High-performance γ-MnO2 dual-core, hole-paired fiber for ultrafast photonics

Recently, Professor Xiaohui Li’s research group at Shaanxi Normal University fabricated a γ-MnO segment₂ γ-MnO combination dual core double hole fiber₂ with a special fiber, a double-core hole-pair fiber, measuring its nonlinear absorption curve and used it as a saturated absorber to produce an all-fiber time-locked laser, which achieved a pulse width of about 1 ps and a repetition rate of about 600 MHz.

Experiments show that this fabrication scheme has good stability and is suitable for combining other new materials with special fibers, which greatly expands the applications of special fibers in ultrafast vision and sensing.

Since special fibers have some excellent properties, the use of such properties can expand the application scope of special fibers. Li’s group has accumulated some technical experience in the nonlinear optical properties of new materials, but how to keep the nonlinear properties stable and reproducible is still valuable research. The hole of the fiber is filled with an appropriate concentration of γ-MnO₂the length of the fill is controlled and the two ends are merged into a single-mode fiber, thus completing a sealed optical modulation device.

The successful implementation of this scheme depends on two points: the selection of special optical fibers and new materials on the one hand, and the control of the filling process on the other.

The dual-core, hole-pair fiber was chosen because of its structure with the characteristics associated with photonic crystal fibers, which can withstand higher power laser transmission. the larger diameter of the hole and the close distance from the central core, which favors the integration with the material and the sharp interaction between light and material. the side core located away from the hole and the central core, which has less effect on light transmission.

And the diameter of the central core is not much different from the common single-mode fiber, which can reduce the difficulty of fusion and reduce fusion loss.

γ-MnO₂ is chosen as a filler mainly because of its small band gap, wide internal absorption band spectrum, and its urchin-like structure with better light interaction and more excellent saturation absorption characteristics. In addition, the price is relatively low and suitable for mass production.

In the filling process, anhydrous ethanol is used as a solvent, in which an appropriate amount of the new material is dissolved to prepare a homogeneous dispersion, which is then filled using the capillary effect. It is worth noting that the concentration of the dispersion is directly related to the efficiency of the filling.

The results obtained from the experiments are basically as expected, but there are still some details that need to be improved, such as the effect of temperature on the filling effect during the filling process and the effect of hole size on the filling effect, etc. With the solution to these problems, finally, this scheme will have a strict standard, which makes it have good repeatability and can be applied to more scenarios.

The study is published in the journal Superfast Science.