  We study the nonlinear coupling between orthogonal flexural modes of doubly
clamped InAs nanowire resonators. The two orthogonal modes are formed by the
symmetry breaking and lifting of degeneracy of the fundamental mode. The
presence of a Duffing nonlinearity emerges when a mode is driven to large
amplitudes. In this regime the modes are coupled due to the tension induced
from the large amplitude of oscillations and is reflected in the hysteretic
response of the mode that is not strongly driven. We study the driven-driven
response of the mechanical modes to elucidate the role of nonlinear mode
coupling in such mechanical resonators. The dynamics of the coupled modes
studied here could prove useful in technological applications such as nanowire
based vectorial force sensing.
