  We investigate the possibilities of probing the electroweak scale seesaw
scenarios such as type-I, type-II and type-III seesaw at $e^-\gamma$ and
$\gamma\gamma$ colliders. For the case of type-I seesaw, the heavy neutrinos
can be produced at $e^{-}\gamma$ colliders in association with a $W$ boson. We
study a variety of final states in this case including single and multilepton
modes in association with jets to estimate bounds on the light-heavy neutrino
mixing angle. In case of type-II seesaw, doubly charged multiplets of the
SU$(2)_L$ triplet scalar can be produced in pair at $\gamma \gamma$ collider.
We study the multi-leptonic decay modes coming from this pair production of
doubly charged Higgs and show how one can probe neutrino mass hierarchy. We
also study same sign $W$ boson production from the doubly charged Higgs to
study multilepton modes in association with missing energy. From the type-III
seesaw, we study same sign dilepton+jets and trilepton+jets modes at
$e^-\gamma$ collider which are coming from the neutral and charged component of
the triplet fermion in association with a $W$ boson and $Z$ boson,
respectively. Due to the existing limits on the triplet fermions from the LHC
we choose heavier mass so that the gauge boson originated from the decay of a
neutral multiplet can be sufficiently boosted producing a fat-jet signature in
association with same sign dilepton and trilepton. Finally we estimate bounds
on the light neutrino-heavy triplet fermion mixing angle and compare with the
existing bounds.
