Tunable giant nonlinear optical susceptibility in BaSnO3 quantum wells

Abstract

We investigate theoretically the giant nonlinear optical susceptibilities based on intersubband transitions in the $n$-type ${\mathrm{BaSnO}}_{3}$ quantum well heterostructures. Validity of the effective mass theory, used to compute susceptibility is demonstrated using first-principles calculations. We predict ${\ensuremath{\chi}}^{(2)}$ values up to 200 nm/V and ${\ensuremath{\chi}}^{(3)}$ values up to $8000\phantom{\rule{0.28em}{0ex}}\mathrm{n}{\mathrm{m}}^{2}/{\mathrm{V}}^{2}$, both over a much broader spectral range. ${\ensuremath{\chi}}^{(2)}$ is estimated from the THz region to the boundary with visible light, a range four times broader than current semiconductor quantum wells. This opens a possibility to make tunable nonlinear optical devices operating in the important range from THz to visible light.