論文 - 石榑　崇明

Applicability of the Mosquito method to fabricate fan-in/out device for single-mode multicore fiber

Matsui H., Yakabe S., Ishigure T.

2019 IEEE CPMT Symposium Japan, ICSJ 2019 （2019 IEEE CPMT Symposium Japan, ICSJ 2019）     63 - 66 2019年11月

ISSN  9781728109787

　概要を見る

© 2019 IEEE. We have proposed the Mosquito method for fabricating polymer optical waveguides. By applying the Mosquito method, three-dimensional multimode and even single-mode graded-index (GI) circular cores can be formed. In this paper, for fabricating low-loss fan-in/out waveguide using the Mosquito method, the fabrication conditions are investigated to improve the uniformity of optical characteristics in multiple cores. Furthermore, the hexagonally arrayed single-mode cores are formed under a precise temperature control.

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Fabrication and Evaluation for Polymer Waveguide Optical Amplifier Incorporated with Rare Earth-Metal Polymer Composite

Horie T., Fukui T., Ishigure T.

2019 IEEE CPMT Symposium Japan, ICSJ 2019 （2019 IEEE CPMT Symposium Japan, ICSJ 2019）     167 - 168 2019年11月

ISSN  9781728109787

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© 2019 IEEE. We fabricate polymer optical waveguide amplifiers with europium (Eu)-aluminum (Al) polymer composite incorporated in their cores applying the Mosquito method. With decreasing the length of the waveguide with a step of 1 cm (cut-back method), the length dependence of the optical gain is measured under signal and pumping light is coupled to the core coaxially. The optical gain tends to increase as the waveguide length increases.

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Y-branched multimode/single-mode polymer optical waveguides for low-loss WDM MUX device: Fabrication and characterization

Ishigure T., Nakayama T., Nakazaki F., Hama H.

Proceedings - Electronic Components and Technology Conference （Proceedings - Electronic Components and Technology Conference）  2019-May   550 - 555 2019年05月

ISSN  9781728114989

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© 2019 IEEE. In this paper, we represent low-loss Y-branched multimode polymer optical waveguides with graded-index (GI) cores applicable to an optical coupler as a MUX device in coarse wavelength division multiplexing links. We apply the Mosquito method as well as the imprint method to form the Y-branched structures in polymers. We experimentally confirm that the insertion loss (including the coupling, propagation, bending, and multiplexing losses) in the multimode GI-core Y-branched waveguide is approximately 1-dB lower than the same Y-branched waveguide with step-index (SI) core. In addition, we also succeeded in fabricating Y-branched single-mode polymer waveguides applying the Mosquito method. In order to satisfy the single-mode condition, the core diameter needs to decrease to 10 mm and less.

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

Morimoto Y., Ishigure T.

Optics Express （Optics Express）  27 （ 8 ） 10839 - 10853 2019年04月

研究論文（学術雑誌）, 共著, 査読有り

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© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement 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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Structural Design and Fabrication for Low Loss Y-branched Polymer Waveguide Coupler Devices

Nakazaki F., Ishigure T.

2018 British and Irish Conference on Optics and Photonics, BICOP 2018 - Proceedings （2018 British and Irish Conference on Optics and Photonics, BICOP 2018 - Proceedings）  2019年03月

ISSN  9781538673614

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© 2018 IEEE. Along with the wide deployment of cloud computing services, the introduction of optical interconnect technology has supported the rapid growth of data throughput in datacenter over the last couple of years. So far, multimode fiber (MMF) links have been widely installed in datacenter networks, hence the limitation of bandwidth distance product of MMF links is a current issue. In the future, wavelength division multiplexing (WDM) transmission technology could be applied even to the MMF links, by which the transmission capacity could increase because multiple optical signals with different wavelengths are multiplexed in one fiber.In, this paper, Y-branched polymer optical waveguide couplers with SI and GI square cores are fabricated using the imprint method in order to apply to a multiplexing (MUX) device in the MMF WDM links. To fabricate low loss MUX devices, three different Y-branch structures are designed and actually fabricated. Then, their optical characteristics are compared. It is confirmed that the loss of GI waveguide is lower than that of SI waveguide, independent of the multiplexing structure, because the light leakage at the multiplexing region (two-cores junction) could be reduced due to the strong light confinement effect.

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Application of the Mosquito Method to Polymer Optical Coupling Devices

Nakamura J., Ishigure T.

2018 British and Irish Conference on Optics and Photonics, BICOP 2018 - Proceedings （2018 British and Irish Conference on Optics and Photonics, BICOP 2018 - Proceedings）  2019年03月

ISSN  9781538673614

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© 2018 IEEE. We develop a fabrication method of polymer optical waveguide in which the cores are aligned in the vertical direction to the substrate. Applying lightwave propagation simulation, several fabrication processes are investigated to realize a low-loss lens-free optical coupler to multimode fibers (MMF). Finally, an about 750-μm long graded-index core is directly formed on a VCSEL chip by which high coupling efficiency between the VCSEL and MMF is attained.

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Application of GI polymer optical waveguide to coupling devices between multimode fiber and VCSEL

Hatai R., Ishigure T.

2018 British and Irish Conference on Optics and Photonics, BICOP 2018 - Proceedings （2018 British and Irish Conference on Optics and Photonics, BICOP 2018 - Proceedings）  2019年03月

ISSN  9781538673614

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© 2018 IEEE. In this paper, required specifications to a polymer waveguide based compact restricted mode launch (RML) device for multimode fibers are investigated. We confirm that a smaller spot size on the MMF launch end is necessary to enhance the effective modal bandwidth (EMBc), whereas a lower numerical aperture does not always allow the high EMBc. In addition, we determine the design guideline of polymer waveguide based RML exciters using the beam propagation method simulation.

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3-Dimensional channel-shuffling single-mode polymer waveguides: Design and fabrication

Rasel O., Ishigure T.

2018 IEEE CPMT Symposium Japan, ICSJ 2018 （2018 IEEE CPMT Symposium Japan, ICSJ 2018）     143 - 144 2019年01月

ISSN  9781538654422

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© 2018 IEEE. This paper introduces 3-dimensional channel-shuffling single-mode circular core polymer optical waveguides for optical printed circuit boards (OPCBs) using the unique fabrication technique, named the Mosquito method. In this waveguide, the fabricated cores are horizontally and vertically bent to have crossover structures, where a height gap between two core layers is added in order to obtain higher wiring density.

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Low-loss single-mode polymer optical waveguides: Comparison between direct-curing and the mosquito methods

Morimoto Y., Hikita M., Matsui H., Fujihara Y., Ishigure T.

2018 IEEE CPMT Symposium Japan, ICSJ 2018 （2018 IEEE CPMT Symposium Japan, ICSJ 2018）     145 - 146 2019年01月

ISSN  9781538654422

　概要を見る

© 2018 IEEE. We experimentally investigate the optical properties of single-mode polymer optical waveguides fabricated using two fabrication methods: The direct curing method and the Mosquito method. We demonstrate the characteristic differences between step-index square core single-mode waveguides and graded-index circular core single-mode waveguides composed of the same polymer materials.

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Fabrication for Y-branched multimode polymer optical waveguides using the Mosquito method

Nakayama T., Ishigure T.

2018 IEEE CPMT Symposium Japan, ICSJ 2018 （2018 IEEE CPMT Symposium Japan, ICSJ 2018）     155 - 158 2019年01月

ISSN  9781538654422

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© 2018 IEEE. In this paper, Y-branched multimode polymer optical waveguides are fabricated using the Mosquito method for applying them to multiplexing (MUX) devices for WDM transmission.

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Graded-index polymer optical waveguide for restricted mode launch device enabling high-bandwidth, longer-reach multimode fiber link

Hatai R., Ishigure T.

2018 IEEE CPMT Symposium Japan, ICSJ 2018 （2018 IEEE CPMT Symposium Japan, ICSJ 2018）     71 - 74 2019年01月

ISSN  9781538654422

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© 2018 IEEE. In this paper, a compact restricted mode launch device for multimode fibers (MMFs) using graded-index polymer optical waveguide is designed and fabricated. We focus on an axially tapered shaped structure and demonstrated that the tapered structure could improve the effective modal bandwidth of MMF. Moreover, the optimum tapered structure is investigated using the beam propagation method simulation.

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Fabrication for organic-inorganic hybrid resin based single-mode polymer optical waveguides using the imprinting method for high density optical circuit

Fujihara Y., Ishigure T.

2018 IEEE CPMT Symposium Japan, ICSJ 2018 （2018 IEEE CPMT Symposium Japan, ICSJ 2018）     125 - 126 2019年01月

ISSN  9781538654422

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© 2018 IEEE. Single-mode polymer optical waveguides applicable to silicon photonics technologies are fabricated using the imprinting method. Organic-inorganic hybrid resins are applied to fabricate the waveguides with low propagation loss at longer wavelengths and with high thermal resistance. The obtained optical waveguides have a graded refractive index distribution, by which the single-mode condition could be satisfied with a larger core size.

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Application of the mosquito method for implementing waveguides on surface emitting light sources

Nakamura J., Ishigure T.

2018 IEEE CPMT Symposium Japan, ICSJ 2018 （2018 IEEE CPMT Symposium Japan, ICSJ 2018）     123 - 124 2019年01月

ISSN  9781538654422

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© 2018 IEEE. We investigate direct implementation of polymer optical waveguides on a chip of surface emitting light sources (VCSEL). After confirming the position accuracy of the core, the core is successfully formed on the chip.

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Direct fabrication for multimode/single-mode polymer optical waveguides on printed circuit board using the mosquito method

Marushima C., Ishigure T.

2018 IEEE CPMT Symposium Japan, ICSJ 2018 （2018 IEEE CPMT Symposium Japan, ICSJ 2018）     159 - 162 2019年01月

ISSN  9781538654422

　概要を見る

© 2018 IEEE. We have proposed the Mosquito method to fabricate polymer optical waveguides with graded-index (GI) circular cores and demonstrated their excellent optical property. We have employed glass substrate which has a smooth surface for the waveguide fabrication using the Mosquito method. However, waveguides integrated on PCBs are expected for the on-board optical interconnection applications. The Mosquito method have a capability to directly fabricate waveguides on PCBs.In this paper, optical waveguides are fabricated on PCBs directly using FR-4 substrates which are a standard PCB. Here, the waveguide facet termination process is very important. Generally, waveguide ends are cut with the PCB using a dicing saw or polished after fabricating the waveguides separately from PCBs. In this paper, we propose a new waveguide facet termination process, which could be involved in the Mosquito method, and report the improvement of coupling efficiency to other optical components because the waveguide ends have sufficiently smooth surfaces.

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Fabrication and evaluation for polymer waveguide coupler devices using the imprint method

Nakazaki F., Ishigure T.

2018 IEEE CPMT Symposium Japan, ICSJ 2018 （2018 IEEE CPMT Symposium Japan, ICSJ 2018）     175 - 178 2019年01月

ISSN  9781538654422

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© 2018 IEEE. For further increase of data rate in multimode fiber (MMF) links widely deployed in datacenters, wavelength division multiplexing (WDM) transmission technology is expected to be introduced. In this paper, we propose a Y-branched polymer waveguide with graded-index core for optical coupler in the MMF WDM links. The low loss structure of the Y-branched polymer waveguide is designed applying BPM simulation, and designed waveguide structures are actually fabricated using an imprint method to confirm their applicability to a low-loss optical coupler in MMF WDM links.

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

Xu X., Ma L., Shi Y., Ishigure T., He Z.

Optics Express （Optics Express）  27 （ 16 ） 22419 - 22428 2019年

　概要を見る

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement 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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Circular core single-mode 3-dimensional crossover polymer waveguides fabricated with the Mosquito method

Rasel O., Ishigure T.

Optics Express （Optics Express）  27 （ 22 ） 32465 - 32479 2019年

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© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement 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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Design and Fabrication of Broadband Polymer Mode (De)Multiplexer Using a Direct Inscribing Method

Xu X., Ma L., Marushima C., Ishigure T., He Z.

IEEE Photonics Journal （IEEE Photonics Journal）  10 （ 6 ）  2018年12月

　概要を見る

© 2009-2012 IEEE. We demonstrate the design and fabrication of a mode (de)multiplexer based on the tapered mode-selective coupler. The proposed device is directly inscribed in the substrate material by a needle-type liquid micro-dispenser and a three-axis robot stage using commercially available UV-curable resins. The fabricated mode (de)multiplexer has an excess loss less than 0.3 dB, a coupling ratio higher than 0.93, and an extinction ratio higher than 23 dB within a broadband of 100 nm around 1550 nm. The near field patterns of LP{11} mode at different wavelengths were successfully observed using an infrared charge-coupled-device camera. The fabrication tolerance on the spacing, core diameter deviation, and core circularity were investigated and the results imply that our fabrication process can satisfy the requirements on it. The proposed method is capable of fabricating functional devices for high-speed on-board optical interconnects.

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Direct Fabrication for Polymer Optical Waveguide in PMT Ferrule Using the Mosquito Method

Ishigure T., Masuda H., Date K., Marushima C., Enomoto T.

Proceedings - Electronic Components and Technology Conference （Proceedings - Electronic Components and Technology Conference）  2018-May   1103 - 1108 2018年08月

ISSN  9781538649985

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© 2018 IEEE. In this paper, we represent an innovative technology for integrating optical devices: direct fabrication for polymer optical waveguide in a PMT ferrule, a ferrule for polymer waveguides connected with a mechanically transferable (MT) connector using the Mosquito method.

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Accurate core alignment for polymer optical waveguide in the mosquito method for high-efficient coupling

Morimoto Y., Date K., Ishigure T.

Proceedings - Electronic Components and Technology Conference （Proceedings - Electronic Components and Technology Conference）  2018-May   2444 - 2449 2018年08月

ISSN  9781538649985

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© 2018 IEEE. We demonstrate the importance of vertical position accuracy of formed core in the polymer optical waveguides fabricated using the Mosquito method for 3-dimensional wiring. We theoretically confirm the core vertical position deviation from the designed position is caused by the several fabrication parameters, the needle size and the needle-scanning speed. As an example of 3-dimensional wiring, we focus on the optical path conversion by 45-degree mirrors, and experimentally investigate the influence of the core vertical position on the coupling efficiency to other components via a 45-degree mirror. By forming the cores on appropriate height in the cladding, graded-index core optical waveguides exhibit a slight loss increment as low as 0.2 dB due to mirror structure, realizing the high efficient coupling via a 45-degree mirror.

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