Читать книгу VCSEL Industry - Babu Dayal Padullaparthi - Страница 22

Present semiconductor lasers utilize quantum wells (QWs) as shown in Figure 1.5 for the light emitting and amplification layer for almost all semiconductor lasers and LEDs. The QW [15] has a thickness of several nanometers (1 nm = 10^–9 m). Grain‐shaped quantum dots [16, 17] that have a several‐nanometer box size can be used to further reduce the threshold current in semiconductor lasers. The optical gain necessary for lasing using multiple quantum wells (MQWs) is further explained in Chapter 2.

Figure 1.5 Quantum well structure with separate optical confinement. (a) The carrier densities of electron and holes in a quantum well structure. (b) The quantum well laser where the optical field is confined by the double heterostructure.

Source:[8]. [Image Courtesy of Genichi Hatakoshi.]