Yuji Matsuura

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.

Hollow-fiber delivery of high-power pulsed Nd:YAG laser light

We propose hollow fibers for delivery of high-peak-power pulsed Nd:YAG laser light. Hollow fibers with an internal polymer layer were fabricated by a liquid-phase coating technique. We reduced the losses of the fibers in the near-infrared region by producing a silver film that was very smooth owing to use of an ultrasonic wave for mixing of the silver and the reducer solutions in the silver-plating process. The straight losses of the 1-m-long polymer-coated fibers were 0.3 dB for the 700-mum bore size and 0.1 dB for the 1000-mum bore fiber.

Vacuum-cored hollow waveguide for transmission of high-energy, nanosecond Nd:YAG laser pulses and its application to biological tissue ablation

A vacuum-cored hollow waveguide has been found to transmit 1064-nm, Q-switched Nd:YAG laser pulses. With this scheme, laser-induced air breakdown was completely suppressed, and the laser-induced damage threshold of the waveguides inner coating was significantly increased. With a 1-m-long, 1-mm inner-diameter, cyclic olefin polymer-coated silver hollow waveguide, the maximum transmitted laser energy was as great as 158 mJ/pulse (20.1 J/cm(2)), at a repetition rate of 10 Hz in a 90 degrees -bent waveguide condition. The corresponding transmitted peak laser power was 17.6 MW. With the transmitted laser pulses, deep ablation of myocardium tissues was demonstrated in vitro.

Flexible small-bore hollow fibers with an inner polymer coating.

Flexible hollow-glass fibers with small-bore diameters of 250 and 320 mum have been developed for Er:YAG laser delivery. The fibers consist of a glass capillary tube and an inner coating of silver and polymer thin films that are deposited by use of a simple liquid-phase technique. The 250-mum-bore fiber exhibits a straight loss of 0.8 dB/m and a bending loss of 1.2 dB when it is bent 180 degrees at the output end, with a bending radius of 2 cm. The maximum energy delivered by the fibers is ~100 mJ.

Refractive indices and extinction coefficients of polymers for the mid-infrared region

Refractive indices and extinction coefficients of several polymers have been measured for the wide infrared wavelength region. The polymers used as coating materials have also been found useful for low-loss hollow waveguides for the transmission of Er:YAG, CO, and CO(2) laser light, respectively.

High-power Nd:YAG laser picosecond pulse delivery by a polymer-coated silver hollow-glass waveguide

An oscillator-amplifier high-power Nd:YAG laser system was used for transmission of a single 50-ps-long pulse or a train of pulses through a cyclic olefin polymer-coated silver hollow-glass waveguide. The maximum energy that was transmitted was 150 mJ for the train of pulses and 40 mJ for the single pulse, from which followed a delivered power of 100 GW/cm(2) . The characteristics that were obtained make these waveguides promising for the delivery of high-power laser pulses in medical as well as other applications.

Aluminum-coated hollow glass fibers for ArF-excimer laser light fabricated by metallorganic chemical-vapor deposition

A hollow fiber composed of a glass capillary tube and a metal thin film upon the inside of the tube is proposed for the delivery of ArF-excimer laser light. From theoretical analysis, aluminum is chosen as the metal layer. A thin aluminum film is deposited by metallorganic chemical-vapor deposition, with dimethylethylamine alane employed as the source material. Measured loss spectra in vacuum-ultraviolet and ultraviolet regions and losses for ArF-excimer laser light show the low-loss property of the aluminum-coated fiber at the 193-nm wavelength of ArF-excimer laser light. The straight loss of the 1-m long, 1-mm-bore fiber is 1.0 dB.

Low loss smart hollow waveguides with new polymer coating material

Abstract A new kind of cyclic olefin polymer COP-E48R has been selected as the dielectric material for a silver hollow glass tube. Owing to its lower extinction coefficient at the wavelength of 10.6 μm, transmission losses for the CO 2 laser light has been reduced significantly in the COP-E48R-coated silver (COP-E48R/Ag) hollow glass waveguide. By properly selecting the film thickness of COP, Er:YAG and CO 2 laser light are shown to be transmitted with low loss simultaneously or independently. Delivery properties of red and green pilot beams were also evaluated.

Delivery of F2-excimer laser light by aluminum hollow fibers.

A hollow fiber composed of a glass-tube substrate and an aluminum thin film coated upon the inside of the tube delivers F2-excimer laser light. A smooth, aluminum thin film was deposited by using metal-organic chemical vapor deposition using dimethylethylamine:alane (DMEAA) as the precursor. It was shown that the transmission loss of the fiber with a 1.0-mm inner diameter was as low as 0.5 dB/m for the fiber with 1.0-mm diameter when the bore of the fiber is pressurized with an inert gas to remove the absorption of air. When the fiber is bent at the radius of 30 cm, the additional loss was 1.6 dB.

New and simple method for fabricating polymer-coated silver hollow fibers with large mechanical strength

Abstract A new method is proposed for fabricating polymer-coated silver hollow glass fibers to avoid the flexibility deterioration after the curing process. Transmission properties of fibers made by the two procedures with and without curing process are compared. Little difference was observed in the transmission properties at the wavelength 2.94 μm of Er:YAG laser light and 10.6 μm of CO2 laser light. The polymer layer is shown to be stable after 2-h, 5-W, continuous wave CO2 laser light transmission.