Lv Jinman, Hao Xiaotao, Chen Feng
Opt Express. 2016 Oct 31;24(22):25482-25490. doi: 10.1364/OE.24.025482.
We report on the green up-conversion and near-infrared (NIR) emission in Er, MgO co-doped nearly stoichiometric LiNbO waveguides fabricated by femtosecond laser writing. The waveguides with so-called Type I geometry by laser writing support nearly single-mode propagation of light at NIR wavelength of 1.55 μm. In addition, it has been found that the guidance is only along the vertical (i.e., TM) polarization, which is due to the laser-induced positive changes of extraordinary index in the guiding core. The green up-conversion at 550 nm and 528 nm, corresponding to the transitions of S → I, H → I, as well as the NIR luminescence emission at C-band centered at 1550 nm under I → I transition have been realized in the waveguides, respectively. Our results have shown that the intensities of the guided-wave green up-conversion and NIR emissions are higher than those obtained from the bulk, which may be owing to the enhanced intracavity optical intensities of the waveguide with respect to the bulk.
我们报道了通过飞秒激光写入制备的掺铒、氧化镁的近化学计量比铌酸锂波导中的绿色上转换和近红外（NIR）发射。通过激光写入具有所谓I型几何结构的波导支持在1.55μm近红外波长下光的近单模传播。此外，已经发现这种导光仅沿着垂直（即横磁，TM）偏振方向，这是由于激光诱导的导光芯中异常折射率的正向变化所致。在波导中分别实现了对应于S→I、H→I跃迁的550nm和528nm的绿色上转换，以及在I→I跃迁下以1550nm为中心的C波段的近红外发光发射。我们的结果表明，导波绿色上转换和近红外发射的强度高于从块状材料获得的强度，这可能是由于波导相对于块状材料腔内光强度增强所致。
