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We newly synthesized cross-linked silicone from methyl and deuterated phenyl ( d -phenyl) groups in various amounts and used the resultant polymers to fabricate single-mode optical waveguides. We measured the losses and birefringence of the waveguides by the cutback method and Senalmont ellipsometry, respectively. The propagation loss decreased as we increased the d -phenyl content. The propagation loss was 0.23 dB/cm at 1.55 μm for a waveguide fabricated using cross-linked silicone with a 95-mol.% d -phenyl content. In contrast, the birefringence increased with increasing d -phenyl content. This indicates that the increase in phenyl content influences the orientation of optically anisotropic phenyl groups in the film, resulting in a birefringence increase. The birefringence value was 2.0×10 −4 for a waveguide fabricated from cross-linked silicone with a 27-mol.% d -phenyl content.

We propose a tunable optical dispersion compensator (TODC) that uses an arrayed waveguide grating (AWG) and a flat mirror. The TODC employs simple and cost-effective optics, and its chromatic dispersion can be changed simply by translating the AWG. We obtained a 3-dB bandwidth of 39 GHz when the dispersion was tuned within 800 ps/nm, and a maximum dispersion of plusmn3000 ps/nm.

We describe the proof-of-concept demonstration of flexible chromatic dispersion compensation over the entire L-band region wavelength-division-multiplexing transparent networks operating at over 40 Gb/s using span-by-span compensation with an arrayed-waveguide grating and an liquid crystal on silicon-based multichannel tunable dispersion compensator.

This letter proposes a centralized frequency stabilization technique for uplink signals in dense wavelength- division- multiplexed passive optical networks; it is based on dithering the transmission spectra of the demultiplexer. To ensure that the proposed technique achieves a wide capture range, a planar lightwave circuit is developed that incorporates a Mach–Zehnder interferometer and two arrayed waveguide gratings. Experimental results show that the wide capture range of $\pm$ 25 GHz is established without any significant power penalty.

Polymeric optical waveguides fabricated using a newly developed silicone resin have a low birefringence as well as low propagation loss and good environmental stability. Optical waveguide circuits including a directional coupler, an arrayed waveguide grating (AWG) multi/demultiplexer, and a digital thermooptic (TO) switch are successfully realized using the silicone resin.

Palladium-catalyzed polycondensation between p-diethynylbenzene (HC⋮CPhC⋮CH) and 2,5-diiodo-3-hexylthiophene (ITh(Hex)I) has been carried out under various conditions by changing the polymerization temperature, medium, and added amines. The polycondensation gives the polymer (PAE-1) with a Mn of about 3 × 104 (by GPC, polystyrene standards) and an [η] value of 0.8 dL g-1. By using neat NEt3 as the medium, the polymerization proceeds fast. 1H-NMR spectroscopic analysis indicates that oligomeric PAE-1 obtained at short polymerization time has a CI bond (Th(Hex)I bond) as the major terminal group, which is consistent with results of the basic Pd-catalyzed CC coupling reaction. The CI terminal bond of oligomeric PAE-1 reacts with 1,3,5-triethynylbenzene and 1,2,4,5-tetraethynylbenzene to give polymers with Mn values of 8.7 × 105 and 2.3 × 106 (by GPC), respectively, and the polymers are considered to have star-type structures. All the polymers show two (main and sub) photoluminescence PL peaks at 456 ± 3 and ...

Various π-conjugated copolymers constituted of π-excessive thiophene, selenophene, or furan units (Ar) and π-deficient pyridine or quinoxaline (Ar‘) units have been prepared in high yields by the following organometallic polycondensation methods: (i) n X−Ar−Ar‘−X + n Ni(0)Lm → (-Ar−Ar‘)-n (X = halogen, Ni(0)Lm = zerovalent nickel complex), (ii) n X−Ar−X + n Me3Sn−Ar‘−SnMe3 → (-Ar−Ar‘)-n (palladium catalyzed), and (iii) a X−Ar−X + b X−Ar‘−X + (a + b)Ni(0)Lm → (-Ar)x(Ar‘)-y. Powder X-ray diffraction analysis confirms an alternative structure of a polymer prepared by the method ii. The copolymers have a molecular weight of 5.4 × 103 to 3.3 × 105 and an [η] value of 0.37 to 4.4 dL g-1. π−π* absorption bands of the copolymers generally show red shifts from those of the corresponding homopolymers, (-Ar)-n and (-Ar‘)-n, and the red shifts are accounted for by charge-transferred CT structures of the copolymers. For example, an alternative copolymer of thiophene and 2,3-diphenylquinoxaline gives rise to an absorp...

We propose a spatial beam transformer (SBT) for a wavelength selective switch, which is monolithically integrated on a silica-based planar lightwave circuit (PLC). The PLC-integrated SBT has advantages such as freedom from precise alignment and the elimination of expensive bulk optics. In addition, the aspect ratio can be freely designed simply by redesigning the layout of the SBT without adding any other optical components. We successfully tuned the aspect ratio from 7.9 to 87.5 simply by changing the PLC layout.

Palladium-catalyzed polycondensation between dihalo aromatic compounds X-Ar-X (3-hexyl-2,5-diiodothiophene, 2,5-dibromoselenophene, and 3,4-dinitro-2,5-dibromothiophene) and diethynyl aromatic compounds HC≡C-Ar'-C≡CH (2,5-diethynylpyridine, 3-hexyl-2,5-diethynylthiophene, and p-diethynylbenzene) in the presence of triethylamine gives soluble π-conjugated poly(aryleneethynylene) (PAE) type polymers (-Ar=C≡C-Ar'-C≡C-) n when Ar and/or Ar' contains the long alkyl substituent and/or pyridine ring

Palladium-catalyzed polycondensation between 2,5-bis(trimethylstannyl)thiophene and 5,8-dibromoquinoxaline derivatives gives soluble new π-conjugated polymers, which exhibit absorption bands at 575 ± 30 nm assignable to intramolecular charge transfer bands and show the three-photon resonant third-order nonlinear optical susceptibility χ(3) of about 5 × 10−11 esu.

We realized a wide-passband multi-channel tunable optical dispersion compensator for 88 WDM signals with 50-GHz spacing by combination of an arrayed-waveguide and bulk gratings. It utilizes a novel optics arrangement for high wavelength resolution.

Linear and χ(3) spectra of vacuum-deposited thin films of polythiophene (PTh, prepared by an organometallic process) show vibronic structures with an energy difference of about 1500 cm−1 (0.19 eV). The vibronic structure is more clearly observed in the χ(3) spectrum and is considered to originate from coupling with the vc=c vibration of the thiophene ring. Large χ(3) anisotropy with a χ∥(3)/χ⊥(3) value of about six is observed with the PTh vacuum deposited on substrates covered with a rubbed poly(p-phenylene) thin layer.

We propose a novel optical configuration for a multichannel tunable optical dispersion compensator (TODC) with channel-by-channel operation across the entire L-band. The TODC consists of a cyclic frequency arrayed-waveguide grating whose free spectral range coincides with the channel spacing, a bulk grating, and a liquid crystal on silicon. We achieved channel-by-channel compensation over 50 channels with a maximum chromatic dispersion of ±800 ps/nm.

We propose a novel optical configuration for a channelized tunable optical dispersion compensator (TODC) with channel-by-channel operation across entire the L-band. The TODC consists of a cyclic frequency arrayed-waveguide grating (AWG) whose free spectral range (FSR) coincides with the channel spacing, a bulk grating and a liquid crystal on silicon. We achieved channel-by-channel compensation over 50 channels with a maximum chromatic dispersion of 800 ps/nm.

Nearly transform-limited pulses with a temporal width of 744 fs were produced by compensating up to fourth order chirp in a supercontinuum lightwave by employing a tunable optical dispersion compensator based on liquid crystal on silicon and two arrayed-waveguide gratings.

We propose a novel configuration for a tunable optical dispersion compensator (TODC) with increased bandwidth. We demonstrate 40-wavelength channelized compensation for 400-ps/nm chromatic dispersion with a 40-GHz bandwidth using the proposed TODC.

A wavelength tunable optical filter is a beneficial optical component for dense wavelength-division-multiplexed systems. We report a high-performance polymeric arrayed-waveguide grating (AWG)-based tunable filter made of cross-linked silicone and operating around 1.55 /spl mu/m. This filter exhibited a TE-TM polarization shift of

We propose a tunable optical dispersion compensator (TODC) using an arrayed-waveguide grating (AWG) and a flat mirror. The TODC employs simple and cost-effective optics, and its chromatic dispersion can be changed simply by translating the AWG. We obtained a tuning range of plusmn 250 ps/nm, a group delay ripple of Lt 3.5 ps and an insertion loss of 6.3 dB.

We propose an error signal transfer method for remote frequency stabilization in DWDM-PON. The error signal is embedded in a downlink signal using a supervisory frame; the effectiveness of this method is experimentally confirmed.

We demonstrate a tunable optical dispersion compensator consisting of an arrayed-waveguide grating and a liquid crystal on silicon. We obtained a tuning range of ± 800 ps/nm with a bandwidth of 16 GHz.

We propose hybrid AWG-free space focusing optics which is about a half size of the conventional 2-f system. Using this optics, we demonstrate a 40-channel 100-GHz spacing wavelength blocker with the 0.5-dB passband of 76 GHz.

Humidity dependence of the refractive index of deuterated polymethylmethacylate (d-PMMA) is examined at a wavelength of 1.3 μm using the return loss method. The refractive index of d-PMMA increases as humidity increases at room temperature, while it decreases as humidity increases at temperatures higher than 60 °C. This humidity dependence was ascribed to the counterbalance between moisture sorption and swelling. Some hydrophobic polymers, such as silicone resin and fluorinated epoxy resin were affected by humidity to a lesser degree than d-PMMA.

We have developed the first silica-based PLC type 32 x 32 optical matrix switch. The switch is the largest scale waveguide type switch yet reported, which has excellent optical characteristics with an average insertion loss of 6.6 dB.

We have investigated two kinds of polymeric thermo-optical (TO) components, i.e. a 1×8 digital TO switch relying on adiabatic mode evolution and a TO tunable filter using a thermally-controlled arrayed-waveguide grating (AWG). Cross-linked waveguides are developed to have low insertion loss, polarization independence, moisture insensitivity, and thermo-stability. The 1×8 TO switch is composed of seven 1×2 switch elements in a tree configuration, which we designed with a wide branching angle and a short heater length.

A polarization-independent polymeric thermo-optic tunable filter is realized with

We demonstrate a thermo optic wavelength tunable filter (TOWTF) with a tuning range of > 25 nm that covers the gain-shifted EDFA band (L band, 1570-1610 nm), where our polymer has a low transmission loss. We achieved this by employing more heater power than previously reported. We fabricated the arrayed waveguide grating (AWG) demultiplexer on a silicon substrate using silicone resin as the waveguide material.

Humanin (HN) and S14G HN (HNG) are recently discovered polypeptides that rescue cells from death induced by multiple different types of familial Alzheimer's disease genes and by amyloid-beta. However, the cytoprotective activity of these peptides against other cell death-inducing stimuli remains unclear. In this study, we demonstrated, using three different methods (MTS assay, caspase-3 assay, and detection of DNA fragmentation), that both HN and HNG protect PC12 cells from death elicited by serum deprivation. This implies the potential of the peptides to rescue cells from a broad spectrum, if not all, of cell death-inducing factors. Further investigations on HN may lead the possible application of this peptide as therapeutic agent for the treatment of other neurodegenerative diseases.

This paper reviews our recent work on various planar-waveguide-type optical switching devices. Specifically we investigated N x N thermo-optic (TO) matrix switches. The matrix switch consists of N2 switching units and the switching unit has two cascaded Mach-Zehnder interferometers (MZIs). Switching is achieved by using a phase control technique based on the TO effect. The switching power of an MZI unit and the switching speed are typically 0.4 W and 2 ms, respectively. For N equals 16, we realized non-blocking connection with a very low-loss of 6.6 dB and a high-extinction ratio of 55 dB. We have also developed 1 x N configuration switches for use in optical path cross-connect systems. By integrating TO switches and arrayed-waveguide grating multi/demultiplexers, we fabricated single-chip optical add/drop multiplexers (OADM) for use in all-optical wavelength division multiplexing (WDM) routing systems. We have developed a power consumption reduction technique that is effective for all MZI TO switches as regards large scale integrated switch applications.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Recently, photonic networks based on wavelength division multiplexing (WDM) systems have developed considerably in response to the explosive growth of the Internet. Devices with novel functions are required for photonic networks, and planar lightwave circuits (PLCs) are being considered to meet this need. This paper reports recent progress on PLCtype devices with advanced functions developed for the photonic networks. We describe fabrication techniques anddevice applications for silica and silicone polymer based PLC technologies.1. Introduction The rapid and global spread of the Internet is accelerating the growth of optical communications networks. Photonic networks based on wavelength division multiplexing (WDM) systems [1, 2] have played a key role in increasing the capacity and flexibility of these communications networks. IP traffic is still growing at a higher rate than expected, making further increases in backbone network capacity a critical issue. In response to this, the WDM channel

We have developed a 2x2 digital optical switch (DOS) composed of four I x2 DOS elements and a thermo-optic wavelength tunable filter using silicone resin waveguides. The 2x2 DOS operated with a switching power of 380 mW, a very low crosstalk of less than —60 dB, and a low insertion loss of less than 2.5 dB at 1 .55 pin. The tunable filter operated with amaximum power of 2.5 W, a tuning range of > 30 nm, a crosstalk of < -30 dB, and response time of < 60 ms. We alsoapplied our polymer tunable filter to a WDM/SCM LAN system to confirm its practicality.Keywords: thermo-optic digital switch, wavelength tunable filter, AWG, polymer waveguides 1. INTRODUCTION Polymer waveguides have received much attention because the excellent processability of polymer materials enables us tofabricate the waveguides using easy and low-cost techniques such as the spin-coating method at low [1 -3]. To use thesewaveguides as optical components, we must improve their propagation loss, polarization-dependent optical properties, andoperational reliability. Transparent, heat-resistant, and low-hygroscopic polymer materials have been developed to satisfythese requirements [4-71 . Aromatic

Several organic materials with a bulky donor group have been developed for second‐order nonlinear optics. Among these materials, 2‐adamantylamino‐5‐nitropyridine (AANP) crystal has the largest second‐order nonlinear optical coefficient. By second‐harmonics measurement at 1.064 μm, coefficients of d31 and d33 were determined to be 80 and 60 pm/V, respectively. Angle‐tuned phase‐matched second‐harmonic generation with a conversion efficiency=2×10−3 W−1 has been demonstrated using a 1 mm AANP bulk crystal at 1.064 μm.

A digital thermo-optic switch formed using silicone resin exhibits an insertion loss of 30 dB at 1.55 μm, and operates even at 80 °C.

Molecular design of processable nonlinear optical (NLO) polymers is discussed for applications to devices such as ultrafast optical switches. Channel waveguides must be fabricated in order to develop polymeric NLO switching devices that can be driven with lower laser power. For these purposes, we propose molecular structures that reduce attenuation loss and allow the development of highly processable NLO polymers. Third-order nonlinear optical properties, χ(3), of the novel NLO polymers are around 10−10 esu in the 1.5 μm wavelength region. Even in off-resonant regions, the χ(3) values are around 5 × 10−11 esu. Single Mode channel waveguides of the polymers are fabricated using a standard photo-process. Attenuation loss through a film and also for a single mode waveguide at 1.32 μm wavelength is Measured. Nonlinear optical properties of novel, processable, heteroaromatic polymers with large χ(3) are also discussed. Several types of heteroaromatic polymers are developed with a structure in which π-electron excessive heteroaromatic compounds and π-electron deficient heteroaromatic compounds are combined to induce strong nonlinearity. The charge transfer between heteroaromatic rings on the π-conjugated sequences is thought to influence the properties of certain excited states that enhance χ(3) These polymers have excellent potential for use in fabrication of optical switching devices.

We propose and demonstrate a multi-channel tunable optical dispersion compensator (TODC) that consists of an arrayed-waveguide grating (AWG) and liquid crystal on silicon (LCOS). By utilizing the AWG with a large angular dispersion and the LCOS with a flexible phase setting, we can construct a compact and flexible TODC that has a wide tuning range of chromatic dispersion. We confirmed experimentally that the TODC could realize channel-by-channel CD compensation for six WDM channels with a ± 800 ps/nm range and a 3 dB bandwidth of 24 GHz. We believe that the multi-channel operation of this TODC will help to reduce the cost and power consumption of high-speed optical transmission systems.

A 100 GHz-spacing 48-channel planar lightwave circuit (PLC)-type demultiplexer with a spectral modulation function for monitoring signal light wavelengths is reported. The demultiplexer is composed of a Mach-Zehnder interferometer (MZI) and two arrayed-waveguide gratings. Its centre wavelength can be shifted more than 100 Hz with a modulating signal applied to a thermo-optic heater on the MZI section.

A copolymer of pyridine-2,5-diyl and indigo-6,6′-diyl has been prepared by dehalogenation polycondensation using Ni(0) complex. The copolymer forms a good film, and the film shows the three-photon resonant third-order nonlinear susceptibility χ(3) of about 10−11 esu at absorption of poly(pyridine-2,5-diyl) unit.

Two types of polymer thermo-optic wavelength tunable filter (TOWTF) have been developed, each with a pair of triangular phase shifters. One filter is designed for a large-scale WDM system (32 channels, 0.8 nm spacing), the other for a small-scale WDM system (10 channels, 0.8 nm spacing). The arrayed waveguide number is optimised thus reducing the operating power required by the filters. Moreover, both filters operated with a low crosstalk of < –25 dB.

We have demonstrated a high-performance 1×8 digital thermo-optic (TO) switch that uses silicone resin waveguides. The compact 40 mm long switch employs short Y-branching switches with a large branching angle. It has a low insertion loss of less than 3 dB and a low crosstalk of less than -40 dB at 1550 nm. The switch characteristics are maintained over wide wavelength regions around 1.3 and 1.55 µm. They are also stable over a wide temperature range of -10 to 75°C and a humidity range of 30 to 90%RH.

The authors have developed a polymer thermo-optic wavelength tunable filter with a pair of triangular phase shifters on an arrayed-waveguide grating, which provides a fast response and wideband tunability. This filter operated with a response time of 2–60 ms and a tunability of > 20 nm.

A high-performance 1/spl times/8 digital thermo-optic (TO) switch that uses silicone resin waveguides has been developed. The compact 40 mm long switch uses short Y-branching switches with a large branching angle. It has a low insertion loss of

Polymer waveguides made with deuterated silicone resin have a low propagation loss of 0.5 dB/cm at 1.55 µ m, and offer long term stability in the humid conditions of 90% RH at 75° C. A digital thermooptic switch formed using the silicone resin waveguides exhibits an insertion loss of 30 dB at 1.55 µ m. This switch is insensitive to wavelengths in the range of 1535–1620 nm, and operates properly even at 80° C.

A 0.8 nm spacing polymeric arrayed-waveguide grating (AWG) multiplexer operating around 1550 nm is realised using a silicone resin waveguide. The AWG multiplexer has an insertion loss in the range 9-13 dB, a crosstalk of

A polymer waveguide Y-branch thermo-optic (TO) switch was fabricated using deuterated fluoromethacrylate polymers. The influence of humidity on transmission in the switch was examined at 16, 44 and 80% RH. A transmission of –1.3 dB and a crosstalk of

Poly(aryleneethynylene) type π-conjugated polymers (PAEs) are synthesized and the third-order optical susceptibility χ(3) of their thin films is evaluated. There is a red-shift in the electronic absorption of the PAE caused by an intramolecular charge transfer (CT) interaction when π-electron excessive heteroaromatic rings are introduced into the π-conjugation. The χ(3) value of the PAEs is enhanced by increasing the CT interaction and reaches more than 10-11 esu in the near resonant region. The increase in the π-electron delocalization caused by the CT interaction is found to be the main factor enhancing χ(3). This introduction of a CT interaction into a π-conjugation is an effective concept for the design of large χ(3) materials.