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Behaviour of Electromagnetic Waves in Different Media and Structures Part 11

Tham khảo tài liệu 'behaviour of electromagnetic waves in different media and structures part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 288 Behaviour of Electromagnetic Waves in Different Media and Structures electromagnetic waves. This difference can be explained in the presence of a magnetic field the energy spectrum of electronic is interruptions. In addition the Landau level that electrons can reach must be defined. In other word the index of the absorption process must satisfy the condition fl r n ỉì fi B N N fi 0 fl 0 17 in function Delta - Dirac. This is different from that for case absent a magnetic field index of the landau level that electrons can reach after the absorption process is arbitrary therefore the dependence of the absorption coefficient on ÌỈ is not continuous. Fig. 12. The dependence of on the ÌỈ Presence of an external magnetic field 4. Effect of magnetic field on nonlinear absorption of a strong electromagnetic wave in a cylindrical quantum wire 4.1 The electron distribution function in a cylindrical quantum wire in the presence of a magnetic field with case of confined phonons We consider a wire of GaAs with a circular cross section with radius R and length Lz embedded in AlAs. The carries confined electrons are assumed to be confined by infinite potential barriers and free along the wire s axis Oz . A constant magnetic field with the magnitude B is applied parallel to the axis of wire. In the case the Hamiltonian is given by Bau Trien 2010 H n.l .N i A t -an f Nyzan f N 22 h m k qz-hm k qz-hm k qz n N kz m k qz 2L _ 2jCqz n nlílJN Nl U aniựi Ni Ẽ q anự N Ẽ m k qz m k qz n r N kz m k n N qz 18 Where the sets of quantum numbers n f N and n f N characterizing the states of electron in the quantum wire before and after scattering with phonon A k an N J is the Effect of Magnetic Field on Nonlinear Absorption of a Strong Electromagnetic Wave in Low-dimensional Systems 289 creation annihilation operator of a confined electron kz is the electron wave vector along the wire s z axis hml. L bmk- is the creation operator annihilation operator of a confined optical phonon for state .