Papers - Ishigure, Takaaki

Fabrication for Single-Mode Core Fan-in/Out Polymer Optical Waveguide using the Mosquito Method

Matsui H., Yakabe S., Ishigure T.

2019 IEEE 2nd British and Irish Conference on Optics and Photonics, BICOP 2019 (2019 IEEE 2nd British and Irish Conference on Optics and Photonics, BICOP 2019)   2019.12

ISSN  9781728149486

　View Summary

© 2019 IEEE. We have developed the Mosquito method for fabricating polymer optical waveguides. By using the Mosquito method, three-dimensional array of circular cores with graded-index (GI) profile can be formed. In this paper, to realize an effective coupling element for multicore fibers (MCF) and singlemode fibers, fan-in/out polymer optical waveguides are focused. For low-loss fan-in/out waveguide, the Mosquito method is applied where the fabrication conditions are investigated to improve the optical properties in multiple cores. Furthermore, fan-in/out structure for 7-core MCF is successfully fabricated.

• Access to Document (DOI)

Fabrication for Single-Mode Tapered Optical Waveguides for Spot-Size-Converter

Kobayashi Y., Sakaguchi Y., Ishigure T.

2019 IEEE 2nd British and Irish Conference on Optics and Photonics, BICOP 2019 (2019 IEEE 2nd British and Irish Conference on Optics and Photonics, BICOP 2019)   2019.12

ISSN  9781728149486

　View Summary

© 2019 IEEE. For low-loss connection between silicon waveguides and conventional single-mode fibers, single-mode tapered polymer optical waveguides are fabricated using the Mosquito method, which work as a spot-size converter (SSC). In this research, the axially tapered shaped core is formed by accelerating the needle scan during the core dispense. In addition, the degradation of cross-sectional core shape from circle to ellipse is addressed by using a curved needle. The fabricated 12-mm long tapered waveguide with perfect circular core cross section exhibits an effective MFD conversion from 4.1 μm to 8.1 μm.

• Access to Document (DOI)

Simulation of refractive index profile formed in polymer optical waveguides fabricated using the Mosquito method

Sakaguchi Y., Ishigure T.

2019 IEEE CPMT Symposium Japan, ICSJ 2019 (2019 IEEE CPMT Symposium Japan, ICSJ 2019)     145 - 146 2019.11

ISSN  9781728109787

　View Summary

© 2019 IEEE. In polymer optical waveguides fabricated using the Mosquito method, the diffusion occurs between the core and cladding monomers during the interim time that is from the moment that the liquid core monomer is dispensed to when the UV curing begins, and a graded-index type refractive index profile is formed in the core. In this paper, the diffusion coefficient of monomer is measured. Then, a diffusion simulation model is created, which can calculate the concentration distribution of monomer using the diffusion coefficient that depends on the monomer concentration. Finally, the refractive index profiles formed in the cores are simulated and the output near-field patterns are theoretically estimated to evaluate the core diameter and numerical aperture dependences on the interim time.

• Access to Document (DOI)

A 53-Gbit/s/ch Active Optical Cable Utilizing GI Polymer Waveguide for High-density On-board Optical Interconnects

Kohmu N., Ishii M., Ishigure T.

2019 IEEE CPMT Symposium Japan, ICSJ 2019 (2019 IEEE CPMT Symposium Japan, ICSJ 2019)     31 - 34 2019.11

ISSN  9781728109787

　View Summary

© 2019 IEEE. In this paper, we propose a low loss and cost-effective assembly in optical transceiver for on-board applications by applying graded-index (GI) core polymer waveguides to effectively couple the signal light between light sources/photodetectors and multimode fibers (MMFs). In order to satisfy the requirements for higher bandwidth data transmission, on-board optical interconnects have been anticipated in datacenter networks. When applying active optical cables (AOCs) to the on-board interconnects, the assembly density between optical devices and fibers is an important issue. Hence, polymer optical waveguides with densely aligned cores are one of the promising candidates to be an interface between the active components and fibers. In this paper, GI circular core polymer optical waveguides are applied to the onboard wiring. We demonstrate the ability of GI core waveguide to achieve low-loss coupling with optical transceivers due to tightly confined optical field in the core. Furthermore, we propose to utilize the lens function of GI core in the transceiver assembly. We theoretically demonstrate that the GI core enables to improve the coupling efficiency by 0.6 dB as a cylindrical lens. Meanwhile, by just inserting a perpendicularly bent GI core waveguide between an optical transmitter and an MMF, we successfully transmit a 53.125-Gbit/s PAM4 optical signals experimentally.

• Access to Document (DOI)

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 2019.11

ISSN  9781728109787

　View Summary

© 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.

• Access to Document (DOI)

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 2019.11

ISSN  9781728109787

　View Summary

© 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.

• Access to Document (DOI)

Fabrication for polymer microchannels with circular cross-section using photo-curable PDMS

Nakazawa R., Ishigure T.

2019 IEEE CPMT Symposium Japan, ICSJ 2019 (2019 IEEE CPMT Symposium Japan, ICSJ 2019)     119 - 122 2019.11

ISSN  9781728109787

　View Summary

© 2019 IEEE. In this paper, microchannels with circular cross-sections are fabricated using the Mosquito method in order to mimic microvascular networks. We experimentally confirm that microchannels with straight and Y-branched channel patterns are fabricated by applying photo curable PDMS(poly dimethyl siloxane) to the Mosquito method. Compared to our previous trials with heat-curable PDMS, the photo-curable PDMS allows to fabricate the microchannels in one-third of curing time. Finally, liquid flow in the fabricated Y-branched microchannels is confirmed by flowing water with red-colored pigment: the water with pigment is injected to a channel from the two-port side and the state of the liquid flow in the microchannel is observed.

• Access to Document (DOI)

MMF Exciter Composed of Graded-Index Core Polymer Optical Waveguide Fabricated Applying the Mosquito Method and the Imprint Method

Hatai R., Nakazaki F., Nakayama T., Ishigure T.

2019 IEEE CPMT Symposium Japan, ICSJ 2019 (2019 IEEE CPMT Symposium Japan, ICSJ 2019)     133 - 134 2019.11

ISSN  9781728109787

　View Summary

© 2019 IEEE. In this paper, we evaluate the optical properties of low-loss Y-branched multimode polymer optical waveguide couplers with graded-index (GI) cores fabricated by different methods: the Mosquito method and the imprint method in order to apply them to coarse wavelength division multiplexing (CWDM) transmission. We confirm the low insertion loss of those waveguides regardless of fabrication method in a wavelength range from 850 to 1060 nm for CWDM. Furthermore, we succeeded in transmitting a 26 Gbps signal through the GI waveguide at 850-nm wavelength.

• Access to Document (DOI)

Polarization dependence analysis of polymer optical waveguides

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

2019 IEEE CPMT Symposium Japan, ICSJ 2019 (2019 IEEE CPMT Symposium Japan, ICSJ 2019)     183 - 186 2019.11

ISSN  9781728109787

　View Summary

© 2019 IEEE. The polarization-dependent optical properties of single-mode polymer optical waveguides are experimentally investigated. We apply the two fabrication methods for single-mode polymer optical waveguides: the direct curing method and the Mosquito method, and compare the optical properties of step-index square-core waveguides and graded-index circular-core waveguides fabricated by the above two methods, respectively.

• Access to Document (DOI)

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 2019.05

ISSN  9781728114989

　View Summary

© 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.

• Access to Document (DOI)

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 2019.04

　View Summary

© 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.

• Access to Document (DOI)

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)   2019.03

ISSN  9781538673614

　View Summary

© 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.

• Access to Document (DOI)

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)   2019.03

ISSN  9781538673614

　View Summary

© 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.

• Access to Document (DOI)

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)   2019.03

ISSN  9781538673614

　View Summary

© 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.

• Access to Document (DOI)

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 2019.01

ISSN  9781538654422

　View Summary

© 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.

• Access to Document (DOI)

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 2019.01

ISSN  9781538654422

　View Summary

© 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.

• Access to Document (DOI)

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 2019.01

ISSN  9781538654422

　View Summary

© 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.

• Access to Document (DOI)

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 2019.01

ISSN  9781538654422

　View Summary

© 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.

• Access to Document (DOI)

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 2019.01

ISSN  9781538654422

　View Summary

© 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.

• Access to Document (DOI)

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 2019.01

ISSN  9781538654422

　View Summary

© 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.

• Access to Document (DOI)