Tsuneo Manabe

Third-order optical non-linearities of CuCl-doped glasses in a near resonance region

Third-order optical non-linearities of CuCl microcrystallites with sizes of 6.8-11.0 nm in glasses were investigated. Absolute values of third-order non-linear susceptibilities, |χ (3) (-ω 1 : ω 1 , -ω 1 , ω 1 )|, were measured in the resonance region by a degenerate four-wave mixing method and |χ (3) (-ω 2 : ω 1 , -ω 1 , ω 2 )| were measured in the near resonance region by a non-degenerate four-wave mixing method. |χ (3) (-ω 1 : ω 1 , - ω 1 , ω 1 )| was strongly dependent on the frequency, ω 1 , of incident beam, while |χ (3) (-ω 2 : ω 1 , - ω 1 , ω 2 )| was less dependent on the frequency, ω 2 , of incident beam under the resonant excitation condition. In the non-degenerate four-wave mixing configuration in which the pumping frequency is resonant with the confined excitons, the figure of merit, |χ (3) |/α, was enhanced to more than an order of magnitude compared with that in the degenerate four-wave mixing configuration in a near resonance region.

Ultraviolet irradiation effect on the third-order optical nonlinearity of CuCl-microcrystallite-doped glass

We investigate the effect of irradiation by a UV pulse laser on the third-order optical nonlinearity of CuCl-microcrystallite-doped glass as a function of the irradiation’s shot number, energy density per pulse, and wavelength. The response time τ is estimated from the luminescence decay time of the CuCl excitons. The absolute value of the third-order nonlinear susceptibility χ(3) is measured by degenerate four-wave mixing. Values of both τ and χ(3) decrease after UV irradiation. The figure of merit for the optical nonlinearity, χ(3)/ατ, where α is the absorption coefficient, is almost constant before and after UV irradiation and is approximately 500 esu cm s-1 in the case of 8-nm CuCl microcrystallites. This value is 1 order of magnitude larger than that of CdSxSe1-x-microcrystallite-doped glasses. The mechanism by which τ and χ(3) are decreased is discussed, considering defects levels formed at the interface between CuCl microcrystallites and glass matrix.

Large Enhancement of Third-Order Optical Susceptibility in CuCl Quantum Dots Embedded in Glass

We report third-order optical nonlinearity of CuCl microcrystallites with radii of 1.5-8.0 nm in glass. We measured absolute values of third-order susceptibility χ(3) using degenerate four-wave mixing and imaginary χ(3) by absorption saturation measurements. The highest value of χ(3) was obtained to be 2×10-6 esu for microcrystallites with the mean radius of 4 nm which were embedded in the glass with the volume fraction of about 0.5%. We found that the figure of merit, χ(3)/ατ, where α and τ are the absorption coefficient and the response time, respectively, is also increased upon an increase of radii in the range of 1.5-4.5 nm.

Quenching treatment for improvement of nonlinear optical response time in high-χ(3) CuCl-doped glasses

Abstract Quenching treatments were performed on CuCl microcrystallite-doped glasses prepared by a melting method. Radiative decay time measurement and χ (3) measurement for the quenched glasses were performed using ps and ns laser. The glasses showed that the radiative decay time were shortened by one order of magnitude without a decrease of third-order nonlinear susceptibility χ (3) after the quenching treatment from above 300°C. The distorted structure of CuCl microcrystallites quenched from high temperature was considered to be most effective for the shortening of the lifetime of Z 3 exciton.

New Dielectric Material on Front-Panel of PDP

We developed a new transparent dielectric material on the front-panel of Plasma Display Panel (PDP). We found that a glass composition named YPT124 exhibited not only excellent dielectric properties but also were high transparency. The relative dielectric constant of the bulk glass is 8.3 and the transmittance of 20mm thick fired film with 2.8mm thick substrate is 83%. The relative dielectric constant and transmittance of this new material is 30% lower and 10% higher than the present commercial material respectively.