WDM photon pair source stabilized in a wide temperature range with cascaded optical nonlinearities and DFG monitoring.

In this paper, we report a multi-channel wavelength division multiplexed (WDM) photon pair source operating in a wide temperature range. The photon pair generation rates in multiple WDM channels were stabilized against changes in the operation temperature by combining the spectral flatness of cascaded optical nonlinearities (cascaded sum frequency generation/spontaneous parametric downconversion) with a differential frequency generation monitoring feedback system. The proposed method was experimentally validated using a type-I periodically poled LiNbO3 ridge waveguide device as the photon pair source. We successfully generated 16 WDM photon pairs at almost the same rate (0.024358 ± 0.000631 pairs/s/Hz), even when the operating temperature was varied from 27.01 °C to 60.16 °C.

Multimode-based polarization independent WDM devices using different order modes for TE and TM polarizations.

Multimode based polarization independent (PI) wavelength division multiplexing (WDM) devices are proposed and experimentally demonstrated. The key concept is to utilize two different order modes for the orthogonal polarizations, ith-order mode for TE and jth-order mode for TM (i ≠ j) polarization respectively to extend the flexibility for designing devices. PI coupler composed of a multimode directional coupler and mode converters is introduced as a basic device. Then, we apply PI coupler to Mach Zehnder interferometer (MZI) and Bragg grating bandpass filters. PI MZI is achieved by optimizing the combination of two phase shifters in the interferometer arms. PI bandpass uses 3dB-PI coupler and polarization rotate Bragg gratings that induce mode coupling between the polarizations. Each device showed good matching in the spectrum between TE and TM polarizations in term of operation wavelength. The proposed concept can be a promising approach to realize PI WDM functions without introducing polarization diversity scheme in which a polarization beam splitter, two devices designed for each polarization and a polarization beam combiner are required.

45-degree curved micro-mirror for vertical optical I/O of silicon photonics chip.

The broadband vertical optical inputs/outputs (I/Os) of silicon (Si) photonics pose significant challenges in terms of practical applications. Herein, we worked on a vertical optical I/O using a 45° curved micro-mirror. To verify the optical coupling characteristics, a simulation was conducted. As a result, efficient broadband optical coupling with various types of single-mode optical fibers was obtained owing to its lens function. An integration technology of the curved mirror was also developed based on the semiconductor manufacturing process. A curved micro-mirror with a spherical surface was obtained, and the vertical optical I/O with its lens function was demonstrated experimentally.

Silicon wire waveguide TE0/TE1 mode conversion Bragg grating with resonant cavity section.

Silicon wire waveguide TE0/TE1 mode conversion Bragg grating can be used in wavelength add/drop and polarization rotation Bragg diffraction. The device can implement many filtering functionalities required in wavelength division multiplexing optical communications. In this paper we describe TE0/TE1 mode conversion Bragg grating device incorporating resonant cavity section to obtain narrow transmission wavelength peak. Theoretical calculation agreed with measured wavelength response.

Silicon waveguide polarization rotator sampled Bragg grating.

In this Letter, we demonstrate, to the best of our knowledge, the first experimental results of sampled Bragg grating with polarization rotator function. Silicon waveguide is used. Multiple polarization-independent reflection wavelength peaks were obtained.

Generation of highly stable WDM time-bin entanglement by cascaded sum-frequency generation and spontaneous parametric downconversion in a PPLN waveguide device.

In this paper we report the generation of wavelength-division-multiplexed, time-bin entangled photon pairs by using cascaded optical second nonlinearities (sum-frequency generation and subsequent spontaneous parametric downconversion) in a periodically poled LiNbO3 device. Visibilities of approximately 94% were clearly observed in two-photon interference experiments for all the wavelength-multiplexed channels under investigation (five pairs), with insensitivity to the polarization states of the photon pairs. We also evaluated the performances in terms of quantum-key-distribution (QKD) applications by using four single-photon detectors, which enables to evaluate the QKD performance properly. The results showed long-term stability over 70 hours, maintaining approximately 3% of the quantum error rate and 110 bit/s of the sifted key rate.

Highly efficient phase-sensitive parametric gain in periodically poled LiNbO3 ridge waveguide.

We have developed a periodically poled LiNbO3 (PPLN) ridge waveguide device and experimentally demonstrated a phase-sensitive optical parametric amplification. The highly efficient net phase-sensitive parametric gain of +18.6 dB is obtained in a cascaded second harmonic generation and difference frequency generation configuration. The phase-sensitive gain is greater by +5.8 dB in comparison with the phase-insensitive gain. We successfully confirmed the phase-sensitive amplification with a high gain in the PPLN ridge waveguide.

Polarization rotation Bragg diffraction using Si wire waveguide grating and polarization rotator.

We report polarization independent Bragg grating wavelength filter with high diffraction efficiency. A rib waveguide polarization rotator and antisymmetric grating structure for fundamental to first order diffraction are used to generate the polarization rotation Bragg diffraction. The diffraction efficiencies and peak wavelengths become the same for two orthogonal input polarizations. Strong diffraction is attained easily. The concept was verified by simulation and experiment. Polarization independent band-pass filter consisting of polarization beam splitter and polarization rotation Bragg diffraction was experimentally demonstrated.

Neurotropin(®) ameliorates chronic pain via induction of brain-derived neurotrophic factor.

Neurotropin (NTP)(®), a non-protein extract isolated from the inflamed skin of rabbits inoculated with vaccinia virus, is used clinically for the treatment of neuropathic pain. Moreover, NTP may activate the descending pain inhibitory system. Depression-like behavior is often complicated by chronic pain. However, little is known about NTP-mediated prevention of mood disorders in chronic pain and its molecular mechanisms. We aimed to investigate the effects of NTP on brain-derived neurotrophic factor (BDNF)-mediated signaling and gene expression in chronic pain. In addition, these effects of NTP were compared with pregabalin which is an anticonvulsant, anxiolytic analgesic used to treat neuropathic pain and fibromyalgia. A chronic constriction injury model was established in Sprague-Dawley rats. The pain response was assessed using a paw withdrawal latency (PWL) test and depression was assessed by the immobility time in a forced swim test (FST). NTP was orally administered in two doses of 50 NU (Neurotropin Unit) and 100 NU/kg for 7 days from day 7 after injury. To measure the analgesic and anti-depressant effects of NTP, either K252a (a tyrosine kinase inhibitor), or 5,7-dihydroxy tryptamine (5,7-DHT, a selective toxin for 5-HTergic neurons) was administered by intracerebroventricular injection. Changes in pERK1/2 and pCREB (immunohistochemistry), 5-HT, and BDNF protein level (ELISA) and BDNF mRNA (RT-PCR) were measured in the anterior cingulate cortex (ACC) and in the rostral ventromedial medulla (RVM) 14 days after injury. After injury, the rats showed a decrease in PWL associated with the increase in time of immobility in FST. In this injury model, NTP blocked both the decrease in PWL and the increase in the FST, while pregabalin (10 mg/kg, po.) did not affect the increase in the FST. These effects of NTP were reversed by K252a, and 5,7-DHT. The analgesic effects of pregabalin were not reversed by K252a. NTP normalized the injury-induced excessive activation of pERK1/2 associated with decreased pCREB and BDNF mRNA in the ACC and in the RVM, and these changes were reversed by 5,7-DHT. In contrast, pregabalin did not affect either pCREB or BDNF levels in the chronic pain model. NTP ameliorated chronic pain and pain-related depression by normalizing the induction of BDNF associated with the 5-HTergic system. Pregabalin showed the analgesic effects but had no effects on either depression or the BDNF pathway. These results suggest that NTP may represent an additional drug strategy for chronic pain associated with depression.

Polarization rotation Bragg grating using Si wire waveguide with non-vertical sidewall.

We report polarization independent Bragg grating wavelength filter using polarization rotation. A non-vertical waveguide sidewall and antisymmetric grating structure can be used to generate the polarization rotation of the fundamental modes. The diffraction efficiencies and peaks becomes the same for two orthogonal input polarizations. The concept was verified by simulation and experiment.

Cutaneous magnetic stimulation reduces rat chronic pain via activation of the supra-spinal descending pathway.

Recent studies have demonstrated that magnetic stimulation (MS) can induce cellular responses such as Ca(2+) influx into the cultured neurons and glia, leading to increased intracellular phosphorylation. We have demonstrated previously that MS reduces rat neuropathic pain associated with the prevention of neuronal degeneration. Thus, we aimed to elucidate the actions of MS in relation to modulation of spinal neuron-glia and the descending inhibitory system in chronic pain. The male SD rats intrathecally implanted with catheters were subjected to sciatic nerve ligation (CCI). MS is a low power apparatus characterized by two different frequencies, 2 KHz and 83 MHz. Rats were given MS to the skin (injured sciatic nerve) for 10 min from the seventh day after CCI. The paw withdrawal latency (PWL) evoked by thermal stimuli was measured for 14 days after CCI. Immunohistochemistry for Iba-1 or GFAP was performed after 4% paraformaldehyde fixation (microscopic analysis). We employed microdialysis for measuring CSF 5-HIAA as a reflection of 5-HT release by MS stimulation. Following CCI, rats showed a decrease in PWL after CCI, and the decrease continued until the 14th day. With MS treatment, the decrease in PWL was reduced during the 10-14 day after CCI. Injection of JNK-1 inhibitors on the 14th day antagonized the analgesic effect of MS. MS also eliminated the CCI-induced decrease in GFAP immunoreactivity. Moreover, MS evoked spinal 5-HT release reflected by increase in spinal 5-HIAA level. Thus, we demonstrate that a novel magnetic stimulator used cutaneously can ameliorate chronic pain by not only preventing abnormal spinal neuron-glia interaction, but also through the activation of the supra-spinal descending inhibitory system.

Deep learning prediction of falls among nursing home residents with Alzheimer's disease.

AIM: This study aimed to use a convolutional neural network (CNN) to investigate the associations between the time of falling and multiple complicating factors, including age, dementia severity, lower extremity strength and physical function, among nursing home residents with Alzheimer's disease. METHODS: A total of 42 people with Alzheimer's disease were enrolled. We evaluated falling events from nursing home admission (baseline) to 300 days later. We assessed the knee extension strength and Functional Independence Measure locomotion item and carried out the Mini-Mental State Examination at baseline. To predict falling, participants were categorized into three classes: those who fell within the first 150 (or 300) days from baseline or those who did not experience a fall within the study period. For each class, 1000 bootstrap datasets were generated using 42 actual sample datasets, and were used to propose a CNN algorithm and cross-validate the algorithm. RESULTS: Eight (19.0%), 11 (26.2%) and 31 participants (73.8%) fell within 150 or 300 days after the baseline assessment or did not fall until 300 days or later, respectively. The highest accuracy rate of the CNN classification was 0.647 in the factor combination extracted from the Mini-Mental State Examination score, knee extension strength and Functional Independence Measure locomotion item score. CONCLUSIONS: A CNN based on multiple complicating factors could predict the time of falling in nursing home residents with Alzheimer's disease. Geriatr Gerontol Int 2020; ••: ••-••.

P150glued-associated disorders are caused by activation of intrinsic apoptotic pathway.

Mutations in p150glued cause hereditary motor neuropathy with vocal cord paralysis (HMN7B) and Perry syndrome (PS). Here we show that both overexpression of p150glued mutants and knockdown of endogenous p150glued induce apoptosis. Overexpression of a p150glued plasmid containing either a HMN7B or PS mutation resulted in cytoplasmic p150glued-positive aggregates and was associated with cell death. Cells containing mutant p150glued aggregates underwent apoptosis that was characterized by an increase in cleaved caspase-3- or Annexin V-positive cells and was attenuated by both zVAD-fmk (a pan-caspase inhibitor) application and caspase-3 siRNA knockdown. In addition, overexpression of mutant p150glued decreased mitochondrial membrane potentials and increased levels of translocase of the mitochondrial outer membrane (Tom20) protein, indicating accumulation of damaged mitochondria. Importantly, siRNA knockdown of endogenous p150glued independently induced apoptosis via caspase-8 activation and was not associated with mitochondrial morphological changes. Simultaneous knockdown of endogenous p150glued and overexpression of mutant p150glued had additive apoptosis induction effects. These findings suggest that both p150glued gain-of-toxic-function and loss-of-physiological-function can cause apoptosis and may underlie the pathogenesis of p150glued-associated disorders.