Yusuke Nasu

We describe a low-loss single-mode waveguide in planar light-wave circuit (PLC) glass doped with boron and phosphorus, which is more difficult to write than pure-silica glass. The written waveguide has a rectangular core, a symmetric near-field pattern, and a propagation loss of 0.35 dB/cm. The loss that originates from the mode-field mismatch between the mode-field diameters of the written and the PLC waveguides is less than 0.1 dB/point. In addition, we successfully connected PLC waveguides wi

L-Lactate, traditionally considered a metabolic waste product, is increasingly recognized as an important intercellular energy currency in mammals. To enable investigations of the emerging roles of intercellular shuttling of L-lactate, we now report an intensiometric green fluorescent genetically encoded biosensor for extracellular L-lactate. This biosensor, designated eLACCO1.1, enables cellular resolution imaging of extracellular L-lactate in cultured mammalian cells and brain tissue.

L-Lactate is increasingly appreciated as a key metabolite and signaling molecule in mammals. However, investigations of the inter- and intra-cellular dynamics of L-lactate are currently hampered by the limited selection and performance of L-lactate-specific genetically encoded biosensors. Here we now report a spectrally and functionally orthogonal pair of high-performance genetically encoded biosensors: a green fluorescent extracellular L-lactate biosensor, designated eLACCO2.1, and a red fluore

The authors recently proposed the multiple-phase-shift (MPS) technique, in which multiple phase shifts are introduced in sampled fiber Bragg gratings (SFBGs) to realize dense channel spacing. In this paper, the MPS technique is studied in detail, and it is shown that it can densify SFBGs both spectrally and spatially. Then, the paper presents that the MPS technique is applicable to densify the spectra of not only simple SFBGs but also various kinds of complex SFBGs, such as apodized, sinc-, and

To extend the operation wavelength range of dual-polarization optical hybrids (DPOH), we propose a highly symmetrical interferometer design for a polarization beam splitter and an optical hybrid to reduce temperature and wavelength dependence. The design successfully decreases this dependence, and a fabricated DPOH with silica-based planar lightwave circuits provides temperature-insensitive performance with a polarization extinction ratio of over 25 dB and phase errors of less than 3 degrees ove

Apoptosis plays a pivotal role in development and tissue homeostasis in multicellular organisms. Clustering of Bak proteins on the mitochondrial outer membrane is responsible for the induction of apoptosis by evoking a release of pro-apoptotic proteins from mitochondria into cytosol. However, how the protein cluster permeabilizes the mitochondrial membrane remains unclear because elucidation of the cluster characteristics such as size and protein density has been hampered by the diffraction-limi

l-Lactate is a monocarboxylate produced during the process of cellular glycolysis and has long generally been considered a waste product. However, studies in recent decades have provided new perspectives on the physiological roles of l-lactate as a major energy substrate and a signaling molecule. To enable further investigations of the physiological roles of l-lactate, we have developed a series of high-performance (Δ<i>F</i>/<i>F</i> = 15 to 30 <i>in vitro</i>), intensiometric, genetically enco

The extension of optical add/drop multiplexing (OADM) systems to metro-core and metro-access networks has led to the need for economical and compact OADM devices. In this paper, we demonstrate a 1-in. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 100 GHz spacing 40-channel (ch) single-chip variable attenuator multiplexer/demultiplexer based on a monolithic 2.5%-Delta silica planar lightwave circuit (PLC) and stacked photodiode arrays. We a

Apoptosis plays a pivotal role in development and tissue homeostasis in multicellular organisms. Dysfunction of apoptosis is involved in many fatal diseases such as cancer. Visualization of apoptosis in living animals is necessary to understand the mechanism of apoptosis-related diseases. Here, we describe a genetically encoded fluorescent probe for imaging apoptosis in living multicellular organisms, based on spontaneous complementation of two fragments of a green fluorescent protein (GFP) vari

We fabricated an ultra-compact InP-based DP-QPSK modulator by the hybrid integration of an InP twin-IQ modulator and a PLC polarization multiplexing circuit for the first time. 112-Gb/s DP-QPSK modulation is successfully demonstrated.

Fluorescent protein (FP)-based biosensors are genetically encoded tools that enable the imaging of biological processes in the context of cells, tissues, or live animals. Though widely used in biological research, practically all existing biosensors are far from ideal in terms of their performance, properties, and applicability for multiplexed imaging. These limitations have inspired researchers to explore an increasing number of innovative and creative ways to improve and maximize biosensor per

Abstract Far‐red and near‐infrared (NIR) genetically encoded calcium ion (Ca 2+ ) indicators (GECIs) are powerful tools for in vivo and multiplexed imaging of neural activity and cell signaling. Inspired by a previous report to engineer a far‐red fluorescent protein (FP) from a biliverdin (BV)‐binding NIR FP, we have developed a far‐red fluorescent GECI, designated iBB‐GECO1, from a previously reported NIR GECI. iBB‐GECO1 exhibits a relatively high molecular brightness, an inverse response to Ca

We propose a novel polarization dependent frequency shift (PDf) reduction method for fabricating a silica-based PLC DQPSK demodulator incorporating an asymmetrically positioned half-wave plate, and demonstrate error-free 43-Gbit/s demodulation for any incident SOP. The PDf has a detrimental effect on the demodulation performance of a DQPSK signal, and it is degraded by various kinds of PLC fabrication errors. In this paper, we focus on the polarization crosstalk in the coupler, which is one of t

A novel technique for fabricating densely spaced superstructure fibre Bragg gratings (SSFBGs) by introducing multiple phase shifts (MPSs) is proposed and demonstrated. This technique can realise the same bandwidth and density as conventional SSFBGs with much shorter length, and can use the fibre and phase mask efficiently. An MPS-SSFBG having double channel density and triple channel density has been successfully fabricated.