  Thanks to a new derivation of the fundamental equations governing multimode
dynamics for a semiconductor laser near its threshold, we identify regimes of
existence of a pure phase instability (and of a mixed phase-amplitude
turbulence regime) which give an alternative satisfactory interpre- tation of
the deterministic multimode dynamics observed in some devices. The existence of
intrinsic noise generated by the phase instability reconciles in the same
description the deterministic and random features of the semiconductor
dynamics.
