Over the past 15 yr or more, researchers have been trying to achieve gain for electromagnetic fields in the terahertz frequency region using biased semiconductor superlattices, but with little success. In this work, we employ our model of the excitonic states in biased GaAs/Al0.3Ga0.7As semiconductor superlattices to find the optimal structures for amplification of terahertz radiation. In particular, we determine the optimum well width, barrier width, and bias field for terahertz fields with frequencies ranging from 1 to 4 terahertz. We find that gain coefficients on the order of 40 cm−1 should be achievable over most of this frequency range.
References
The material parameters used in our simulations can be found in Ref. 34.
We set 10 Å as the lower limit for both layers because the envelope function approximation has reduced accuracy below that size.
Given the BSSL structure (w = 96 and b = 12 Å), there are a total of 121 data sets for different bias fields. Because the number is small, we did not apply the initial screening, but worked with all the data.
