In previous years, ultrafast fiber lasers have actually brought in substantial attention due to their applications in essential research study, biomedicine and market.
Compared to rare-earth-doped ultrafast fiber lasers which can just run in restricted spectral variety, ultrafast Raman fiber lasers have a unique benefit of wavelength dexterity. However, their attributes such as pulse energy, pulse width, and stability of the pulse train are even worse than their rare-earth-doped equivalents.
Amongst various type of pulse shaping systems, dissipative soliton (DS) is a legitimate strategy to enhance pulse energy and stability.
With regard to saturable absorbers, nonlinear optical loop mirror (NOLM) is a method suitable with all polarization preserving (PM) fiber setup and might attain long-lasting steady pulse operation.
Just recently, researchers from the Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences have actually established a Raman DS fiber laser mode-locked by a NOLM, and the associated work was released on Optics Express.
In the DS mode locking, spectral filtering is essential for spectral and pulse shaping. For that reason, in their experiment, an all-fiber Lyot filter that bases upon the birefringence and dispersion of PM fiber was used to work as a spectral filter.
Furthermore, a 1064 nm enhanced spontaneous emission source was utilized as a pump source in mode locked Raman fiber laser for the more enhancement of pulse stability.
Their experiment showed that steady 1120 nm Raman DS pulses with normal DS functions might be acquired at a repeating rate of 1.23 MHz. The greatest pulse energy and least expensive pulse width is 1.23 nJ and 63 ps, respectively. Signal to sound ratio of the radio frequency spectrum of the Raman DS is as high as 85 dB.
The speculative outcome revealed that NOLM-based Raman DS ought to be an appealing option for wavelength-flexible linearly-polarized pulses generation with high pulse stability. For that reason, this work can supply an unique method to obtain linearly-polarized ultrafast laser at versatile wavelengths.
This work was supported by the National Life Sciences Structure of China and China Postdoctoral Science Structure.