論文 - 石榑　崇明

Tactile Pressure Sensor Based on Flexible Polymer Optical Waveguides Fabricated by the Mosquito Method

Yin Y., Ishigure T.

2023 IEEE CPMT Symposium Japan, ICSJ 2023    176 - 179 2023年

　概要を見る

In this paper, a polymer-based optical waveguide sensor is created to address several issues in optical fiber-based sensors. The unique feature of our optical waveguide is its 3-D core arranged design fabricated using the Mosquito method to which poly dimethyl siloxane (PDMS) is applied as the cladding for a flexible tactile sensor. The core monomer is dispensed into the PDMS monomer to have a 3D lattice structure. We demonstrate that the fabricated waveguide sensors exhibit a high repeatability of the pressure sensing. We find that the measurement range is from 0 MPa to 0.164 MPa when an organic inorganic hybrid resin, NP-C01-KO is used as the main core material. By examining the effect of the numerical aperture and the core size on the sensitivity, we confirm that bending loss could cause the output power variation when a load is applied to the sensor.

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Structural Investigation of Rare-Earth Metal Polymer Composite Doped Optical Amplifiers for Higher Gain

Ono K., Ishigure T.

2023 IEEE CPMT Symposium Japan, ICSJ 2023    125 - 126 2023年

　概要を見る

Embedded optical waveguides with a circular core doped with europium (Eu)-aluminum (Al) polymer composite are fabricated using the Mosquito method, and the relationship between the core diameter and amplification gain is investigated. Further increase in gain is expected by setting up the amplification measurement system appropriately for waveguides with large core diameters.

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Polymer Optical Waveguide Type 3-D MUX Device for Mode Division Multiplexing Links

Ichinose R., Kowatari T., Ishigure T.

2023 IEEE CPMT Symposium Japan, ICSJ 2023    208 - 211 2023年

　概要を見る

Using the Mosquito method, we fabricate waveguides with 3-dimensionally arranged cores to be applied to a MUX device for mode-division multiplexing technology. Applying the developed MUX, the different higher-order modes, LP11a and LP11b in one few-mode fiber core can be individually excited.

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Polymer Optical Waveguide Type 3-D MUX device for Mode Division Multiplexing Links

Ichinose R., Kowatari T., Ishigure T.

Proceedings - Electronic Components and Technology Conference 2023-May   1804 - 1808 2023年

ISSN  05695503

　概要を見る

In this paper, we fabricate a polymer optical waveguide with 3-dimensional core arrangement applicable to a MUX device for mode-division multiplexing technology. We apply the Mosquito method that we developed as a fabrication technique to fabricate single-mode and multimode polymer optical waveguides with circular cores. Because of the unique fabrication procedures of the Mosquito method, 3-dimensional core arrangement is possible, and thus a polymer optical waveguide with a functionality of MUX devices that can launch all the propagating modes in a few-mode fiber (FMF) can be fabricated. We emphasize that the different higher-order modes, LP11aand LP11b in one core could be individually excited using the fabricated waveguide type MUX devices.

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Polymer Optical Waveguide Coupler with Vertically Bent Cores

Itaru N., Kohmu N., Ishigure T.

2023 IEEE CPMT Symposium Japan, ICSJ 2023    89 - 92 2023年

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In this paper, polymer optical waveguides with 90-degree bent GI cores are fabricated using the Mosquito method. Material combinations that allow the formation of GI cores even with a diameter as large as 70 ?m are screened. By further adjusting the interim time, the desired parabolic GI core can be fabricated to realize a low-loss coupling device.

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Low Loss Design and Fabrication for Tapered Waveguide Based Spot Size Converter

Kondo F., Furuta Y., Kaneda H., Fujii T., Ishigure T.

2023 IEEE CPMT Symposium Japan, ICSJ 2023    168 - 171 2023年

　概要を見る

In this paper, propagating mode analysis is performed to optimize the core cross-sectional shape of polymer optical waveguide to be applied to a low loss adiabatic coupler to Si photonics chips when it is fabricated using the Mosquito method.

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Error-Free Three-Dimensional Multimode Crossover Graded-Index Polymer Waveguides for Board-Level Optical Circuitry

Rasel M.O.F., Yamauchi A., Ishigure T.

Journal of Lightwave Technology 40 （ 19 ） 6465 - 6473 2022年10月

ISSN  07338724

　概要を見る

In this paper, we experimentally introduce a low-loss 3-dimensional (3D) symmetric crossover multimode optical waveguides realized with parabolic graded-index (GI) profiles using the Mosquito method. This compact crossover multimode waveguide is comprised of two S-bend core groups (6 Ch. × 6 Ch.), where the last six cores cross over the first six cores, maintaining a height gap at the crossover section to avoid the smudging from needle scan. The suitable height gap for this crossover multimode structure is 0.7 mm. The insertion loss of this multimode crossover waveguide is 1.64 dB at 850 nm wavelength. The insertion losses of this multimode crossover waveguide are compared with separately fabricated 3D S-bend waveguides, and it indicates that multimode crossover structures do not exhibit remarkable excess loss. The interchannel crosstalk of this waveguide is less than -45 dB. This crossover multimode waveguide demonstrates sharply open optical and electrical eye diagrams and transmits error-free data at 26 Gb/s.

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Formation of 3D Polymer Optical Waveguides

Yakabe S., Manabe K., Sasaki D., Ishigure T.

SEI Technical Review  （ 95 ） 5 - 10 2022年10月

ISSN  13434349

　概要を見る

The Mosquito method, a polymer optical waveguide fabrication method invented by Professor Ishigure at Keio University, enables the three-dimensional (3D) formation of core patterns in cladding using a commercially available micro dispenser and a multi-axis syringe-scanning robot. This fabrication method is expected to be used to realize devices required for 3D waveguides such as Fan-in/Fan-out (FIFO) devices, which are essential for the introduction of multicore fibers (MCF). On the other hand, prior studies have mainly examined multimode waveguides, and several issues need to be solved for making single-mode devices. In particular, the core shape tends to deteriorate from circular due to monomer flow caused by needle scanning in the cladding, which is a factor that increases the connection loss with the optical fiber. This paper presents a theoretical and experimental study on the fabrication of single-mode waveguides by the Mosquito method and the formation of circular cores using the method to reduce connection loss with single-mode optical fibers.

Fabrication of Y-Branched GI Core Polymer Waveguide and its Application to CWDM MUX Device for Multimode Fiber

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

Journal of Lightwave Technology 40 （ 9 ） 2915 - 2925 2022年05月

ISSN  07338724

　概要を見る

This paper describes the characteristics of graded-index (GI) core Y-branched polymer optical waveguides as optical couplers for multimode fibers (MMFs) in coarse wavelength division multiplexing links with a restricted mode launch function. In this paper, we compare two GI-core Y-branched waveguides fabricated using different methods: the Mosquito method and the imprint method. Error free transmission is confirmed when transmitting a 25.6125-Gbps NRZ optical signal (PRBS31) at 850-nm wavelength through a 100-m long OM3 fiber using the waveguide as an optical coupler. We also discuss the function of a restricted mode launch exciter for a 1-km long MMF. From the effective modal bandwidth analysis, realizing higher bandwidth-distance product in long MMFs should be possible by reducing the core size of the waveguide coupler.

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90°-bent graded-index core polymer waveguide for a high-bandwidth-density VCSEL-based optical engine

Kohmu N., Ishii M., Hatai R., Ishigure T.

Optics Express 30 （ 3 ） 4351 - 4364 2022年01月

　概要を見る

In this paper, we present a low-loss optical assembly utilizing a 90°-bent graded-index (GI) core polymer optical waveguide on vertical cavity surface emitting laser (VCSEL) based optical transceivers. The proposed assembly can replace conventional components such as mirrors and lenses for realizing subminiature optical engines applicable to on-board integration. To minimize the total insertion loss of the waveguide when connected to a high-speed VCSEL and a GI-core multimode fiber (MMF) at each end, the characteristics of the beam emitted from VCSELs are measured and taken into consideration for the waveguide design. In order to confirm the effect of insertion loss reduction by the waveguide numerical aperture control, 90°-bent GI-core polymer waveguides are fabricated applying the Mosquito method. The fabricated waveguide exhibits a total insertion loss as low as about 2 dB at 850-nm wavelength, which includes the coupling losses at both ends, bending, and propagation losses. We also investigate a way to reduce the insertion loss when a gap exists between the waveguide and VCSEL chip. We theoretically and experimentally confirm that filling the gap with a high index resin can reduce the coupling loss by 5 dB.

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Fabrication for single/few-mode Y-branch waveguide using the Mosquito method

Hatai R., Hama H., Ishigure T.

Optics Express 30 （ 3 ） 3524 - 3537 2022年01月

　概要を見る

In this paper, Y-branched circular core single-mode/few-mode polymer optical waveguides are designed and fabricated using the Mosquito method we have developed. They comprise a low loss multiplexing (MUX) device for mode division multiplexing. In the Mosquito method, since a liquid core monomer is dispensed into another liquid cladding monomer while the needle scans along the path of the wiring patterns, it was difficult to form in-plane core crossings and core branches. In this paper, to form single-mode/few-mode Y-branched cores, we apply a unicursal needle-scan path for the Y-branch structure with the Mosquito method. For MUX device applications, cores satisfying the single-mode condition are successfully formed on the two-port side while the one-port side has a few-mode core.

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High-Density Electrical and Optical Assembly for Subminiature VCSEL-Based Optical Engine

Kohmu N., Ishii M., Ishigure T.

IEEE Transactions on Components, Packaging and Manufacturing Technology 12 （ 1 ） 27 - 36 2022年01月

ISSN  21563950

　概要を見る

In this article, we propose a subminiature (10.9 mm $\times56.6$ mm) vertical cavity surface-emitting laser (VCSEL)-based optical engine with a low crosstalk penalty for onboard applications. When applying optical engines to onboard interconnects, ICs [laser drivers and transimpedance amplifiers (TIAs)] and active optical devices (light sources and photodetectors) must be mounted densely to make the footprint as small as possible. It is a concern that such a high-density integration could increase the crosstalk between transmitter (Tx) and receiver (Rx) devices, which could be caused by the supply current difference between the circuit from laser drivers to light source and the circuit from photodetectors to TIAs. In this article, by inserting a gap in the ground electrode, a compact optical engine (less than half of the footprint of quad small form-factor pluggable-double density (QSFP-DD) compliant engines) enabling a 25.78-Gb/s error-free optical transmission is successfully fabricated. We optimize the gap width to decrease the crosstalk while maintaining efficient heat dissipation via the electrode. We compare the characteristics of the fabricated optical engine to the engine with the gap-less ground electrode structure formed in the same compact size. Then, we both theoretically and experimentally confirm a link power budget savings of about 1.8 dB, which is sustained even under high-temperature ( $T_{c} = 70\,\,^{\circ }\text{C}$ ) operation. In addition, to realize further high-density assembly, we also represent a lens-less optical coupling by inserting a 90o-bent graded-index (GI) core polymer waveguide between the optical transmitter and multimode fiber. The transmission performance of the 90o-bent GI-core waveguide is preliminarily evaluated, and we successfully transmit 53.125-Gb/s PAM4 optical signals experimentally.

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Design and Fabrication of Three-dimensional Polymer Optical Waveguide-based Fan-in/out Device for Multicore Fibers

Yamaguchi Y., Yakabe S., Ishigure T.

2022 European Conference on Optical Communication, ECOC 2022 2022年

　概要を見る

In this paper, a compact (10-mm long) and low-loss fan-in/-out polymer waveguide is successfully fabricated using the Mosquito method, in which four cores three-dimensionally vary their arrangemnent from one end to the other and they are precisely aligned to couple to a multicore fiber.

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Design and Fabrication of Three-dimensional Polymer Optical Waveguide-based Fan-in/out Device for Multicore Fibers

Yamaguchi Y., Yakabe S., Ishigure T.

2022 IEEE CPMT Symposium Japan, ICSJ 2022    41 - 44 2022年

　概要を見る

Compact and low-loss fan-in/-out waveguides are successfully fabricated using the Mosquito method, in which four cores vary their arrangement three-dimensionally from one end to the other and they are precisely aligned to couple to multicore fibers.

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90-degree bent core polymer optical waveguide coupler for low loss lens-less light coupling between laser / photodetector and fiber

Suemori D., Ishii M., Kohmu N., Ishigure T.

Proceedings - Electronic Components and Technology Conference 2022-May   436 - 440 2022年

ISSN  05695503

　概要を見る

In this paper, we present direct fabrication of vertically 90-degree bent core polymer optical waveguide couplers to be integrated in optical engines enabling lens-less light coupling between laser source / photodetector and fiber with low loss. We apply the Mosquito method that we developed as a fabrication technique for single-mode and multimode polymer optical waveguides with circular cores. Because of the unique fabrication procedures of the Mosquito method, three-dimensional core alignment is possible, and thus 90° bent core can be formed directly on a laser chip. We would like to emphasize that the bending radius as small as 2 mm or less could be formed, while the insertion loss of the waveguide is as low as 5 dB.

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Fabrication for Circular Cross-Sectional Microchannels and Their Application for On-off Valves

Uehara K., Hori Y., Ishigure T.

2022 IEEE CPMT Symposium Japan, ICSJ 2022    119 - 122 2022年

　概要を見る

Polymer microchannels with circular cross-sections for on-off valves are designed and fabricated using the Mosquito method. By demonstrating liquid-flow and by applying load to the fabricated microchannels, we confirm that the microchannels appropriately close to stop flowing the liquid as an on-off valve.

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Single-mode polymer waveguide for fan-in/fan-out of multicore fiber by the mosquito method

Yakabe S., Ishigure T.

Proceedings of SPIE - The International Society for Optical Engineering 12007 2022年

ISSN  0277786X

　概要を見る

In this paper, in order to apply to optical connection components such as fan-in-fan-out (FIFO) devices for multicore fibers (MCFs), we design polymer optical waveguides with circular cores satisfying the single-mode condition, which are fabricated using the Mosquito method, and experimentally demonstrate that the optimum S-shape bent core waveguide can be fabricated as designed. The Mosquito method is a technique we have developed to form circular cores in both multimode and single-mode waveguides using a commercially available microdispenser and multi-axis syringe scanning robot. We have demonstrated that single-mode waveguides fabricated by the Mosquito method can be coupled with SMF with low loss. However, in order to realize a waveguide type FIFO device for MCFs by the Mosquito method, it is necessary to maintain micron-order positioning accuracy for the cores while three dimensionally aligning multiple cores in FIFO patterns. Since the pitch between the cores on the MCF side is very narrow, the core position is likely to deviate from the design value due to the liquid monomer flow caused by needle scan. We statistically confirm the possible amount of deviation from the design position by needle scan and feed it back to the program of needle scan path for the FIFO. We successfully fabricate a four-core FIFO with a desired core pitch. It is experimentally confirmed that the insertion loss is 1.4 dB on average. From these investigations, we confirm that the Mosquito method has an ability to fabricate small and low-loss FIFO devices.

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Investigation of fabrication conditions for Y-branched polymer optical waveguides using the Mosquito method

Sekitani K., Hatai R., Ishigure T.

2022 IEEE CPMT Symposium Japan, ICSJ 2022    100 - 101 2022年

　概要を見る

In this paper, the conditions for fabricating Y-branched optical waveguides using the Mosquito method are discussed, focusing on the viscosity of the monomer and the branch angle. With increasing the viscosity of core monomer, the Y-branching structures tend to be distorted particularly when the branching angle is larger than 0.5 degree. After finding out the appropriate fabrication conditions, Y-branched optical waveguides in which two-port cores are vertically stacked are fabricated, taking the advantage of the Mosquito method: the ability to form three-dimensional core wiring patterns. Single-mode and multimode cores are successfully formed in which we could confirm the light propagation.

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GI-core Multimode and Single-mode Polymer Waveguides for High-density Co-packaging

Ishigure T.

2022 Optical Fiber Communications Conference and Exhibition, OFC 2022 - Proceedings 2022年

　概要を見る

We present unique polymer optical waveguide coupler devices fabricated using the Mosquito method to apply for adiabatic coupling with Si photonics chips, three-dimensional fan-in/fan-out devices for multicore fibers, and MUX devices for mode division multiplexing.

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GI-core Multimode and Single-mode Polymer Waveguides for High-density Co-packaging

Ishigure T.

Optics InfoBase Conference Papers 2022年

　概要を見る

We present unique polymer optical waveguide coupler devices fabricated using the Mosquito method to apply for adiabatic coupling with Si photonics chips, three-dimensional fan-in/fan-out devices for multicore fibers, and MUX devices for mode division multiplexing.