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Interband and Intersubband optical transition

2. Outline. Optical absorption in quantum structuresFermi's Golden RuleDifferences in quantum structures (quantum well) Form of wavefunctions for "non-excitonic"quantum well absorptionSubbands and densities of statesCalculation of optical absorption matrix elementSelection rules, Experimental geometry.

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Interband and Intersubband optical transition

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    1. Interband and Intersubband optical transition Illia Marderfeld

    2. 2 Outline Optical absorption in quantum structures Fermi’s Golden Rule Differences in quantum structures (quantum well) Form of wavefunctions for "non-excitonic"quantum well absorption Subbands and densities of states Calculation of optical absorption matrix element Selection rules, Experimental geometry

    3. 3 Optical absorption in quantum structures

    4. 4 What are the assumptions and approximations we must consider?

    5. 5 Fermi’s Golden Rule

    6. 6 The matter-field interaction Hamiltonian (I)

    7. 7 The matter-field interaction Hamiltonian (II)

    8. 8 Differences in quantum structures case

    9. 9 Form of wavefunctions for "non-excitonic“ quantum well absorption (quantum well) Start by neglecting any excitonic effects (and other Coulomb effects – many particle effects) Treat the initial state as being some electron state corresponding to an electron in the valence band or some lower subband Treat the final state as an electron in the conduction band or a higher subband

    10. 10 Wavefunctions of initial and final states

    11. 11 Normalization of quantum well wavefunctions

    12. 12 Subbands and densities of states

    13. 13 Subbands

    14. 14 Density of states in a subband

    15. 15 DOS in Q.W. case

    16. 16 DOS in Q.W. case (II)

    17. 17 Special case of "infinite“ Q.W. density of states

    18. 18 Comparison of bulk DOS with Q.W. DOS

    19. 19 Optical absorption

    20. 20 Optical matrix elemen

    21. 21 Interband optical absorption

    22. 22 Interband optical absorption (II)

    23. 23 Calculation of interband optical absorption

    24. 24 2D "joint"density of states in energy

    25. 25 Selection rules

    26. 26 Interband and Intersubband Absorption

    27. 27 Intersubband optical transition

    28. 28 Polarization selection rules

    29. 29 Experimental geometry

    30. 30 Energy lost

    31. 31 The absorption coefficient

    32. 32 Orders of magnitude

    33. 33 Justification of separation of wavefunction

    34. 34 Separation of wavefunction

    35. 35 Envelope functions

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