Is there specific software that is used for creating a virtual environment?
SDN refers to a great number of potential solutions. In most cases, it is software built into the hardware. So Cisco, Juniper, Brocade and other networking makers offer software solutions, often that have no particular name. They are just the SDN options of that gear.
Pure software does exist and a common example of it is ZeroTier which is designed as a complete virtual networking layer on top of your physical network and has no interaction with the underlying hardware so it completely agnostic.