  We show that the in-plane heterostructures realized in vertical cavities with
high contrast grating(HCG) reflector enables exotic configurations of
heterostructure and photonic wells. In photonic crystal heterostructures
forming a photonic well, the property of a confined mode is determined by the
well width and barrier height. We show that in vertical-cavity in-plane
heterostructures, anisotropic dispersion curvatures plays a key role as well,
leading to exotic effects such as a photonic well with conduction band like
well and a valence band like barrier. We investigate three examples to discuss
the rich potential of this heterostructure as a platform for various physics
studies and propose a system of two laterally coupled cavities which shows the
breaking of parity-time symmetry as an example.
