# Optically induced transparency in bosonic cascade lasers

## TL;DR

This paper demonstrates that bosonic cascade lasers can become transparent to resonant THz pulses under specific optical pumping conditions, revealing unique optical properties not present in fermionic cascades.

## Contribution

It introduces the phenomenon of optically induced transparency in bosonic cascade lasers and analyzes the conditions under which this occurs.

## Key findings

- Cascade becomes transparent to THz pulses at certain pump conditions
- Populations of intermediate levels change during pulse passage
- Fermionic cascade lasers do not exhibit these properties

## Abstract

Bosonic cascade lasers are terahertz (THz) lasers based on stimulated radiative transitions between bosonic condensates of excitons or exciton-polaritons confined in a trap. We study the interaction of an incoming THz pulse resonant in frequency with the transitions between neighboring energy levels of the cascade. We show that at certain optical pump conditions the cascade becomes transparent to the incident pulse: it neither absorbs nor amplifies it, in the mean field approximation. The populations of intermediate levels of the bosonic cascade change as the THz pulse passes, nevertheless. In comparison, a fermionic cascade laser does not reveal any of these properties.