21 May 2004
Our pick of the papers presented during a packed session on fiber lasers.
This year’s CLEO, IQEC and the newly launched PhAST conference attracted a total of 1651 papers. Judging by the busy rooms at all the CLEO and IQEC oral presentations, it’s safe to say that both conferences upheld their reputation of showcasing all the latest breakthroughs in fundamental optics. PhAST was also well attended, especially the keynote sessions which were standing-room only.
At CLEO’s high-power fiber laser session, where delegates were queuing up outside the hall for the next available seat or space to stand at the back, a variety of results were announced. Here’s a selection:
• Valentin Gapontsev from IPG Photonics presented details of a linearly polarized 250 W singlemode Yb-doped fiber laser. Operating continuous wave at around 1076 nm, Gapontsev said the system had an extinction ratio > 23 dB and an M2 < 1.04. He added that the company is now working on a 450 W version and that stimulated Raman scattering was the major effect limiting the output power.
• A collaboration between Friedrich-Schiller University in Germany and US firm Nufern detailed its work on high-power, linearly polarised fiber lasers. Based on a Yb-doped polarizing-maintaining large mode area fiber, the laser emits 312 W at 1090 nm, has an extinction ratio of around 17 dB and an M2 of 1.1. The team is now looking into higher doping concentrations.
• Researchers from Friedrich-Schiller University have also teamed up with Crystal Fibre of Denmark to work on large-mode-area microstructured fiber lasers. The team described a singlemode microstructured ytterbium-doped air-clad fiber with a mode field diameter of 45 µm and a pump light absorption of 16 dB/m. Using this fiber, the researchers have obtained 14 W at 1030 nm.