Abstract

It is well admitted that the nonorthogonal nature of the laser modes can lead to an enhancement of the quantum noise level in the laser structure. The rate of spontaneous emission into any mode increased with respect to the case of orthogonal eigenmode by an excess noise factor k_n defined as^1,2 where ϕ_N(z) denotes adjoint eigenmodes. The excess noise factor has been analyzed in distributed feedback^3,5 as well as two-mirror lasers.⁵ In the latter case⁶ the length of the active medium is taken to be the same as the length of the laser cavity. However, in laser systems often the length of the active medium is shorter than the length of the cavity and additional devices are introduced. In general, it leads to the extra cavity distributed losses in the structure.

© 1994 IEEE