Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 7

From quantum mechanics, the energy levels for electrons and holes in the quantum-well laser structure shown in Fig. 4.28 are given by
and
where E c and E v are the conduction and valence-band energies (see Fig. 4.1), d is the active layer thickness, h is Planck's constant, and m e and m h are the electron and hole masses as defined in Example 4.1. The possible energy-level transitions that lead to photon emission are given by
If E g = 1.43 eV for GaAs, what is the emission wavelength between the i = j = 1 states if the active layer thickness is d = 5 nm