Dynamics in a CO₂ laser with combined action of pump switching and loss modulation

This report shows some features of the dynamical behavior of a CO₂ laser with pump switching and sinusoidal loss modulation. The dynamics of the system to be investigated is quite different from that of an autonomous system. The duration of the laser pulse is very short in comparison with the characteristic times which determine the CO₂ dynamical behavior (in particular, with the relaxation times of the energy levels involved). Thus, several variables do not have enough time to reach its stationary values and the laser does not follow adiabatically a steady state. The experiments were performed with a waveguide single-mode CO₂ laser with pump excitation. The losses were modulated with an intracavity acousto-optical Ge modulator. The experimental approach was to tune the cavity length and record the amplitude of subharmonic components in the power spectrum of the laser output for each fixed modulation frequency and driving voltage. With the use of cavity detuning as a control parameter. The authors construct the dynamical bifurcation diagrams of the power spectra at different modulation frequencies.