부산대학교 도서관

We investigate the possibility of a hole-assisted fiber (HAF) with lower attenuation property by considering two loss factors, Rayleigh scattering loss ${\alpha }_R$ and air-hole scattering loss ${\alpha }_h$. The ${\alpha }_R$ property is numerically investigated by considering the glass material dependence of Rayleigh scattering coefficient. We derive that the ${\alpha }_R$ reduction of 0.03 dB/km at $\lambda$ = 1.31 μm is potentially expected by combining the smaller core diameter and lower relative reflective index difference with suitable air-hole design while ensuring the optical compatibility to conventional single-mode fiber (SMF). Concerning ${\alpha }_h$ in HAF, we experimentally examine the relationship between etching condition of the air-holes and ${\alpha }_h$. Here, we considered the effect of the etching on both before and after stretching of the drilled preform. It is confirmed that ${\alpha }_h$ varies not only with the etching amount but also with the order of the etching and stretching processes. Our results show that ${\alpha }_h$ can be minimized by optimizing the etching amount of both before and after preform stretching simultaneously. These results show that HAF with lower ${\alpha }_R$ is potentially realized by considering the modified step index profile, appropriate air-hole design, and suitable air-hole etching process.