A two-mode photonic crystal fiber includes a core of a substantially transparent core material. Among the interconnection layers, the uppermost one is made of a wiring material such as aluminum or aluminum alloy, while the lower one is made of Cu or Cu alloy. The first magnetization fixed layer and the first magnetization free layer have perpendicular magnetic anisotropy, and the second magnetization fixed layer and the second magnetization free layer have in-plane magnetic anisotropy. The invention also describes pharmaceutical compositions containing such nucleoside compounds alone or in combination with other agents active against RNA-dependent RNA viral infection, in particular HCV infection.