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Journal ArticleDOI

High‐resolution infrared spectroscopy with a tunable diode laser

01 May 1970-Applied Physics Letters (American Institute of PhysicsAIP)-Vol. 16, Iss: 9, pp 351-354
TL;DR: In this paper, a current tunable Pb0.88Sn0.12 Te diode laser was used to obtain the absorption spectrum of SF6 near the P(16 and P(20) CO2 laser lines at 10.6μm by both direct and heterodyne techniques.
Abstract: A current‐tunable Pb0.88Sn0.12 Te diode laser was used to obtain the absorption spectrum of SF6 near the P(16) and P(20) CO2 laser lines at 10.6μm by both direct and heterodyne techniques. Because of its narrow linewidth, the diode laser can perform high‐resolution spectroscopy beyond the limits of conventional instruments moreover, its infrared frequency can be tuned continuously over a range much greater than attainable with a gas laser.
Citations
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Journal ArticleDOI
TL;DR: In this article, a new technique was presented for obtaining the absorption spectra of small samples and low concentrations of gases, which makes use of currently available sources of wavelength-tunable intense coherent light such as the optical parametric oscillator, dye laser, or tunable diode laser.
Abstract: A new technique is presented for obtaining the absorption spectra of small samples and low concentrations of gases. The technique makes use of currently available sources of wavelength‐tunable intense coherent light such as the optical parametric oscillator, dye laser, or tunable diode laser. The absorbed power is detected by the heating and resultant pressure rise in the absorbing gas. An initial experiment with a 15‐mW He–Ne laser operating at 3.39 μ has shown a sensitivity adequate to measure the absorption of a concentration of 10−8 of methane in nitrogen. It is expected that, with higher‐power sources of tunable ir radiation, it may be possible in the future to detect concentrations of impurities as low as 10−13.

498 citations

Journal ArticleDOI
Peter Werle1
TL;DR: In this paper, the main features and applications of tunable diode laser absorption spectroscopy are reviewed and the main characteristics of the currently available semiconductor diode lasers with respect to spectroscopic applications and sensitive detection techniques are discussed.

473 citations

Journal ArticleDOI
TL;DR: In this paper, a cw difference-frequency spectrometer was developed for the 2.2 to 4.2 μm infrared region by mixing argon and tunable dye lasers in LiNbO3.
Abstract: A cw difference-frequency spectrometer has been developed for the 2.2 to 4.2 μm infrared region by mixing argon and tunable dye lasers in LiNbO3. A resolution of 5 × 10−4 cm−1 with continuous scans up to 1 cm−1 and a scan precision better than 2 × 10−3 cm−1 have been achieved. Tunable ir powers of ~1 μW have been obtained, enabling sensitive absorption measurements and real-time spectroscopy. The range, resolution, speed, and sensitivity of this difference-frequency technique are demonstrated by absorption traces of water vapor, ammonia, methane, and nitrous oxide.

230 citations

Journal ArticleDOI
P.W. Smith1
01 Apr 1972
TL;DR: This is a tutorial review on the subject of mode selection in lasers that discusses some systems for frequency stabilization of single-frequency lasers, and concludes with examples of laser applications where mode-selection techniques are required.
Abstract: This is a tutorial review on the subject of mode selection in lasers. We begin with a historical review. After an introduction to the subject of modes in laser resonators and a brief review of the theory of laser gain saturation, the main body of the paper is devoted to a discussion of various mode-selection techniques, many which can be used to produce single-frequency laser operation. We discuss some systems for frequency stabilization of single-frequency lasers, and conclude with examples of laser applications where mode-selection techniques are required.

179 citations

Journal ArticleDOI
19 Feb 1971-Science
TL;DR: Preliminary experiments indicate that tunable Pb1-xSnxTe diode lasers will be useful in the identification and sensitive detection of most of the atmospheric pollutant gases and are attractive replacements for spectrometers and fixed-frequency laser sources where operation at cryogenic temperatures is not a serious impediment.
Abstract: Preliminary experiments indicate that tunable Pb(1-x)Sn(x)Te diode lasers will be useful in the identification and sensitive detection of most of the atmospheric pollutant gases. For point-sampling applications, concentrations in the parts-per-billion range should be measurable with very high specificity. For long-range atmospheric transmission techniques, the improved resolution capability and tunability of these diode lasers make them attractive replacements for spectrometers and fixed-frequency laser sources where operation at cryogenic temperatures is not a serious impediment. By using these lasers as tunable local oscillators in the infrared heterodyne configuration, remote passive detection of gases present in smokestack effluent appears possible. Finally, pulsed operation at temperatures available with simple cryogenic coolers permits immediate application to the fast detection of gases present in automobile exhaust and in chemical processing plants.

170 citations

References
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Journal ArticleDOI

143 citations

Journal ArticleDOI
TL;DR: In this paper, the quantum phase-noise-limited Lorentzian power spectral densities of diode lasers were directly measured and quantitatively analyzed, and the predicted inverse dependence of linewidth on laser power was also demonstrated.
Abstract: The quantum-phase-noise-limited Lorentzian power spectral densities of ${\mathrm{Pb}}_{0.88}$${\mathrm{Sn}}_{0.12}$Te diode lasers were directly measured. Linewidths as narrow as 54 kHz were observed and quantitatively analyzed. The predicted inverse dependence of linewidth on laser power was also demonstrated. These results were obtained from the beat-note spectra produced by heterodyning the diode laser, operating cw at 10.6 \ensuremath{\mu}m, with a stable, single-frequency C${\mathrm{O}}_{2}$ gas laser.

127 citations

Journal ArticleDOI
TL;DR: In this article, a CO2-N2-He laser with passive Q-switching was obtained, using SF6 gas as the saturable absorber, achieving a peak power of 1 kW in what appears to be a single transverse mode.
Abstract: Passive Q‐switching of a CO2–N2–He laser has been obtained, using SF6 gas as the saturable absorber. Peak power is 1 kW, in what appears to be a single transverse mode. This is 200 times the CW level for the same configuration and one‐fifth that obtained with a mechanical Q switch. Pulse rates are in the range 103 to 104 pulses per sec. Operation is on a single vibrational‐rotational line, unlike the case of CW operation.

94 citations

Journal ArticleDOI
TL;DR: In this article, the saturation of a CW infrared laser beam by SF6 has been measured as a function of pressure of SF6 and added buffer gases (He, Kr, and C2H6).
Abstract: The saturation of absorption of a CW infrared laser beam by SF6 has been measured as a function of pressure of SF6 and added buffer gases (He, Kr, and C2H6). The results are interpreted by means of a four-state linear kinetic model for saturation of vibrational energy levels by intense infrared radiation, which predicts equalization of upper and lower level populations at power densities of approximately 10 W/cm2. Vibrational and rotational deactivation cross sections are derived from these data with the aid of this model, which suggests that previously observed pulse transparency effects may be interpreted in terms of this same model.

71 citations

Journal ArticleDOI
TL;DR: In this article, the vapor growth and annealing-diffusion steps were performed in a special quartz ampoule which remained sealed throughout the process, and the threshold current densities were dependent on diode surface conditions and could be reduced by at least 50% by etching.
Abstract: Diode lasers with emission wavelengths as long as 28 μ have been fabricated using Pb1−xSnxTe with x up to 0.27. Properties of laser diodes at 77°K and 12°K have been measured for a number of compositions in the range 0.15 ≤ x ≤ 0.27. The vapor growth and annealing‐diffusion steps were performed in a special quartz ampoule which remained sealed throughout the process. Threshold current densities were dependent on diode surface conditions and could be reduced by at least 50% by etching.

61 citations