Publications by authors named "Takaaki Ishigure"

24 Publications

  • Page 1 of 1

Mosquito method based polymer tapered waveguide as a spot size converter.

Opt Express 2021 Mar;29(6):9513-9531

We create a compact low-loss spot-size converter (SSC) which utilizes a tapered core polymer optical waveguide with circular cross-sectional graded-index (GI) core using the Mosquito method we developed. First, we theoretically analyze the mutual diffusion between the core and cladding monomers, which is a feature unique to the Mosquito method when forming GI cores. The monomer diffusion effect depends on the initial core diameter that is dispensed by a microdispenser and the diffusion time before UV curing: in a small core the monomer diffuses more rapidly than in a large core. Using this diffusion dependence on the initially dispensed core diameter, it is theoretically found that a tapered polymer waveguide based SSC can adiabatically convert the mode-field diameter between 4.0 and 8.6 μm at a 1550-nm wavelength waveguide as short as 4 mm. Next, the tapered waveguide based SSC with the designed structure is experimentally fabricated using the Mosquito method, and we confirm an 8-mm long tapered waveguide with an insertion loss of 1.83dB functions as a SSC that converts the MFD from 4.7 μm to 7.5 μm at 1550-nm wavelength.
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http://dx.doi.org/10.1364/OE.418938DOI Listing
March 2021

Guanine crystals regulated by chitin-based honeycomb frameworks for tunable structural colors of sapphirinid copepod, Sapphirina nigromaculata.

Sci Rep 2020 02 10;10(1):2266. Epub 2020 Feb 10.

School of Integrated Design Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.

Sapphirinid copepods, which are marine zooplankton, exhibit tunable structural colors originating from a layered structure of guanine crystal plates. In the present study, the coloring portion of adult male of a sapphirinid copepod, Sapphirina nigromaculata, under the dorsal body surface was characterized to clarify the regulation and actuation mechanism of the layered guanine crystals for spectral control. The coloring portions are separated into small domains 70-100 µm wide consisting of an ordered array of stacked hexagonal plates ~1.5 µm wide and ~80 nm thick. We found the presence of chitin-based honeycomb frameworks that are composed of flat compartments regulating the guanine crystal plates. The structural color is deduced to be tuned from blue to achromatic via yellow and purple by changing the interplate distance according to vital observation and optical simulation using a photonic array model. The framework structures are essential for the organization and actuation of the particular photonic arrays for the exhibition of the tunable structural color.
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http://dx.doi.org/10.1038/s41598-020-59090-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7010661PMC
February 2020

Circular core single-mode 3-dimensional crossover polymer waveguides fabricated with the Mosquito method.

Opt Express 2019 Oct;27(22):32465-32479

We experimentally fabricate circular core 3-dimensional (3D) crossover single-mode polymer optical waveguides using a photomask free unique fabrication technique named the Mosquito method for realizing channel shuffling. The 3D crossover structure is accomplished by forming four cores (2 ch. × 2 ch.) with different heights: the last two channels cross over the first two channels with horizontal and vertical core bending. We compare the insertion losses between the fabricated 3D single-mode crossover waveguide and 3D S-bend core waveguides fabricated separately, which correspond to the lower and upper channels in the crossover waveguide. Then, we investigate the effect of the core crossover on the loss, and find that almost negligible additional loss is observed. The average insertion losses of this 6-cm long 3D crossover single-mode waveguide are 3.95 and 3.81 dB at 1310 nm, and 5.74 and 4.80 dB at 1550-nm wavelength, for the lower and upper channels, respectively. The interchannel crosstalk in this crossover waveguide is observed to be lower than -40 dB, while the 1 dB radial alignment tolerance is ± 1.7 and ± 2.1 µm at 1310 and 1550 nm, respectively. These results suggest that the fabricated circular core single-mode 3D crossover polymer waveguides could have a great impact for high-bandwidth-density on-board and inter-chip optical interconnect applications.
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http://dx.doi.org/10.1364/OE.27.032465DOI Listing
October 2019

Directly inscribed multimode polymer waveguide and 3D device for high-speed and high-density optical interconnects.

Opt Express 2019 Aug;27(16):22419-22428

A 75-cm-long circular-core polymer waveguide compatible with standard 50-μm-core multimode fibers (MMFs) is designed and fabricated by using a direct inscribing method for high-speed and high-density optical interconnects. The fabricated waveguide has low loss (<0.044 dB/cm at 850 nm) and low crosstalk (<-34 dB with a core pitch of 62.5 μm) with a negligible coupling loss with the MMFs. It also exhibits a low bending loss (<0.08 dB/mm with a bending radius of 4 mm), which agrees well with calculated results. Error-free NRZ data transmission over the 75-cm-long waveguide at 25 Gb/s is demonstrated, and 4 × 25 Gb/s short wavelength division multiplexing (SWDM) is realized on a straight waveguide. Moreover, a two-layer waveguide and a 3-dimensional (3D) Y-splitter/combiner are also fabricated for 3D integration.
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http://dx.doi.org/10.1364/OE.27.022419DOI Listing
August 2019

Design for polymer optical waveguides realizing efficient light coupling via 45-degree mirrors.

Opt Express 2019 Apr;27(8):10839-10853

We design graded-index (GI) circular-core waveguides to realize low-loss light coupling via 45-degree mirrors using a ray-trace simulator. The waveguide's structural parameters, which determine the insertion loss of the waveguides with 45-degree mirrors, are the cladding thickness, the core size, the refractive index of materials, and the mirror angle. The optimum waveguide structural parameters are determined, and the GI circular-core waveguide with the appropriate structural parameters which is actually fabricated exhibits much lower total link loss than step-index (SI) core waveguides. The tight optical confinement of the GI-core contributes to the reduction of loss increment due to the mirror structure.
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http://dx.doi.org/10.1364/OE.27.010839DOI Listing
April 2019

Core position alignment in polymer optical waveguides fabricated using the Mosquito method.

Opt Express 2018 Jun;26(12):15632-15641

We fabricate multimode polymer optical waveguides with circular graded-index (GI) cores which are aligned in parallel at desired positions using the Mosquito method. In the Mosquito method, three-dimensional wiring patterns can be formed with a simple process. However, the core position is likely to deviate from the designed position because of multiple fabrication factors. Hence, in this paper, the dominant parameters to influence on the core height in the cladding are investigated both theoretically and experimentally. In particular, a linear relationship between the core height and the needle-tip height is confirmed with theoretical fluid analysis. Using this relationship, we succeeded in fabricating a waveguide in which the maximum variation of the core height from the designed value is controlled to be less than 10 µm.
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http://dx.doi.org/10.1364/OE.26.015632DOI Listing
June 2018

Low-loss graded-index polymer crossed optical waveguide with high thermal resistance.

Opt Express 2018 Feb;26(4):4512-4521

In this paper, crossed polymer waveguides with graded-index (GI) square cores are fabricated using the soft-lithography method. We experimentally demonstrate that the fabricated GI-core crossed waveguides exhibit a much lower insertion loss than conventional step index (SI)-core counterparts, which is almost independent of the cross angle. We also show in this paper that the crossed waveguides fabricated applying organic-inorganic hybrid resins show remarkably high thermal resistance compared to the waveguides fabricated utilizing an acrylate resin and a dopant system we previously reported.
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http://dx.doi.org/10.1364/OE.26.004512DOI Listing
February 2018

Circular core single-mode polymer optical waveguide fabricated using the Mosquito method with low loss at 1310/1550 nm.

Opt Express 2017 Apr;25(8):8524-8533

We fabricate low-loss single-mode (SM) polymer optical waveguides using a photomask-free simple technique named the Mosquito method. The insertion losses of a 5-cm long SM polymer waveguide fabricated are 2.52 dB and 4.03 dB at 1310- and 1550-nm wavelengths, respectively. The coupling loss between a single-mode fiber and the waveguide is as low as 0.5 dB including the Fresnel reflection. The 0.5-dB misalignment tolerance in the radial direction is ± 2.0 μm at 1550 nm. The Mosquito method is promising for fabricating SM polymer optical waveguides compatible with silicon photonics chips.
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http://dx.doi.org/10.1364/OE.25.008524DOI Listing
April 2017

Low-loss light coupling with graded-index core polymer optical waveguides via 45-degree mirrors.

Opt Express 2016 Feb;24(4):3550-61

We experimentally investigate the optical loss of graded-index (GI) core polymer optical waveguides with a 45-degree mirror on their one end fabricated using the photo-addressing method. In addition, we also theoretically analyze the loss of GI square-core waveguides with mirrors using a ray-trace simulation tool. Then, in the waveguide based optical link including the optical path conversions via 45-degree mirrors, we show that GI waveguides realize lower total optical loss than conventional step-index (SI) core waveguides. The lower loss in the GI waveguide link is attributed to the tight optical confinement at the core center even after reflection at the mirrors.
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http://dx.doi.org/10.1364/OE.24.003550DOI Listing
February 2016

Index-profile design for low-loss crossed multimode waveguide for optical printed circuit board.

Opt Express 2015 Aug;23(17):22262-73

We present an index profile design for remarkably low loss multimode optical crossed waveguide. In this paper, we theoretically calculate the light propagation loss in crossed waveguides with step-index (SI) and graded-index (GI) square cores utilizing a ray tracing simulation. In this simulation, we focus on the index exponent values for the GI profile, which allows low crossing loss even if the number of crossing is as large as 50 or even if the crossing angle is as low as 20°. It is revealed that an index exponent of 2.0 for the GI core strongly contributes to exhibit 35 times lower loss (0.072 dB after 50-perpendicular crosses) compared to the loss of the SI-core counterpart (2.58 dB after the same crossings). The GI cores with a smaller index exponent exhibit better loss in crossed waveguides with a wide range of crossing angles from 30° to 90°. Furthermore, we discuss the effect of the refractive index profile at the intersection on the optical loss of crossed waveguides.
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http://dx.doi.org/10.1364/OE.23.022262DOI Listing
August 2015

Fan-in/out polymer optical waveguide for a multicore fiber fabricated using the mosquito method.

Opt Express 2015 Jan;23(2):1585-93

A fan-in/out polymer optical waveguide with 25-μm cores and 40-μm interchannel pitch is fabricated for a multimode multicore fiber using a microdispenser. We design a fan-in/out structure to which the Mosquito method is applicable since the Mosquito method is capable of drawing a circular graded-index core three-dimensionally. Then, we experimentally fabricate a 10-cm long fan-in/out polymer waveguide with seven cores, which is expected to connect a multicore fiber and a fiber ribbon. A minimum insertion loss of 5.26 dB at 850-nm wavelength for a 10-cm long fan-in/out waveguide is experimentally observed. Causes of variation in the insertion loss and interchannel pitch are discussed.
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http://dx.doi.org/10.1364/OE.23.001585DOI Listing
January 2015

Analysis of interchannel crosstalk in multimode parallel optical waveguides using the beam propagation method.

Opt Express 2014 Apr;22(8):9675-86

We theoretically analyze the origin of inter-channel crosstalk in densely aligned multimode parallel optical waveguides for on-board interconnects using the Beam Propagation Method. In this paper, we demonstrate that the inter-channel crosstalk due to mode coupling is very low in graded-index (GI) circular-core waveguides because the propagation constants of the propagating modes are discrete. Additionally, it is also found that the waveguides with GI-type circular cores is sensitive to the optical confinement in the cladding: low-power cladding modes largely decrease the mode conversion.
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http://dx.doi.org/10.1364/OE.22.009675DOI Listing
April 2014

Accurate interchannel pitch control in graded-index circular-core polymer parallel optical waveguide using the Mosquito method.

Opt Express 2014 Apr;22(7):8426-37

We successfully fabricate polymer optical waveguides with graded-index (GI) circular cores whose diameter and interchannel pitch are accurately controlled using the Mosquito method: GI-core waveguides with 250-, 125- and 62.5-μm pitches are successfully obtained. The Mosquito method utilizing a microdispenser is a very simple technique for fabricating GI-circular-core polymer optical waveguides. The accurately controlled pitch is confirmed by a high connectivity with a commercially available multimode fiber (MMF) ribbon with a 125-μm pitch. Furthermore, by inserting the waveguide between two 12-channel MMF ribbons, we experimentally demonstrate 11.3 Gbps × 12 Ch. parallel signal transmission through a GI-core waveguide with a 125-μm pitch for the first time to the best of our knowledge.
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http://dx.doi.org/10.1364/OE.22.008426DOI Listing
April 2014

Photonic bandgap Bragg fiber sensors for bending/displacement detection.

Appl Opt 2013 Sep;52(25):6344-9

We demonstrate an amplitude-based bending/displacement sensor that uses a plastic photonic bandgap Bragg fiber with one end coated with a silver layer. The reflection intensity of the Bragg fiber is characterized in response to different displacements (or bending curvatures). We note that the Bragg reflector of the fiber acts as an efficient mode stripper for the wavelengths near the edge of the fiber bandgap, which makes the sensor extremely sensitive to bending or displacements at these wavelengths. Besides, by comparison of the Bragg fiber sensor to a sensor based on a standard multimode fiber with similar outer diameter and length, we find that the Bragg fiber sensor is more sensitive to bending due to the presence of a mode stripper in the form of a multilayer reflector. Experimental results show that the minimum detection limit of the Bragg fiber sensor can be as small as 3 μm for displacement sensing.
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http://dx.doi.org/10.1364/AO.52.006344DOI Listing
September 2013

Carbon nanotube/polymer composite coated tapered fiber for four wave mixing based wavelength conversion.

Opt Express 2013 Feb;21(3):3651-7

Department of Electrical Engineering and Information Systems, University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan.

In this paper, we demonstrate a nonlinear optical device based on a fiber taper coated with a carbon nanotube (CNT)/polymer composite. Using this device, four wave mixing (FWM) based wavelength conversion of 10 Gb/s Non-return-to-zero signal is achieved. In addition, we investigate wavelength tuning, two photon absorption and estimate the effective nonlinear coefficient of the CNTs embedded in the tapered fiber to be 1816.8 W(-1)km(-1).
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http://dx.doi.org/10.1364/OE.21.003651DOI Listing
February 2013

Fabrication and inter-channel crosstalk analysis of polymer optical waveguides with W-shaped index profile for high-density optical interconnections.

Opt Express 2011 Jul;19(15):14018-30

Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.

For applications in high-density and high-speed optical interconnections, we propose to utilize polymer parallel optical waveguides (PPOWs) with so-called W-shaped refractive index profile in the core area. A W-shaped index profile is composed of a parabolic index distribution surrounded by a narrow index valley, followed by a cladding with a uniform refractive index. We expect that W-shaped index profiles contribute to decreasing the inter-channel crosstalk due to mode conversion in the waveguides. In this paper, we investigate how much the index difference of the index valley improves the crosstalk value. First, we fabricate polymer waveguides with various index profiles by changing the composition of the copolymer for cladding. We show the results that a 1-m long W-shaped profile PPOW has not only low propagation loss (0.027 dB/cm), but an inter-channel crosstalk (~-40 dB) lower than those of graded index (GI) core PPOW we previously fabricated. Next, we theoretically analyze the propagation loss and inter-channel crosstalk in polymer waveguides with different index profiles by means of a ray tracing model in which the light scattering effect is included. The calculation results indicate that the index valley surrounding each core works properly for preventing the power coupling from the cladding modes to the propagation modes, and consequently, very low inter-channel crosstalk is realized with W-shaped index profiles.
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http://dx.doi.org/10.1364/OE.19.014018DOI Listing
July 2011

Observation of stimulated Brillouin scattering in polymer optical fiber with pump-probe technique.

Opt Lett 2011 Jun;36(12):2378-80

Precision and Intelligence Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.

Stimulated Brillouin scattering (SBS) in a perfluorinated graded-index polymer optical fiber (POF) with 120 μm core diameter was experimentally observed for the first time, to the best of our knowledge, at 1.55 μm wavelength with the pump-probe technique. Compared to spontaneous Brillouin scattering previously reported, the Brillouin gain spectrum (BGS) was detected with an extremely high signal-to-noise ratio, even with a short POF (1 m) and scrambled polarization state. We also investigated the BGS dependences on probe power and temperature, which indicate that SBS in a POF measured with this technique can be utilized to develop high-accuracy temperature sensing systems.
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http://dx.doi.org/10.1364/OL.36.002378DOI Listing
June 2011

GI-core polymer parallel optical waveguide with high-loss, carbon-black-doped cladding for extra low inter-channel crosstalk.

Opt Express 2011 May;19(11):10931-9

Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokoham 223-8522, Japan.

Graded-index (GI) polymer parallel optical waveguides with high-absorption, carbon-black-doped cladding are fabricated using the preform method in order to reduce the inter-channel crosstalk. The waveguides exhibit a lower inter-channel crosstalk (<-69.3 dB) than optically-transparent-clad waveguides (~-33.7 dB) and maintain low propagation loss (0.029 dB/cm). We characterize the waveguides with different concentration of carbon black in order to confirm the required concentration (required absorption loss) for keeping the inter-channel crosstalk low enough. In addition, carbon-black-doped waveguides are fabricated directly on a substrate by means of a soft-lithography method. Crosstalk is sufficiently decreased despite the high scattering loss of the core material, while insertion loss is not increased. Furthermore, we fabricate a waveguide with a high-scattering-loss cladding to confirm the origin of low crosstalk in carbon-black-doped waveguides. We confirm that high scattering loss of cladding is not necessarily as effective for crosstalk reduction as high absorption loss of cladding.
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http://dx.doi.org/10.1364/OE.19.010931DOI Listing
May 2011

Polymer optical waveguide with multiple graded-index cores for on-board interconnects fabricated using soft-lithography.

Opt Express 2010 Jun;18(13):14191-201

Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, Kohoku-ku, Yokohama, Japan.

We successfully fabricate a polymer optical waveguide with multiple graded-index (GI) cores directly on a substrate utilizing the soft-lithography method. A UV-curable polymer (TPIR-202) supplied from Tokyo Ohka Kogyo Co., Ltd. is used, and the GI cores are formed during the curing process of the core region, which is similar to the preform process we previously reported. We experimentally confirm that near parabolic refractive index profiles are formed in the parallel cores (more than 50 channels) with 40 microm x 40 microm size at 250-microm pitch. Although the loss is still as high as 0.1 approximately 0.3 dB/cm at 850 nm, which is mainly due to scattering loss inherent to the polymer matrix, the scattering loss attributed to the waveguide's structural irregularity could be sufficiently reduced by a graded refractive index profile. For comparison, we fabricate step-index (SI)-core waveguides with the same materials by means of the same process. Then, we evaluate the inter-channel crosstalk in the SI- and GI-core waveguides under almost the same conditions. It is noteworthy that remarkable crosstalk reduction (5 dB and beyond) is confirmed in the GI-core waveguides, since the propagating modes in GI-cores are tightly confined near the core center and less optical power is found near the core cladding boundary. This significant improvement in the inter-channel crosstalk allows the GI-core waveguides to be utilized for extra high-density on-board optical interconnections.
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http://dx.doi.org/10.1364/OE.18.014191DOI Listing
June 2010

High-density channel alignment of graded index core polymer optical waveguide and its crosstalk analysis with ray tracing method.

Opt Express 2010 Jun;18(13):13368-78

Graduate School of Science and Technology, Keio University, Kohoku-ku, Yokohama, Japan.

We fabricate graded index (GI) multi-channel polymer optical waveguides comprised of poly methyl methacrylate (PMMA)-poly benzyl methacrylate copolymer for the purpose of achieving high thermal stability in the GI profiles. The waveguides obtained show slightly higher propagation loss (0.033 dB/cm at 850 nm) than doped PMMA based GI-core polymer waveguides we have reported, due to the excess scattering loss inherent to the mixture of copolymer and homo-polymer in the core area. In this paper, we focus on the influence of the excess scattering loss on mode conversion and inter-channel crosstalk. We simulate the behavior of light propagating inside the core with and without the scattering effect. Using the simulation, the excess loss experimentally observed in the copolymer-core waveguide is successfully reproduced, and then, we find that the excess scattering loss of 0.008 dB/cm could increase the inter-channel crosstalk from -30 dB to -23 dB which agrees with the experimentally observed value. Although the simulation of the inter-channel crosstalk was performed only on our GI-core polymer optical waveguides, it is capable of modeling the conventional SI rectangular-core waveguides. Some amount of excess scattering is generally observed in the conventional SI-core waveguides, and thus, the application of this simulation to SI-core waveguides allows a feasible design for high-density alignment of the waveguides.
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http://dx.doi.org/10.1364/OE.18.013368DOI Listing
June 2010

Carbon nanotube-doped polymer optical fiber.

Opt Lett 2009 Oct;34(20):3077-9

Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University,3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.

We present a method to fabricate graded-index multimode polymer optical fibers doped with carbon nanotubes (CNTs). Such fiber structures provide the means to fully utilize the exceptional optical properties of the CNTs. The core region of the fiber is composed of CNTs and polymethyl methacrylate (PMMA) with the addition of diphenyl sulfide (DPS), which acts as the dispersion stabilizer of CNTs in PMMA as well as the dopant to increase the refractive index of the core. Utilizing 2.5 cm of the fiber as a saturable absorber, passively mode-locked lasing with duration of 3.0 ps and repetition rate of 30.3 MHz was demonstrated.
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http://dx.doi.org/10.1364/OL.34.003077DOI Listing
October 2009

Polymer parallel optical waveguide with graded-index rectangular cores and its dispersion analysis.

Opt Express 2009 Aug;17(18):15959-68

Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.

A low-loss and high-bandwidth polymer parallel optical waveguide with graded-index (GI) rectangular cores is fabricated for high-speed and high-dense optical interconnections. We demonstrate that the near-parabolic index profile formed in the rectangular-shaped core GI waveguide exhibits superior properties similar to those of GI circular core waveguides we previously reported. In particular, we focus on the modal dispersion in the GI polymer waveguides with rectangular cores by showing experimental results. In this paper, the GI rectangular cores are fabricated using the preform method. However, conventional photo-lithography and imprinting processes are viable to fabricate a similar waveguiding structure, by which fabrication of a printed circuit board embedding this waveguide would become feasible.
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http://dx.doi.org/10.1364/OE.17.015959DOI Listing
August 2009

Fabrication of Carbon nanotube poly-methyl-methacrylate composites for nonlinear photonic devices.

Opt Express 2008 Jul;16(15):11337-43

Department of Electronic Engineering, The University of Tokyo, Tokyo, Japan.

Carbon nanotubes (CNT) are an attractive material for photonic applications due to their nonlinear optical properties, such as the nonlinear saturable absorption and high third order nonlinearity. However their utilization has been hindered by the lack of flexibility on the device design which rises from the current methods of Carbon nanotube deposition within the optical system. A suitable approach to solve this problem is to embed the CNTs in an optical material from which complex devices such as optical waveguides or optical fibers can be fabricated. Here, we propose a novel method to fabricate Carbon nanotube-doped poly-methyl-methacrylate (PMMA) composites in which the Carbon nanotubes are dispersed in the methyl-methacrylate (MMA) monomer solution prior to and during the polarization process. This method allows the bundle separation and dispersion of the CNT in a liquid state without the need for solvents, hence simplifying the method and facilitating the fabrication of volume CNT-PMMA. Volume fabrication makes this technique suitable for the fabrication of CNT-doped polymer fibers. In this paper, we also analyzed the merits of adding dopants such as diphenyl sulfide (DPS) and benzyl benzoate (BEN) to the CNT-PMMA composite and we observed that DPS plays the role of CNT dispersion stabilizer that can improve the device performance. The CNT-PMMA composite was employed to implement passive mode-locked laser.
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http://dx.doi.org/10.1364/oe.16.011337DOI Listing
July 2008

Polymer waveguide with 4-channel graded-index circular cores for parallel optical interconnects.

Opt Express 2007 Apr;15(9):5843-50

A polymer waveguide with 4-channel graded-index circular cores is fabricated by the preform method. Very low loss (0.028 dB/cm at a wavelength of 850 nm) and high bandwidth (83 Gbps for 1 m, estimated) properties are experimentally demonstrated by the new waveguide for the first time. By densely aligning the cores during the preform fabrication, a waveguide with a pitch size of 56 mum and a core diameter of 50 mum is obtained, which is expected to be utilized in high-speed and high-density parallel optical interconnections.
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http://dx.doi.org/10.1364/oe.15.005843DOI Listing
April 2007
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