Laser 2003: A welcome relief

Laser 2003 (June 23–26; Munich, Germany) seemed like a breath of fresh air after the generally lackluster Conference on Laser and Electro-Optics (CLEO; Baltimore, MD) earlier in June and the ongoing wariness that currently pervades the optoelectronics industry.

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Laser 2003 (June 23–26; Munich, Germany) seemed like a breath of fresh air after the generally lackluster Conference on Laser and Electro-Optics (CLEO; Baltimore, MD) earlier in June and the ongoing wariness that currently pervades the optoelectronics industry. A busy exhibit hall with many booths occasionally filled to capacity, combined with many working demonstrations of applied photonics, served to create a buoyant feeling that has been missing from most optoelectronics events for some time.

Exhibitors seemed generally happy with the turnout, typically reporting plenty of booth traffic—although many also noted that few visitors actually had money to spend right now. Nonetheless, Patrice Malavieille, président directeur général of SEDI Fibres Optiques (Evry, France), echoed a common sentiment, saying, "We're very satisfied; this is the first good event we've attended for the past year."

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A solid-state laser is pumped with high-performance laser-diode bars arranged in a ring around the laser gain material. The optical axis of the laser is left unblocked. The laser construction is scalable and the beam optics can be customized.
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Also satisfied were the organizers of Laser 2003. The exhibitor count increased by 8% (to 846) compared to Laser 2001, while the number of visitors also increased by about 6%, to more than 20,000. Given the current economic and business conditions, these numbers were a pleasant surprise to many and mean that this conference continues to be one of the largest optoelectronics events held anywhere.

The exhibit occupied three halls and included demonstrations of many different laser types as well as applications ranging from welding metals to specialized imaging for the life sciences.

In the laser field, an increasing number of solid-state alternatives to the low-power blue (488-nm) ion laser are available. Several examples were on display, including the Novalux (Sunnyvale, CA) device seen previously at CLEO and a new 25-mW laser from Picarro (Sunnyvale, CA). Meanwhile, the fiber-laser power wars continue. SPI (formerly Southampton Photonics) announced that it had achieved 600 W from a single fiber laser. SPI claims this is the highest power reported to date with a single-fiber gain module.

A novel slab laser developed at the Fraunhofer Institute was shown by EdgeWave (both in Aachen, Germany). The laser combines short pulse duration with high peak output power and can drill fine channels or create hollow cavities in glass. Another novel laser design—the "ring-focus" laser—was shown by Myos (Giebelstadt, Germany) in which diode-laser bars are arranged in a ring around a common focal point to provide a relatively high but evenly distributed output for materials processing (see figure).

At least three disk lasers were at the show, with outputs ranging from 30 W to 2 kW. Rofin Sinar (Hamburg, Germany) first showed its pre-production system at Laser two years ago. This year the company had a 2-kW product at its booth and indicated in a press conference that a 4-kW version may not be too far behind. Also showing disk lasers were Trumpf (Ditzingen, Germany) and Prenovatec (Meiningen, Germany).

The most prevalent applications exhibited were marking and engraving, with materials ranging from plastics to glass. Most of the marking systems (or so it seemed) were based on diode pumping. On the welding front, Lasag (Thun, Switzerland) was demonstrating its Shadow system, which uses a single 50-ms pulse from a 500-W average power laser to create a single weld that can be up to 3 in. long. Scanning the pulse means the weld does not have to be in a straight line. The ability to create a single continuous weld in this way is of particular interest in applications requiring a hermetic seal (such as a pacemaker).

Technical sessions

Off the exhibit floor, the technical conferences were also well attended. They were organized or supported by a number of organizations including the German Scientific Laser Society (WLT); SPIE (Bellevue, WA), which held its European Conference on Biomedical Optics during Laser; and the International Society of Laser Surgery and Medicine (ISLSM), which held the first world laser-medicine congress together with the German Society of Laser Medicine. Also collocated with Laser was CLEO Europe/EQEC (European Quantum Electronics Conference)—after several years of moving this event around Europe, a long-term agreement was apparently reached this year to continue the collocation of CLEO Europe/EQEC at Laser.

CLEO Europe featured 17 tracks ranging from solid-state lasers and nonlinear optical materials through materials processing, nanostructures, and biophotonic analytical techniques. Forty-eight post-deadline papers highlighted recent European research. For example, Andreas Tünnermann and his group at Friedrich Schiller University of Jena (Germany) and a team from Crystal Fibre (Birkerod, Denmark) continued their work on high-power, air-clad, large-mode-area, ytterbium-doped photonic-crystal fiber lasers, reporting up to 80-W output power with a slope efficiency of 78%.

Crystal Fibre was also part of a team reporting a new thermo-optic switch that uses phase transitions of a thermochromic liquid crystal inside a photonic crystal fiber. And a team at the University of Wales (Aberystwyth, Wales) described an interesting experiment in chaotic optical communication using an external-cavity laser diode; a 1-GHz message was effectively decoded in closed-loop and open-loop receivers.

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