The transmission coefficient T (blue solid line), reflection coefficient R (red dashed line), and their summation T + R (yellow dash-dot line) as a function of momentum k at Ω = ω_c = 10, J = 4. For the perfect cavity, (a) η = 0.1. For the imperfect cavity, (b) λ = 800, γ = 0.01 and (c) λ = 8, γ = 1.