We study theoretically the conditions under which optical bistability is achievable in a two-subband system in a semiconductor quantum well. We consider the interaction of the two-subband system with a continuous wave electromagnetic field, which induces intersubband transitions. For the description of the system dynamics we use the effective nonlinear density matrix equations. We solve these equations analytically, in the steady state, for a GaAs/AlGaAs quantum well structure. For several combinations of the values of the parameters three real solutions of the population inversion arise and the phenomenon of optical bistability prevails.

In our discussion of electronic parameters for charge (hole or electron) transfer along DNA we have omitted to mention that, regarding the tight-binding description of hole transport, the corresponding tight-binding parameters should be taken with the opposite sign of the calculated on-site energies and transfer hopping integrals. This means that for describing hole transport at the base-pair level, the on-site energies EbpH presented in the second row of table 2 and the hopping transfer integrals tbpH presented in the second column of table 3 should be used with opposite signs in order to provide the tight-binding parameters of eq. (10). Similarly, for describing hole transport at the single-base level, the on-site energies EbH presented in the eleventh row of table 1 and the hopping transfer integrals tbH presentedin the second column of tables 4–7 should be used with opposite signs in order to provide the tight-binding parameters of eq. (13). Moreover, on p. 300, 8 lines below eq. (14), in the calculation of charge transfer hopping parameters the separation between adjacent base-pairs in B-DNA should read 3.4 ̊A, instead of 3.14 ̊A.

Recent years have witnessed tremendous research in quantum dots as excellent models of quantum physics at the nanoscale and as excellent candidates for various applications based on their optoelectronic properties. This review intends to present theoretical and experimental investigations of the near-field optical properties of these structures, and their multimodal applications such as biosensors, biological labels, optical fibers, switches and sensors, visual displays, photovoltaic devices and related patents.