Hybrid-Integrated Tunable Hollow Waveguide DBR Laser
We propose a novel hybrid-integrated tunable laser with a hollow waveguide distributed Bragg reflector, enabling a wide continuous tuning with a single-tuning parameter. The wavelength tuning of hollow waveguide lasers is demonstrated for the first time.
Fabrication and characterization of hollow waveguide distributed bragg reflectors
We present the fabrication and characterization of a novel distributed Bragg reflector consisting of a grating loaded slab hollow waveguide. In this structure, we are able to obtain a high reflectivity even by using thin and short surface gratings because of the large contrast in refractive indices between a grating material and an air-core. We fabricated a slab hollow waveguide Bragg reflector with 620µm long, 190nm deep 1st-order circular grating composed of SiO2 exhibiting strong Bragg reflection at 1558nm with an air-core thickness of 10µm for TM mode. The peak reflectivity is 65% including fiber coupling loss, the 3dB bandwidth is 2.8nm and the grating-induced loss is less than 0.5dB.
Continuous calibration of a vacuum ultraviolet system from 65 to 125 nm by a cascade arc and comparison with the calibrated line radiation of a hollow cathode.
A high-power stationary helium cascade arc has been developed as a standard source for continuum radiation in the VUV spectral range from 65 to 125 nm. The calibration of the VUV system response was based on the calculated and measured continuum radiation of a 2-mmphi pure He arc. Diagnostics of the arc plasma in partial thermal equilibrium yielded the electron density and the temperature that were inserted in the calculations of the continuous radiation. The results were compared with the helium, argon, and krypton radiation lines of a high-current hollow cathode lamp. This lamp was built according to the construction drawings of a hollow cathode, which was calibrated by means of the electron synchrotron radiation at the Physikalisch Technische Bundesanstalt Berlin.