Tetsuya Yamasaki

Planar gradient-index glass waveguide and its applications to a 4-port branched circuit and star coupler

Planar gradient-index glass waveguides with nearly circular cross sections have been fabricated by the ion migration method. A low-loss branched circuit and star coupler are demonstrated.

Growth of ZnSe single crystals by iodine transport

Abstract Large ZnSe single crystals (14x14x20 mm3) have successfully been grown from the vapor phase by iodine transport. Substrates with large area (10x10 mm2) for epitaxial growth were prepared by cutting the crystal. It is important to control the temperature fluctuation and seed direction for rapid growth. As an etchant for the measurement of dislocation density, the NaOH solution on (111)B is better than the Br-CH3OH solution on (111)A. The etch-pit density is (2–7)x104/cm2. The iodine concentration in the crystal is about 200 ppm. The resistivity of the ZnSe crystal annealed in molten Zn is 0.03 Ω cm.

Highly Integrated Distributed-Index Planar Microlens And Its Characteristics

A. 2-D arrayed planar microlens with a diameter of 180 μm was monolithically integrated by an ion exchange technique. The focal length of the lens was 0.45 mm and N.A. was as large as 0.2. Distance between each lens is about 190 pm in the longitudinal direction and 300 μm in the vertical direction. Aberration of the lens can be controlled by applied voltage at the electromigration.

Optical Guided-Wave Oil Leak Sensor

From safety considerations an all-optical waveguide-type oil leak sensor would be advantageous in hazardous enviroments such as Oil Refineries. The all-optical oil leak sensor is expected to be intrinsically safe, since any electrical or electronic type sensor always runs the risk of igniting combustable gases and possibly causing a serious explosion [1].