  We present detailed experimental study on noise-seeded intermodal modulation
instability (IM-MI) in normal dispersion region of a conventional step-index
fiber. The sharp refractive index contrast between core and cladding leads to
large group velocity mismatch between the spatial modes, coaxing to efficient
IM-MI and generation of multiple spectral peaks along with Raman peaks.
Evolution of the spectrum with pump powers and fiber lengths are observed.
Experimental findings are well supported with the theoretical framework based
on bimodal-MI model considering the distinct dispersion parameters of the
participating modes.
