  Domain-engineered quasi-phase-matching (QPM) devices are known for its
versatility and ability to tune the nonlinear optical frequency conversion
process. In this paper, a simple approach is presented to generate multiple
quasi-phase-matched second-harmonic generation (SHG) in the phase reversal
optical superlattice (PROS) structure. Theoretical studies are carried out by
simulation based on the domain reversed lithium niobate QPM devices. The nature
of the generated multiple SHG spectra is analyzed when the phase reversal (PR)
domains are distributed at equal and unequal intervals along the length of the
device. The distribution of phase reversal domains at equal intervals is
limited to the generation of dual SHG peaks irrespective of its number. On the
contrary, we could generate equal-intensity multiple SHG peaks with PR domains
distribution at unequal interval. Using this scheme, five peaks QPM SHG are
generated by distributing four PR domains in specific locations of the PROS QPM
device. The dependency of the PR domain and its location in the PROS QPM device
are analyzed to design desirable multi-wavelength converters
