Optical-referenceless optical frequency counter with twelve-digit absolute accuracy.

A simpler and more accurate measurement of absolute optical frequencies (AOFs) is very important for optical communications and navigation systems. To date, an optical reference has been needed for measuring AOFs with twelve-digit accuracy because of the difficulty in measuring them directly. Here, we focus on an electro-optics-modulation comb that can bridge the vast frequency gap between photonics and electronics.

Direct f-3f self-referencing using an integrated silicon-nitride waveguide.

We have achieved the simultaneous generation of a 2.6-octave-wide supercontinuum (SC) spectrum over 400-2500 nm and third-harmonic light solely by a dispersion-controlled silicon-nitride waveguide (SiNW). To increase the visible intensity of the SC light component, we fabricated low-loss 5-mm-long deuterated SiNWs with spot-size converters by low-temperature deposition.

Spatially resolved spectral phase interferometry with an isolated attosecond pulse.

We demonstrate spatially resolved supercontinuum spectral phase interferometry with an isolated attosecond pulse (IAP). The measured spatial-spectral interferogram over the broadband region indicates a high degree of IAP coherence in both spatial and spectral domains. In addition, the spectral-delay interferogram shows periodic temporal oscillations over the full IAP continuous spectrum, which indicates high temporal coherence.

Optical nonlinearity enhancement with graphene-decorated silicon waveguides.

Broadband on-chip optical frequency combs (OFCs) are important for expanding the functionality of photonic integrated circuits. Here, we demonstrate a huge local optical nonlinearity enhancement using graphene. A waveguide is decorated with graphene by precisely manipulating graphene's area and position.

Intractable hiccups (singultus) abolished by risperidone, but not by haloperidol.

Hiccups or singulata are rhythmic involuntary movements of the diaphragm, caused by a variety of conditions that interfere with the functions of the nerve nuclei in the medulla and supra-spinal hiccup center. Although neurotransmitters and receptors involved in the pathophysiology of hiccups are not defined well, dopamine has been considered to play an important role. In some cases, chlorpromazine or other antipsychotics are used for the treatment of intractable hiccups but their efficacy is often limited.

First Japanese family with primary familial brain calcification due to a mutation in the PDGFB gene: an exome analysis study.

Aims: Primary familial brain calcification (PFBC) is a rare disorder characterized by abnormal deposits of calcium in the basal ganglia and cerebellum. PFBC can present with a spectrum of neuropsychiatric symptoms resembling those seen in dementia and schizophrenia. Mutations in a few genes have been identified as causing PFBC: namely, the SLC20A2 gene that codes for the sodium-dependent phosphate transporter and the PDGFRB gene that codes for the platelet-derived growth factor receptor β (PDGF-Rβ).

Carrier-envelope offset locking with a 2f-to-3f self-referencing interferometer using a dual-pitch PPLN ridge waveguide.

We demonstrate that a 2f-to-3f self-referencing interferometer (SRI) becomes a useful tool for stabilizing a carrier-envelope offset frequency of an Er-doped fiber laser. A dual-pitch periodically poled lithium niobate (PPLN) ridge waveguide, consisting of two monolithically integrated segments with different quasi-phase matching pitch sizes, allows us to generate third-harmonic light with high efficiency. By using this device, we obtain a 45-dB signal-to-noise ratio in 100-kHz bandwidth of a heterodyne beat signal and instability of the in-loop f CEO of 8 × 10(-18) at 1 s of averaging time.

Phase-noise characteristics of a 25-GHz-spaced optical frequency comb based on a phase- and intensity-modulated laser.

We investigated phase-noise characteristics of both a phase/intensity-modulated laser with 25-GHz mode spacing and a mode-locked fiber laser with carrier-envelope-offset (CEO) locking. As the separation from the frequency of the continuous wave (CW) laser diode (LD) for a seed light source increases, the integrated phase noise of each comb mode of both the phase/intensity-modulated laser and supercontinuum light originating from it increases with the same slope as a function of mode number. The dependence of the integrated phase noise on mode number with the phase/intensity-modulated laser is much larger than with the mode-locked fiber laser of the CEO locking.

Generation of 120-fs laser pulses at 1-GHz repetition rate derived from continuous wave laser diode.

We report the first demonstration of continuous-wave laser diode based 100-fs-class pulse lasers operating at a gigahertz repetition rate without a mode-locking technique. We describe the performance of a 1-W, 120-fs optical pulse train at 1 GHz and a 1-W, 80-fs optical pulse train at 250 MHz by using a simple configuration. Sub-100-fs pulse durations are achieved by using a progressive expansion of the spectrum in the self-phase modulation process in an erbium-doped fibre amplifier.

Efficient 494 mW sum-frequency generation of sodium resonance radiation at 589 nm by using a periodically poled Zn:LiNbO3 ridge waveguide.

A solid-state-laser based single-frequency 589 nm light source that can be easily used in the laboratory is needed for sodium spectroscopy studies and cold sodium atom experiments. This paper shows that by using a periodically poled Zn-doped LiNbO(3) ridge waveguide for sum-frequency generation, we can obtain a high conversion efficiency to 589 nm light from two sub-watt 1064 and 1319 nm Nd:YAG lasers via a simple single pass wavelength conversion process without employing an enhancement cavity. A 494 mW light at 589 nm is generated and achieves overall conversion efficiency from the laser power of 41%.

Demonstration of carrier envelope offset locking with low pulse energy.

We demonstrate a carrier-envelope-offset (CEO)- locked frequency comb with 230-pJ fiber coupling pulse energy by using a passively mode-locked Er-fiber amplifier laser. For the generation of an octave-bandwidth spectrum in a highly nonlinear fiber and the second harmonic in a self-referenced interferometer with the lower pulse energy, we use a tellurite photonic crystal fiber and a direct-bonded quasi-phasematched LiNbO3 ridge waveguide, respectively. Our method is feasible for locking the CEO with a lower pulse energy to obtain a low-noise and highaccuracy optical frequency comb at telecommunications wavelengths.

Dynamical study of femtosecond-laser-ablated liquid-aluminum nanoparticles using spatiotemporally resolved x-ray-absorption fine-structure spectroscopy.

We study the temperature evolution of aluminum nanoparticles generated by femtosecond laser ablation with spatiotemporally resolved x-ray-absorption fine-structure spectroscopy. We successfully identify the nanoparticles based on the L-edge absorption fine structure of the ablation plume in combination with the dependence of the edge structure on the irradiation intensity and the expansion velocity of the plume. In particular, we show that the lattice temperature of the nanoparticles is estimated from the L-edge slope, and that its spatial dependence reflects the cooling of the nanoparticles during plume expansion.

Neuroleptic withdrawal with remitted schizophrenics: a naturalistic follow-up study.

Despite proven efficacy of maintenance pharmacotherapy in schizophrenia, indefinite neuroleptic treatment may not be optimal for all patients. It is uncertain how long maintenance therapy should be continued and how to identify those patients who can withdraw eventually from neuroleptics. Prospective randomized controlled studies are the ideal approach for evaluation of medication, however they are inevitably for the short term and may not be suitable for addressing the above-mentioned issue.

Two cases of neuroleptic-induced prolonged extrapyramidal symptoms.

Neuroleptic-induced extrapyramidal symptoms (EPS) are generally categorized as acute, withdrawal and tardive EPS. Here, we report two cases of a unique late-onset, long-lasting EPS (e.g.

Sampling measurement of soft-x-ray-pulse shapes by femtosecond sequential ionization of Kr+ in an intense laser field.

We propose a sampling technique for measuring the shape of ultrashort soft-x-ray pulses. The technique uses the transient state of Kr+ ions that is produced by the femtosecond sequential evolution of Kr ions during optical-field-induced ionization as an ultrafast x-ray-absorption sampling gate. We demonstrate the technique by measuring the pulse shape of the 51st harmonic (15.

A case of myclonus, resembling epileptic seizure, induced by short-term sulpiride treatment.

An 86-year-old woman with delusional disorder was treated with oral sulpiride at a dose of 200 mg/day. On the seventh day of treatment, she suddenly developed abrupt brief rhythmical contractions every 5 s in her neck muscles, orofacial muscles, muscles of upper limbs and lower legs bilaterally. Although there was no impairment of consciousness, her speech was interrupted by the myoclonic episodes.