ASSP 2005 delves into high powers at new wavelengths

The 2005 Advanced Solid-State Photonics topical meeting (ASSP; Feb. 6-9; Vienna, Austria) marked the 20th anniversary of the Optical Society of America’s (OSA) topical meeting that started out simply as “Tunable Solid-State ­Lasers” and has evolved to encompass the wider field of solid-state lasers, nonlinear optics, and associated technologies.

Jun 1st, 2005
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The 2005 Advanced Solid-State Photonics topical meeting (ASSP; Feb. 6-9; Vienna, Austria) marked the 20th anniversary of the Optical Society of America’s (OSA) topical meeting that started out simply as “Tunable Solid-State ­Lasers” and has evolved to encompass the wider field of solid-state lasers, nonlinear optics, and associated technologies.

For the first time since 2000 (Davos, Switzerland), ASSP was held outside North America; attendees were treated to a marvelous venue, great weather, a memorable banquet, an overflow of exhibitors, and a strong technical session from a host of presenters representing 31 countries.

First held in 1983, ASSP was originally run on an ad-hoc basis; with the adoption of OSA management in 1985, this meeting has thrived and represents one of the most successful and well-attended of the many OSA topical meetings. From a modest start with 134 attendees in 1985, the meeting in Vienna set a new record in attendance and exhibitors with 373 registrants and 39 tabletop exhibitors. The meeting had three days of solid technical sessions, including a marathon schedule on Monday that included evening postdeadline and poster sessions. The range of topics was broad, including the latest advances in the rapidly developing area of high-power fiber lasers and femtosecond sources.

The overall quality of the papers was very high, and many of the papers at the poster sessions, which usually are limited-interest presentations, would have been well suited for oral presentation at other meetings. European representation was high in papers and attendees, and the meeting showed that European R&D in the field is very active and, in some areas, dominant over the rest of the world.


A team of researchers from the University of Michigan, Nufern, and Fraunhofer USA described a 400-W polarized all-fiber ­laser at ASSP 2005. The laser is simple, with the coiled polarization-maintaining/large-mode-area (PM/LMA) fiber serving as the polarizing element; 405 W of continuous-wave power was produced from 610 W of coupled pump power.
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Some areas that stood out included high-power diode-pumped solid state ­lasers-for example, a 1-kW-average-power, 5-ns-pulsewidth, 10-kHz pulse-rate system from Fraunhofer (Aachen, Germany) designed for laser materials processing, and the Mercury system at Lawrence Livermore National Laboratory (Livermore, CA), which produces 35 J/pulse. High-power fiber lasers were presented, including a 66-W thulium-doped fiber laser with 61% slope efficiency, developed at the University of Southampton (Southampton, England) in cooperation with the University of Sydney (Sydney, Australia), and an all-fiber, polarized, ytterbium-doped 400‑W system developed by a team from the University of Michigan (Ann Arbor, MI), Nufern (East ­Granby, CT), and ­Fraunhofer USA (Plymouth, MI), which emits at 1086 nm (see figure). Mid-IR tunable lasers based on the material Cr:ZnSe were presented, with work reported from the Technical University of Vienna (Vienna, Austria) and Coherent (Santa Clara, CA).

Work was presented on directly ­diode-pumped ytterbium-doped materials that produce high average powers in modelocked, femtosecond-duration pulses, with the majority of work on new crystals emerging from a variety of French and German groups. High-power femtosecond sources were described that were based on fiber lasers and in some cases used photonic fibers for pulse compression, with application to precision laser machining. Here, work from German, French, and United States groups was reported, with the leading efforts centered in Europe.

Nonstandard wavelengths

The general theme for this year’s postdeadline session was higher powers at nonstandard wavelengths. Fiber lasers as pump sources for solid-state crystals were discussed in two papers, with a 60‑W continuous-wave (CW) 1645-nm Er:YAG laser reported by the University of Southampton and a 40-W CW 2050-nm Ho:YLF laser reported by Q-Peak (Bedford, MA). A group from the Massachusetts Institute of Technology (Cambridge, MA) announced the demonstration of an octave-spanning modelocked Ti:sapphire laser with carrier stabilization, with application to optical clocks, and a French group demonstrated a high-peak-power photonic-crystal fiber. The session concluded with a description by Craig Denman, from the Air Force Research Laboratory/Directed Energy Directorate (Kirtland AFB, NM), of a 50-W single-frequency 589-nm source for sodium-guide-star applications.

On the exhibition side of the symposium, 39 companies displayed their products at the tabletop exhibition; products displayed represented a diverse offering from fiber lasers to diode lasers to ­diode-pumped solid-state lasers. The ASSP exhibition focused on those looking to source products and components going into their DPSS lasers. The exhibition hall was overflowing long after the coffee breaks ended.

A high point of the meeting was the evening banquet hosted by the mayor and governor of Vienna, Michael Häupl, and the Vienna City Administration held at the Wiener ­Rathauskeller (City Hall of Vienna). The dinner ­speaker, ­ultrafast-laser-researcher Gerard Mourou of the University of Michigan (Ann Arbor, MI), gave a humorous and informative overview of the development of solid-state lasers; the banquet was capped off with a friendly roast of Peter “Shapes” Moulton.

PETER MOULTON is president of Q-Peak (Bedford, MA) and MERRILL APTER is vice president of sales and marketing at nLight (Vancouver, WA).

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