Manabu Taniwaki

Cyclic olefin polymer-coated silver hollow glass waveguides for the infrared

Cyclic olefin polymer (COP) is newly used as the inner dielectric of infrared, hollow glass waveguides because of its low extinction coefficient in the mid-infrared region. A liquid-flow coating and dry-cure process are employed to form the COP layer on the inside of a silver-coated hollow glass tube. In the coating process, cyclohexane is chosen as the solvent of COP to form a smooth and uniform COP layer. It is shown that COP-coated silver hollow glass waveguides show low loss properties for CO(2), CO, and Er:YAG laser light when the thickness of the COP layer is properly chosen.

Multihundred-watt CO laser power delivery through chalcogenide glass fibers

Power transmission characteristics for the 5‐μm band CO laser through chalcogenide glass fibers have been measured. With 1000‐μm core diameter, 1‐m‐long, As‐S and Ge‐As‐S glass fibers, the maximum transmitted powers have reached as high as 226 and 180 W, respectively. By applying antireflection coatings to the fibers, drastic increases in transmission efficiency have been demonstrated.

1‐kW, capacitively coupled radio frequency discharge excited CO laser with a closed‐cycle fast axial flow

A capacitively coupled transverse radio frequency discharge has been successfully applied to excite a CO laser with a closed‐cycle fast axial flow. The discharge and laser characteristics are described and the role of the O2 added to CO/N2/He mixtures is discussed. For a mixture of CO/N2/He/O2=7.5/12.5/80/0.8 an output of about 1 kW has been obtained at an entrance gas temperature of 160 K. Stable output with good beam quality has been demonstrated.

Observation of High Laser Gain at 703 nm in a New Chemical System

Visible stimulated emission has been observed in a chemically produced O4* complex system. A maximum positive gain of 2.8% has been measured at 703 nm. Experimental results imply high possibility that a visible chemical laser might be realized by the present system.

The Pseudospark Switch?A High-Voltage Gas Discharge Switch for High-Power Applications

A pseudospark switch, which can substitute thyratrons in pulsed power applications, was successfully tested at hold-off voltages up to 25 kV and peak currents up to 18 kA. A lifetime test was performed until 3.6×107 shots, without showing any significant degradation of the switch. Current rise rates up to 6×1011 A/s and a current reversal capability of 100% are additional features of this switch, which can help to improve the performance of pulsed power devices.

Fabrication of cyclic olefin polymer (COP)-coated silver hollow glass waveguides for the infrared

Cyclic Olefin Polymer (COP)-coated silver hollow glass waveguides were proposed and fabricated for IR laser light transmission such as Er:YAG, CO, and CO2 lasers. Silver mirror reaction and liquid-flow coating technique were employed to form the silver and dielectric layers inside the fused glass capillary tube for the simplicity, lower cost and potentiality of mass-production. Hollow waveguides with the length of 2m, and the inner diameters of 700 μm and 1mm have been successfully fabricated. It is shown that COP- coated silver hollow glass waveguides can be used to transmit Er:YAG, CO, and CO2 laser light with low losses when the thickness of COP layer is properly chosen. The measured spectra in the visible and mid-IR regions also show that uniform films were deposited inside the tube. Comparisons were also made among the waveguides that were inner-coated with other dielectric materials used before.

1-KW, ROOM-TEMPERATURE, FAST-AXIAL-FLOW CO LASER EXCITED BY A RADIO-FREQUENCY DISCHARGE

A fast-axial-flow rf-discharge-excited CO laser has been scaled up to produce an output power of more than 1 kW at room temperature (280-290 K). The discharge section is composed of eight discharge tubes, to which rf power is capacitively coupled. An output power of 1220 W is obtained with an Xe-added mixture, with corresponding electrical conversion eff iciency and specific output of 7.9% and 1.8 W/cm(3), respectively. Scaling characteristics of the scheme are discussed. The temperature dependence of the output, the output stability, and the beam properties are also reported.

Distributed computing for CO laser simulation

A new simulation code of CO laser has been developed for the recent distributed environment. The partial simulation code is transferred from the server and processed by the clients. The Java language which is independent on computer variation is introduced into the system description.

PC-based beam mode analysis of CO laser

A simple and compact computer code for the output beam mode analysis of the CO laser has been developed. The theoretical model based on the asymptotic expansion is converted to the computer model, which is divided into smaller structural modules. The program is described in C language in order to be compiled and executed by PCs, Mackintoshes, and workstations. The beam mode profiles under the multiline operation and misaligned cavity conditions are analyzed.

Flexible laser simulator constructed in the integrated information processing environment

Execution, transfer, storage and display of laser simulation have been improved. The technology of virtual machine has been introduced to integrate different hardware and software environments. The same binary code for laser simulation is executed in the integrated environments.