Economy tempers enthusiasm at AHPSL 2008

SAN DIEGO, CA--Despite the upbeat tone of the presenters related to prospects for semiconductor laser sales into industrial, defense, display, and medical markets, much of the talk during breaks and lunches at the second annual Applications of High-Power Semiconductor Lasers (AHPSL) conference, sponsored by IntertechPira (Portland, ME and Surrey, England) and held in San Diego from October 7–8, centered on the economy and the worldwide financial crisis. Attendance for AHPSL was approximately the same as last year, but not as good as conference organizers would have liked. In fact, conference director Olga Adamovich confirmed that two pre-conference seminars were cancelled due to poor attendance. Unfortunately, it is impossible to find out if the economy is to blame (certainly, several people were drawn away by the FABTECH conference in Las Vegas held the same week), although many attendees I spoke with mentioned travel restrictions in their companies and the potential for layoffs if the economy doesn’t improve.

But on the flip side, attendees and presenters were optimistic about the defense and medical markets, which are anticipated to remain strong in 2009 and beyond due to increased military spending and contract awards, as well as overall growth in the “necessary, non-aesthetic” medical sector. Unfortunately, the display sector and the industrial sector may not fare as well; already it was announced that Micron Technology is reducing its global workforce by 15% due to declining customer demand and oversupply of flash memory chips; unfortunately, as goes the semiconductor market, so goes demand for consumer electronics and correspondingly, the optics and photonics components--and semiconductor lasers--at the heart of many of these consumer devices.

In addition to economic conditions, several attendees (myself included) were disappointed by the “commercial” and “product promotional” nature of some of the presentations at AHPSL. But now for the good news: Constant technology improvements in brightness, wavelength offerings, and increased lifetime (as well as reduced power consumption) of semiconductor lasers continue to drive innovation and new applications.

Technology advances

In session 2, Advances in Technology and Pumping, Robert Martinson from nLight (Vancouver, WA), described how their new “Pearl” architecture--which incorporates single emitters into a scalable package--enables 100 W output power from a 105 µm fiber-coupled device, with 50% or better wall-plug efficiency (way better than diode laser bars), for applications in fiber-laser pumping. Martinson said that nLight’s roadmap calls for $20/W by late 2009 or early 2010. Detlev Wolff from Jenoptik Laserdiode (Jena, Germany) described a new passively cooled laser diode mount design that, in addition to moving from soft solder to hard solder, dramatically improves lifetime of 100 W devices (and higher) to beyond 10,000 hours. And Rajiv Pandey from DILAS Diode Laser (Tucson, AZ) described a 2 x 15-bar laser head (incorporating spatial interleaving and polarization beam combining) with a custom beam-shaping module that delivers 2–2.5 kW of power with an approximate 40 mm mrad beam parameter product (BPP).

Stepping aside from product descriptions, David Schleuning from Coherent (Santa Clara, CA) presented “Lateral Modes and Slow-Axis Divergence in Broad Area Semiconductor Lasers,” explaining how patterned emitters can produce near-field images that translate to improved flat-top profiles in laser output and improved BPP and efficiency values. Apparently, the fast axis is not impacted by packaging, optics, and temperature changes as much as the slow axis. And Iulian Petrescu-Prahova from Intense U.S. (North Brunswick, NJ) gave a mathematically charged presentation proposing a new power-extraction efficiency product, or PEEP figure of merit, for defining both efficiency and brightness of laser diodes. His in-depth discussion of ways to reduce facet heating--the primary reason for laser diode degradation--borrowed from some research findings in the SHEDS program (see www.laserfocusworld.com/articles/330758). And John-Mark Hopkins from the University of Strathclyde (Glasgow, Scotland), presented a comprehensive research update on optically pumped semiconductor disk lasers (SDLs) that combine high power with excellent beam quality, including breakthroughs from Coherent and OSRAM as well as the University. He even described a gallium antimonide-based SDL that is challenging some mid-IR devices in the 2 µm region. These three sessions generated many questions; it was clear the audience was hungry for information on the fundamental physics of laser diode design.

Industrial and display applications

The two markets that may be affected most by the economic downturn are seeing a revolution in the incorporation of semiconductor lasers. Arc welding is being replaced by diode-pumped solid-state (DPSS) and fiber lasers in many industrial processes (see www.laserfocusworld.com/articles/341585), and laser and LED lighting is replacing energy-hungry lamps in display backlighting and ushering in the era of laser TV (although admittedly, the $7000 Mitsubishi laser TV is not expected to sell well next to comparably sized $4000 LCD TVs).

In session 1, Industrial Applications, Eran Elizur from Kodak Graphic Communications in Canada described how digital imaging and digital printing are transforming the printing industry. He described Kodak’s Squarespot laser imaging process that delivers photographic quality to offset printing using a thermal laser imaging head at 830 nm with a proprietary light valve design to deliver up to 960 2–20 µm sized pixels at 60 W to the printing substrate. He also described a new thermal color filter (TCF) process in partnership with DuPont that uses lasers to transfer color to donor substrates with a 30% cost savings compared to LCD photolithography processes. Stuart Woods from Coherent in the U.K. gave a thorough overview presentation of industrial semiconductor laser applications with a focus on heat-treating, cladding, and welding of materials. Direct diode advantages are system costs roughly half to two-thirds of comparable laser systems, material absorption of laser energy is better than CO2 systems, part fit-up requirements are relaxed in many cases, and the 40% wall-plug efficiency cannot be beat. The remaining industrial-laser presentations focused on laser-assisted thermoplastic fiber placement, efficient drying in sheet-fed offset printing, and surface texturing of honeycomb shapes in 18.6% efficient polysilicon solar cells.

Presentations in session 4, Display Applications, were all surprisingly similar in nature. Leading the session was Matt Brennesholtz from Insight Media, who described the myriad use for RGB semiconductor lasers and LEDs in projectors, laser TVs, as display backlights, and in consumer digital projectors and touted the impending doom of UHP lamps. Product presentations followed from Sony on their high-power red laser diode arrays, Arasor’s NECSEL lasers (from Novalux acquisition), and QPC’s and OSRAM’s RGB lasers.

Defense and medical applications

Session 3, Defense, Aerospace, and Homeland-Security Applications, and Session 5, Medical and Biomedical applications, describe markets that should fare well despite economic woes.

Daylight Solutions (Poway, CA) presented their vision for compact, tunable mid-IR quantum-cascade lasers for biological and weapons detection, Northrop Grumman Cutting-Edge Optronics (St. Charles, MO) presented a new patent-pending ceramic micro-channel cooler for high-power devices.

Medical presentations included a market overview from Frost & Sullivan, as well as presentations on lasers for hair removal, photodynamic therapy, and other aesthetic purposes. Unfortunately, sales of lasers for these “aesthetic” applications will no doubt suffer in a down economy.

--Gail Overton