  We investigate extended Wilson loop operators, in particular tetrahedron
operator in (2 + 1)-dimensional Chern-Simons-Witten theory. This operator
emerges naturally from the contribution terms in twoparticle scattering
amplitude. We evaluate this diagram non-perturbatively in terms of vacuum
expectation values of Wilson loop operators, especially for gauge group SU(N)
with specific choices of representations. On the other hand, we also discuss
the perturbative calculation of vacuum expectation value in this theory. We
show that, up to the third order, this values of unknotted Wilson loop
operators are identical to the non-perturbative result.
