Dense and Nanoporous Glasses as Host Matrices to Grow Quantum Dots for Optical and Photonic Applications.

Quantum dots (QDs) grown within inorganic glasses (hereafter referred to as "QD glasses") are promising candidates for an expanding list of applications such as nonlinear optical (NLO) devices. However, lots of research into NLO properties of QDs still uses polymer-based matrices, whose low laser damage threshold hinders practical applications. This can be explained by the difficulties typically encountered by researchers wishing to grow QDs within glass matrices. Fortunately, much progress has been made, not only as regards dense glass but also in the use of nanoporous (NP)  glass which is prepared and explored as a macro-matrix in the growth of QDs. In situ growth techniques for the preparation of QD glasses are more appealing than ex situ methods, as the former can effectively avoid agglomeration of the QDs and the need for application of prior treatments such as ligand exchange. Here, a review of advances in growth techniques of QDs in both dense and NP glasses is provided, with a discussion on the effect of glasses on the emission nature of the grown QDs, the routes to tune emission, enhancing optical performance and, finally, potential applications of QD glasses. The overview of directions and future challenges of this area are also presented.