# An Analysis of Diffracted Mode Outcoupling in the Context of Optical Gain Measurements of Organic Thin Films: A Diffracted Emission Profile Method

## TL;DR

This paper introduces a new method for measuring optical gain in organic thin films using diffracted emission profiles.

## Contribution

The paper presents the Diffracted Emission Profile (DEP) method as an extension of the scattered emission profile technique.

## Key findings

- The DEP method uses a one-dimensional grating to partially decouple waveguide modes for measuring optical gain.
- The method transfers the waveguide mode's growth and decay to the transverse mode profile of the diffracted mode.
- The approach is applied to determine the amplification signature of an organic copolymer.

## Abstract

The sustained interest in efficient, low-cost, and straightforward-to-manufacture lasers has prompted intense research into organic semiconductor laser emitter materials in recent decades. The main focus of this research is determining the optical gains and losses of amplified spontaneous emission (ASE) in order to describe materials by their amplification signature. A method that has been used for decades as the standard technique for determining gain characteristics is the variable-stripe-length (VSL) method. The success of the VSL method has led to the development of further measurement techniques. These techniques provide a detailed insight into the nature of optical amplification. One such method is the scattered emission profile (SEP) method. In this study, we present an extension of the SEP method, the Diffracted Emission Profile (DEP) method. The DEP method is based on the detection of ASE by partial decoupling of waveguide modes diffracted by a one-dimensional grating integrated into a planar waveguide. Diffraction causes a proportion of the intensity to exit the waveguide, transferring the growth and decay process of the waveguide mode to the transverse mode profile of the diffracted mode. In the present article, an approach to determine the amplification signature of an organic copolymer is presented, utilizing partial decoupled radiation.