Range Of Fiber Lasers Research Articles

A switchable dual-wavelength fiber laser based on phase-shifted fiber Bragg grating combined with Sagnac loop

A switchable dual-wavelength erbium-doped fiber (EDF) laser is proposed and demonstrated. The interference filter is achieved by employing a phase-shifted fiber Bragg grating (PSFBG) combined with Sagnac loop structure. By adjusting polarization controller (PC) states, the birefringence effect is introduced to weaken mode competition, then stable and switchable dual-wavelength fiber laser can be realized. Based on coupled-mode theory and transmission matrix, the Sagnac loop transmission characteristics are studied. The experimental results show that the proposed fiber laser can operate in switchable dual-wavelength output mode at room temperature just by simply adjusting PC. The output wavelength range of fiber laser is 1 556.128–1 556.384 nm, the side mode suppression ratio (SMSR) is over 45 dB, and dual-wavelength spacing as small as 0.048 nm is achieved, which can be used in high-fineness dense wavelength division multiplexing (DWDM) systems and similar structures.

203 W all-polarization-maintaining picosecond thulium-doped all-fiber laser

High-power ultrafast fiber lasers are important sources for a number of applications including material processing, pump source for optical parametric oscillator, and supercontinuum generation. Ultrafast thulium-doped fiber lasers, which extend the wavelength range of fiber lasers from 1.8 to 2.1 m, have rapidly developed in the last several years and the average output power of the ultrafast thulium-doped fiber amplifiers has reached a hundredwatt level. The broad and smooth gain spectrum of thulium-doped fiber makes it a well-suited gain medium for generating the ultrashort laser pulses and broad wavelength tunability. However, previous reports on ultrafast thulium-doped fiber lasers and amplifiers were related to non-PM fiber configuration. These ultrafast thulium-doped fiber lasers and amplifiers may suffer the environmental instability, which means that these fiber sources are sensitive to externally-induced changes, like significant temperature variations and mechanical perturbations which will influence the fiber birefringence property. An effective method to eliminate this environmental instability is to build an all-PM, thulium-doped all-fiber MOPA configuration where the light polarizes only along the slow or fast axis in the PM fiber and PM-fiber components. Here, we demonstrate a high-power all-polarization-maintaining picosecond thulium-doped all-fiber master-oscillator power-amplifier (MOPA) system. The linearly-polarized thulium-doped all-fiber MOPA yields 203 W of average output power at central wavelength of 1985 nm with a polarization extinction ratio of 15 dB. The pulse duration of 15 ps at 611.5 MHz repetition-rate results in a peak-power of 22 kW in the final thulium-doped fiber power amplifier. To the best of our knowledge, this is the highest average output power ever reported for a picosecond-pulsed thulium-doped all-fiber laser at 2 m wavelength. Furthermore, high-power linearly-polarized thulium-doped fiber laser with compact and simple design is greatly demanded for a variety of applications, such as coherent polarization beam combination, and frequency conversion in nonlinear crystals.