Control of emission diffraction angles and laser threshold in mixed-order sampled distributed feedback laser with organic gain media

Abstract

The control of laser emission angles in laser devices is essential for many optoelectronic and photonic applications such as optical sensing and displays. In this context, we studied the light diffraction pattern of laser beams in a one-dimensional sampled distributed feedback resonator having organic gain media. The gratings consist of the repetition of supercells having a mixed-order sampled grating in which 1st-order gratings surround a 2nd-order grating. The experimental results showed that the diffraction angles of the laser beams are quite diverse depending on the supercell structures. We demonstrate that the interval of the diffraction angle (θ) of the laser beams is inversely proportional to the length of the supercell experimentally and theoretically. By tuning the length of supercells as well as the length of 1st-order and 2nd-order regions, the interval θ was tuned from 0.1° to 43° with the different arc emission patterns. With the reduction of θ, i.e., the longer 1st-order region, a significant decrease in the laser threshold was obtained, resulting in the lowest lasing threshold of 2.5 ± 0.1 μJ/cm2 with ∼3.5 ns of a long pulse width excitation source.

Scattered Emission Profile Technique for Accurate and Fast Assessment of Optical Gain in Thin Film Lasing Materials

“…Thin-film materials such as metal halide perovskites and colloidal quantum dots have garnered a lot of research interest as active media for lasers. − Over the past decades there have been numerous demonstrations of optically pumped lasing from these materials. − Simultaneously, there have also been several developments toward pushing high current densities into light-emitting diodes (LEDs), with the goal of achieving injection lasing. − Indeed, such thin-film injection lasers, when achieved, would eliminate a number of shortcomings of today’s heterointegrated lasers on chips, by enabling cost-effective processing, ease of manufacturing, and lattice-independent substrate compatibility. They can also allow to envisage new concepts, such as flexible lasers. , …”