Compact, Low-Cost Tunable Laser Source for Remote Chemical Sensing

115 Compact, Low-Cost Tunable Laser Source for Remote Chemical Sensing--Aculight Corporation, 40 Lake Bellevue, Suite 100, Bellevue, WA 98005-2480; (206) 451-9558 Dr. Mark S. Bowers, Principal Investigator Mr. Charles I. Miyake, Business Official DOE Grant No. DE-FG03-97ER82308 Amount: $75,000 Advanced laser sources are sought by the Department of Energy for remote sensing of gases and other effluents emitted by the nuclear weapons production process. Currently-available laser sources suitable for such detection are too large, inefficient, and expensive to be used in portable systems. This project will develop a new laser source that is compact, low-cost, and suitable for a portable system to perform on-site and remote chemical spectroscopy in the mid-infrared spectral region. The new laser source combines recent advances in continuous-wave diode laser technology with state-of-the-art nonlinear optical frequency conversion technology. The source will generate radiation in the 2.5 to 4 micron region by frequency shifting a continuous-wave, single-frequency diode laser in an optical parametric oscillator (OPO) that uses the new nonlinear material, periodically-poled lithium niobate (PPLN). The output wavelength of the OPO can be tuned continuously in the desired spectral region using simple controls. The Phase I project will demonstrate the feasibility of the approach by building a discrete cavity PPLN OPO that is pumped by a tunable, high-power diode laser source. Measurements of the OPO oscillation threshold, mid-infrared output power, and tuning characteristics will be performed and compared to a numerical model. The stability of the OPO system will be quantified to determine the suitability of this device as a source for small, portable analysis instruments. Phase II will develop, fabricate, test, and deliver to DOE a prototype laser source for a fieldable spectroscopic instrument. Commercial Applications and Other Benefits as described by the awardee: The proposed technology will dramatically decrease the cost of tunable, narrowband, mid-infrared sources compared to present technologies. Several commercial applications exist, including methane/ethane sensing, proliferation monitoring sensors, and scientific research markets.