Second-order nonlinear optical properties and relaxation characteristics of poled linear epoxy polymers with tolane chromophores

Abstract

A new linear epoxy polymer containing 4-amino-4′-nitrotolane chromophores attached to the chain backbone was synthesized in an attempt to enhance both the poling-induced nonlinear optical susceptibility and its long-term stability. The polymer films poled by corona discharge showed very large nonlinear optical doubling coefficients of d33 ≂ 89 pm/V and d31≂25 pm/V for incident light of 1.06 μm wavelength, and a linear electro-optic coefficient r13≂8 pm/V at 633 nm wavelength. Poling-induced alignment of the nonlinear optical moieties showed no detectable decay in two weeks at ambient temperature, as studied by the birefringence. Even at 100 °C the relaxation time estimated from the birefringence decay was ca. 450 h, consistent with roughly 16% decrease in dij coefficients in 20 h at this temperature and also the extrapolation from the dielectric α relaxation characteristics. The dielectric α relaxation temperatures of the poled polymer samples exhibited higher values than that of the unpoled counterpart. This unusual behavior may be due to a significant contribution of Maier–Saupe thermotropic interactions among the tolane moieties that favor parallel alignment.

Role of Temperature in Controlling Performance of Photorefractive Organic Glasses

“…[49,51,52] Combinations of several factors complicate the data tractability. For example, in poled polymers, relaxation times obtained in SHG experiments were reported as both increasing [58] and decreasing [51,59] functions of the poling field strength. Therefore, it is important to take into account experimental conditions when comparing the data obtained by different techniques.…”

Effect of pressure and temperature on chromophore reorientation in a side-chain nonlinear optical polymer

“…Many researchers have performed relaxation studies [3][4][5][6][7][8][9][10][11][12] at temperatures near and above the glass transition temperature (T g ) that show a direct connection between chromophore reorientation and the long-range ␣-type motion of the polymer backbone. However, other experiments performed at temperatures below the T g show that chromophore reorientation appears to couple to secondary relaxations in guest-host systems.…”

A new guest-host system: towards stable second-order optical nonlinearity

“…Second order nonlinear optical polymeric materials have recently been extensively investigated [1][2][3][4][5][6]. The interest in these materials is mainly due to their large electronic nonlinear susceptibility and the ease of processing them into good optical quality thin films.…”