When a periodic ray orbit is stable, there always exists a resonance mode that is strongly localized on the stable periodic ray orbit. Selective pumping has been used to lase a resonance mode associated with the stable periodic ray orbit by limitting the pumping region to the narrow area covering a short stable periodic ray orbit. When a periodic ray orbit is unstable, basically, there exist no resonance modes being localized on the unstable periodic ray orbit. However, in the research field of quantum chaos, weak localization on a short unstable periodic orbit called a quantum scar that is a scar in a uniform distribution due to quantum ergodicity has been studied often by using quantum billiards. Scarring phenomena also have been found in optical billiards. However, scar modes are not always found in an arbitrary range of wave numbers. By numerical simulation of a fully-chaotic billiard laser where all of periodic ray orbits are unstable, I will show that with the selective pumping where the pumping region is limited to the narrow area covering a short unstable periodic ray orbit, the resonance wave functions cooperate to localize the light intensity of the stationary lasing state on the unstable periodic ray orbit in the self-organized manner that realizes an optimal intensity pattern for getting the external pumping energy efficiently. In spite of no sharp scars in cold cavity resonance modes, locking of the resonance modes enables strong localization on the short unstable periodic ray orbit. We call this localized stationary lasing mode a "deep nonlinear scar mode" in order to make it distinguished from a shallow linear scar mode of a cold cavity.