Non‐Resonant z‐Scan Characterization of the Third‐Order Nonlinear Optical Properties of Conjugated Poly(thiophene azines)

Abstract

The nonlinear optical properties of a functionalized poly(thiophene azine), namely, poly(3,4-didodecylthiophene azine), PAZ, at the optical telecommunication wavelength of 1550 nm are investigated by means of the closed-aperture z-scan technique in both thin films and solutions. Values of chi((3))=(2.4+/-0.4)x10(-13) esu, n(2)=(4.0+/-0.7)x10(-15) cm(2) W(-1), and gamma=(4.5+/-0.7)x10(-34) esu are estimated for the third-order (Kerr) susceptibility, the intensity-dependent refractive index, and the molecular second hyperpolarizability of solution samples, respectively. A very small dependence on the polymer chain length is found. Markedly higher values of (4.4+/-1.1)x10(-11) esu, (6.6+/-1.0)x10(-13) cm(2) W(-1), and (5.0+/-0.8)x10(-33) esu are measured for the corresponding quantities in thick (up to 20 mum) polymer films cast on quartz plates. The enhancement of the NLO responses on going from solution to solid samples is attributed to a partially ordered structure and to the presence of interchain interactions leading to greater pi-electron delocalization in the cast polymer films. The results are compared with those previously obtained by using third-harmonic generation (THG), taking into account that those data were measured under conditions of three-photon resonance, whereas our z-scan measurements are fully off-resonance.

Application of Near‐IR Absorption Porphyrin Dyes Derived from Click Chemistry as Third‐Order Nonlinear Optical Materials

“…The Imχ (3) values of Por−Zn−TCNE and Por−Zn−TCNQ were 1.7×10 −14 esu and 3.6×10 −14 esu, while the nonlinear absorption coefficients β were 7.9×10 −13 m W −1 and −1.7×10 −13 , respectively. Comparing to other organic molecules measured by Z‐scan, the third‐order nonlinear values of our compounds were relatively good …”

Third-Order Nonlinear Optical Behavior of Novel Polythiophene Derivatives Functionalized with Disperse Red 19 Chromophore

“…THG technique has the advantage of measuring nonlinearities of pure electronic origin; however, very few examples are found in the literature on the use of this technique to measure (3) in PT. For instance, the technique was used in polythiophene azines, which exhibited a (3) value of 5.4 × 10 −11 esu at 1550 nm [42]. This value is larger than the one we observed for P1 and P2; however, it must be noticed that the wavelength of 1550 nm (5 ns pulses) induced three-photon resonant effect enhancement (the maximum absorption of polymer coincided with the THG wavelength).…”

“…(3) (−3 , , , ) measured through THG 2PA or by -scan Reference Poly(thiophene azines) 5.4 × 10 −11 esu at 1550 nm (5 ns pulses) [42] Polythiophene derivative 2 × 10 −11 esu at 2100 nm (4 ns pulses) [43] Push-pull azobenzene polymers 1.7 × 10 −11 esu at 1064 nm (30 ps pulses) [36] Regioregular P3HT 2PA = 300 GM (per repeated unit) at 800 nm (fs pulses) [32] Azopolymer derived RD1 = −60.1 cm/GW at 532 nm (ps pulses) [ and 194 GM per repeated basic monomeric unit. Notoriously, this value is very close to the value of 300 GM (per repeated unit) measured in the regioregular poly(3-hexylthiophene) (P3HT) at the same wavelength (800 nm) in diluted solution in chloroform [32].…”

Synthesis and Third‐Order Nonlinear Optical Properties of Triphenylene Derivatives Modified by Click Chemistry

“…Compared to other organic molecules measured by Z‐scan, the third‐order nonlinear values of our compounds were relatively good 16. 17 CATP1 shows a larger Im χ (3) value compared to ATP , which can be ascribed to the introduction of electron‐acceptor (cyano) groups from TCNE and may help increase the third‐order nonlinear susceptibility of the compound by modifying charge transfer within the molecule 18. In addition, CATP2 shows a lower Im χ (3) value compared to CATP1 , which can be attributed to an increment of the π‐conjugated ranges in CATP2 and could have an influence on the charge transfer, hinering the polarizabilities of the molecule 19.…”