Quasi-continuous-wave operation of an organic thin-film distributed feedback laser

Rabe, Torsten; Gerlach, K.; Riedl, Thomas; Johannes, H.‐H.; Kowalsky, Wolfgang; Niederhofer, Jürgen; Gries, Wolfgang; Wang, J.; Weimann, Thomas; Hinze, P.; Galbrecht, Frank; Scherf, Ullrich

doi:10.1063/1.2337873

Cited by 52 publications

(46 citation statements)

References 20 publications

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“…To date, there have been so far only demonstrations of quasi-cw operation in DFB lasers based on a modified PFO derivative containing 12% of statistical 6,6-(2,2 0 -octyloxy-1,1 0 -binaphthalene) binaphthyl interchain spacer groups. When pumped at a very low duty cycle (<0.1%) with pulses of 400 μm duration these sources generated sequences of laser pulses with repetition rates up to 5 MHz [191,192]. Triplet "scavengers", which are routinely used to address the problem of triplet absorption in liquidstate dye lasers, have been tested as a possible solution to the same problem in conjugated polymers [193].…”

Section: Laser and Photonics Reviewsmentioning

confidence: 99%

Organic solid‐state integrated amplifiers and lasers

Grivas

Pollnau

2012

Laser & Photonics Reviews

209

202

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Solid-state organic amplifiers and lasers are attractive for hybrid integration due to their compatibility with different material platforms, straightforward processing, and possibility to optimize easily their optical and electronic properties by molecular engineering. Advances in the gain medium design and synthesis in combination with new resonator architectures led to tremendous improvements in temporal and spectral properties, lifetime stability, gains produced and operating threshold powers, which triggered interest in their use for a broad range of integrated photonic applications. In this contribution, the current state-of-the-art in the field of organic solid-state amplifiers and lasers is reviewed from the aspects of fabrication technology, gain materials, and device performance. Furthermore, examples of the progress of this technology from a laboratory curiosity to one that demonstrates practical integrated photonic applications are highlighted. An outlook is also provided on research areas and applications that are likely to shape further developments of this technology. (Figure reprinted from [296],

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Section: Laser and Photonics Reviewsmentioning

confidence: 99%

Organic solid‐state integrated amplifiers and lasers

Grivas

Pollnau

2012

Laser & Photonics Reviews

209

202

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“…Rabe et al demonstrated quasi-cw operation at a repetition rate of 5 MHz in a poly(9,9-dioctylfl uorene) derivative containing 6,6′-(2,2′-octyloxy-1,1′-binaphthalene)binaphthyl spacer groups of 12% (BN-PFO) without triplet quenchers. [ 9 ] This high repetition rate could be obtained because of the small spectral …”

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confidence: 99%

Quasi‐Continuous‐Wave Organic Thin‐Film Distributed Feedback Laser

Sandanayaka

Yoshida

Inoue

et al. 2016

Advanced Optical Materials

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wileyonlinelibrary.com COMMUNICATIONoverlap between emission and triplet absorption in BN-PFO. [ 10 ] Therefore, the development of organic laser dyes with less spectral overlap between the excited-state absorption and emission is crucial for the realization of cw and quasi-cw lasing with low threshold.In our group, we have continuously investigated the optical and amplifi ed spontaneous emission (ASE) characteristics of many organic materials with the aim of realizing electrically pumped organic laser diodes. [21][22][23][24][25][26][27] Among them, 4,4′-bis[( Ncarbazole)styryl]biphenyl (BSBCz) is one of the most promising candidates because a vacuum-deposited fi lm of the host material 4,4′-bis( N -carbazolyl)-1,1′-biphenyl (CBP) blended with 6 wt% BSBCz, the chemical structures of which are shown in Figure 1 a, possesses outstanding optical and ASE characteristics, such as a high photoluminescence quantum yield ( Φ PL ) of nearly 100% and short PL lifetime ( τ PL ) of about 1.0 ns, leading to a large radiative decay constant ( k r ) of about 10 9 s −1 and low ASE threshold energy of about 0.3 µJ cm −2 . [ 23,26 ] In this paper, we report quasi-cw surface-emitting lasing in a distributed feedback (DFB) device based on this BSBCz:CBP blend fi lm. In this laser device, we obtained the highest repetition rate (up to 8 MHz) and the lowest threshold (on the order of 0.25 µJ cm −2 ) ever reported for a quasi-cw laser based on organic thin-fi lm systems. The incorporation of triplet quenchers is not necessary in our blend fi lm because of its high Φ PL and no signifi cant spectral overlap between the emission and triplet absorption of BSBCz. [ 24 ] In a DFB structure, a laser oscillation takes place when the following Bragg condition is satisfi ed: mλ Bragg = 2 n eff Λ , where m is the order of diffraction, λ Bragg is the Bragg wavelength, n eff is the effective refractive index of the gain medium, and Λ is the period of the grating. [ 28,29 ] When considering a second-order mode ( m = 2), the grating period is calculated to be Λ = 280 nm using the reported n eff and λ Bragg for BSBCZ. [ 21,22 ] A grating with Λ = 280 nm provides surface-emitting lasing in a direction normal to the substrate plane as shown in Figure 1 b. Although a second-order grating typically leads to a higher lasing threshold compared to a fi rst-order grating, surface-emitting lasing using a second-order grating is suitable for the fabrication of electrically pumped organic laser diodes having an organic light-emitting diode structure showing the same surface emission. [ 30,31 ] Using electron beam lithography and reactive ion etching, such gratings were directly engraved onto silicon dioxide surfaces over a 5×5 mm 2 area. Figures 1 c,d shows scanning electron microscopy (SEM) images of a representative grating fabricated in this study. We obtained Λ = 280 ± 2 nm and a grating depth of d = 70 ± 5 nm from the SEM images, which are in perfect Since the discovery of organic solid-state lasers, [1][2][3][4][5][6] great efforts have been devoted to th...

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“…We consider both the case where stimulated emission is absent, mimicking the conditions observed in confocal scanning microscopy, 12 fluorescence lifetime imaging and organic light-emitting diodes (OLEDs), 13,22 as well as the case where it is present such as in dye lasers 23 or optically pumped organic semiconductor lasers (OSL). [24][25][26][27][28][29] In the latter, we find that although the short-time dynamics are left mostly unaffected, the achievable OSL repetition rate is increased by a factor Γ T . …”

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confidence: 99%

“…16, 45 In optically pumped organic semiconductor lasers (OSLs), the solid-state analog of dye lasers, triplets also limit CW and quasi-CW operation. [26][27] This can occur both through TTA and singlettriplet annihilation (STA). In the latter, energy is lost when a singlet transfers its excitation to a neighboring triplet, thus exciting it to a higher energy level, T n , which subsequently relaxes.…”

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confidence: 99%

Plasmonic Sinks for the Selective Removal of Long-Lived States

et al. 2011

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The use of plasmonic nanostructures for the removal of unwanted long-lived states is investigated. We show that the total decay rate of such a state can be increased by up to four orders of magnitude, as compared to its intrinsic radiative decay rate, while leaving other neighboring optical transitions unaffected. For the specific case of molecular triplet excited states, we show that the use of a "plasmonic sink" has the potential to reduce photobleaching and ground state depletion by at least two orders of magnitude. We consider, in addition, the impact of such structures on the performance of organic semiconductor lasers and show that, under realistic device conditions, plasmonic sinks have the capacity to increase the achievable laser repetition rate by a factor equal to the triplet decay rate enhancement. We conclude by studying the effect of exciton diffusion on the triplet density in the presence of metallic nanoparticles. KeywordsPlasmons, Sinks, Nanoshells, Purcell Effect, Quenching, Triplets, Organic Lasers, Photobleaching, Non-radiative decay Plasmonic nanoparticles and antennas have demonstrated significant potential for enhancing the luminescence of adjacent emitters. [1][2][3][4][5][6] The mechanisms for enhancement, however, can be varied and the origin of the increased brightness difficult to unravel. For example, the nanostructure can serve to increase the local electric field at the excitation wavelength resulting in an increased excitation rate, 7-9 or equivalently, absorption efficiency of the emitter. In addition, the scattering cross-section of the particle or radiation pattern of the antenna can lead to a higher collection or out-coupling efficiency for the emitted light. 2, 10 Finally, and most importantly for this work, the increased photonic density of states at the emission wavelength can result, via the Purcell effect, in an increased radiative decay rate, Γ R , for the emitter. [1][2][8][9][10] This effect, however, is typically concomitant with an unwanted and stronger increase in the non-radiative decay rate, Γ NR , due to Joule heating of the metal. [9][10] In the usual case where Γ NR >> Γ R , increases in quantum yield, φ F , are only possible for emitters with very low intrinsic yields 0 R NR φ < Γ Γ . 11 In this work, we show that instead of being detrimental, the high non-radiative decay rate typical of emitters in close proximity to plasmonic structures can be exploited to selectively remove unwanted excited states in a number of physical systems.In molecular systems, for example, the build-up of large triplet state populations prevents the efficient excitation of organic molecules with high repetition rates or continuous sources, 12-13 and can be a significant source of photobleaching. 14-17 Indeed,Hale et al. first proposed and demonstrated the possibility of using plasmonic nanoparticles to increase the photostability of organic thin films. 18 In a later section weshow that in that case, the effect fits into the "diffusive regime", which has several advantages, bu...

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Quasi-continuous-wave operation of an organic thin-film distributed feedback laser

Cited by 52 publications

References 20 publications

Organic solid‐state integrated amplifiers and lasers

Organic solid‐state integrated amplifiers and lasers

Quasi‐Continuous‐Wave Organic Thin‐Film Distributed Feedback Laser

Plasmonic Sinks for the Selective Removal of Long-Lived States

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