A giant controllable gap in the optical spectrum of a semiconductor laser subject to intense feedback with rotated polarization

TL;DR

This paper demonstrates that intense optical feedback with polarization rotation can create a giant, tunable spectral gap in a semiconductor laser, explained by a carrier density grating model.

Contribution

It introduces a new method to control the spectral gap in semiconductor lasers using polarization rotation under intense feedback conditions.

Findings

Spectral gap exceeds one terahertz in width.

Gap position and size are tunable via feedback polarization angle.

Theoretical model based on carrier density grating explains the observations.

Abstract

A semiconductor laser subject to delayed optical feedback is investigated in the limit of extremely intense feedback power. In a range of feedback polarization rotation angles the emission spectra of the laser reveal a giant gap with width of more than a terahertz. The position of the gap and its width are shown to be regulated by means of feedback polarization rotation angle. We demonstrate that a theoretical approach, based on carrier density grating induced potential, explains our experimental results.