Direct Writing of Polymer Lasers Using Interference Ablation

Abstract

Optically pumped polymer lasers [1][2][3][4][5][6][7][8] achieved in a simple and effi cient way not only introduce new laser designs and laser sources, but also lay excellent physical and technical bases for the realization of electrically pumped organic lasers. As the most promising solution for polymer lasers, the distributed feedback (DFB) geometry has been investigated extensively. [9][10][11][12] A variety of fabrication schemes have been demonstrated to construct the DFB cavities, such as UV embossing, [ 12 ] nanoimprint lithography, [13][14][15] photolithography, [ 16 ] soft lithography, [ 17 ] liquid imprinting, [ 18 ] micromolding, [ 19 ] electron beam lithography, [20][21][22] reactive ion etching, [ 22 , 23 ] and reactive electronbeam deposition. [ 24 ] However, a simple and low-cost technique that enables highly reproducible mass fabrication is required for the easy realization and more profound investigation of the polymer lasers based on the DFB confi guration.In this work a direct-writing technique is reported that achieves large-area 1D and 2D DFB polymer lasers. The polymer thin fi lm is exposed to a single-shot illumination of the interference pattern of one UV laser pulse at 266 nm. Thus, the DFB structures consisting of periodically distributed polymer nanowires (1D case) or square lattices of polymer nanoislands (2D case) with a period of about 350 nm are easily produced, which support low-threshold lasing in the green region of the visible spectrum. Different 1D and 2D photonic structures can be written with periodic, quasi-periodic, and even aperiodic patterns, generating various designs of the photonic structures and laser devices. Herein, the direct writing and the lasing behaviors of the 1D grating and 2D square lattices of polymeric semiconductors are demonstrated.A typical light-emitting conjugated polymer, poly[(9,9-dioctylfl uorenyl-2,7-diyl)-alt-co -(1,4-benzo-{2,1 ′ ,3}-thiadiazole)] (ADS133YE, from American Dye Source, Inc.), is employed as the active material, which produces green light under excitation by a blue or UV laser. During fabrication, a solution of 15 mg mL − 1 ADS133YE in chloroform is spin-coated onto a fused silica glass substrate (15 mm × 15 mm × 1 mm), producing a thin, solid fi lm with a thickness of 100-200 nm, depending on the speed of spin-coating. Then, the thin-fi lm sample is exposed to the interference pattern of a UV laser pulse for about 6 ns, which corresponds to the pulse length of the UV laser. This induces ablation of the polymer at the bright interference fringes, resulting in the structure used for the 1D polymer lasers. For the fabrication of the 2D structures, we simply rotate the sample and perform a second exposure process, with further exposures performed as required. In this work, the square lattice structures are realized by double exposure with the sample rotated once by 90 degrees. Figure 1 a,b show the molecular structure and the spectroscopic properties of ADS133YE, respectively. The blue curve in Figure 1 b shows that the absorption o...

Organic solid‐state integrated amplifiers and lasers

“…For organic hosts that are not UV photosensitive conventional optical photolithography in combination with reactive ion etching (RIE) is a potential patterning route [63,64]. Other micro-and nano-structuring methods employed include electron beam lithography [64][65][66][67][68] laser interference ablation [69,70], two-photon polymerization [71] and the pen-drawing technique [72]. In Figs.…”

Distributed feedback lasing in a metallic cavity

“…Periodic metallic cavities are typically integrated with an active waveguide to form the plasmonic lasers. [7][8][9][10][11][12] In particular, for distributed feedback (DFB) polymer lasers, [13][14][15][16][17] the quenching channel of the metallic cavity is a main hurdle to decrease the device threshold and to realize the electrically pumped polymer laser. [18][19][20] If the active layers are in full contact with the metallic structures, quenching of the excited state of the active material at the interface would occur.…”

Gain- and feedback-channel matching in lasers based on radiative-waveguide gratings

“…This requires vertical surface-emitting resonance mode and its overlap with the peak of the gain spectrum that is determined by the photoluminescence spectrum of the active medium and the structural parameters of the DFB cavity. Since the demonstration of a polymer laser, 1 great interests were attracted in designing various polymer lasers, [2][3][4][5] fabricating micro-and nano-structures, [6][7][8][9] and investigating related photophysical mechanisms. [10][11][12] However, the systematical relationship between the emission properties and the geometry of the distributed feedback (DFB) cavity, in particular, the interaction between the photonic resonance mode and DFB mechanisms, needs to be investigated quantitatively for optimized design of a laser device.…”