Organic solid-state ultraviolet-laser based on spiro-terphenyl

Abstract

We report on organic semiconductor lasers based on spiro-terphenyl as active gain medium in a second-order distributed feedback (DFB) structure. In contrast to neat p-terphenyl, the spiro-linked compound forms vitreous amorphous films—an essential prerequisite for low loss laser structures. Spiro-terphenyl shows amplified spontaneous emission in the ultraviolet part of the spectrum at 381 nm. Thin-film lasers with DFB grating periods between 200 and 230 nm exhibit emission wavelengths between 361.9 and 393.8 nm. The minimum threshold energy density under optical pumping is as low as 8.9μJ∕cm2 (383 nm). Therefore, the novel spiro-linked compound paves the way for low-threshold, widely tunable organic semiconductor lasers advancing into the ultraviolet spectral region.

The energy transfer mechanism of a photoexcited and electroluminescent organic hybrid thin film of blue, green, and red laser dyes

“…At present, stimulated emission behavior, including amplified spontaneous emission (ASE), is observed in organic lasing dyes [4][5][6][7][8][9][10], yet the stimulated emission is eventually hampered by the low-efficiency energy transfer mechanism and concomitant singlet-triplet annihilation, which prohibits a sustained population inversion [11,12]. In addition, the low efficiency problem caused by annihilation can be resolved by adding an auxiliary film-forming polymer to dilute the laser dye mixed solutions [13,14].…”

Lasers organiques accordables dans l'UV (309–322 nm)

“…Les colorants UV ayant des segments piconjugués à la fois courts et rigides pour garantir une émission efficace dans l'UV sont rares, et qui plus est l'excitation dans l'UV profond nécessaire pour le pompage optique conduit à une photodégradation extrêmement rapide qui empêche le plus souvent d'atteindre le seuil laser avant le seuil de dégradation. La plus basse longueur d'onde laser obtenue à ce jour directement à partir d'un matériau organique en couche mince est de 361 nm [9]. This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.…”

Optical amplification and stability of spiroquaterphenyl compounds and blends

“…Due to the large Stokes shift with reduced self-absorption and the low tendency towards crystallisation, they exhibit low thresholds for stimulated emission in thin films. First-order Distributed Feedback (DFB) lasers have been realized with these materials [4]- [6]. A recent major breakthrough in the field of organic lasers, albeit in other material systems, was the demonstration of pumping schemes using inexpensive inorganic diode lasers [7]- [9] which arises more interest for tunable UV emitter materials.…”

“…In this contribution we compare a series of novel spiroquaterphenyls for the suitability in distinct organic lasers. The compounds 2-5 ( Figure 1) differ from the first generation of spiro compounds [1]- [6] by π-electron donating ether groups at different positions that introduces flexibility which is needed for better processing from the melt and may reduce brittleness in films on flexible substrates. Depending on the position (para or meta), the π-electron system is enlarged, shifting the optical transitions bathochromically, or not.…”