Takaoka Eiko

The thermo-optic constants of the flux grown RbTiOAs4 (RTA) have been measured from 0.4577 to 0.7931 mum. These results were fitted to the temperature phase-matching bandwidths (FWHM) for harmonic generation of the Nd:YAG laser and the Nd:YAG laser-pumped KTiOAsO4 (KTA) optical parametric oscillator (OPO), and were used to construct the thermo-optic dispersion formula that can be used for good reproduction of the temperature-dependent phase-matching conditions in the 0.459-3.129 mum range. Applications to the quasi phase-matching are presented.

YCa4O(BO3)(3) has been found to have the phase-matching points where the temperature variation of the phase-matching angle (dtheta(obs)/dT) becomes zero for type-1 second-harmonic generation at 0.5321 mum at phi = 30.8degrees and phi = 180degrees. We also found that the temperature sensitivity of the phase-matching angle in the zx plane differs between the phi = 0degrees and phi = 180degrees propagation directions in this material. In addition, the thermo-optic dispersion formula of YCa4O(BO3)(3) is presented.

K2Al2B2O7has been found to be phase matchable for type-1 sum-frequency generation (SFG) at 0.193 μm by mixing the Nd:YAG laser wavelength at 1.0642μm and the SFG output of the RbTiOAsO4optical parametric oscillator tuned at 0.2358 μm. An average power of 200 mW at 10 kHz was obtained in a 7-mm-long crystal. In addition, the Sellmeier equations and the thermo-optic dispersion formula, which predict well the phase-matching conditions and temperature phase-matching bandwidths (FWHM) for second-harmonic generation and SFG in the 0.193–0.669–μm range, are presented. © 2003 Optical Society of America.

ZnGeP2 has been found to be phase-matchable for SHG from 1.60 to 5.27μm at 20°C. The new Sellmeier and thermo-optic dispersion formulas that reproduce well the phase-matching conditions of the post 1990 crystals are presented. © 2003 Optical Society of America.

Some garbage collection (GC) algorithms use a given threshold to control their behavior. Objects are classified according to their lifetimes, and the optimum threshold is used to efficiently collect unnecessary objects. Determining the approximate threshold value is crucial to such algorithms because the threshold value has a strong influence on the algorithm efficiency. Since memory usage depends on how intensively applications are being run, it is necessary to dynamically adjust the threshold. Demographic feedback-mediated tenuring (DFMT) is an algorithm that adjusts the threshold dynamically according to cell usage pattern. In this scheme, permanent objects are copied repeatedly in the space for the young generation. Our adaptive garbage collection (AGC) is an efficient garbage collection algorithm that solves this problem. AGC adjusts the threshold dynamically according to the fraction of cells used. We propose GC cost as a measure for quantitatively evaluating the efficiency of generation-dependent garbage collection with the copy scheme, and compare AGC and FGC (GC using DFMT). We show that AGC performs more efficiently for most applications.

YCa4O(BO3)(3) has been found to be 90degrees phase-matchable for type-1 SHG at 0.8325 mum along z. In addition, we report the new experimental data on the phase-matching properties of YCa4O(BO3)(3) together with the improved Sellmeier's equations that reproduce well our new experimental results.

AgGaS2 has been found to be 90° phase matchable at 192 °C for sum-frequency mixing between the output of the KTP parametric oscillator at 3.2627 μm and its pump source at 1.0642 μm. The thermooptic dispersion formula that can be used for good reproduction of the temperature-dependent phasematching conditions thus far reported in the literature as well as our new data for second-harmonic generation of a CO2 laser and its harmonics at 1.7652-5.2955 μm is presented. © 1999 Optical Society of America.

AgCa(1-x)ln(x)Se(2) with x = 0.474 was found to be 90 degrees phase matchable for third-harmonic generation of CO2 laser wavelengths 9.2714-10.5910 mu m by means of temperature tuning. Sellmeier equations and the thermo-optic constant for this crystal are presented. (C) 1999 Optical Society of America. OCIS codes: 160.6840, 140.3470, 190.4970.

The high accuracy Sellmeier equations of GaSe were constructed from the phase-matching conditions for harmonic generation of a CO2 laser and published refractive indices. The high accuracy thermo-optic dispersion formula is also presented.

The thermooptic constants of AgGaSe2 have been measured at 2.052, 3.3913, 5.2955, and 10.5910 mu m. These results combined with the literature values were used to construct the thermooptic dispersion formula which correctly reproduces the temperature dependent phase-matching conditions for second-harmonic generation (SHG) and sum-frequency generation (SFG) of a CO2 laser as well as the thermally induced lensing effects for the 2.05 mu m pumped parametric oscillators (OPO).

90 degrees phase-matched parametric oscillation up to 4.3 mu m was obtained in the undoped KTiOAsO4 (KTA) crystal by pumping with the 1.928 mu m output of a KTiOPO4 (KTP) parametric oscillator pumped by an Nd:YAG laser at 1.064 mu m. The oscillator is continuous tunable hom 3.4 to 4.3 mu m. The improved Sellmeier's equations are presented.

In the list processing language, dynamic memory management is indispensable, and hence various methods have been proposed. In one such method, the object is discriminated according to its life, time and garbage collection (GC) is applied efficiently to the unnecessary object, based on a preset “threshold.” A problem is how the threshold should be set in order to realize the most efficient GC. This paper points out that the threshold that realizes the highest efficiency depends on the application to be executed, and proposes the technique of adaptive garbage collection (AGC). An experiment toward its implementation is reported. AGC is a kind of GC which adjusts the threshold dynamically according to memory use, so that efficient operation is realized for a variety of applications. Experiments aiming at the realization of AGC show that applications have their own pace in consuming the memory, and the optimal value of the threshold is related to that pace. It is seen also that the memory‐consuming pace of the application is related closely to the data in the interpreter, leading to the definition of the useful parameter for realizing the efficient AGC. Copyright © 1995 Wiley Periodicals, Inc., A Wiley Company