The noncollinear interaction between guided optical waves and magnetostatic waves under inclined bias magnetic field is studied in detail. The diffraction efficiency (DE) and the mode-conversion efficiency (MCE) of guided optical waves with magnetostatic forward volume waves in the bismuth-doped yttriu-miron-garnet (Bi-doped YIG) waveguide are calculated numerically. The calculation results indicate that the DE and the MCE are different in physical conception and the DE is not equal to the MCE in magnitude under inclined bias magnetic field. The DE may be greatly increased by using an appropriately inclined bias magnetic field, which has been experimentally confirmed in a pure YIG waveguide. By using an inclined bias magnetic field and the Bi-doped YIG waveguide, under the phase-matching conditions, the maximum DE can come up to 79.5% or more.

In ferromagnetic media, besides originating from the splitting of the excited state resulting from the spin-orbit interaction, magneto-optical effects also arise from the splitting of the ground state caused by both the exchange interaction and the applied field. In view of the standpoint mentioned above, it is shown by calculation that the Faraday rotation 0 depends linearly on magnetization M in both the regions of T<T, (Curie temperature) and of high temperature for the medium with high T c, but nonlinearly on M and Tin the usual temperature region between the above two regions.

Having used the classical electromagnetic field theory and combined it with the effective-field conception, in this paper we show that: 1) The real part θ of Faraday rotation φ in any kind of the magneto-optical (MO) material can be expressed in the fundamental form of θ=VLHi. 2) The differences in the MO properties of the different kinds of the MO media mainly result from both the characteristics and the size of their effective field Hi and especially, the different temperature properties in various media are discussed. 3) The relationship between the real part θ and the imaginary part ψ of φ can be described by the effective extinction coefficient η*. 4) The other MO properties are predicted. It is proved that the effective field Hv, which is concerned in both the spin-orbital interaction and the exchange interaction (or the indirect exchange interaction) in media, can be expressed in the form of Hv=vM (or E1=1viMi). Some theoretical results are verified by experiments.

The s-d mixing model, in which electron-photon coupling was taken into account, was employed to study the effect of optical irradiation on the moment of a magnetic impurity embedded in a nonmagnetic base. The local magnetic moment was calculated self-consistently by employing the Green-function technique. There exists notable photomagnetic effect, while the energy level configuration meets the resonant-absorption condition and the effective on-site energy of local electrons approaches the Fermi energy Ef. The change of local moment primarily originates from the transition between a d-like local state and a p-like local (extended) state. The mechanism of photomagnetic effect of a magnetic impurity is that the optical irradiation breaks the original balance of electron distribution under Column interaction (Hubbard repulsion) via the change of local energy-level position and the decrease of its lifetime and hence results in the variation of local magnetic moment.

In some paramagnetic media, the effective field Hi, which includes an effective exchange field and an applied field, can cause a splitting of the ground level. In the temperature region T>Tc (Tc is the Curie temperature), there are certain probability distributions of electrons on two energy levels due to ground-state splitting. This induces the ground level for a double transition. It is shown that there are several temperature behaviors for the magneto-optical Faraday effect in paramagnetic media. If the applied field is not too large, the ratio of the Verdet constant to the magnetic susceptibility is V/x=A (1+BT) in some media, or V/x=A (1+B/T) in other media. It is also indicated that both the real part θ' and imaginary part θ" of the Faraday rotation are proportional to the effective field Hl, and show similar temperature behaviors beyond the region of optical absorption.