論文 - 石榑　崇明

Low-loss Subminiature Multimode Branched Polymer Optical Waveguide

Atsumi K., Azuma K., Ishigure T.

British and Irish Conference on Optics and Photonics, BICOP 2024 in Proceedings British and Irish Conference on Optics and Photonics 2024 2024年

　概要を見る

We design subminiature multimode 1x2 and 1x4 branched polymer optical waveguides with circular cores, and then applying a new needle-scan path to the Mosquito method to experimentally fabricate low-loss waveguide couplers.

Loss Reduction of Single-mode Y-branched Polymer Optical Waveguide for MUX/DEMUX Devices in Mode Division Multiplexing Links

Sakai S., Ishigure T.

13th IEEE CPMT Symposium Japan: Innovation of Packaging Technology for Advanced Heterogeneous Integration, ICSJ 2024    200 - 203 2024年

　概要を見る

Using the Mosquito method, we fabricate asymmetric single-mode Y-branched waveguides applicable to MUX/DEMUX devices for MDM technology. In order to reduce the insertion loss of Y-branched waveguides, we reexamine the fabrication conditions of symmetric single-mode Y-branched waveguides.

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Fixed Connection of Single-Mode Polymer Optical Waveguide with Single-Mode Optical Fiber

Toshida S., Ishigure T.

13th IEEE CPMT Symposium Japan: Innovation of Packaging Technology for Advanced Heterogeneous Integration, ICSJ 2024    164 - 165 2024年

　概要を見る

We demonstrate forming a waveguide module by adhering a core in a polymer waveguide and a single-mode fiber (SMF) to stabilize the connection at high temperature. We confirm that the connections are stably maintained at 86°C.

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Fabrication of GI core polymer optical waveguides enabling low loss with small bend radius (~1 mm) using high Δ resins

Karakawa M., Ishigure T.

British and Irish Conference on Optics and Photonics, BICOP 2024 in Proceedings British and Irish Conference on Optics and Photonics 2024 2024年

　概要を見る

In this paper, we fabricate GI-core multimode polymer optical waveguides with remarkably high Δ (~0.069) applying the Mosquito Method, by which the bending loss as low as 0.4 dB under 1-mm bending radius is attained.

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Evaluation and Analysis of Polarization Dependent Polymer Optical Waveguide Characteristics

Wakabayashi T., Ishigure T.

13th IEEE CPMT Symposium Japan: Innovation of Packaging Technology for Advanced Heterogeneous Integration, ICSJ 2024    196 - 199 2024年

　概要を見る

We design a measurement system to evaluate polarization dependent characteristics of polymer optical waveguides fabricated by the Mosquito method to be applied to a coupler between a single-mode fiber and silicon photonics chip. We observe the dependence of birefringence in single-mode polymer waveguides on their numerical aperture.

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Direct Connection of Multimode Polymer Waveguide and Multimode Fibers Using the Mosquito Method

Nakamura T., Ishigure T.

13th IEEE CPMT Symposium Japan: Innovation of Packaging Technology for Advanced Heterogeneous Integration, ICSJ 2024    154 - 155 2024年

　概要を見る

In this paper, we investigate the monomer dispensing conditions for the Mosquito method to accurately arrange the cores on the desired positions. Then, direct connection of waveguide core and multimode fiber is realized with the Mosquito method.

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Step and graded-index core-based polymer multimode interference splitters for photonic integrated circuits

Rasel M.O.F., Afsary N., Alam M.K., Tasnim F., Sakib M.N., Hatai R., Ishigure T.

Optik 290 2023年10月

ISSN  00304026

　概要を見る

This paper demonstrates step-index (SI) and graded-index (GI) core-based multimode interference (MMI) splitters realized with polymer materials for photonic integrated circuits (PICs). These SI and GI index-based MMI splitters guide the input light through the multimode waveguide following the self-imaging principles and demonstrate the multiple outputs with the same uniformity when the self-imaging length is obtained. We numerically design and develop (1 ×5) MMI splitters using the beam propagation method (BPM), and we use the RSoft CAD BeamPROP solver for the structural design and waveguide characterization. The structures of the SI and GI MMI splitters are optimized by investigating the structural parameters, particularly the width and length of the multimode waveguide and the core spacing between the output ports with the maximum uniform intensity at the self-imaging length. We also compare the structural design and optical properties of the SI and GI MMI waveguides. The excess losses of the SI MMI splitter are 1.09 and 1.12 dB for transverse electric (TE) and transverse magnetic (TM) modes, respectively, while for the GI MMI splitter, the losses are 0.57 dB and 0.56 dB for TE and TM modes, respectively at 1.55 µm. The power splitting efficiency for the SI MMI splitter is 77%, and for the GI MMI splitter, it is 88%. We also investigate the polarization dependence loss (PDL) for both MMI splitters, and the losses for the SI and GI MMI splitters are 0.024 dB and 0.004 dB, respectively.

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Fabrication of Circular Cross-Section Microchannels with 3-D Lattice Arrangement and Their Use as On-Off Valves

Uehara K., Hori Y., Ishigure T.

Micro 3 （ 3 ） 620 - 631 2023年09月

　概要を見る

In this paper, circular cross-section microchannels with 3-D lattice arrangements are designed and fabricated using the Mosquito method in order to construct on-off valves. The 3-D microchannels with on-off valves consist of two types of lines: the flow lines for chemical liquid flow and the control lines to activate the valves. We confirmed that both a circular cross-section and a PDMS with low elastic modulus used as the microchannel material contribute to a valve that can be closed with a lower pressure. Then, we demonstrated liquid flow to evaluate the functionality of the valve. Fluorescein solution was flown into a flow line. We found that the fluorescence intensity decreases at the intersection between the flow and control lines when the flow line is closed by the inflation of the control line, experimentally confirming the functionality of the valve microchannels fabricated via the Mosquito method.

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Graded-index core-based polarization beam splitters realized with symmetric polymer directional couplers

Tasnim F., Afsary N., Rasel M.O.F., Ishigure T.

Optics Continuum 2 （ 5 ） 1040 - 1052 2023年05月

　概要を見る

In this paper, we design and demonstrate polymer-based polarization beam splitters realized with parabolic graded-index (GI) directional couplers at 1550 nm. We design and investigate these beam splitters by using the beam propagation method (BPM) and the RSoft CAD BeamPROP solver is used for model design and characterization. We study the splitting ratio of 50:50 and 100:0 of these beam splitters for both transverse electric (TE) and transverse magnetic (TM) modes of the polarized light. In particular, the 50:50 beam splitters exhibit an output efficiency of 95% due to the absence of polarization. However, in the presence of the polarization effect, the polarization dependency is analyzed and manipulated successfully, and the output efficiency increases by approximately 98% at an incident angle of 31° due to the polarized launch field. Moreover, the 100:0 beam splitters act as the switching devices realized with parabolic GI polymer directional couplers. The insertion losses of the GI beam splitters are 0.162 dB and 0.186 dB, while the excess losses are 0.148 dB and 0.149 dB for TE and TM modes, respectively. Also, the polarization extinction ratio (PER) of the 100:0 beam splitters is >25 dB and >20 dB for TE and TM modes, respectively.

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VCSEL-based optical transceiver with a 90°-bent graded-index core polymer waveguide coupler for 25.78-Gb/s transmission

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

Optics Continuum 2 （ 5 ） 998 - 1012 2023年05月

　概要を見る

In this paper, we propose a low-loss assembly of optical elements [vertical cavity surface emitting laser (VCSEL)/photodiode (PD)] and a 90°-bent graded-index (GI) core polymer optical waveguide for compact high-speed optical transceivers. The air gap between the 90°-bent GI-core waveguide and VCSEL/PD chips are filled with a high-index resin, and we demonstrate a reduction not only of the Fresnel reflection loss but also of the coupling loss due to the lower divergence angle of VCSEL and fiber output beams. In this paper, the core size and NA of the 90°-bent GI-core in the polymer waveguide are redesigned to match the specific launch conditions realized with the gap filled with resins, resulting in theoretical estimates of insertion losses as low as 0.82 dB and 1.38 dB for the waveguides on the transmitter and receiver sides, respectively. Such low insertion losses are obtained not by step-index core but GI core waveguides. After redesigning the structure, 90°-bent GI-core polymer waveguides with a bending radius of 1 mm are experimentally fabricated using the Mosquito method, and we experimentally demonstrate that the insertion loss of the waveguide can be reduced by about 4 dB when the 100-µm air gap is filled with an optical adhesive (na = 1.51). In addition, an error-free 25.78-Gb/s data transmission is successfully demonstrated over a 100-m MMF link using the fabricated VCSEL based transceivers with 90°-bent GI core polymer optical waveguides.

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Fabrication of Multimode Polymer Optical Waveguide Based Splitter by the Mosquito Method and Investigation of Its Signal Splitting Ratio

Azuma K., Ishigure T.

2023 IEEE CPMT Symposium Japan, ICSJ 2023    123 - 124 2023年

　概要を見る

In this paper, multimode Y-branched waveguides with low insertion losses are designed and fabricated applying our original fabrication method of polymer optical waveguides named the Mosquito Method, and then, light splitting ratios of the fabricated Y-branched waveguides are investigated for application to DEMUX devices.

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Unique Optical Connect Structure with Polymer Waveguide Fabricated by the Mosquito Method

Furuta Y., Kondo F., Ito A., Ichinose R., Kaneda H., Fujii T., Ishigure T.

2023 IEEE CPMT Symposium Japan, ICSJ 2023    41 - 44 2023年

　概要を見る

We develop a unique optical connect structure with polymer waveguide fabricated by the Mosquito method for Co-Packaged Optics. We present the details of this optical connect structure and evaluation results of prototype waveguide.

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Temperature Dependence of Coupling Loss from SMF to Polymer Optical Waveguides with Various Refractive Index Profiles

Kinoshita R., Ishigure T.

2023 IEEE CPMT Symposium Japan, ICSJ 2023    172 - 175 2023年

　概要を見る

In this paper, we theoretically estimate the temperature dependence of coupling loss between single-mode (SM) polymer optical waveguides and general-purpose SM fiber (SMF), and discuss about the applicability of polymer optical waveguides to co-packaged optics (CPO). Although SM polymer optical waveguides are expected to be applied as an element of CPO, their small cores require precise mode-field adjustment with precise alignment of the cores. The mode-field and alignment positions of polymer waveguides are conce1ed to be affected by their operation temperature, particularly when integrated with Si photonics chips that could be a heat source. Simulation results show that the properties are maintained even under high-temperature operation.

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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

　概要を見る

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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