May 25, 2007, Bothell, WA--Aculight Corporation has introduced a single-frequency, continuous-wave (CW) optical parametric oscillator (OPO), called Argos, that provides multiwatt, widely tunable, near- to mid-IR output. With what Aculight says is the highest power and broadest mode-hop-free tuning range of any OPO on the market, Argos is well-suited for applications such as photoacoustic and cavity-ringdown spectroscopy for trace-gas detection.
In addition to its power and range, the OPO is robust, according to Angus Henderson, principal scientist at Aculight. "We've shipped devices to customers in the U.S. and Europe and the units reach their destinations without requiring any realignment or expert installation," he says.
Argos is a fiber-pumped, singly resonant OPO that provides rapid, continuous tuning from 1.4 to 2 µm and from 2.4 to 3.9 µm. It operates at room temperature and produces simultaneous output at two wavelengths with available power between 1 and 5 W over the tuning range. The linewidth of the OPO output has been measured to be as low as 60 kHz. In tandem with the device's 60 GHz mode-hop-free rapid tuning range, this enables high-resolution spectroscopy in a wavelength region where alternate laser sources are unavailable. The unit is compact enough for use in facilities where space is at a premium; the OPO head measures just 5 x 6 x 14 in. with a control unit of 10 x 19 x 19 in.
Aculight developed Argos under a Small Business Innovation Research (SBIR) award from the National Institute of Standards and Technology (NIST; Boulder, CO). The technology was originally developed as a tool to improve detection of impurities in semiconductor process gases. For instance, cavity-ringdown spectroscopy is widely used to monitor for water vapor, a contaminant that causes substantial losses in semiconductor yield. Until now, diode lasers emitting around 1.3 µm have been used to detect the vapor; the Argos prototype will enable targeting of stronger absorption lines in the vicinity of 2.7 µm for water-molecule detection. Said Henderson, "Using Argos' mid-IR wavelength, you can potentially detect with around 10 times the sensitivity compared with the use of near-IR. This could mean a significant improvement in the semiconductor-manufacturing process."
Researchers at Rice University (Houston, TX) also used the Argos in a photoacoustic-spectroscopy demonstration to detect ammonia with ultra-high sensitivity. The researchers aim ultimately to use the technique to help develop compact, portable, highly selective sensing instruments for applications ranging from urban, industrial, and rural emission monitoring to biomedical and clinical diagnostics. Current technologies for these types of sensing include mass spectroscopy with gas chromatography and Fourier-transform interferometry. While both methods are highly sensitive, they have drawbacks in unit size, portability, and affordability, among others.
Aculight will demonstrate Argos at the upcoming 38th annual meeting of the Division of Atomic, Molecular and Optical Physics (DAMOP) from June 5-9, 2007, in Calgary, Canada. The company will also feature it at the 62nd Ohio State University International Symposium on Molecular Spectroscopy scheduled for June 18-22, 2007, in Columbus, Ohio, and at the 6th International Conference on Tunable Diode Laser Spectroscopy (TDLS) from July 9-13, 2007, in Reims, France.