The paper presents results of stability analysis of optical modulator including injection laser diode affected by microwave modulating signals. The injection laser is considerably non-linear oscillating system. It was investigated different modes of the system with help of theoretical analysis technique, which is based on oscillation theory. The conversion of deterministic systems to chaotic mode was investigated with help of first recurrence map or Poincaré map. The numerical value of injection laser parameters were calculated. The rate equations of injection laser diode affected by microwave modulating signals are numerical calculated, when the system is close to chaotic mode. Theoretical and experimental results are compared with each other.