Huaiqin Lin

Observation of Dissipative Soliton Resonance in a Net-Normal Dispersion Figure-of-Eight Fiber Laser

High-energy square pulses operating in dissipative soliton resonance region are experimentally observed in an erbium-doped figure-of-eight fiber laser with large net-normal dispersion for the first time to our knowledge. The dissipative soliton resonance is achieved by using the nonlinear-amplifying-loop-mirror mode-locked technique. The output pulse duration broadens linearly with the increase of pump power, while the peak power maintains a constant value. At the maximum pump power of 620 mW, the intracavity pulse energy is up to 379.2 nJ, and the average output power is 14.02 mW.

Dissipative soliton resonance in an all-normal-dispersion Yb-doped figure-eight fibre laser with tunable output

We report on the generation of large pulse duration-tuning and wide wavelength-tunable mode-locked pulses, operating in a dissipative soliton resonance (DSR) region, by an all-normal-dispersion Yb-doped figure-eight fibre laser. For the case of a DSR operating at 1045.1 nm, the pulse duration varies from 26.3 ps to 8.621 ns with the increase of pump power. At the maximum pump power of 400 mW, the pulse energy is as high as 4.8 nJ. In particular, through properly adjusting the polarization controllers, the DSR can be wavelength-tuned in a wide range from 1037.3 to 1075.3 nm. To the best of our knowledge, this is the widest tunable range ever reported for DSR operation. This wavelength-tunable mode-locked fibre laser with a high-energy output may be well-suited for many potential applications.

Tunable and Switchable Dual-Wavelength Dissipative Soliton Operation of a Weak-Birefringence All-Normal-Dispersion Yb-Doped Fiber Laser

We report on the generation of tunable and switchable dual-wavelength dissipative solitons (DSs) in a weak-birefringence all-normal-dispersion Yb-doped fiber laser based on the nonlinear polarization rotation technique. By virtue of the weak-birefringence operation, the switchable dual-wavelength DSs with a wide wavelength-tunable range and variable wavelength spacing are observed for the first time. The variable wavelength spacing is a result from the similar order of magnitude between the polarization controller-induced birefringence change and the fiber birefringence. It is suggested that a widely tunable wavelength spacing of the tunable and switchable dual-wavelength DSs could be realized through introducing an extra birefringence change whose magnitude is comparable with the fiber birefringence.

Theoretical and experimental analysis of splicing between the photonic crystal fiber and the conventional fiber using grin fibers

Photonic crystal fibers (PCFs) are widely used in all-fiber, high-power lasers and supercontinuum sources. However, the splice loss between PCFs and conventional fibers limits its development. Grin fibers and coreless fibers were used as a fiber lens to achieve low-loss, high-strength splicing between PCFs and single-mode fibers (SMFs). The beam propagation method was used to optimize the lengths of grin fibers and coreless fibers for a minimum splice loss. The splice loss changing with the lengths of grin fiber, coreless fiber, and the air-hole collapsed region was systematically studied theoretically and experimentally. Ultimately, a minimum splice loss of 0.26 dB at 1064 nm was realized between a high-nonlinear PCF and a conventional SMF with this method.

A low-cost CW-pumped supercontinuum source

In order to resolve the conflict of high performance and high cost for a continuous wave (CW)-pumped supercontinuum (SC) source under low-power pumping conditions (less than ~20 W), a cascaded-fiber configuration of a short photonic crystal fiber (PCF) and a short low-cost conventional fiber is proposed to replace long high-cost PCFs. By cascading a 60 m low-cost conventional nonlinear fiber with a 90 m PCF pumped by a 24 W CW fiber laser, a higher-quality SC with a 10 dB bandwidth of 230 nm and a 5 dB bandwidth of 176 nm is demonstrated. This SC also has a maximum output power of 13.9 W. Both the spectral performance and the output power properties for this SC source are superior to those for the SC from the 200 m high-cost PCF, and these results demonstrate the effectiveness of the method in realizing a low-cost, high-quality SC source.

Widely and Continuously Tunable Continuum Generation From CW-Pumped Cascaded Fibers

A tunable continuum with multiwatt output power is demonstrated for the first time through the pumping of cascaded fibers by using a continuous-wave (CW) ytterbium fiber laser. The central wavelength of the output continuum can be tuned continuously and monotonically by varying input pump power, with a wide wavelength-tunable range from 1.2 to 1.4 μm and a 3-dB bandwidth of tens of nanometers. Two configurations of the cascaded fibers both display the power-dependent wavelength tunability. The output spectral characteristics are presented, and the generation of the CW-pumped tunable continuum is tentatively attributed to the seed-dependent Raman amplification.

20-W Wavelength-Tunable Picosecond Yb-Doped Fiber MOPA Source Seeded by an NPR Mode-Locked Fiber Laser

We demonstrated a high-power wavelength-tunable picosecond Yb-doped fiber master oscillator power amplifier source without any tunable elements for the first time. This wavelength-tunable output was realized based on the birefringence-induced filter effect of the nonlinear polarization rotation mode-locked fiber laser, which worked as the seed source. Through cascaded single-mode Yb-doped fiber preamplifiers together with two double-cladding Yb-doped fiber amplifiers, the pulses were amplified up to 21.2-W output power in the wavelength range from 1038.4 to 1060 nm with a pulse duration of 9.5 ps, an optical signal-to-noise ratio of 25 dB, and a beam quality M2 of 1.16 at the repetition rate of 178 MHz.