Kyoto University · 물리·천문학
Ryohei Morita 교수의 연구실은 주로 고출력·고속·고효율 광학 소자, 특히 포토닉 크리스탈 표면 발광 레이저(PCSEL)의 원천 기반 기술 개발에 중점을 두고 있습니다. 단일 모드 레이저 작동을 통해 높은 출력과 좁은 스펙트럼 폭, 빠른 직접 변조 성능을 실현하기 위한 물리적 메커니즘과 구조 설계에 대한 체계적 연구를 수행하고 있으며, 특히 파장 조절, Q-스위칭, 스펙트럼 라인폭 최소화 등 응용 중심의 혁신을 이룹니다. 이는 자유공간 통신, 초해상도 거리 측정, 마이크로제조 등 다양한 분야에서의 소형·저비용 레이저 솔루션 개발에 기여하고 있습니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
We examined the state of sodium electrochemically inserted in HC prepared at 700–2000 °C using solid state Na magic angle spinning (MAS) NMR and multiple quantum (MQ) MAS NMR.
Photonic crystal surface-emitting lasers (PCSELs), which use a two-dimensional photonic crystal as the laser cavity, can achieve both high output powers and narrow beam divergence angles owing to single-mode lasing over a large area. High-speed, high-power, direct modulation of PCSELs is expected to realize compact and power-saving optical transmitters without bulky lens systems and fiber amplifiers for free-space optical communications. In this paper, we realize high-speed, high-power, free-spa
Photonic-crystal surface-emitting lasers (PCSELs) are capable of single-mode, high-power lasing over a large resonator area owing to two-dimensional resonance at a singularity point of the photonic band structure. Since the number of photons in the lasing mode in PCSELs are much larger than those in conventional semiconductor lasers, PCSELs are in principle suitable for coherent operation with a narrow spectral linewidth. In this paper, we numerically and experimentally investigate intrinsic spe
Short-pulse high-peak-power lasers are crucial laser sources for various applications such as non-thermal ultrafine material processing and eye-safe high-resolution remote sensing. Realizing such operation in a single semiconductor laser chip without amplifiers or external resonators is expected to contribute to the development of compact, affordable laser sources for such applications. In this paper, we demonstrate short-pulse high-peak-power photonic-crystal surface-emitting lasers based on si
We demonstrate self-pulsation with a pulse width of 100 ps and a beam divergence angle of 0.35° in a photonic-crystal surface-emitting laser by introducing a saturable absorber section and employing a new double-hole photonic crystal.
We propose photonic-crystal surface-emitting lasers based on photon-photon resonance to extend the direct modulation bandwidth. We experimentally demonstrate over 10-GHz direct modulation with over 1-W high output power under continuous-wave operation.
We develop time-dependent three-dimensional coupled-wave theory for photonic-crystal surface-emitting lasers (PCSELs), which enables comprehensive analyses of lasing characteristics of high-power PCSELs under high current injection including relaxation oscillation, spatial hole-burning, and lasing spectra.
Photonic-crystal surface-emitting lasers (PCSELs) are capable of single-mode, high-power lasing over a large resonator area owing to two-dimensional resonance at a singularity point of the photonic band structure. Since the number of photons in the lasing mode in PCSELs are much larger than those in conventional semiconductor lasers, PCSELs are in principle suitable for coherent operation with a narrow spectral linewidth. In this paper, we numerically and experimentally investigate intrinsic spe
We report theoretical and experimental results on intrinsic spectral linewidths of 1-mm-diameter PCSELs under continuous-wave operation, and we demonstrate 1-kHz-class intrinsic spectral linewidths with 5-W-class output power.
環境・エネルギー問題の解決に向け，リチウムイオン電池(LIB)などの蓄電池に注目が集まっている。LIBにはリチウムやコバルトなどの希少な元素が使われているが，今後も電池需要の増加が見込まれるなか，こうした元素を用いない新型蓄電デバイスの実現に向けた研究開発が進められている。リチウムをナトリウムに置き換えたナトリウムイオン電池(NIB)はLIBに匹敵する性能を持つ新規蓄電池の一つとして注目されており，膨大な物質が電極物質として研究されている。なかでも難黒鉛化性炭素（ハードカーボン；HC）はNIBの負極活物質として期待されている。また，リンはほかの材料に比べてとりわけ多くのナトリウムを吸蔵できるためNIB高容量化に寄与する材料として研究が進められている。しかし，HCは非晶質炭素であり，リンも電気化学的にNaを導入した場合非晶質となることが多いため，X線回折(XRD)などの回折法によるナトリウムの吸蔵状態や充放電機構の解明は難しかった。本研究ではHCおよびリンを対象とし，物質の状態によらず測定核種を直接観測できる核磁気共鳴(NMR)や第一原理計算を活用してナトリウム吸蔵状態や充放電機構の解明
