Poincaré maps representing the laminar phase evolution I_n+1 = f(I_n): (a) comparison between two different data acquisitions: six consecutive laminar phases counting around seven peaks each : experimental points in purple with the fit in orange and 16 laminar phases : experimental points in red with the fit in blue; (b) a comparison between the intermittency (red points) and chaotic regime (black points); fits are represented, fixing (black) or not (orange) the intersection value with the bisector line.