Nonlinear optical processes in a polydiacetylene measured with femtosecond duration laser pulses
TL;DR: In this article, the temporal response of the third-order nonlinear optical susceptibility in poly bis(toluene sulfonate) of 2,4•hexadiyne•1,6 diol was determined by time-resolved degenerate four-wave mixing using tunable dye laser pulses with 300 fs duration.
Abstract: The temporal response of the third‐order nonlinear optical susceptibility in poly bis( p‐toluene sulfonate) of 2,4‐hexadiyne‐1,6 diol was determined by time‐resolved degenerate four‐wave mixing using tunable dye laser pulses with 300 fs duration. In the material’s absorption region these experiments were combined with saturated absorption techniques yielding a measurement for the excited state lifetime of 1.8 ps. Off resonance the nonlinear response was determined to be optical pulse width limited.
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TL;DR: The current status of organic low-molecular weight and polymeric materials for third-order nonlinear optics is reviewed in this paper, where the importance of organic materials lies in their promise of large nonlinear optical figure of merit, high optical damage thresholds, ultrafast optical responses, architectural flexibility, and ease of fabrication.
Abstract: The current status of organic low-molecular weight and polymeric materials for third-order nonlinear optics is reviewed. The importance of organic materials lies in their promise of large nonlinear optical figure of merit, high optical damage thresholds, ultrafast optical responses, architectural flexibility, and ease of fabrication. Organic materials exhibiting interesting third-order nonlinear optical properties are discussed to illustrate the importance of structure–property correlations. Results on emerging organic materials that include liquids, dyes, fullerenes, charge-transfer complexes, π-conjugated polymers, dye-grafted polymers, organometallic compounds, composites, and liquid crystals are presented. Organic nonlinear optical materials seem promising for a wide range of applications and their potential for integrated optics should be further explored.
413 citations
TL;DR: In this paper, the authors investigated the relaxation dynamics of photoexcitations in cast films of polydiacetylenes, poly[4,6-decadiyne-1,10-diol bis([(n-butoxycarbonyl)methyl]urethane)] (PDA-3BCMU) and poly[5,7-dodecadiyn- 1,12-diox bis([n- butoxycarbonyl)methyl)urethANE)] (pDA-4BCMU), and in electrochemically prepared
Abstract: The relaxation dynamics of photoexcitations in cast films of the polydiacetylenes, poly[4,6-decadiyne-1,10-diol bis([(n-butoxycarbonyl)methyl]urethane)] (PDA-3BCMU) and poly[5,7-dodecadiyne-1,12-diol bis([n-butoxycarbonyl)methyl]urethane)] (PDA-4BCMU), and in electrochemically prepared films of poly(3-methylthiophene) (P3MT) were investigated by femtosecond absorption and picosecond luminescence spectroscopies. 1Bu free excitons, generated by 100-fsec pump pulses, relaxed to the self-trapped (ST) state with time constants of 150 ± 50 fsec in PDA-3BCMU and 70 ± 50 fsec in P3MT. The difference was explained in terms of the relative sizes of the side chains. PDA-3BCMU has bulky side chains that are linked by hydrogen bonds, while P3MT has a repeating unit that contains a ring structure with a small methyl group. The lifetimes of the ST excitons at 10 K (290 K) were 2.0 ± 0.1 (1.5 ± 0.1) psec in PDA-3BCMU, 3.0 ± 0.3 (2.1 ± 0.2) psec in PDA-4BCMU, and 800 ± 100 (800 ± 100) fsec in P3MT. The decay kinetics of the ST exciton were explained by potential crossing and tunneling between two potential curves of the ST exciton and the ground state. The weak temperature dependence indicates that the activation process over the potential barrier between the ST exciton and the ground state is not dominant in the radiationless relaxation of the ST exciton. The relaxation dynamics of fluorescence from the PDA-4BCMU film cannot be represented by a single exponential decay; however, it can be described in terms of a random walk in the fractal dimension. By applying the fractal-dimension model, the spectral dimension was determined to be between 0.50 and 0.85. The spectral changes that are due to several nonlinear-optical processes, i.e., hole burning, Raman gain, and the dynamic Stark effect, were also observed in femtosecond-resolved spectra. The third-order susceptibility was determined for these nonlinear processes, such as absorption saturation at the exciton transition, Raman gain, and the resonant Kerr effect from the observed spectral change. The third-order susceptibility that corresponds to absorption saturation in PDA-3BCMU and in P3MT was obtained as Im[χ1111(3)(−ω;ω,ω,−ω)] equal to −2.6 × 10−9 and −3.5 × 10−10 esu, respectively, for ħω = 1.97 eV. The third-order susceptibility that corresponds to the Raman gain in PDA-3BCMU and in P3MT was determined to be Im[χ1111(3)(−ω2;ω2,ω1,−ω1)] equal to 5.8 × 10−10 and −1.5 × 10−10 esu, respectively, for ħω1 = 1.97 eV and ħω2 = 1.79 eV. From the resonant Kerr experiment in the P3MT film, |Δχ(3)|≡|χ1111(3)(−ω2;ω2,ω1,−ω1)−χ1122(3)(−ω2;ω2,ω1,−ω1)|=3.9×10−11 esu was determined for ħω1 = 1.97 eV and ħω2 = 1.88 eV.
176 citations
TL;DR: In this article, the authors used deegenerate four-wave mixing measurements, using 45 ps pulses at 1064 nm, to determine the magnitude of the third-order optical susceptibility tensor for thin films of a conjugated porphyrin polymer.
Abstract: Degenerate four-wave mixing measurements, using 45 ps pulses at 1064 nm, have been used to determine the magnitude of the third-order optical susceptibility tensor for thin films of a conjugated porphyrin polymer. The time dependence of the signals indicates that the dominant response is fast relative to the duration of the optical pulses. It is shown that a response on this time scale cannot be consistent with a mechanism in which resonant absorption is significant, and therefore that the primary component of the susceptibility must correspond to an instantaneous electronic polarization. The microscopic polarizability per macrocycle of the polymer is approximately 3 orders of magnitude greater than that of the monomera result that indicates the role of inter-macrocycle conjugation in the nonlinearity. This appears to be the largest one-photon−off-resonance third-order optical susceptibility reported for any organic material.
112 citations
TL;DR: In this article, a diacetylene compound (PDATAZ) was designed and synthesized, which readily formed a complementary hydrogen bonding self-assembly at the air−water interface or in the solid state with barbituric acid (BA) or cyanuric acids (CA), and revealed some important insights on the chromatic properties of polydiacetylenes.
Abstract: In the present study, a new diacetylene compound (PDATAZ), which readily forms a complementary hydrogen bonding self-assembly at the air−water interface or in the solid state with barbituric acid (BA) or cyanuric acid (CA), was designed and synthesized. The photopolymerization studies of PDATAZ and its assembly with BA or CA have revealed some important insights on the chromatic properties of polydiacetylenes. It was found that the chromatic property of polydiacetylenes is determined by whether the polymer chain is capable of adopting a linear chainlike shape. With the continuous increase of the length of the polymer chain, the original linear polyenyne backbone starts to “self-fold” to a “zigzag” structure due to the free rotation of single bonds within the polymer chain. The efficient π-electron delocalization along the polyenyne backbone is interrupted by this process, leading to a chromatic change from the blue to red form of polydiacetylenes. If there are strong intermolecular interactions existing b...
109 citations
TL;DR: A unified picture of nonlinear optical phenomena in both classes of materials is presented and the specific implications for organic-based optical devices are discussed.
Abstract: Recognition that organic solids possess some of the largest all-optical nonlinearities of all known materials has resulted in an interdisciplinary effort directed at both the basic understanding and exploitation of these effects. Parallel efforts on ionrganic semiconductors have already reached a mature stage whereby the origin of the effects, together with the prospects for device applications, are well known and appreciated. In this article, a unified picture of nonlinear optical phenomena in both classes of materials is presented. The specific implications for organic-based optical devices are discussed.
102 citations
References
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29 Sep 1983
762 citations
TL;DR: In this article, a transient three-pulse scattering technique for measuring ultrafast dephasing times in condensed matter is analyzed using a perturbative solution of the density matrix equation.
Abstract: A novel transient three-pulse scattering technique for measuring ultrafast dephasing times in condensed matter is analyzed using a perturbative solution of the density matrix equation. The advantages of this technique include subpulsewidth resolution, a clear distinction between homogeneous and inhomogeneous broadening, and sensitivity to spectral cross-relaxation. Its application to the case of a multilevel resonance is also considered. We report results of femtosecond dephasing experiments with dye molecules in liquids and in a polymer host. The dephasing time is determined to be less than 20 fsec for dyes in solution at room temperature. At low temperatures in polymers, a transition from homogeneous to inhomogeneous broadening has been observed and studied as a function of temperature.
242 citations
TL;DR: In this paper, a new ultrafast optical waveguide gate based on a nonlinear optical interaction in a waveguide interferometer is presented. Butler et al. used a modified Mach-Zehnder Interferometer, 2 cm long, fabricated in a LiNbO 3 substrate.
Abstract: We present a new ultrafast optical waveguide gate based on a nonlinear optical interaction in a waveguide interferometer. A train of signal pulses is gated by control pulses which change the refractive index in only one arm of the interferometer. The principle of operation is demonstrated using a modified Mach-Zehnder interferometer, 2 cm long, fabricated in a LiNbO 3 substrate. The experiments were performed with a near-infrared dye laser which produced 5 ps pulses at \lambda = 840 nm. A maximum modulation on the order of 10-3was obtained for a peak control power of 2 W. Experimentally, we determined the appropriate nonlinear coefficient of LiNbO 3 to be n_{2} = 3 \times 10^{-9} (MW/cm2)-1. As possible applications of the structure we describe an all-optical inverter, an XOR gate, and an AND gate. We conclude with a brief description of a random number generator encoder and decoder based on a few all-optical logic gates.
170 citations
TL;DR: In this article, the spectral and temporal dependence of the material's third order nonlinear optical susceptibility χ(3) was measured for the wavelength range from 9×10−9 esu at 6515 A to 5× 10−10 esu in 7015 A.
Abstract: Degenerate four‐wave mixing of tunable dye laser pulses in good optical quality single crystal platelets of poly bis(p‐toluene sulfonate) of 2, 4‐hexadiyne‐1, 6 diol (PTS) polydiacetylene was used to measure the spectral and temporal dependence of the material’s third order nonlinear optical susceptibility χ(3). For the wavelength range measured ‖χ(3)‖ varied from 9×10−9 esu at 6515 A to 5×10−10 esu at 7015 A. The material’s response time was determined to be less than the optical pulse width (≂6 ps) over this wavelength range.
169 citations