system.

Multi-wavelength graphene-based Q-switched erbium-doped fiber laser

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.

Q-Switched Thulium-Doped Domestic Silica Fiber Laser

We report a cladding-pumped Tm3+-doped domestic silica fiber laser operated at 2μm and actively Q-switched with an acousto-optic modulator. Pulse trains are obtained as pumped by a 785 nm laser diode. The maximum average output power is 1.27W. Peak power up to 4.2kW and pulse energy up to 840 μJ are obtained with the pulse duration of 200 ns produced at a repetition rate of 1 kHz. The laser performance is studied under different repetition rates and pump powers. Lastly, we give some discussion.

An Effective Thermal Splicing Method to Join Fluoride and Silica Fibers for a High Power Regime

A repeatable and simple thermal splicing method for low loss splice between fluoride and silica fibers is presented. The minimum splicing loss of 0.58 dB is achieved experimentally with this approach. Meanwhile, the power capacity of this splicing joint is also tested with a high power fiber laser. The maximum input power is up to 15 W, only limited by the available power of the laser source. To the best of our knowledge, this is the first report on thermal splicing between fluoride and silica fibers operating in a high power regime without any complicated ion-assisted deposition process.

Fabrication of a 145-m long microstructured optical fiber taper and its supercontinuum generation

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.