Papers - Tanabe, Takasumi

Demonstration of Nighttime Thermoelectric Power Generation with Radiative Cooling Utilizing Low-Cost Commercial Materials

Tanto Y., Yomoda A., Kokubu J., Sugano R., Tanabe T.

16th Pacific Rim Conference on Lasers and Electro-Optics, CLEO-PR 2024  2024

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We conducted controlled experiments on nighttime thermoelectric generation using cost-effective, commercially available materials under various weather conditions, both with and without a blackbody filter for radiative cooling, achieving efficiencies of up to 53.3 mW/m2,.

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Small-error transmission and filter operation at 300 GHz using dissipative Kerr soliton frequency comb

Yomoda A., Imamura M., Tanikawa K., Kogure S., Sugano R., Fujii S., Kawanishi S., Tanabe T.

CLEO: Science and Innovations, CLEO: S and I 2024 in Proceedings CLEO 2024, Part of Conference on Lasers and Electro-Optics  2024

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Using a soliton microcomb, we generated 300 GHz waves and demonstrated a transmission experiment at 10 Gbit/s with an ultra-low bit-error rate of 10-9. We also demonstrated a photonic filter in the 300 GHz region, which adds another functionality in the terahertz regime.

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Vicinity of exceptional point-induced mode-locking in coupled microresonators

Imamura R., Fujii S., Nakashima A., Tanabe T.

CLEO: Science and Innovations, CLEO: S and I 2024 in Proceedings CLEO 2024, Part of Conference on Lasers and Electro-Optics  2024

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A coupled-cavity system with gain and loss enables mode-locking without natural saturable absorbers. Our theoretical and numerical findings demonstrate significant modulation in system Q near the exceptional point (EP), even with minor refractive index changes and minimal Kerr effect involvement.

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Transmission in the 300 Ghz Band Using a Soliton Comb

Imamura M., Yomoda A., Tanikawa K., Kogure S., Sugano R., Kawanishi S., Fujii S., Tanabe T.

16th Pacific Rim Conference on Lasers and Electro-Optics, CLEO-PR 2024  2024

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We generated terahertz waves at 300 GHz using a soliton comb, focusing on characteristics such as low phase noise, and successfully demonstrated an error-free 10 Gbit/s transmission with a bit-error rate below 10-9.

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Towards Deterministic Perfect Soliton Crystals in Microtoroids with Saturable Absorption

Matsuyama H., Takano A., Imamura R., Wang H., Fujii S., Tanabe T.

16th Pacific Rim Conference on Lasers and Electro-Optics, CLEO-PR 2024  2024

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We utilized silica microtoroid resonators to achieve high repetition rate mode-locking and perfect soliton crystals. We then transfer graphene onto microtoroids to enable saturable absorption and study the impacts on its properties, including the Q value.

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Study on Chaos Synchronization of Cascaded Microresonator Optical Frequency Combs

Lemcke D., Moreno D., Fujii S., Nakashima A., Uchida A., Tanabe T.

CLEO: Science and Innovations, CLEO: S and I 2024 in Proceedings CLEO 2024, Part of Conference on Lasers and Electro-Optics  2024

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By numerically investigating the synchronization of cascaded microresonator frequency combs, we find the optimal transmittance parameters and discover that partial injection from the leader is sufficient. We also present preliminary experimental results.

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Soliton Comb Generation Using a Small Prism Coupling Module

Mototani Y., Fujii S., Kimura S., Hashimoto Y., Yamakawa T., Imamura R., Tanabe T.

16th Pacific Rim Conference on Lasers and Electro-Optics, CLEO-PR 2024  2024

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We developed a compact prism coupling module conforming to the 1U CubeSat standard and demonstrated soliton microcomb generation with an ultrahigh-Q MgF resonator to explore the robustness of the miniaturized multi-wavelength light source.

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Mode-Locking Induced by Exceptional Point Proximity in Coupled Microresonators

Tanabe T., Imamura R., Fujii S.

Conference on Lasers and Electro Optics Pacific Rim CLEO PR 2024 in Proceedings 2024 Conference on Lasers and Electro Optics Pacific Rim CLEO PR  2024

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We introduce a mode-locking mechanism using coupled microcavities near exceptional points in the context of non-Hermitian physics, eliminating the need for traditional saturable absorbers. It offers a compact, efficient solution for generating ultrafast pulses.

Pulse formation in the Stokes region through dispersion tailoring in silica microresonators

Otake R., Imamura R., Fuji S., Tanabe T.

Signal Processing in Photonic Communications Sppcom 2024 in Proceedings Advanced Photonics Congress 2024 Part of Optica Advanced Photonics Congress  2024

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We show numerically that a pulse with a peak power of ~200W is formed in the Stokes region in a silica microresonator when careful dispersion tailoring is performed.

Pulse formation in the Stokes region through dispersion tailoring in silica microresonators

Otake R., Imamura R., Fuji S., Tanabe T.

Specialty Optical Fibers Sof 2024 in Proceedings Advanced Photonics Congress 2024 Part of Optica Advanced Photonics Congress  2024

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We show numerically that a pulse with a peak power of ~200W is formed in the Stokes region in a silica microresonator when careful dispersion tailoring is performed.

Pulse formation in the Stokes region through dispersion tailoring in silica microresonators

Otake R., Imamura R., Fuji S., Tanabe T.

Specialty Optical Fibers Sof 2024 in Proceedings Advanced Photonics Congress 2024 Part of Optica Advanced Photonics Congress  2024

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We show numerically that a pulse with a peak power of ~200W is formed in the Stokes region in a silica microresonator when careful dispersion tailoring is performed.

Pulse formation in the Stokes region through dispersion tailoring in silica microresonators

Otake R., Imamura R., Fuji S., Tanabe T.

Bragg Gratings Photosensitivity and Poling in Glass Waveguides Bgpp 2024 in Proceedings Advanced Photonics Congress 2024 Part of Optica Advanced Photonics Congress  2024

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We show numerically that a pulse with a peak power of ~200W is formed in the Stokes region in a silica microresonator when careful dispersion tailoring is performed.

Pulse formation in the Stokes region through dispersion tailoring in silica microresonators

Otake R., Imamura R., Fuji S., Tanabe T.

Novel Optical Materials and Applications Noma 2024 in Proceedings Advanced Photonics Congress 2024 Part of Optica Advanced Photonics Congress  2024

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We show numerically that a pulse with a peak power of ~200W is formed in the Stokes region in a silica microresonator when careful dispersion tailoring is performed.

Pulse formation in the Stokes region through dispersion tailoring in silica microresonators

Otake R., Imamura R., Fuji S., Tanabe T.

Solar Energy and Light Emitting Devices Soled 2024 in Proceedings Advanced Photonics Congress 2024 Part of Optica Advanced Photonics Congress  2024

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We show numerically that a pulse with a peak power of ~200W is formed in the Stokes region in a silica microresonator when careful dispersion tailoring is performed.

Pulse formation in the Stokes region through dispersion tailoring in silica microresonators

Otake R., Imamura R., Fuji S., Tanabe T.

Nonlinear Photonics Np 2024 in Proceedings Advanced Photonics Congress 2024 Part of Optica Advanced Photonics Congress  2024

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We show numerically that a pulse with a peak power of ~200W is formed in the Stokes region in a silica microresonator when careful dispersion tailoring is performed.

Pulse formation in the Stokes region through dispersion tailoring in silica microresonators

Otake R., Imamura R., Fuji S., Tanabe T.

Integrated Photonics Research Silicon and Nanophotonics Ipr 2024 in Proceedings Advanced Photonics Congress 2024 Part of Optica Advanced Photonics Congress  2024

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We show numerically that a pulse with a peak power of ~200W is formed in the Stokes region in a silica microresonator when careful dispersion tailoring is performed.

Photonic crystal nanocavities structure: Characteristics and applications in non-linear optics

Daud N.A., Tanabe T., Azizan M.D.H., Azmi A.I., Saris N.N.H., Muhammad N.A.

2024 IEEE Asia Pacific Conference on Applied Electromagnetics Apace 2024    86 - 89 2024

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This paper investigates the structural characteristics of photonic crystal (PhC) nanocavities and their application in non-linear optics. By leveraging the unique ability of these nanocavities to confine light within tiny volumes, the study explores their capacity to enhance non-linear optical effects such as frequency conversion and optical switching. Key design strategies, including defect engineering and cavity resonance optimization, are discussed to illustrate how these structures amplify light-matter interactions. The paper also discusses practical applications as optical devices namely as optical modulator and photoreceiver. Finally, all-silicon transmission link has also been demonstrated. We successfully achieved 0.1 Gb/s all-silicon scheme transmission link at 5 m distance with ~ 10 μW.

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Versatile tuning of Kerr soliton microcombs in crystalline microresonators

Fujii S., Wada K., Sugano R., Kumazaki H., Kogure S., Kato Y.K., Tanabe T.

Communications Physics 6 ( 1 )  2023.12

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Microresonator-based optical frequency combs emitted from high-quality-factor microresonators, also known as microcombs, have opened up new horizons to areas of optical frequency comb technology including frequency metrology, precision sensing, and optical communication. To extend the capability of microcombs for such applications, large and reliable tunability is of critical importance. Here, we show broad spectral tuning of Kerr soliton microcombs in a thermally controlled crystalline microresonator with pump-detuning stabilization. The fundamental elements composing frequency combs, namely the center frequency, repetition frequency, and carrier-envelope offset frequency, are spectrally tuned by up to −48.8 GHz, −5.85 MHz, and −386 MHz, respectively, leveraging thermal effects in ultrahigh-Q crystalline magnesium fluoride resonators. We further demonstrate a 3.4-fold enhancement of soliton comb power resulting from thermal expansion with a temperature change of only 28 K by employing quantitative analyses of the fiber-to-resonator coupling efficiency.

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Stability and mutual coherence of Raman combs in high-Q silica microresonators

Sugawara S., Fujii S., Kawanishi S., Tanabe T.

Optics Continuum 2 ( 7 ) 1588 - 1596 2023.06

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We investigated the stability and mutual coherence of a Raman microcomb in a silica microrod resonator by monitoring the output power and longitudinal mode spacings. The results indicate that we can obtain a stable Raman comb formation without the need for four-wave mixing processes. The use of a Raman comb will open the possibility of simplifying the setup because it will relax the phase matching condition usually required for microresonator frequency comb generation. Although there are some restrictions in regard to using a Raman comb for applications due to the coexistence of the comb components in different mode families, a proof-of-concept demonstration shows that it is sufficiently stable and robust for applications such as optical communications.

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Mode-locking System of Coupled Microcavities with Gain and Nonlinear Loss

Imamura R., Fujii S., Nakashima A., Tanabe T.

2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023  2023

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Ultrahigh repetition rate lasers are vital light sources, and a mode-locked laser with whispering-gallery-mode (WGM) microresonators would provide a cost-effective on-chip solution. We have already reported numerically on the mode-locking in an erbium (Er) ion-doped resonator that was coated with polymer-dispersed carbon nanotubes (CNTs) [1]. Although mode-locking is possible, the required Q is still high, so the experiment remains challenging. In this work, we show that a coupled microresonator system with a gain resonator coupled to a nonlinear loss resonator will solve this problem. It is based on the idea of employing the Q revival of the gain cavity when the loss is increased at the cavity with additional loss, which is known to exist in the vicinity of the exceptional point [2].

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