arXiv subjects

Soma Kogure

Publications and source records attributed to Soma Kogure.

5 recordsLinked to original sources

arXiv2026

Transmission of signals in the 300 GHz band with a bit-error rate below ${10}^{-9}$ using a soliton comb

To address the increasing demand for ultra-high-capacity wireless communication, terahertz (THz) frequencies near 300 GHz are attracting attention as a new spectral frontier. This work presents the first experimental demonstration of error-free (BER $< 1\times10^{-9}$) 10 Gbps transmission in the 300 GHz band using a soliton microcomb generated in an integrated silicon nitride (SiN) microring resonator. While many previous microcomb-based THz demonstrations have focused on coherent modulation formats and operation near the forward-error-correction (FEC) limit, this work investigates a simple intensity-modulation/direct-detection (IM-DD) on-off keying (OOK) architecture suitable for low-complexity THz links and fiber-wireless integrated systems. Although the experiment was conducted in a short back-to-back waveguide configuration, the generated THz wave enabled stable low-BER transmission without FEC or advanced offline signal processing. Analysis of the error-free threshold power indicates the feasibility of free-space transmission over several tens of meters with high-gain antennas and THz-band amplifiers. These results demonstrate the feasibility of robust low-complexity THz photonic links based on soliton microcombs for short-range fiber-wireless integrated systems.

physics.optics↗

arXiv2025

Architecture for coherent dual-comb spectroscopy and low-noise photonic microwave generation using mechanically actuated soliton microcombs

Dissipative Kerr soliton microcombs have inspired various intriguing applications such as spectroscopy, ranging, telecommunication, and high purity microwave generation. Mechanically actuated soliton microcombs provide enhanced controllability and flexibility for Kerr solitons, thus enabling technological progress to be made on such practical applications. Here, we present architectures for coherent dual-comb techniques and ultralow-noise microwave generation by exploiting the mechanical actuation of ultrahigh-Q crystalline microresonators. By unifying a pump laser, we demonstrate highly coherent dual-soliton combs using distinct resonators with slightly different repetition rates. We also report significant phase noise reduction achieved by directly generating Kerr solitons from a sub-Hz linewidth ultrastable laser. This study paves the way for further advancements in a wide variety of applications based on Kerr soliton microcombs.

physics.optics↗

arXiv2023

Mechanically actuated Kerr soliton microcombs

Mode-locked ultrashort pulse sources with a repetition rate of up to several tens of gigahertz greatly facilitate versatile photonic applications such as frequency synthesis, metrology, radar, and optical communications. Dissipative Kerr soliton microcombs provide an attractive solution as a broadband, high-repetition-rate compact laser system in this context. However, its operation usually requires sophisticated pump laser control to initiate and stabilize the soliton microcombs, particularly in millimeter-sized ultrahigh-Q whispering-gallery resonators. Here, we realize a mechanically actuated soliton microcomb oscillator with a microwave repetition rate of 15 GHz. This enables direct soliton initiation, long-term stabilization, and fine tuning, where the operation now lifts the prerequisite pump laser tunability that must be relaxed if the technology is to be widely used outside the laboratory environment. We reveal the prospects for using this method with a wide range of applications that would benefit from mechanical soliton actuation such as optical clocks, spectral extension, and dual-comb spectroscopy.

physics.optics↗

arXiv2023

Versatile tuning of Kerr soliton microcombs in crystalline microresonators

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.

physics.optics↗

arXiv2021

Dissipative Kerr soliton microcombs for FEC-free optical communications over 100 channels

The demand for high-speed and highly efficient optical communication techniques has been rapidly growing due to the ever-increasing volume of data traffic. As well as the digital coherent communication used for core and metro networks, intensity modulation and direct detection (IM-DD) are still promising schemes in intra/inter data centers thanks to their low latency, high reliability, and good cost performance. In this work, we study a microresonator-based frequency comb as a potential light source for future IM-DD optical systems where applications may include replacing individual stabilized lasers with a continuous laser driven microresonator. Regarding comb line powers and spectral intervals, we compare a modulation instability comb and a soliton microcomb and provide a quantitative analysis with regard to telecom applications. Our experimental demonstration achieved a forward error correction (FEC) free operation of bit-error rate (BER) <10^(-9) with a 1.45 Tbps capacity using a total of 145 lines over the entire C-band and revealed the possibility of soliton microcomb-based ultra-dense wavelength division multiplexing (WDM) with a simple, cost-effective IM-DD scheme, with a view to future practical use in data centers.

physics.app-ph↗