Month: March 2026

Quantum cascade lasers (QCLs) are powerful mid-infrared (MIR) light sources for gas sensing, but factors such as manufacturing complexity, efficiency, system integration, and portability have limited their adoption for gas sensing systems so far. Optical gas sensing is widely used by industrial, environmental, and medical sectors where noncontact measurement, real-time response, and reliable operation are required. Applications such as process monitoring, emissions measurement, and respiratory gas analysis often involve complex gas mixtures and rapidly changing conditions, which demand sensors capable of both selectivity and sensitivity.

Many established optical sensing systems operate within the near-infrared (NIR) range (~0.83 to 1.55 µm), where efficient light sources and highly sensitive detectors are available.

Decades of development driven by the telecommunications industry led to reliable components—including indium gallium arsenide (InGaAs) detectors—that enable low-power operation and fast response times. But gas absorption features within the NIR spectrum are generally weaker and often lie close together spectrally, which can limit the ability to distinguish multiple gases within complex mixtures.

MIR (~3 to 11 µm) sensing addresses these limitations by targeting stronger and more distinct absorption bands. Although MIR technologies are less mature overall, the improved spectral separation available within this region supports more specific gas identification. QCLs provide a flexible and spectrally precise MIR light source, which enables direct access to narrow absorption features within a wide wavelength range and extends the applicability of MIR-based optical sensing to environments in which high measurement specificity is required.

Laser Focus World

On Friday, March 20, Sarah Kromer defended her PhD Dissertation titled Tuning Metal Interactions Through Ligand Modification in Platinum(II) Dimers. Sarah is one of the very few ultrafast laser experts in Phil Castellano group, and she contributed immensely to multiple cutting edge collaborations with leading research centers, both nationwide and internationally. Congratulations, Sarah! We hope to see you around for a while.

Is putting carbon-free laser-driven fusion energy on the grid by the 2030s possible? In August 2022, when the team of scientists at Lawrence Livermore National Lab’s (LLNL) National Ignition Facility (NIF) fired a shot that achieved a yield of 1.35 megajoules (MJ) of fusion energy with 1.9 MJ of laser energy, it was a long-awaited scientific breakthrough signaling fusion burn.

Later that same year during another inertial fusion (a.k.a. laser-driven fusion) experiment, scientists achieved a yield of 3.15 MJ of fusion energy with 2.05 MJ of laser energy and attained ignition. It was a thermonuclear fusion reaction created within the lab—and it kicked off a global race to put carbon-free laser-driven fusion energy on the grid by the 2030s or 2040s.

“This was a turning point when NIF first successfully showed that inertial fusion was possible, and the key is having the right kind of fuel—deuterium-tritium—and using lasers to compress and fuse it to generate gain (more energy out than put in),” says Arianna Gleason, staff scientist and deputy director of SLAC’s High Energy Density Science division. “It’s like sustaining the fuel of a star—just for a fraction of a second within a laboratory.”

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