We have fabricated and characterized polymeric slab asymmetric waveguides doped with a near-infrared-emitting dye, 2-(6-(p-dimethylaminophenyl)-2,4-neopentylene-1,3,5-hexatrienyl)-3-ethylbenzothiazolium perchlorate. Upon nanosecond photopumping, the waveguides have shown a small-signal gain coefficient of 37.2 ± 2.1 cm-1 at 820 nm for a pump fluence of 1.57 mJ/cm2 (314 kW/cm2). The loss coefficient and transparency fluence have been found to be 7.3 ± 1.0 cm-1 at 820 nm and 0.14 mJ/cm2 (28 kW/cm2), respectively. It is shown that a small-signal gain of 19.7 ± 2.3 dB is achievable in a 1.2-mm-long waveguide. Furthermore, near-infrared laser emission from self-assembled luminescent polymer microcavities has been demonstrated. The microrings are formed around silica optical fibers of varying diameters (80, 125, and 200 μm) and the larger microresonators have an overall quality factor of ~2 × 103, which is limited by surface roughness and scattering. We illustrate how the laser threshold varies inversely with both the quality factor and the inner diameter of the microrings. The free spectral range and the intensity variation of the laser output are also presented.
We demonstrate laser emission in polymer-based microrings doped with a near infrared emitting dye, 2-(6-(4-Dimethylaminophenyl)-2,4-neopentylene-1,3,5-hexatrienyl)-3-methyl-benzothiazolium perchlorat. We fabricate our poly(1-vinyl-2-pyrrolidone)-based microrings containing 0.5 wt % of the dye. They exhibit lasing at around 840 nm under transverse nanosecond photoexcitation at 532 nm. Optical feedback is provided by total internal reflection. The threshold for lasing is found to be 311 μJ/cm2. The cavity has a Q-factor larger than 2000, which is limited by the resolution of our detection system.
We study light amplification and laser emission in polymer gain media containing a near-infrared emitting dye, 2-(6-(4-dimethylaminophenyl)-2,4-neopentylene-1,3,5-hexatrienyl)-3-methyl-benzothiazolium perchlorat, with a view to the development of polymer amplifiers and lasers operating in the 800-nm region of the spectrum. Nanosecond gain spectroscopy is carried out by use of amplified spontaneous emission. Multimoded poly(1-vinyl-2-pyrrolidone)-base planar waveguides, 50 μm in thickness, doped with 0.5 wt% dye show a moderate net small-signal gain coefficient of 2.6±0.3 cm-1 (11.3±1.3 dB/cm) at 820 nm for the pump fluence of 115 μJ/cm2 (23.1 kW/cm2). Moreover, we have fabricated polymer microring cavities 200 μm in diameter with the same material composition. The moderate optical gain in the material allows laser emission to occur at around 840 nm under transverse nanosecond photoexcitation at 532 nm. The threshold for lasing is found to be 311 μJ/cm2 (62.2 kW/cm2).
We present the results of a study of the optical properties of an organic dye, (1,4-Bis[2-[4-[N,N-di(p-tolyl)amino]phenyl]vinyl]benzene)-doped polymer for photonic device applications. We have measured considerable modal gains of up to 33 cm-1 at 501 nm at a range of pump fluences using the variable stripe length method. In addition, we have incorporated the material into a planar waveguide laser, which operates at a low-lasing threshold. The measured laser threshold agrees well with that predicted for a 1-cm Fabry-Perot type cavity. We have also made 80-micron diameter microrings, which operate at a low lasing threshold and exhibit lasing in a small number of narrow, well-defined cavity modes.
We have successfully incorporated a near-infrared-emitting compound, 2-(6-(4-Dimethylaminophenyl)-2,4-neopentylene-1,3,5-hexatrienyl)-3-methyl-benzothiazolium Perchlorat, into poly(1-vinyl-2-pyrrolidone)-base planar waveguides. The variable-stripe-length method is employed to deduce the net gain coefficient of the waveguides, 1 cm in length, doped with 0.5 wt.% of the compound. The gain spectroscopy has revealed a moderate net modal gain of 2.6 cm-1 at 820 nm for the pump fluence of 22.6 μJ/cm2 (3.8 kW/cm2). The waveguides have exhibited lasing at 820 nm when they are transversely photoexcited at 532 nm with a nanosecond Nd: YAG laser. The Fresnel reflection at the polymer-air interfaces acts as a low-finesse Fabry-Perot cavity. The threshold for lasing has been found to be 24.5 μJ/cm2 (4.1 kW/cm2).
We report on two-photon pumped frequency upconverted emission in doped PMMA fibers. The PMMA fibers were doped with a novel organic chromophore 1,4-bis(4-diphenylamino-styryl)-benzene (referred to as SP35) which is designed specifically to emit in the blue spectral region. Strong upconverted blue emission was observed in the fibers when longitudinally pumped at 800nm with a Titanium Sapphire laser. We measured a large two-photon absorption cross section for SP35 of 7.8 x 10-19cm4/GW using the non-linear transmission method. Our study shows that a well designed organic chromophore in combination with a suitable fiber geometry makes this system appealing for the development of an upconversion blue laser source.
We report on a large optical gain, over the wide spectral range, and lasing in a glass-clad polymer optical fiber that uses a novel highly fluorescent stilbenoid compound, 1,4-bis(4-diphenylamino-styryl)-benzene. The compound has a high quantum yield of 0.85 in polystyrene and a large Stokes shift of about 80 nm. A fiber doped with 0.2-wt. % of the compound is photoexcited with a thin striped shape area at 355 nm with nanosecond optical pulses, and the emission from one end is monitored as a function of the excitation length to deduce the net gain coefficient. The gain spectroscopy has revealed a broad optical gain exceeding 25 cm-1 and up to 36 cm-1 at 494 nm that covers a spectral range of about 70 nm when the fiber is transversely photoexcited at 12 mJ/cm2. The large gain has been utilized to demonstrate blue laser emission at 489 nm from the fiber (which is only 1.4 cm in length) in a low finesse cavity defined by the Fresnel reflections at the fiber-air interfaces. The threshold for lasing is found to be 1.7 mJ/cm2.
We report our investigation of light amplification and lasing in a glass-clad step-index polymer optical fiber that uses a novel blue-emitting stilbenoid compound. The compound, 1,4-bis(4-diphenylamino-styryl)-benzene, is designed and synthesized specifically for the blue region of the spectrum and has a high quantum yield of 0.85 in polystyrene and a relatively large Stokes shift of ~50 nm. The variable stripe length method is employed to deduce the net gain coefficient of a fiber doped with 0.2-wt. % of the compound. The gain spectroscopy has revealed a broad optical gain exceeding 25 cm-1 and up to 36 cm-1 at 494 nm that covers a wide spectral range of about 70 nm when the fiber is transversely photoexcited at 12 mJ/cm2. An analysis shows that the saturation effect expected for homogeneously broadened gain accounts for the amplified spontaneous emission output behavior at longer excitation lengths. The linear waveguide loss is measured to be 0.7 cm-1 at 494 nm. The large gain and the low waveguide loss have allowed the unequivocal demonstration of blue laser emission at 489 nm from the fiber (which is only 1.4 cm in length) in a very low finesse cavity defined by the Fresnel reflections at the fiber-air interfaces. The threshold for lasing is found to be 1.7 mJ/cm2. The results presented here will open the door to the study and development of very compact polymer fiber lasers and amplifiers.