In this work, we report on the formation and characterization of monomode KTiOPO<sub>4</sub> waveguide at 1539 nm by 6.0 MeV C<sup>3+</sup> ion implantation with the dose of 2×10<sup>15</sup> ions/cm<sup>2</sup> and Rb<sup>+</sup>-K<sup>+</sup> ion exchange, respectively. The relative intensity of light as a function of effective refractive index of TM modes at 633 nm and 1539 nm for KTiOPO<sub>4</sub> waveguide formed by two different methods were compared with the prism coupling technique. The refractive index (n<sub>z</sub>) profile for the ion implanted waveguide was reconstructed by reflectivity calculation method, and one for the ion exchanged waveguide was by inverse Wentzel–Kramers–Brillouin. The nuclear energy loss versus penetration depth of the C<sup>3+</sup> ions implantation into KTiOPO<sub>4</sub> was simulated using the Stopping Range of Ions in Matter software. The Rutherford Backscattering Spectrometry spectrum of KTiOPO<sub>4</sub> waveguide was analyzed after ions exchanged. The results showed that monomode waveguide at 1539 nm can be formed by ion implantation and Rb<sup>+</sup> -K<sup>+</sup> ion exchange, respectively.
As an important and efficient method of particles size measurement, laser scattering has attracted great interest in the last decades. The sheath flow method has received extensive attention for its specific characteristic in cell detection and other fields. In this work, we report on a study of sheath flow method in laser scattering particles size measurement. In the particles size measurement system, an optical fiber laser was used as laser source, the light sensitive was confined to circular region with a diameter of less than 10μm by micro-lens focusing structure. Based on the scattering theoretical analysis of the particle size distribution from the scattering light energy, an improved sheath flow structure is proposed to obtain accurate and reliable scattering light signal from the particle passing through sheath flow pool. The digital voltage signals were measured via the amplification circuit and the data acquisition card. Numerical calculations and experiment results show that the sheath flow system is effective in the laser scattering particles size measurement.
A novel design based on near forward light scattering detection system to measure size and concentration distribution of particles in liquids is reported. According to theory of Mie scattering, the influence of relative refractive index, particles size and wavelength on the detection results are discussed. A green optical fiber laser with 532nm was used as the excited light source. As a key part in the detection system, the focusing system using a lens structure to confine light sensitive area with Gauss distribution less than 80 μm<sup>2</sup>. The lateral size of the sample cell is limited to 100μm. In order to measure the particles in non-overlapping state and improve the accuracy and repeatability, a novel structure in the sample cell was used and particle velocity through the sample cell was controlled by high precision stepper motor control system of micro circulation pump. Particle light scattering signal acquisition was completed by the poly lens combination system, according to the receiving angle relative to the measured particle, which can adjust the light scattering direction to obtain better particles light scattering signal. Photoelectric signal conversion, amplification and acquisition are all the devices with high precision. The measurement results showed that the measurement system was accurate and stable when the particles size in the range of 0.5-5μm.
We report on the fabrication and characterization of KTiOPO4 optical waveguides formed by Rb+-K+ ion exchange in high-purity RbNO3 melt at 340°C for 90 min and subsequent He+-ion irradiation at energy of 500 keV and fluence of 3×1016 ions/cm2. The irradiation of KTiOPO4 crystals with He+ ions was simulated using the stopping range of ions in matter (SRIM’2006) software. The dark mode spectra of the samples were measured with the prism coupling method. The reconstructed refractive index profiles of the planar waveguide show a barrier in the middle of the guiding region, and a refractive index enhancement region on each side of the barrier, indicating the formation of a double waveguide.
The GaN film with micron thickness was fabricated on the (100) cleavage plane of β-Ga<sub>2</sub>O<sub>3</sub> single crystal by nitridation with NH<sub>3</sub> gas flow rate of 400 sccm at 950°C for 10h. The GaN film has small cavities, suggesting that the growth mechanism is three dimensional growth mode like Volmer-Weber model. The thickness of GaN film formed by nitridation is about 1.18 μm. There are GaN (002) and (004) diffraction peaks in the XRD spectra, indicating that the epilayer has a strong <i>c</i>-axis preferred orientation. The photoluminescence spectra, transmittance spectra and Raman spectra of the GaN film were investigated.