1. M. Laemmlin, G. Fiol, C. Meuer, et al., Electron. Lett. 42, 697 (2006).
2. R. H. Dicke, Phys. Rev. 93, 99 (1954).
3. A. V. Andreev, V. I. Emel’yanov, and Yu. A. Il’inskiĭ, Cooperative Phenomena in Optics: Superradiance, Bistability, Phase Transitions (Nauka, Moscow, 1988) [in Russian].
4. P. P. Vasil’ev, Kvantovaya Élektron. 24, 885 (1997) [Quantum Electron. 27, 860 (1997)].
5. P. P. Vasil’ev, H. Kan, H. Ohta, and T. Hiruma, Phys. Rev. B 64, 5209 (2001).