Diarylethenes for Memories and Switches

Switches, and Actuators Masahiro Irie,*,† Tuyoshi Fukaminato,‡ Kenji Matsuda, and Seiya Kobatake †Research Center for Smart Molecules, Rikkyo University, Nishi-Ikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan ‡Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

Nanoparticles (NPs) and molecular/supramolecular switches have attracted considerable interest during the past decade on account of their unique properties and prominent roles in the fields of organic chemistry and materials science. Materials derived from the combination of these two components are now emerging in the literature. This critical review evaluates materials which comprise NPs functionalised with well-defined self-assembled monolayers of molecular and supramolecular switches. We draw attention to the fact that immobilisation of switches on NPs does not, in general, hamper their switching ability, although it can impart new properties on the supporting particles. This premise leads us to the discussion of systems in which switching on the surfaces of NPs can be used to modulate reversibly a range of NP properties—optical, fluorescent, electrical, magnetic—as well as the controlled release of small molecules. Finally, we discuss examples in which molecular switches direct reversible self-assembly of NPs (308 references).

Nanoparticles functionalised with reversible molecular and supramolecular switches

The electronic component package of the present invention includes a sealed chamber; a liquid or gel contained in the sealed chamber; at least one electronic component disposed in the sealed chamber in physical and thermal contact with the liquid or gel; and at least one electrical conductor electrically coupled to the electronic component and extending out of said sealed chamber. The electronic component(s) may include any one or combination of a radiation emitter, a thermal or optical sensor, a resistor, and a microprocessor or other semiconductor component.

High power radiation emitter device and heat dissipating package for electronic components

Silica-based planar lightwave circuits (PLC) provide various important devices for both optical wavelength-division-multiplexing networks and optical access network. This paper is an overview of recent progress in PLC technology including optical power splitters, arrayed-waveguide gratings, thermooptic switches, and hybrid integrated PLC's.

Silica-based planar lightwave circuits

An optical waveguide circuit includes a plurality of waveguides with different lengths. Grooves (12) are formed in the waveguide by removing the upper cladding and the core of the waveguide (4) or by removing the upper cladding, the core and the lower cladding of the waveguide (4), and filled with a material (10) which have a refractive index temperature coefficient whose sign is different from the temperature coefficient of the effective refractive index of the waveguide. The difference between the lengths of the removed parts of the adjacent waveguides is proportional to the difference between the lengths of the remaining parts of the adjacent waveguides.

Optical waveguide circuit, its manufacturing method and optical waveguide module having the optical waveguide circuit

A self‐holding and optical–optical 2×2 switch using a Mach–Zehnder interferometer with a thermally irreversible photochromic (PC) guest/host polymer cladding is reported. The device was fabricated using a silica‐based integrated optic Mach–Zehnder interferometer with a PC cladding polymer. Cross‐bar switching was achieved by using ultraviolet (313 nm) and visible (≳500 nm) light. The switching state was self‐holding in the dark. Switching was observed with a crosstalk ratio of −12 dB and an excess loss of 7 dB at 1.55 μm.

Self‐holding photochromic polymer Mach–Zehnder optical switch

The refractive index change of photochromic diarylethene derivatives in solid polymer was studied with a view to fabricating an optical switching device. The reaction time required for a symmetric diarylethene photochromic compound in a copolymer of fluoroethyl methacrylate and methyl methacrylate (film thickness: 10 μm) was 20–30 s when exposed to UV light (intensity: 5.3 mW cm−2 at 350 nm) to form a closed ring and about 10 s with visible light (intensity: 3.7 mW cm−2 at 500 nm) to form an open ring. The refractive index change at 1.30 μm, measured with a prism coupler, was 0.0005 per 10 wt.% of diarylethene photochromic compound. The iteration number of the photochromic reactions in the polymer film decreased in the following order: symmetric, asymmetric diarylethene and acid anhydride. We propose a new type of self-holding optical switch combining a heat stable photochromic material with silica planar lightwave circuits.

Refractive index change in photochromic diarylethene derivatives and its application to optical switching devices

The present invention relates to a UV-A,UV-B discriminating sensor provided with a photochromic compound or photochromic composition as the sensor portion, the photochromic compound or photochromic composition coloring under exposure to UV of wavelength greater than or equal to 280nm or less than or equal to 400nm, and wherein at least a portion of the photochromic layer is covered with a layer containing a pigment which absorbs UV of wavelength less than 320nm, or with a layer containing a pigment which absorbs UV of a wave length greater than or equal to 320nm but less than or equal to or equal to 400nm.

UV-A, UV-B discrimination sensor

We investigated photochromism and the refractive index change Δn in polymethylmethacrylate (PMMA) films made using 16 compounds of 1,2-diarylethene derivatives. The derivatives were classified as maleic anhydride or hexafluorocyclopentene diarylethene in type according to their structure. In PMMA films, the photochromic reactivity of maleic anhydride diarylethene derivatives strongly depends on their substituent structure. On the contrary, the photochromism of hexafluorocyclopentene diarylethene derivatives is observed in PMMA films regardless of their substituent. We found that Δn increased in proportion to the absorbance charge increase. Moreover, both Δn and ΔA were also proportional to the concentrations of the photochromic compounds. We believe that both Δn and ΔA are related to changes in the molecular structure of 1,2-diarylethene derivatives. We fabricated one transparent PMMA film of each type. Each film contained a high concentration of dispersed diarylethene derivatives. The changes in refractive index and absorbance of the maleic anhydride diarylethene type saturated at more than 15 wt.%. However, the changes in the hexafluorocyclopentene diarylethene type with a long alkyl chain were in proportion to the concentrations of the compound, and we obtained the largest refractive index change (0.0018) yet reported for 1,2-diarylethene derivatives in transparent PMMA films.

Fumihiro Ebisawa

Papers

Optical waveguide circuit, its manufacturing method and optical waveguide module having the optical waveguide circuit

Self‐holding photochromic polymer Mach–Zehnder optical switch

Refractive index change in photochromic diarylethene derivatives and its application to optical switching devices

UV-A, UV-B discrimination sensor

Refractive index changes in photochromic diarylethene derivatives in polymethylmethacrylate films