Lyapunov exponent of the chaotic component in the cosine cavity. The dashed curve is the maximal Lyapunov exponent λ 1 versus the length L of the cavity. The insets are two representative Poincaré surfaces of section of the closed billiard system without leads attached to it: mixed dynamics for L = 1.8 μ m (upper right) and chaotic dynamics for L = 0.5 μ m (lower left). Altogether nine cases of different values of L are shown: L = 0.5 , 0.55 , 0.6 , 0.67 , 0.8 , 1.0 , 1.33 , 1.5 , 1.8 μ m . Other parameters are M = 0.15 μ m and W = 0.24 μ m .