January 26, 2022
Christopher Stolz, an associate program manager in charge of the NIF optics supply, has been elected as a fellow of SPIE, the international society for optics and photonics.
Stolz has worked at LLNL in the laser directorate as a thin-film engineer for more than 30 years—first in the Atomic Vapor Laser Isotope Separation (AVLIS) program and then at NIF.
“I am very honored to be recognized by SPIE for not only my technical contributions to the laser program at LLNL, but also for my service to both SPIE and Optica (formerly OSA) conference leadership,” he said, “including launching an annual thin film laser damage competition that has been a favorite event at the SPIE Laser Damage Conference since 2008. This competition has revealed interesting trends in laser damage of optical coatings over a wide spectral and pulse length range that have inspired research projects by multiple international groups.”
Stolz helped pioneer the use of Ion Beam Sputtering (IBS) for high-fluence pulsed-laser systems, including both AVLIS and NIF.
“Because of its low losses and environmental insensitivity, this is an ideal technology for spectrally challenging diagnostic optics and ultra-stable laser systems like the front end of NIF,” he said.“Working with industry, this coating technology was scaled 10 times in size to meet the needs of the laser program, which led the pathway to scale this technology for the first LIGO (Laser Interferometer Gravitational-wave Observatory) cavity mirrors. Today, this is the technology of choice for commercial optical pulsed lasers.”
During his career, Stoltz has focused on understanding how micron-scale and smaller defects limit the laser fluence in complex optical interference coating structures. He directed the research teams that performed the first 3D modeling of nodular defects to understand the impact of polarization on light intensification within nodular defects as well as the temporal characteristics of how light decays from these resonant structures.
With a summer student, he was the first to experimentally validate with photothermal microscopy up to a hundredfold absorption reduction of ejected nodules to better understand the laser conditioning effect of optical coatings.
With Laboratory Directed Research and Development (LDRD) funding, his team was the first to build a photothermal microscope based on an optical lock-in technique combined with a charge-coupled device (CCD) camera to speed up data acquisition by six orders of magnitude.
Also with LDRD funding, his team pioneered using femtosecond laser machining to remove fluence-limiting defects from optical coatings while creating the proper pit geometry to minimize light intensification by wave guiding. His last LDRD project developed a deposition and etch process, similar to what has been used by the extreme ultraviolet EUV lithography group at LLNL, to planarize coating defects, increasing nodular defect laser resistance by a factor of 3 times to 6 times.
More recently, he demonstrated an eightfold increase in the laser resistance of indium tin oxide (ITO), a transparent conductor, by proper placement of the layer within a low electric field location of a Fabry-Perot filter structure.
When he first started working for NIF, Stolz directed the development of new meter-scale deterministic optical coating and finishing technologies at outside optics vendors to replace slow and expensive artisan manual processes to increase the NIF amplifier slab. This helped increase the finish and mirror-coating rate by up to 10 times, improve yield, reduce cost by up to 10 times, and improve optic quality for the construction of NIF.
Each year, SPIE promotes members as new fellows of the society. Stolz is among 58 new fellows of the society this year. Fellows are members of distinction who have made significant scientific and technical contributions in the multidisciplinary fields of optics, photonics, and imaging. The fellows are honored for their technical achievement and for their service to SPIE and the general optics community. More than 1,600 SPIE members have become fellows since the society’s inception in 1955.
SPIE is the international society for optics and photonics, founded to advance an interdisciplinary approach to the science and application of light. The society advances emerging technologies through interdisciplinary information exchange, continuing education, publications, patent precedent, and career and professional growth. Each year, SPIE recognizes accomplishments and meritorious service in the optics, photonics, optoelectronics, and imaging communities it serves.
To see the list of SPIE fellows, click here.
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