Delivery of High Energy Radiation in Mid-infrared Spectral Region by Hollow Waveguides

摘要

Due to increasing requirements to apply high energy mid-infrared radiation in various branches of medicine (cardiology, dentistry, dermatology, urology, gastroenterology), a sufficiently flexible and lossless delivery system is required. To transport these high energy pulses in a mid-infrared region, special cyclic olefin polymer-coated silver (COP/Ag) hollow glass waveguides were prepared and tested. The length of the waveguides was 0.5 m and inner diameter 1 mm. As a radiation source, an Er:YAG laser was used. The system generated energy up to 2.16 J or 2.35 J (depending on the repetition rate used - 3 Hz or 4 Hz, respectively). The length of transmitted pulses was measured to be 110 μs to 550 μs, depending on the pumping level. The output radiation was coupled into the COP/Ag hollow glass waveguide and the throughput and losses values were measured against the input radiation parameters. The transmission obtained was 91%. The maximum peak power up to 3 kW and mean power up to 5 W were delivered without any breakdown. The characteristics obtained make this specially constructed COP/Ag hollow glass waveguide a very promising device for the delivery of high-energy laser pulses in medicine and also in other applications.