There have been two major problems in the fabrication of fast optical non-linear devices based on quantum dots embedded in glasses [1]. One is the geometry non-homogeneity of dot size, which broadens the narrow transition lines. Thus no sharp resonant was obtained experimentally, as expected theoretically. The other is non-ideal growth of microcrystallites with the presence of trap-related transitions which slow down the response time of the device [2-4]. The origin of traps in semiconductordoped glasses (SDG) has been ascribed to surface states, lattice or surface defects, compositional fluctuations, foreign atoms or vacancies [5-13]. This is generally difficult to clarify, because the presence of traps depends strongly on the glass matrix and preparation conditions. Recently, several studies have revealed a correlation between the presence of traps and the fabrication conditions of colloids and SDG [14-16]. Resch et al. [14] have shown in ZnTe-CdTe co-colloids that excess Cd 2÷ is responsible for the lower energy broad peak at about 700 nm. They also measured the corresponding decay time as 20 ns. Ramsden et al. [15] have observed in the CdS colloid that the lower energy band in luminescence increased with excess amount of Cd 2+ and decreased with additional S 2-. Okamoto et al. [16] tried eliminating the deep trap centres caused by an excess amount of Cd 2÷ in CdS-doped glasses by incorporating excess sulfur. These results suggest that the appearance of traps is caused intrinsically by the relative amount of semiconductor elements in the glasses.