We demonstrate a 0.534p non-volatile, reversible phase shift in an asymmetric Mach-Zehnder interferometer with 400-mu m-long Si-rich SiN phase shifters by UV irradiation and micro-heater heating. By increasing Si dangling bonds and heating temperature, we achieve a 2.5-fold effective refractive index change compared to N-rich SiN. (c) 2025 The Author(s)

The objective of our research is to develop optical switches utilizing the phase transition of manganese telluride (MnTe). Initially, we investigated the fundamental optical properties of MnTe by measuring the complex refractive index spectra of alpha- and beta-MnTe thin films. Notably, the imaginary component of the refractive index exhibited a shift of approximately 1 eV toward higher energy due to the phase transition from the alpha-phase to the beta-phase. First-principles calculations indicated that this shift results from an increase in the band gap, mainly attributed to a reduction in the interatomic distance between manganese (Mn) and tellurium (Te). Furthermore, we conducted physical simulations of light propagation in two optical switch models-the Mach-Zehnder type and the ring resonator type-incorporating MnTe thin films. Both models demonstrated effective ON-OFF operation with extinction ratios ranging from 16 to 17 dB, facilitated by the phase transition of MnTe.

Silicon photonics switches are emerging as a key technology for realizing energy-efficient networks, spanning from intra data center to wafer-scale interconnections. This review focuses on recent developments and prospects of silicon photonics switches operating in the O-band, which is widely used in computing networks designed for artificial intelligence and machine learning applications. We first review our recent works on O-band silicon photonics switches fabricated by 300-mm silicon photonics technology. Specifically, we have expanded the port count of our O-band switches from 8 × 8 to 32 × 32 implemented with double Mach–Zehnder switch elements for a broad operating bandwidth. This switch achieved a 70-nm bandwidth for a crosstalk of less than −20 dB, and an average on-chip loss of 11.8 dB. Next, we discuss switch topologies optimized for wafer-scale interconnection. Conventional switch topologies typically have their input and output ports at opposite ends of the switch matrix, respectively, which poses challenges of long propagation distances and many waveguide intersections for off-chip planar waveguide routing to connect xPUs on substrate. To address this, we propose a topology where input and output ports are placed adjacently. An O-band 8 × 8 switch based on this topology was fabricated and experimentally demonstrated. Finally, we discuss the prospects and challenges of silicon photonic switches. Key issues include insertion loss, switching speed, crosstalk and operating bandwidth, and polarization dependence. These aspects are examined with reference to reports from other research groups, highlighting both current limitations and potential directions for further improvement.

Silicon photonic switches are expected to offer energy efficient switching in future data center networks and artificial intelligence/machine learning clusters. In this paper, we report a strictly non-blocking silicon photonic switch with 32 inputs and 32 outputs based on a path-independent insertion-loss topology, which consists of double Mach-Zehnder (MZ) switch elements to improve the crosstalk performance. The switch chip, therefore, contains 2048 thermo-optic MZ switches. The switch chip was fabricated using a complementary metal-oxide-semiconductor pilot line with the 45-nm technology. The fabricated switch chip was flip-chip bonded to a 2114 land-grid-array (LGA) ceramic interposer, and the electrodes on the chip were connected to a control circuit board. To control the 2048 MZ switches through the LGA 2114 interposer, a single arm of each MZ switch was electrically wired, rather than both arms as in our previous 32 × 32 switches. 99.2% of the MZ switches were connected and operated. The fabricated switch exhibited minimum, maximum, and average on-chip insertion loss of 9.3, 15.6, and 11.8 dB, respectively, and a crosstalk of less than -20 dB over a 70-nm bandwidth. Moreover, using a 100G-ER4 optical transceiver, we demonstrate 100-Gbps signal transmission with a bit error ratio of less than 1 × 10-3, which is mostly due to the amplifier noise.

We propose a novel low-loss phase-change optical switch using MnTe thin film, which has a smaller absorption coefficient than conventional phase-change materials. The designed phase-change optical switch has a loss of 0.388 dB, a crosstalk of -37.7 dB, and an extinction ratio of 37.3 dB.

We demonstrated a reversible and non-volatile optical phase shift in a silicon nitride waveguide by an alternating process sequence of annealing and ultraviolet irradiation. A phase shift of 0.268π was observed in an asymmetric Mach-Zehnder interferometer with a 400-μm-long phase shifter.

We demonstrate a reversible and non-volatile optical phase shift in a silicon-nitride waveguide by a process of thermal annealing and ultraviolet irradiation, and investigate a correlation between phase shifts and charge state of dangling bonds.

ObjectiveBarley, abundant in β-glucan, a soluble dietary fiber, holds promise in obesity prevention. Given the microbial metabolism of dietary fiber in the gastrointestinal tract, we investigated the role of gut microbiota in non-obese individuals consuming high levels of barley.MethodsOur study enrolled 185 participants from “The cohort study on barley and the intestinal environment (UMIN000033479).” Comprehensive physical examinations, including blood tests, were conducted, along with separate assessments of gut microbiome profiling and dietary intake. Participants were categorized into high and low barley consumption groups based on the median intake, with non-obese individuals in the high intake group identified as barley responders while participants with obesity were designated as non-responders. We compared the relative abundance of intestinal bacteria between these groups and used multivariate analysis to assess the association between intestinal bacteria and barley responders while controlling for confounding factors.Results and discussionAmong the fermented food choices, responders exhibited notably higher consumption of natto (fermented soybeans) than non-responders. Moreover, after adjusting for confounders, Butyricicoccus and Subdoligranulum were found to be significantly more prevalent in the intestines of responders. Given natto’s inclusion of Bacillus subtilis, a glycolytic bacterium, and the butyrate-producing capabilities of Butyricicoccus and Subdoligranulum, it is hypothesized that fiber degradation and butyrate production are likely to be enhanced within the digestive tract of barley responders.

We device double-layer stacked silicon photonic MMIs by µ-Transfer Printing. A 900×100-µm 2 -size chiplet consisting of a 220/60-nm-thick silicon core/slab structure is transferred twice onto thermal- and TEOS-SiO 2 under-cladding layers.

The wavelength selective crossconnect (WXC) is a key component of the reconfigurable optical add/drop multiplexer (ROADM). Waveguide type WXC is difficult to increase the number of ports and channels, and free-space type WXC has a low switching speed of milliseconds. To solve these problems, we have proposed a hybrid type WXC. It has microsecond switching speed, where switching is performed by silicon optical circuit and wavelength division (de)multiplexing is performed by free-space optical system. In this paper, we designed the free-space optics and simulated the transmission spectra of a 16-channel 2x2 hybrid-type WXC using CodeV optical simulator. The thickness and the position of the microlens array to be attached to the silicon optical circuit has been designed. The angle of incidence on the grating coupler was 9 degrees, and the thickness of the lens was 0.53 mm. The center of the microlens array was offset by 60.1 mu m from the center of the grating coupler. The distance between the lenses in the freespace optics was optimized for the x-z and y-z planes, respectively. The loss spectra with the light emitted from the grating coupler were simulated for each of the 16 channels. The loss at the center frequency of each channel varies from -0.89 dB to -2.87 dB. The loss can be reduced by optimizing the grating coupler design to be -0.89 dB to -0.91 dB.

A cross-sectional study involving 224 healthy Japanese adult females explored the relationship between ramen intake, gut microbiota diversity, and blood biochemistry. Using a stepwise regression model, ramen intake was inversely associated with gut microbiome alpha diversity after adjusting for related factors, including diets, Age, BMI, and stool habits (β = −0.018; r = −0.15 for Shannon index). The intake group of ramen was inversely associated with dietary nutrients and dietary fiber compared with the no-intake group of ramen. Sugar intake, Dorea as a short-chain fatty acid (SCFA)-producing gut microbiota, and γ-glutamyl transferase as a liver function marker were directly associated with ramen intake after adjustment for related factors including diets, gut microbiota, and blood chemistry using a stepwise logistic regression model, whereas Dorea is inconsistently less abundant in the ramen group. In conclusion, the increased ramen was associated with decreased gut bacterial diversity accompanying a perturbation of Dorea through the dietary nutrients, gut microbiota, and blood chemistry, while the methodological limitations existed in a cross-sectional study. People with frequent ramen eating habits need to take measures to consume various nutrients to maintain and improve their health, and dietary management can be applied to the dietary feature in ramen consumption.

We confirmed a wide band visible light transmission in waveguides utilizing silicon nitride films deposited by CMOS compatible CVD, and also observed a reversible refractive index change of the films in a 1300-nm wavelength band.

We developed a novel drug metabolism and pharmacokinetics(DMPK)analysis platform named DruMAP. This platform consists of a databasefor DMPK parameters and programs that can predict many DMPK parametersbased on the chemical structure of a compound. The DruMAP databaseincludes curated DMPK parameters from public sources and in-houseexperimental data obtained under standardized conditions; it alsostores predicted DMPK parameters produced by our prediction programs.Users can predict several DMPK parameters simultaneously for novelcompounds not found in the database. Furthermore, the highly flexiblesearch system enables users to search for compounds as they desire.The current version of DruMAP comprises more than 30,000 chemicalcompounds, about 40,000 activity values (collected from public databasesand in-house data), and about 600,000 predicted values. Our platformprovides a simple tool for searching and predicting DMPK parametersand is expected to contribute to the acceleration of new drug development.DruMAP can be freely accessed at: https://drumap.nibiohn.go.jp/.

BACKGROUND:Barley, a grain rich in soluble dietary fiber β-glucan, is expected to lower blood pressure. Conversely, individual differences in its effects on the host might be an issue, and gut bacterial composition may be a determinant.METHODS:Using data from a cross-sectional study, we examined whether the gut bacterial composition could explain the classification of a population with hypertension risks despite their high barley consumption. Participants with high barley intake and no occurrence of hypertension were defined as "responders" (n = 26), whereas participants with high barley intake and hypertension risks were defined as "non-responders" (n = 39).RESULTS:16S rRNA gene sequencing revealed that feces from the responders presented higher levels of Faecalibacterium, Ruminococcaceae UCG-013, Lachnospira, and Subdoligranulum and lower levels of Lachnoclostridium and Prevotella 9 than that from non-responders. We further created a machine-learning responder classification model using random forest based on gut bacteria with an area under the curve value of 0.75 for estimating the effect of barley on the development of hypertension.CONCLUSIONS:Our findings establish a link between the gut bacteria characteristics and the predicted control of blood pressure provided by barley intake, thereby providing a framework for the future development of personalized dietary strategies.

Silicon-based optical media present several desirable properties for a wide range of applications. Herein, we propose a novel hybrid integration scheme that combines a silicon photonics platform and a 5.5%-Delta-silica planar-lightwave circuit (PLC) platform. By exploiting the performance advantages of each platform, we fabricated a polarization-insensitive low-crosstalk 8 x 8 silicon photonics switch butt-jointed with a compact 5.5%-Delta-silica PLC-based 100-GHz 8-channel arrayed waveguide grating (AWG). The device was driven by a smartphone-sized (9 cm x 13.5 cm) control board. The fabricated device exhibits a fiber-to-fiber insertion loss of 12.6 dB, an average polarization-dependent loss of less than 0.57 dB, and less than -40 dB leakage to non-target output ports. We also demonstrate two uses of the proposed device. The first is the "DEMUX and Switch" operation, in which the spectrally divided light by the AWG is routed to an arbitrary output port by a subsequent switch. The second is the "Switch and MUX" operation, in which arbitrary wavelengths from arbitrary input ports are merged by the AWG. No spectral degradation was observed in either operation. These results demonstrate the potential of the 5.5%-Delta-PLC/silicon photonics hybrid platform for compact, low-power, and fast-switching applications.

The gut microbiota is closely related to good health; thus, there have been extensive efforts dedicated to improving health by controlling the gut microbial environment. Probiotics and prebiotics are being developed to support a healthier intestinal environment. However, much work remains to be performed to provide effective solutions to overcome individual differences in the gut microbial community. This study examined the importance of nutrients, other than dietary fiber, on the survival of gut bacteria in high-health-conscious populations. We found that vitamin B1, which is an essential nutrient for humans, had a significant effect on the survival and competition of bacteria in the symbiotic gut microbiota. In particular, sufficient dietary vitamin B1 intake affects the relative abundance of Ruminococcaceae, and these bacteria have proven to require dietary vitamin B1 because they lack the de novo vitamin B1 synthetic pathway. Moreover, we demonstrated that vitamin B1 is involved in the production of butyrate, along with the amount of acetate in the intestinal environment. We established the causality of possible associations and obtained mechanical insight, through in vivo murine experiments and in silico pathway analyses. These findings serve as a reference to support the development of methods to establish optimal intestinal environment conditions for healthy lifestyles.

The gut microbiome is an important determinant in various diseases. Here we perform a cross-sectional study of Japanese adults and identify the Blautia genus, especially B. wexlerae , as a commensal bacterium that is inversely correlated with obesity and type 2 diabetes mellitus. Oral administration of B. wexlerae to mice induce metabolic changes and anti-inflammatory effects that decrease both high-fat diet–induced obesity and diabetes. The beneficial effects of B. wexlerae are correlated with unique amino-acid metabolism to produce S-adenosylmethionine, acetylcholine, and l -ornithine and carbohydrate metabolism resulting in the accumulation of amylopectin and production of succinate, lactate, and acetate, with simultaneous modification of the gut bacterial composition. These findings reveal unique regulatory pathways of host and microbial metabolism that may provide novel strategies in preventive and therapeutic approaches for metabolic disorders.

We designed and fabricated a 200-GHz-spacing, 16-channel, 1 × 4 silicon monolithic wavelength selective switch (WSS), adopting a wavefront control configuration with no waveguide crossings. Its basic switching operations were demonstrated with four wavelength channels.

Barley is a grain rich in β-glucan, a soluble dietary fiber, and its consumption can help maintain good health and reduce the risk of metabolic disorders, such as dyslipidemia. However, the effect of barley intake on the risk of dyslipidemia has been found to vary among individuals. Differences in gut bacteria among individuals may be a determining factor since dietary fiber is metabolized by gut bacteria and then converted into short-chain fatty acids with physiological functions that reduce the risk of dyslipidemia. This study examined whether gut bacteria explained individual differences in the effects of barley intake on dyslipidemia using data from a cross-sectional study. In this study, participants with high barley intake and no dyslipidemia were labeled as “responders” to the reduced risk of dyslipidemia based on their barley intake and their gut bacteria. The results of the 16S rRNA gene sequencing showed that the fecal samples of responders (n = 22) were richer in Bifidobacterium, Faecalibacterium, Ruminococcus 1, Subdoligranulum, Ruminococcaceae UCG-013, and Lachnospira than those of non-responders (n = 43), who had high barley intake but symptoms of dyslipidemia. These results indicate the presence of certain gut bacteria that define barley responders. Therefore, we attempted to generate a gut bacteria-based responder classification model through machine learning using random forest. The area under the curve value of the classification model in estimating the effect of barley on the occurrence of dyslipidemia in the host was 0.792 and the Matthews correlation coefficient was 0.56. Our findings connect gut bacteria to individual differences in the effects of barley on lipid metabolism, which could assist in developing personalized dietary strategies.