Tuning the lasing threshold of quantum well exciton-polaritons under a magnetic field in Faraday geometry: A theoretical study

Polariton lasing represents a promising pathway toward the development of ultralow-threshold lasers that operate without requiring population inversion. The application of a magnetic field to a quantum well (QW) microcavity can significantly modify exciton-polariton properties, offering a powerful means to control their condensation dynamics. In this work, we theoretically investigate how a perpendicular magnetic field (Faraday configuration) influences the lasing threshold of QW exciton-polaritons. By incorporating magnetic-field-induced modifications to the exciton effective mass and Rabi splitting, we reveal that the relaxation kinetics—and consequently, the lasing threshold—are strongly affected. Under low-wavenumber pumping, increasing the magnetic field raises the threshold, while under high-wavenumber pumping, the threshold is reached at much lower pump intensities. Moreover, a combined increase of pump energy and magnetic field significantly enhances relaxation efficiency, resulting in a substantially larger population of condensed polaritons. These findings provide valuable insights into the tunability of exciton-polariton condensation via external magnetic fields and offer guidance for the design of next-generation, low-threshold polariton lasers.