$${\lambda = \frac{c}{f} = \frac{3,00 \cdot 10^8\, \mathrm{m/s}}{2,46 \cdot 10^{-15}\, \mathrm{s^{-1}}} = 1,22 \cdot 10^{-7}\, \mathrm{m} = 122\, \mathrm{nm}}$$