Near-Infrared Quantum Cascade Lasers Designed with van der Waals Materials

Abstract

Quantum cascade lasers (QCLs) constitute a leading source of coherent radiation in the mid-IR region. However, their performance outside this region remains unsatisfactory. Indeed, there are currently no QCLs in the near-IR region. Here, we propose that a superlattice of atomically thin layers held together by van der Waals forces may operate near room temperature as a compact and powerful near-IR QCL emitting at a wavelength of $1.66\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$. It can compress over 100 stages within $0.5\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$. The electric field required for operation is about $3\ifmmode\times\else\texttimes\fi{}{10}^{6}\phantom{\rule{0.2em}{0ex}}{\mathrm{V~cm}}^{\ensuremath{-}1}$, while the lasing threshold current density is about $22.4\phantom{\rule{0.2em}{0ex}}{\mathrm{kA~cm}}^{\ensuremath{-}2}$ depending on parameters. Rate-equation analysis reveals that the peak power per unit volume can reach over $0.1\phantom{\rule{0.2em}{0ex}}\mathrm{mW}\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}{\mathrm{m}}^{\ensuremath{-}3}$ in cw operation. Unlike existing QCLs, our device is $p$-type working with holes.