Terahertz wireless communication at 560-GHz band using Kerr micro-resonator soliton comb

Terahertz (THz) waves have attracted attention as carrier waves for next-generation wireless communications (6G). Electronic THz emitters are widely used in current mobile communications; however, they may face technical limitations in 6G with upper-frequency limits. We demonstrate wireless communication in a 560-GHz band by using a photonic THz emitter based on photomixing of a 560-GHz-spacing soliton microcomb in a uni-travelling carrier photodiode together with a THz receiver of Schottky barrier diode. The on-off keying data transfer with 2-Gbit/s achieves a Q-factor of 3.4, thus, satisfying the limit of forward error correction.Comment: 17 pages, 4 figur

Terahertz wireless communication in a 560-GHz band using a Kerr micro-resonator soliton comb

Terahertz (THz) waves have attracted attention as carrier waves for next-generation wireless communications (6 G). Electronic THz emitters are widely used in current mobile communications; however, they may face technical limitations in 6 G with upper-frequency limits. We demonstrate wireless communication in a 560-GHz band by using a photonic THz emitter based on photomixing of a 560-GHz-spacing soliton microcomb in a uni-travelling carrier photodiode together with a THz receiver of Schottky barrier diode. The on-off keying data transfer with 2-Gbit/s achieves a Q-factor of 3.4, thus, satisfying the limit of forward error correction

Wireless data transmission in a 560-GHz band using low-phase-noise terahertz wave generated by photomixing of a pair of distributed feedback lasers injection-locking to Kerr micro-resonator soliton comb

The demand for higher data rates in next-generation mobile wireless communication systems (6G) has led to significant interest in terahertz (THz) waves as a high-frequency, broad modulation bandwidth carrier wave. In this study, we propose and demonstrate a wireless data transfer in the 560-GHz band using low-phase-noise THz waves generated by photomixing of a pair of distributed feedback lasers injection-locking to Kerr micro-resonator soliton comb. Experimental results showed near-error-free on-off keying (OOK) data transfer at 1 Gbit/s in the 560-GHz band, with a Q-factor of 6.23, surpassing the error-free limit. Also, modulation formats of binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) were successfully used, showing clear constellation diagrams and relatively low root mean squared error vector magnitude (rms EVM) values of 23.9% and 23.6%, respectively. Moreover, data transfer at 0.4 Gbit/s in 16 quadrature amplitude modulation (16QAM) demonstrated clear isolated symbols and achieved a low rms EVM value of 8.1%, complying with the IEEE 802.15.3d standard amendment. These demonstrations highlight the potential of using injection-locked DFB lasers with the Kerr micro-resonator soliton comb to achieve high-quality, high-speed wireless data transfer in the 560-GHz band. These findings contribute significantly to the advancement of wireless communication technology in the THz frequency range and pave the way for the realization of 6G wireless communication systems

Model Synthetic Study of Tutin, a Picrotoxane-Type Sesquiterpene : Stereoselective Construction of a cis-Fused 5,6-Ring Skeleton

Picrotoxinin, coriamyrtin, and tutin are representative natural products classified as picrotoxane-type sesquiterpenes and they function as strong neurotoxins. Because they possess a cis-fused 5,6-ring skeleton with a highly congested functionalization, organic chemistry researchers have pursued the development of a stereoselective synthesis method for such skeleton. This study aims to stereoselectively synthesize the cis-fused 5,6-ring skeleton with two tetrasubstituted carbons at both angular positions using a model compound. The results revealed that the desymmetrization of the 2-methyl-1,3-cyclopentanedione moiety via the DL-proline-mediated intramolecular aldol reaction of a pentanal derivative bearing an isopropenyl group and the (iv e-membered ring at the 3- and 5-position, respectively, provided the desired cis-fused skeleton. This reaction can construct four contiguous stereogenic centers of the bicyclic skeleton with the two angular positions in good yield with high stereoselectivity. Further, this reaction was applied to the kinetic resolution of the racemate using L-proline, providing the enantiomeric pure aldol product with the desired skeleton. This method can be utilized for total synthesis of picrotoxane-type sesquiterpenes

Determination of axial length requiring adjustment of measured circumpapillary retinal nerve fiber layer thickness for ocular magnification.

To determine the axial length requiring adjustment of measured circumpapillary retinal nerve fiber layer (cpRNFL) thickness to account for ocular magnification during spectral-domain optical coherence tomography (SD-OCT).In this prospective study, 148 eyes of 148 healthy student volunteers were imaged by two examiners using three-dimensional SD-OCT. In 54 randomly selected eyes, total cpRNFL thickness was measured with and without adjustment for ocular magnification to establish intra-examiner and inter-examiner measurement error. The 148 eyes were then divided into three groups according to the error values: control group (difference in the corrected and uncorrected total cpRNFL thickness was within the measurement error range), thinner group (the corrected total cpRNFL thickness was less than the uncorrected one), and thicker group (the corrected total cpRNFL thickness was more than the uncorrected one). The cutoff values of axial length between the control and the other groups were calculated by receiver operating characteristic analysis.Measurement error ranged from 4.2 to 5.3 µm; the threshold value was defined as 5.3 µm. The cutoff values of axial length between the thinner and the control groups and between the control and the thicker groups were 23.60 (area under the curve [AUC] = 0.959) and 25.55 (AUC = 0.944) mm, respectively.Axial lengths shorter than 23.60 mm and longer than 25.55 mm require adjustment of measured cpRNFL thickness to account for ocular magnification during SD-OCT.UMIN Clinical Trials Registry (http://www.umin.ac.jp/) under unique trial number UMIN000013248 (date of registration: 02/24/2014)

Total Synthesis of (+)-Coriamyrtin via a Desymmetric Strategy of a 1,3-Cyclopentanedione Moiety

This paper describes the total synthesis of (+)-coriamyrtin, a picrotoxane-type sesquiterpene. The natural product is widely known as a neurotoxin of the Coriariaceae family and bears a highly functionalized cis-hydrindane skeleton. Despite being biologically and synthetically attractive molecule, only two examples of the total synthesis are reported to date. Our synthetic strategy involves the highly stereoselective construction of the cis-hydrindane skeleton via the desymmetric strategy of a 1,3-cyclopentanedione moiety using an intramolecular aldol reaction and elaborate functionalization of the cyclopentane ring in the bicyclic structure for the formation of the 1,3-diepoxide moiety of coriamyrtin. Our method could be applied to synthesize various natural products with similar bicyclic skeletons and to expand neurobiological studies using synthesized products

Measurement Error Values of Total cpRNFL Thickness.

<p>cpRNFL = circumpapillary retinal nerve fiber layer; S_w = within-subject variation.</p><p>The values were calculated as 2.77*S_w.</p><p>Measurement Error Values of Total cpRNFL Thickness.</p