The Ikeda differential equation is a scalar delay differential equation with sinusoidal delayed feedback. A form used to model an optical resonator is
where
is the derivative with respect to time
,
is the relaxation rate,
is the delay,
is the feedback strength, and
is a phase offset (Ikeda and Matsumoto
1987, Kubyshkin and Moriakova 2018). For a constant solution
, the equation reduces to
. With
, the linearization about
is
.
An exponential perturbation
therefore gives the characteristic
equation
For appropriate parameter values, the nonlinear equation can exhibit multiple stable periodic orbits and chaos (Ikeda and Matsumoto 1987).