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College of Saint Benedict and Saint John's University

Physics Faculty Publications

2011

Articles 1 - 3 of 3

Full-Text Articles in Physics

High-Power Broadband Laser Source Tunable From 3.0 Μm To 4.4 Μm Based On A Femtosecond Yb:Fiber Oscillator, Tyler W. Neely, Todd A. Johnson, Scott A. Diddams Oct 2011

High-Power Broadband Laser Source Tunable From 3.0 Μm To 4.4 Μm Based On A Femtosecond Yb:Fiber Oscillator, Tyler W. Neely, Todd A. Johnson, Scott A. Diddams

Physics Faculty Publications

We describe a tunable broadband mid-IR laser source based on difference-frequency mixing of a 100 MHz femto second Yb:fiber laser oscillator and a Raman-shifted soliton generated with the same laser. The resulting light is tunable over 3.0 μm to 4.4 μm, with a FWHM bandwidth of 170 nm and maximum average output power up to 125 mW. The noise and coherence properties of this source are also investigated and described.


Experimental Observation Of Ion Beams In The Madison Helicon Experiment, Matt Wiebold, Yung-Ta Sung, John E. Scharer Jun 2011

Experimental Observation Of Ion Beams In The Madison Helicon Experiment, Matt Wiebold, Yung-Ta Sung, John E. Scharer

Physics Faculty Publications

Argon ion beams up to Eb=165 eV at Prf=500 W are observed in the Madison Helicon eXperiment (MadHeX) helicon source with a magnetic nozzle. A two-grid retarding potential analyzer (RPA) is used to measure the ion energy distribution, and emissive and rf-filtered Langmuir probes measure the plasma potential, electron density, and temperature. The supersonic ion beam (M=vi/cs up to 5) forms over tens of Debye lengths and extends spatially for a few ion-neutral charge-exchange mean free paths. The parametric variation of the ion beam energy is explored, including flow rate, rf power, and …


Impact Of Dispersion On Amplitude And Frequency Noise In A Yb-Fiber Laser Comb, Lora Nugent-Glandorf, Todd A. Johnson, Yohei Kobayashi, Scott A. Diddams May 2011

Impact Of Dispersion On Amplitude And Frequency Noise In A Yb-Fiber Laser Comb, Lora Nugent-Glandorf, Todd A. Johnson, Yohei Kobayashi, Scott A. Diddams

Physics Faculty Publications

We describe a Yb-fiber-based laser comb, with a focus on the relationship between the net-cavity dispersion and frequency noise on the comb. While tuning the net-cavity dispersion from anomalous to normal, we measure the relative intensity noise, offset frequency (fCEO) linewidth, and the resulting frequency noise spectrum on the fCEO. We find that the laser operating at zero net-cavity dispersion has many advantages, including an approximately 100× reduction in free-running fCEO linewidth and frequency noise power spectral density when compared to the normal-dispersion regime. At the zero-dispersion point, we demonstrate a phase-locked fCEO …