[1] K. J. Vahala. Optical microcavities. Nature, 424, 839-846(2003).
[4] T. J. Kippenberg, K. J. Vahala. Cavity opto-mechanics. Opt. Express, 15, 17172-17205(2007).
[27] C. M. Bender. Making sense of non-Hermitian Hamiltonians. Rep. Prog. Phys., 70, 947-1018(2007).