Petermann's Effect
  • Klaus Petermann reported from a phenomenological consideration that the spontaneous emission into a gain-guided mode is enhanced by a factor K given by

    where F(x) is the electric field amplitude of the lasing mode with its adjoint being F*(x).

  • He wrote, "The spontaneous emission factor not only increases with decreasing volume of the active layer but also increases with increasing astigmatism", where the former effect is nothing but the Purcell effect. The latter is the Petermann's effect, which comes from bi-orthogonality of modes in non-Hermitian systems.
Experimental observations of the Petermann's Effect
  • Eenhanced spontaneous emission and excess quantum noise have been observed in unstable lasers.
  • Laser linewidth broadening corresponding to 1 ≤ K ≤ 40 were observed.
Last updated: February 25, 2014