Organic Lasers: Recent Developments on Materials, Device Geometries, and Fabrication Techniques

Abstract

Organic dyes have been used as gain medium for lasers since the 1960s, long before the advent of today's organic electronic devices. Organic gain materials are highly attractive for lasing due to their chemical tunability and large stimulated emission cross section. While the traditional dye laser has been largely replaced by solid-state lasers, a number of new and miniaturized organic lasers have emerged that hold great potential for lab-on-chip applications, biointegration, low-cost sensing and related areas, which benefit from the unique properties of organic gain materials. On the fundamental level, these include high exciton binding energy, low refractive index (compared to inorganic semiconductors), and ease of spectral and chemical tuning. On a technological level, mechanical flexibility and compatibility with simple processing techniques such as printing, roll-to-roll, self-assembly, and soft-lithography are most relevant. Here, the authors provide a comprehensive review of the developments in the field over the past decade, discussing recent advances in organic gain materials, which are today often based on solid-state organic semiconductors, as well as optical feedback structures, and device fabrication. Recent efforts toward continuous wave operation and electrical pumping of solid-state organic lasers are reviewed, and new device concepts and emerging applications are summarized.

Manipulation of the electroluminescence of organic light-emitting diodes via fringe fields from patterned magnetic domains

“…Should the emission become sufficiently fast, efficient fluorescence opens a pathway for improved organic lasers. 29 Another mechanism that we expect to yield magneticfield effects up to 300% is anisotropic g-factor spin mixing. Up to this point, the g tensor has been assumed to be isotropic, which leads to only S $ T 0 spin mixing.…”

Two-dimensional distributed feedback lasers with thermally-nanoimprinted perylenediimide-containing films

“…Resonator fabrication by directly engraving the active film by NIL is a very attractive approach for the purpose of obtaining flexible devices prepared in a simple way, thus with high potential to be scalable to mass production. A limitation shown by the organic DFB lasers with imprinted active films reported to date, is their relatively large thresholds (typically various tenths of kW/cm 2 and higher) [3][4][5] in comparison to state-ofthe-art thresholds reported for DFB lasers based on highly efficient organic semiconductors and high quality resonators fabricated over inorganic substrates, often below 1 kW/cm 2 [1,2]. The generally high thresholds of devices with imprinted gratings are a consequence of the difficulty for many active materials to use thermal-NIL (T-NIL) (also called hot-embossing).…”

“…Solution-processed planar waveguide organic lasers are inexpensive, integrable and mechanically flexible optoelectronic devices, with great potential in a variety of applications in the fields of spectroscopy, optical communications and sensing [1,2]. The distributed feedback (DFB) laser, consisting of a waveguide film which includes a relief grating, is a particularly interesting organic waveguide laser for various reasons: it requires low pump energy for operation, thus enabling pumping with compact and cheap sources; the resonator can be easily integrated into other devices; it can be mechanically flexible; has a potentially low production cost; and can be easily integrated with field-effect-transistor geometry, promising for the development of electrically-pumped organic lasers.…”

“…In most organic DFB lasers reported, the resonators have been fabricated over common inorganic transparent substrates (glass, SiO 2 , etc..), by means of electron beam lithography (EBL), holographic lithography (HL), or nanoimprint lithography (NIL), followed by chemical or dry etching [1,2]. Resonator fabrication by directly engraving the active film by NIL is a very attractive approach for the purpose of obtaining flexible devices prepared in a simple way, thus with high potential to be scalable to mass production.…”

“…For 2D organic DFB lasers, as for 1D devices, the most common geometry consists in a surface-relief grating engraved on top of a substrate over which the organic active film is deposited [1,2,9]. There are few reports of 2D DFB lasers with gratings engraved on the active film by T-NIL [10][11][12].…”