Ultrafast photoresponsive materials and molecular photonics applications by guided wave mode geometry

Abstract

Molecular photonics, information processing based on strong interactions of photons and molecules, has attracted much attention, since it can fully utilize many superior properties of both photons and molecules. We have developed polymeric materials showing ultrafast absorption changes in the visible to near-infrared regions including the telecommunication wavelength by photoinduced electron transfer and reverse reactions between substituted pyridinium and its counter anion. By selecting the counter anion we succeeded in making steady and ultrafast absorption changes. Time-resolved absorption and fluorescence spectroscopy upon femtosecond laser excitation revealed reaction mechanism and ultrafast dynamics. In order to fully utilize such photoresponses in molecular photonics, we proposed guided wave mode (GWM) device composed of a prism, a low refractive index polymer film, and a photoresponsive polymer film. The reflectance in this GWM is controlled by many factors such as thickness values and complex refractive indices of two polymer layers as well as an incident angle and wavelength. We successfully achieved sensitive, all optical, and very fast control of reflectance by means of photoinduced complex refractive index changes upon femtosecond laser excitation. r

Ability of dynamic holography in self-assembled hybrid nanostructured silica films for all-optical switching and multiplexing

“…In the present work, the sol-gel method has been employed in the fabrication of easily processable, highquality composite films which consisted of a silica framework, and self-assembled organic mesostructures formed by the nonionic surfactant Pluronic P123 [16] served as the host matrix for various organic dyes and quenchers. The Rhodamine 6G (Rh6G) or carbon (SWNT) nanotubes as the guest molecules are self-organized in the structure of mesostructured silica thin films.…”

Ability of dynamic holography in self-assembled hybrid nanostructured silica films for all-optical switching and multiplexing

“…The recent growth in network-connected devices has lead to an increasing demand on the telecommunications network to interconnect these devices with the possible lowest data transfer delay. Thus far, the materials that have shown the most promise to be used as the thin-film photonic layer are either the molecular beam epitaxy grown semiconductors or the neat organic dye films [ 16 ]. Organic films are certainly a more cost-effective photonic material since they can be readily fabricated at room temperature, using spin or dipcoating techniques.…”

“…In the present work, the sol-gel method has been employed in the fabrication of easily processable, high-quality composite films which consisted of a silica framework, and self-assembled organic mesostructures formed by the nonionic surfactant Pluronic P123 [ 16 ] served as the host matrix for various organic dyes and quenchers. The Rhodamine 6G (Rh6G) or carbon (SWNT) nanotubes as the guest molecules are self-organized in the structure of mesostructured silica thin films.…”

Synthesis and Photophysical Properties of a Photoelectrochromic Polymer Containing the bis(2-(4-Pyridiniumyl)thiazole) Chromophore

“…We have been developing ion-pair charge-transfer complexes showing transient absorption in the visible to NIR region due to photoinduced electron transfer and reverse reactions between redox-active ion-pairs. [15][16][17][18][19] Recently, we reported the synthesis and photoresponses of a fluorene-containing redox polymer, which showed new absorption up to 2000 nm by photoinduced electron transfer from the tetraphenylborate anion in addition to extremely fast photoinduced forward and thermal back electron transfer between iodide anion and fluorene-containing redox polymer in the NIR region. [18,19] We also proposed alloptical spatial light modulation and parallel switching based on photoinduced complex refractive index changes in guided mode geometry.…”

“…[15][16][17][18][19] Recently, we reported the synthesis and photoresponses of a fluorene-containing redox polymer, which showed new absorption up to 2000 nm by photoinduced electron transfer from the tetraphenylborate anion in addition to extremely fast photoinduced forward and thermal back electron transfer between iodide anion and fluorene-containing redox polymer in the NIR region. [18,19] We also proposed alloptical spatial light modulation and parallel switching based on photoinduced complex refractive index changes in guided mode geometry. [20][21][22][23][24][25][26][27][28][29][30][31][32] Both transient bleaching and absorption-type materials can be used in this system.…”