The energy conservation law for optical two-port devices

Abstract

The relationship between the parameters of quadripoles (mirrors, for example) ensuring the fulfillment of the energy conservation law are considered. Apart from the standard balance of transmitted, reflected, and absorbed energy in a traveling light wave, some additional conditions imposed on the amplitudes and phases of the coefficients of the scattering matrix should be met. These conditions have been found by considering the light reflection from the Fabry-Perot interferometer with a quadripole used as one of the mirrors. An additional condition involves the Hamy phase parameter ϑ=Ψ₁+Ψ₂-2Φ, where Ψ₁, Ψ₂ are the phases of the reflected light, and Φ is the phase of the transmitted light. Another condition relates the amplitudes of the reflected light R₁^1/2, R₂^1/2, and the transmitted light T^1/2. At a certain combination of parameters the quadripole becomes unrealizable physically. Specific examples are considered.