High-brightness scalable continuous-wave single-mode photonic-crystal laser

フォトニック結晶レーザーの高輝度単一モード連続動作の実現 --スマート製造を始めとする各種分野のゲームチェンジに向けて--. 京都大学プレスリリース. 2023-06-15.Realizing large-scale single-mode, high-power, high-beam-quality semiconductor lasers, which rival (or even replace) bulky gas and solid-state lasers, is one of the ultimate goals of photonics and laser physics. Conventional high-power semiconductor lasers, however, inevitably suffer from poor beam quality owing to the onset of many-mode oscillation, and, moreover, the oscillation is destabilized by disruptive thermal effects under continuous-wave (CW) operation. Here, we surmount these challenges by developing large-scale photonic-crystal surface-emitting lasers with controlled Hermitian and non-Hermitian couplings inside the photonic crystal and a pre-installed spatial distribution of the lattice constant, which maintains these couplings even under CW conditions. A CW output power exceeding 50 W with purely single-mode oscillation and an exceptionally narrow beam divergence of 0.05° has been achieved for photonic-crystal surface-emitting lasers with a large resonant diameter of 3 mm, corresponding to over 10, 000 wavelengths in the material. The brightness, a figure of merit encapsulating both output power and beam quality, reaches 1 GW cm⁻² sr⁻¹, which rivals those of existing bulky lasers. Our work is an important milestone toward the advent of single-mode 1-kW-class semiconductor lasers, which are expected to replace conventional, bulkier lasers in the near future

デジタル ホウソウ ジダイ ノ キョウザイ カイハツ シュホウ ノ ケンキュウ

研究報

レガシー メディア カラ エイゾクテキ デジタル メディア エノ テンカン ニ トモナウ ユウヨウセイ ニ カンスル ケンキュウ

研究報

Chiral Ice Crystals in Space

We observed the formation of CO, CH3OH, and H2O ices using a cryogenic transmission electron microscope, to determine if chiral ice crystals could form under the conditions of interstellar molecular clouds and young stellar objects (protoplanetary disks) and to clarify the crystalline structure of these ices. Our results suggest that the following ice crystals are chiral: crystalline CO (α-CO) formed on amorphous H2O (a-H2O) grains in a 10-K molecular cloud, crystalline CH3OH formed by the heating of amorphous CH3OH on a-H2O grains at 40–60 K in young stellar objects, and several polymorphs of hydrogen-ordered cubic ice crystals formed by the heating of a-H2O at 80–100 K and direct condensation at 120–140 K in protoplanetary disks. We also investigated candidates for other chiral ices using published data. We found that NH3 I and NH3·H2O I are chiral at low temperature and pressure conditions. If one-handed circularly polarized light is irradiated during the nucleation of these chiral ice crystals, homochiral crystals can be formed. These results have important implications for the origin of interstellar organic molecule homochirality

A multi-ethnic meta-analysis identifies novel genes, including ACSL5, associated with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating progressive motor neuron disease that affects people of all ethnicities. Approximately 90% of ALS cases are sporadic and thought to have multifactorial pathogenesis. To understand the genetics of sporadic ALS, we conducted a genome-wide association study using 1,173 sporadic ALS cases and 8,925 controls in a Japanese population. A combined meta-analysis of our Japanese cohort with individuals of European ancestry revealed a significant association at the ACSL5 locus (top SNP p = 2.97 × 10−8). We validated the association with ACSL5 in a replication study with a Chinese population and an independent Japanese population (1941 ALS cases, 3821 controls; top SNP p = 1.82 × 10−4). In the combined meta-analysis, the intronic ACSL5 SNP rs3736947 showed the strongest association (p = 7.81 × 10−11). Using a gene-based analysis of the full multi-ethnic dataset, we uncovered additional genes significantly associated with ALS: ERGIC1, RAPGEF5, FNBP1, and ATXN3. These results advance our understanding of the genetic basis of sporadic ALS

Structure of Neurosecretory Cells with Immunoreactive Diapause Hormone and Pheromone Biosynthesis Activating Neuropeptide in the Silkworm, Bombyx mori

Immunocytochemistry of diapause hormone (DH) or pheromone biosynthesis activating neuropeptide (PBAN) revealed three clusters of neurosecretory cells present on the ventral midline of the suboesophageal ganglion (SG) of the silkworm: there were 4 cells in the anterior, 6 cells in the medial, and 2 cells in the posterior cluster. Intracellular injection of Lucifer Yellow into an anterior or a medial cell revealed that the cell has a dendritic arborization at the anterior region of the SG and that it projects an axon to the corpus cardiacum (CC) via a branch of the maxillary nerve and an associated nerve of the CC (NCC-V). A dye-filled posterior cell in the larva projects bilaterally-symmetric dendritic branches to the anterior half of the SG that is to expand laterally to fuse the brain after pupation. The axon of the cell, passing through the brain, enters the NCC 3 to spread varicose terminal branches in the CC and associated nerves of the CC

Nivolumab for the treatment of malignant melanoma in a patient with pre-existing myasthenia gravis

A 79-year-old man with lymph node recurrence of malignant melanoma received nivolumab, an antiprogrammed death 1 (PD-1) monoclonal antibody. He had pre-existing ocular myasthenia gravis (MG) and a continued small amount of corticosteroid. Grade 3 creatine phosphokinase elevation appeared after two doses of nivolumab, and the treatment was postponed until it improved to grade 1. After three doses of nivolumab, he experienced diplopia and facial muscle weakness which were consistent with an acute exacerbation of MG, and the symptoms relieved without additional treatment for MG. He achieved shrinkage of metastasis after ten doses of nivolumab. Although a case who died due to MG after administration of nivolumab was reported recently, pre-existing MG is considered not to be always a contraindication of nivolumab