Wavelength Tech Forum: Laser Spectroscopy

New developments in lasers and optical technologies are bringing about exciting changes in spectroscopy. Faster lasers are leading to faster, more sensitive detectors, taking the accuracy of optical measurement to the next level. This month, we talk about the developments in optics and lasers. Our participants are Rob Morris, director of marketing and customer relations at Ocean Optics; and Steven Buckley, technical director of Photon Machines.

Right now, what do you think is new and exciting in the field of laser spectroscopy?

Morris: There are two areas that we see more often these days in our business. First, lasers are becoming faster and faster, and are combined with spectrometers that can measure processes occurring in intervals as small as one billionth of a second. Second, detection technologies like laser-induced breakdown spectroscopy (LIBS) take advantage of how lasers interact with samples to collect absorption data more efficiently than ever.

Buckley: There are a plethora of new laser sources and improved detectors-smaller, faster, and more sensitive. The combination of these with advanced data analysis techniques is aiding the transition of many methods once reserved for specialist laboratories into wider practice. We foresee a continued explosion of new devices enabled by these technologies that will bring optical measurement science to a new level of performance.

Are there groundbreaking applications that are being explored with advanced laser spectroscopy techniques?

Morris: As I understand it, new nanotechnologies and biomedical applications are being built around various laser techniques. There's also a lot of interest from the military in chemical and biological warfare agent detection.

Buckley: There are practical applications and novel emergent technologies. Some of our favorite applications for real-time measurements in practical devices include tunable diode laser spectroscopy and LIBS. For example, LIBS can be used for rapid material analysis, forensics, and measurement of aerosol particles, while tunable diodes can be modulated to make high-speed, high-sensitivity measurements of multiple components in a flowing gas stream. Many groundbreaking applications in process industries (e.g. pharmaceutical, steelmaking, glass, etc.) are emerging as these technologies are deployed.

How are new developments in lasers, for instance ultrafast lasers, affecting spectroscopy?

Morris: There’s a growing need for ultrafast spectrometers to measure the reactions these lasers create when introduced to various samples. Right now, this is a pretty esoteric area, even by analytical instrumentation standards, but one would presume that making the new technologies simpler and more affordable-some of these systems are in the hundreds of thousands of dollars-would open up many more applications.

Buckley: Ultrafast lasers are enabling probing of chemical states following reaction and/or light absorption before energy transfer can occur, allowing improved understanding of reaction dynamics and photophysics. The high bandwidth of femtosecond pulses can be an advantage for broadband excitation. From a practical point of view, ultrafast lasers are interesting for our work in LIBS, as they provide ablation without concomitant sample heating, and can be used to produce filamentation for long-range plasma formation. Some of the most interesting work relates to the proliferation of more flexible, widely tunable laser sources, such as new parametric fiber sources, that are capable of broadband tuning and ultrafast modulation.

What advances are being made in the field of lasers as related to Raman research?

Buckley: High-power blue diode lasers and compact, tunable sources are positive developments for Raman. The tunable sources allow greater application of resonance Raman, which will continue to be an area of Raman development due to the large signal enhancement available.

How will this affect the Raman market over the next 5 years, and what trends do you see emerging?

Buckley: As surface-enhanced Raman and resonance Raman methods become more popular, tunable sources will be increasingly employed in benchtop systems. Increasing applications in diverse areas-the biosciences on one hand and in homeland security/forensics on the other-will have a major impact on growing the market for Raman and other spectroscopic systems.