The role of harmonic and random external forces in a phenomenological nonlinear model of optical heartbeats is investigated. External forces trigger damped oscillations at the natural frequency of the system and higher harmonics. The numerical results are compared with experimental ones.
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.62.Be Biological and medical applications
42.62.Fi Laser spectroscopy
$^1$Physics Department and International Laser Center, Moscow State University, Moscow, 119991, Russia
$^2$Dipartimento di Fisica e Tecnologie Relative, Group of Interdisciplinary Physics, Universitá di Palermo and CNISM-INFM, Viale delle Scienze, ed. 18, Palermo, I-90128, Italy