Keiichi Mito

Phase‐matched second‐harmonic generation in novel corona poled glass waveguides

Second‐order optical nonlinearity χ(2) is induced in glass films by corona poling. The glass films are fabricated by radio‐frequency sputtering Corning7059 onto Pyrex glass substrates. The values of second‐order nonlinear coefficient d33 of the corona‐poled glass films are estimated to be ∼0.5 pm/V. Using the corona‐poled glass films as a waveguide, phase‐matched second‐harmonic generation has been demonstrated in the glass films for the first time. The origin of the χ(2) is considered to be related to the defects in the glass films.

Second‐order optical nonlinearity in corona‐poled glass films

Several experiments were performed to elucidate the origin of the second‐order optical nonlinearity χ(2) induced in the corona‐poled Corning 7059 glass films. The values and the time decay of the second‐harmonic coefficient d33 were measured for the glass films poled on several different kinds of substrates. The value of d33 was found to be dependent on the kinds of substrates. It was also observed that the glass films poled on a soda‐lime substrate showed faster time decay of d33 than those poled on a Pyrex glass substrate. The glass films were also poled at room temperature, and the values of d33 were measured as a function of poling time. As a result, the value of d33 increased with the poling time and approached a value which was close to that obtained for the glass films poled at 100 °C. From the experimental results, it is speculated that the space charge formed in the vicinity of the interface between the glass film and the substrate contributes to the creation of the χ(2). The planar charge densit...

Solid-State Dye Laser with Photo-Induced Distributed Feedback

This paper describes the action of a solid-state dye laser utilizing a photo-induced distributed feedback (DFB) resonator. We solidified rhodamine B into a dried xerogel monolith using the sol–gel method, and used it as an active laser medium. The pump source was third-harmonic generation (THG) produced by a pulsed Nd:YAG laser. We divided the pump beam in two and irradiated the two beams on the active medium. The interference fringes simultaneously form both a spatial periodic modulation of optical gain and a refractive index in the active medium. This periodical structure functions as a DFB resonator. Without an external resonator, we achieved a laser oscillation with a narrowed spectrum. The full width at half maximum (FWHM) of the laser wavelength was approximately 1 nm. We tuned the center wavelength of the laser from 600 nm to 635 nm. In addition, we achieved a second-order DFB laser oscillation with second-harmonic generation (SHG) of a Nd:YAG laser.

Laser Oscillation of Energy Transfer Solid-State Dye Laser with a Thin-Film Ring Resonator

We fabricated an energy transfer solid-state dye laser with a thin-film ring resonator. We combined several organic dyes, such as stilbene 3, coumarin 153, rhodamine B, and cresyl violet. The mixed dyes were embedded into the xerogel thin film by the sol-gel method. We pumped the dye molecules with a pulsed Nd:YAG laser third-harmonic generation (THG). Using the mixed-dye doped thin-film ring resonator, we obtained laser oscillation at four different wavelengths with one pumping source.

Optical quadratic nonlinearity in multilayer corona-poled glass films

Second order nonlinearity via corona poling at room temperature in a Corning 7059 glass film on a Pyrex glass substrate was studied. It was clearly pointed out that the origin of the induced nonlinearity in this waveguide was located at the interface region between a top layer glass film and a glass substrate. This region is formed to be a depletion layer in the consequence of a drift of positive ions towards a negative electrode during corona poling. X‐ray photoelectron spectroscopy measurement on the corona‐poled Pyrex glass substrate gave the evidence that the main mobile ions were sodium ions.

Determination of the thermal conductivity of argon and nitrogen over a wide temperature range through data evaluation and shock-tube experiments

Reliable and well-established methods to measure the thermal conductivity of gases are available only in the moderate temperature range, namely, up to about 1000 K. In the present study, a set of the most probable thermal conductivity values of components of gaseous combustion products in a wide range of temperatures has been obtained through an optimum combination of three procedures: critical assessment of available data in the moderate temperature range, experimental determination by the shock-tube method at high temperatures, and theoretacal estimation of temperature dependence in the intermediate temperature range. Among the components of combustion products, one monatomic gas and one diatomic gas, namely, argon and nitrogen, were studied in the present paper. The shock-tube measurements have been performed in the temperature ranges 1000–4500 K for argon and 500–2200 K for nitrogen. The results of the critical evaluation and the shock-tube measurements have been combined with the aid of theoretically assumed temperature dependence of the thermal conductivity.

Analysis of the Laser Action of a Solid-State Dye Laser with a Thin Film Ring Resonator

This paper presents the fabrication of a compact blue solid-state dye laser and the properties of the laser action based on both experiment and numerical calculation. We solidified Stilbene-3 dye as the active medium for the laser by the sol-gel method and coated the medium around a 3-mm diameter glass rod. We used the glass rod simultaneously as a thin film ring resonator and a light amplifier. We pumped the dye molecules with pulsed Nd:YAG laser third-harmonic generation (355-nm wavelength) and obtained blue laser emission; the center wavelength of the laser output was 433 nm. We also designed a model of the thin film ring laser and simulated a performance of the laser. Because of the agreement between the calculated and experimental results, the validity of the model was assured.

Second order nonlinear optical properties in silica-based glass film waveguides

Phase-matched blue second harmonic generation was observed in a corona-poled Corning 7059 glass film waveguide. The induced quadratic optical nonlinearity was examined by second harmonic generation with a time dependent decay for multi-complex of SiO2,BaO,B2O3 and/or Al2O3. Glass films with every possible combination of composition were fabricated and examined, The glass composition of SiO2-BaO-B2O3 and/or SiO2-BaO-Al2O3 was found to play effective roles in maintaining the induced second order nonlinearity for a longer period of time. This is supposed to be related to distributed traps which come from complex of the glass components.

Perylene Orange Doped Acrylic Polymer for Solid-State Dye Laser

Perylene orange doped acrylic polymer has been applied successfully to the solid-state dye laser system. Its optical properties and laser characteristics have preliminarily been measured. Its superior photostability has been demonstrated as compared to the solid-state dye laser systems reported thus far.

Determination of the thermal conductivity of xenon-helium mixtures at high temperatures by the shock-tube method

The thermal conductivity of gases at high temperatures has been measured by the shock-tube method, which is uniquely suited to measure thermal conductivities of gases at high temperatures above 2000 K. A consistent set of thermal-conductivity data over a wide range of temperatures has been obtained from optimum combinations of shock-tube experiments at high temperatures, previously published data at lower temperatures, and a theoretical correlation of the temperature dependence. In the present study, the thermal conductivity of xenon-helium mixtures has been determined at compositions of 10 and 30 mol% xenon over the temperature range from 300 to 4800 K. Even though there is a large difference between the thermal conductivity of pure xenon and that of helium, it is interesting that the dependences of the thermal conductivity of the mixture on temperature and composition are linear. The experimental results are in good agreement with the predicted values based on the corresponding-states principle and the mixing rule. From these experimental results, interpolating the corresponding-states correlation data, we represent the equation of xenon-helium gas mixtures for thermal conductivity in terms of temperature and composition.