研究者詳細 - 石榑　崇明

論文 - 石榑　崇明

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Design and Fabrication of Y-branched Polymer Waveguide based Optical Coupler

Hatai R., Hama H., Ishigure T.

2021 IEEE CPMT Symposium Japan, ICSJ 2021 184 - 197 2021年

We propose multiplexer devices in short wavelength range wavelength division multiplexing (SWDM) and mode division multiplexing (MDM) systems as applications of graded-index core Y-branched polymer waveguides. We demonstrate 25-Gbps optical signal transmissions at wavelengths of 850 nm and 1060 nm over an MMF via a Y-branched waveguide as an SWDM multiplexer (MUX) device. For an MDM MUX device, a few-mode scale asymmetric Y-branched waveguide is experimentally fabricated and the optical fields of multiple modes transmitted in the waveguide are confirmed.

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Multiplexing Coupler Realized with Y-branched GI Core Polymer Optical Waveguide for Mode Division Multiplexing in a 50-μm Multimode Fiber

Hatai R., Ishigure T.

Proceedings - Electronic Components and Technology Conference 2021-June 1682 - 1688 2021年

ISSN 05695503

In this paper, a novel structure for a multimode Y-branched polymer waveguide type multiplexer (MUX) device for mode division multiplexing (MDM) is proposed. Since the insertion loss of GI core Y-branched waveguides remains low even with the tilted launch beam or a small size of cross-sectional core, we have proposed asymmetric Y-branched MUX device which has different core size at the end of two-port arm. In this paper, we investigate the optimum structure of the asymmetric Y-branched waveguides MDM MUX device using a beam propagation simulation.

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Multimode Interference based Y-Branch Polymer Optical Waveguide Splitter: Design and Investigation

Alam M.K., Afsary N., Rasel M.O.F., Ishigure T.

Proceedings of International Conference on Electronics, Communications and Information Technology, ICECIT 2021 2021年

We demonstrate multimode interference (MMI)-based Y-branch single-mode step-index (SI) core polymer optical waveguide splitter for the development of optical circuitry. This polymer waveguide splitter consists of a single input and multiple (six) outputs realized with organic-inorganic hybrid polymer materials. We set the core width for input and outputs of this polymer waveguide splitter as a single-mode, where the core width is particularly 6.5 mumathrm{m}. We design and demonstrate this Y-branch waveguide splitter using the beam propagation method at 1550-nm wavelength following the self-imaging principle. The power efficiency of this MMI-based Y-branch polymer waveguide splitter is 71%, and the excess loss is 1.4 dB.

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High-efficiency optical coupling between VCSEL and 90-degree-bent Graded-Index Core Polymer Waveguide with Numeral Aperture Optimization

Kohmu N., Ishii M., Ishigure T.

2021 IEEE CPMT Symposium Japan, ICSJ 2021 150 - 153 2021年

In this paper, we propose a higher efficiency optical coupling technique using 90-degree-bent Graded-Index (GI) core polymer waveguide which replaces conventional optical assembly (mirrors and lenses) in vertical cavity surface emitting laser (VCSEL) based optical engines. The 90-degree-bent GI-core polymer waveguides are fabricated using the Mosquito method. However, high coupling loss could be caused by the VCSEL beam divergence due to diffraction in the lens free coupling. We theoretically confirm that total insertion loss including bending loss as well as coupling loss could remain low by the waveguide NA control. Fabricating the 90-degree-bent GI-core polymer waveguides with the optimized NA, a waveguide insertion loss as low as about 2 dB is experimentally achieved.

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Development of 3-Dimensional Single-mode Core Over-Crossing Polymer Optical Waveguides Using the Mosquito Method

Rasel M.O.F., Ishigure T.

2021 IEEE CPMT Symposium Japan, ICSJ 2021 188 - 191 2021年

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

Kimura T., Takasaki M., Hatai R., Nagai Y., Uematsu K., Oaki Y., Osada M., Tsuda H., Ishigure T., Toyofuku T., Shimode S., Imai H.

Scientific Reports （Scientific Reports） 10 （ 1 ） 2020年12月

© 2020, The Author(s). 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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Polarization Dependence of Optical Properties of Single-Mode Polymer Optical Waveguides Fabricated under Different Processes at 1310/1550 nm

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

Journal of Lightwave Technology （Journal of Lightwave Technology） 38 （ 14 ） 3670 - 3676 2020年07月

ISSN 07338724

We experimentally investigate the polarization dependence of the optical properties of single-mode polymer optical waveguides. We compare two types of waveguides composed of the same polymer materials: Step-index square-core waveguides fabricated using the direct curing method and graded-index (GI) circular-core waveguides fabricated using the Mosquito method. We demonstrate that the GI circular-core single-mode waveguides exhibit remarkably small dependence of optical loss on the polarization angle, which is less than 0.1 dB polarization dependent loss (PDL) at both 1310 and 1550 nm wavelengths. This steady polarization property is attributed to the material stress free to the composing polymers during the fabrication process of the Mosquito method and to parabolic GI profile formed in symmetric circular core.

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Investigations on europium aluminum incorporated polymer composite optical waveguide amplifier

Najahatul Huda Saris N., Hamzah A., Sabri S., Ambran S., Mikami O., Ishigure T.

Journal of Physics: Conference Series （Journal of Physics: Conference Series） 1502 （ 1 ） 2020年06月

ISSN 17426588

The gain performance of 50-iun core diameter graded-index (GI) multimode europium aluminum benzyl methacrylate (Eu-Al/BzMA) waveguide was investigated by numerically solving rate and propagation equations using MATLAB. At a fixed waveguide length of 10 cm and gain medium concentration of 13 wt.%, optical gain was found to be dependent on pump power and input signal power. This paper utilized a 532 nm wavelength pump with power varied from 100 mW to 500 mW, together with low (-30 dBm) and high (0 dBm) input signal powers, within the amplification range of 580 to 640 nm wavelength. With the highest pumping power of 500 mW and the lowest input signal power of -30 dBm, a 29-dB optical gain with wavelength of 617 nm was observed from forward pumping amplification. For comparison, an identical waveguide in terms of properties was fabricated through an innovative fabrication method for polymer waveguide - the Mosquito method. The fabricated waveguide was then experimentally tested for -30 dBm input signal power with 200 mW pump power in the attempt to realize future real-world applications of short reach networks such as in Local Area Network (LAN) and in-vehicle optical interconnects.

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Multi-Channel Single-mode Polymer Waveguide Fabricated by the Mosquito Method Realizing Low Connection Loss with Single-mode Optical Fiber Arrays

Yakabe S., Matsui H., Kobayashi Y., Ishigure T.

Proceedings - Electronic Components and Technology Conference （Proceedings - Electronic Components and Technology Conference） 2020-June 156 - 161 2020年06月

ISSN 9781728161808

In this paper, we design a polymer waveguide to satisfy the single-mode condition and fabricate it using the Mosquito method. In order to apply the single-mode waveguides as a connection component with single-mode fibers (SMFs) or with other optical components such as laser / photodetector arrays, there are many issues such as the core shape, the mode-field diameter (MFD) variation, and the accuracy of the core position and pitch.Hence, we experimentally and theoretically demonstrate that the Mosquito method is capable of fabricating polymer optical waveguides with single-mode cores and the above issues on the single-mode connections are addressed in this paper.

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Integrated Optics Europium Aluminum Polymer Optical Waveguide with Graded Index Circular Core

Saris N.N.H., Kadir N.A.A., Hamzah A., Ambran S., Mikami O., Horie T., Ishigure T.

2020 IEEE 8th International Conference on Photonics, ICP 2020 （2020 IEEE 8th International Conference on Photonics, ICP 2020） 20 - 21 2020年05月

ISSN 9781728105185

A Europium Aluminum Benzyl Methacrylate (Eu-Al/BzMA) integrated optical waveguide with 50 μm graded-index multimode circular core is fabricated by applying the Mosquito method for the potential application of optical interconnect. The parabolic index profile of the waveguide core is measured to confirm the profile exhibited by the waveguide. A preliminary experiment of the signal transmission is performed at 26 Gb/s to evaluate its capability in high dense and speed optical interconnections. According to the results, the waveguide successfully demonstrated free bit-error-rate through 5 cm waveguide transmission.

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Optical Amplification in Multiple Cores of Europium Aluminium Composite Incorporated Polymer-Based Optical Waveguide Amplifier by Using Mosquito Method

Saris N.N.H., Hamzah A., Ambran S., Mikami O., Ishigure T., Fukui T.

Lecture Notes in Electrical Engineering （Lecture Notes in Electrical Engineering） 619 25 - 34 2020年

ISSN 9789811512889

© 2020, Springer Nature Singapore Pte Ltd. In this paper, Europium Aluminum Benzyl Methacrylate (Eu–Al/BzMA) optical waveguide amplifier is fabricated with multiple cores of 50 μm diameters by a unique procedure known as the Mosquito method which, utilized a micro-dispenser desktop machine. The waveguides which used the optimum dispensing criteria to fabricate desired core diameter with high precision are then optically tested. The highest optical gain of 1.08 dB/cm with 0.77 dBm/cm insertion loss has been demonstrated in this device at 617 nm amplification wavelength. Suppression of concentration quenching, high compatibility with other materials, ease of fabrication, and low cost make such rare-earth-metal ion-incorporated polymer waveguide amplifiers suitable for providing gain in many integrated optical devices in the communication area.

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Performance of europium Aluminium doped polymer optical waveguide amplifier

Saris N.N.H., Hamzah A., Ambran S., Mikami O., Ishigure T.

Bulletin of Electrical Engineering and Informatics （Bulletin of Electrical Engineering and Informatics） 8 （ 4 ） 1343 - 1350 2019年12月

ISSN 20893191

© 2019 Institute of Advanced Engineering and Science. All rights reserved. In this paper, the graded index (GI) multimode rare-earth metal (RE-M) doped polymer optical waveguide amplifier has been prepared and tested optically. A 10-cm Europium Aluminum Benzyl Methacrylate (EuAl3O3/BzMA)was fabricated via a unique technique known as the “Mosquito Method” which utilizes a micro-dispenser machine. Optical gain from 75 to 150 μm circular core diameter waveguide of 13 wt.% concentration has been demonstrated and measured under forward pumping condition. The cladding monomer deployed in this research is Acrylate resin XCL01, which is a modified photocurable acrylate material. Fundamentally, -30 decibel (dBm) red light signal input and 23 dBm pump power of 532 nm green laser wavelength is implemented within the range of 580 to 640 nm optical amplification wavelength. A maximum gain of 12.96 dB at 617 nm wavelength has been obtained for a 100 μm core diameter of Eu-Al polymer optical waveguide. The effect of different coupler diameter for pumping and the comparison of insertion loss before and after amplification against the performance of the Eu-Al polymer waveguide amplifier are also studied. There exists an optimum core diameter of which the amplifier gain enhancement is at maximum value.

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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年12月

ISSN 9781728149486

© 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.

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Fabrication for Mode Coupling Optical Waveguide using the Mosquito Method

Kowatari T., 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年12月

ISSN 9781728149486

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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年12月

ISSN 9781728149486

© 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.

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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年11月

ISSN 9781728109787

© 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.

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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年11月

ISSN 9781728109787

© 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.

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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年11月

ISSN 9781728109787

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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年11月

ISSN 9781728109787

© 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.

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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年11月

ISSN 9781728109787

© 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.

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