An insight into polarization states of solid-state organic lasers

TL;DR

This paper investigates the polarization states of solid-state organic lasers, exploring how resonator shape and excitation methods influence polarization, revealing a polarization flip in kite-shaped micro-lasers and methods to tailor polarization.

Contribution

It provides new insights into how resonator geometry and excitation strategies affect polarization states in solid-state organic lasers, including polarization flipping and control methods.

Findings

Kite-shaped micro-lasers exhibit TM polarization dominance.

Resonant energy transfer and higher excited state pumping reduce polarization degree.

Different resonator geometries influence the polarization characteristics.

Abstract

The polarization states of lasers are crucial issues both for practical applications and fundamental research. In general, they depend in a combined manner on the properties of the gain material and on the structure of the electromagnetic modes. In this paper, we address this issue in the case of solid-state organic lasers, a technology which enables to vary independently gain and mode properties. Different kinds of resonators are investigated: in-plane micro-resonators with Fabry-Perot, square, pentagon, stadium, disk, and kite shapes, and external vertical resonators. The degree of polarization P is measured in each case. It is shown that although TE modes prevail generally (P>0), kite-shaped micro-laser generates negative values for P, i.e. a flip of the dominant polarization which becomes mostly TM polarized. We at last investigated two degrees of freedom that are available to tailor the polarization of organic lasers, in addition to the pump polarization and the resonator geometry: upon using resonant energy transfer (RET) or upon pumping the laser dye to an higher excited state. We then demonstrate that significantly lower P factors can be obtained.