is referred to as th spectral component, th harmonic of is with period
Spectral component
In telecommunications, spectral component is any of the waves that range outside the interval of frequencies assigned to a signal. Any waveform can be disassembled into its spectral components by Fourier analysis or Fourier transformation. The length of a pulse thereby is detesitions (spectral phase) of these spectral components.
https://en.wikipedia.org/wiki/Spectral_component

Seonglae Cho