# Spectral characteristics of a modified inverted-Y system beyond rotating wave approximation

## TL;DR

This paper investigates the spectral properties of a modified inverted-Y atomic system interacting with multiple fields beyond the rotating wave approximation, revealing complex spectral features useful for multi-channel optical communication.

## Contribution

It introduces a numerical matrix propagation method to analyze spectral characteristics beyond the rotating wave approximation in a complex multilevel atomic system.

## Key findings

- Spectral features show inter-conversion, splitting, and shifting of peaks.
- The study explains results using dressed and doubly dressed state formalism.
- Findings have applications in designing multi-channel optical communication devices.

## Abstract

The spectral properties of a multilevel atomic system interacting with multiple electromagnetic fields, a modified inverted-Y system, have been theoretically investigated. In this study, a numerical matrix propagation method has been employed to study the spectral characteristics beyond the validity regime of the rotating wave approximations. The studied atomic system, comprising of several basic sub-systems i.e. lambda, ladder, vee, N and inverted-Y, is useful to study the interdependence among these basic sub-systems. The key features of the obtained probe spectra as a function of coupling strength and detuning of the associated electromagnetic fields show inter-conversion, splitting and shifting of the transparency and absorption peaks. The dressed and doubly dressed state formalism have been utilized to explain the numerically obtained results. This study has application in design of novel optical devices capable of multi-channel optical communication along with switching.