Spectroscopy semiconductor diode laser

Ng K. C., Ali A. H., Barber T. E. and Winefordner J. D. (1988) Multiple mode semiconductor diode laser as a spectral line source for graphite furnace atomic absorption spectroscopy, Anal Chem 62 1893-1895. 

L. Gianfrani, A. Sasso, G.M. Tino, F. Marin, Rolarization spectroscopy of atomic oxygen by dye and semiconductor diode lasers, n Nuovo Cimento D 10,941 (1988)... 

The method just described is becoming increasingly popular in the monitoring of environmental trace gases, including chemical combustion products, utilizing semiconductor diode lasers. Diode lasers are small and relatively inexpensive, and thus mobile systems for in-situ measurements can and have been devised. The method is now commonly known as tuneable diode laser absorption spectroscopy (TDLAS). For a few examples of its application see Chapter 28. 

I. Melgailis, A. Mooradian Tunable semiconductor diode lasers and applications . In Laser Applications in Optics and Spectroscopy ed. by S. Jacobs, M. Sargent, M. Scully, J. Scott (Addison Wesley, Reading, MA 1975) p. 1... 

Cooper DE, Martinelli RU, Carlisle CB, Riris H, Bour DB, Menna RJ (1993) Measurement of 12C02 13C02 ratios for medical diagnostics with 1.6-iJ,m distributed-feedback semiconductor diode lasers. Appl Opt 32 6727-6731 Dakin JP, Edwards HO, Weigl BH (1995) Progress with optical gas sensors using correlation spectroscopy. Sens Actuators B 29 87-93... 

For high-resolution laser absorption spectroscopy, a narrow-band tuneable CW laser can be used. Possible candidates are dye lasers, Tirsapphire or other vibronic solid-state lasers, and the variety of tuneable semiconductor diode lasers, which cover a spectral range from the blue to the mid-infrared. Of particular importance are the optical parametric oscillators that have been brought to reliable operation in the pulsed as well as in the CW mode with single-mode performance. They can now span the spectral region from 500 to 5000 nm. 

In Table 2 a list of the species detected by LMR to 1998 is presented. However, the pace of develop ments has slowed, since many of the better known free radicals accessible for LMR have now been ob served. As for lesser-known free radicals, LMR is a difficult method for obtaining initial knowledge (at least for polyatomics) because the Zeeman effect must be analysed as well as the zero Held spectrum. In the mid-infrared, the tunable semiconductor diode lasers are another factor in the development of infra red spectroscopy of high sensitivity and resolution, although LMR provides magnetic parameters inac cessible to the diode laser spectroscopy. In Figure 3 the rise and the fall of LMR are illustrated. 

We start with the semiconductor diode laser, which has to date provided the major contribution to applications in high-resolution infrared spectroscopy [7.2]. 

In this spectral range it is up to now the semiconductor diode laser which has been mostly used for high-resolution laser spectroscopy. After HINKLEY [8.37] had first demonstrated in 1970 the superiority of laser spectroscopy over conventional techniques by a high-resolution absorption spectrum of SFg around 10 ym obtained with a Pb-Sn-Te laser, spectra of numerous molecules have been measured with different diode lasers. A review of the literature up to 1975 can be found in the article by HINKLEY et al. [8.38], more recent examples in [8.39] and [8.39a]. 

Smith, R. D. Measurement of isotope ratios by Doppler-ffee laser spectroscopy applying semiconductor diode lasers and thermionic diode detection. Atml. Chem. 1987, 59, 1230-1232. 

It is most reasonable to use continuous lasers in absorption spectroscopy. However, pulse lasers are also used because their use makes it possible to expand the spectral region of the light source. Lasers on dye solutions are used for studying in the near-UV and visible regions. Semiconductor diode lasers are widely applied for the IR spectral region. There are nonlinear optical methods, which allow one to obtain the radiation with the difference (n3 = nj - n2) and summary frequencies. If one of the lasers are tunable, the radiation frequency n3 can be tuned in both UV and IR spectral regions. 

For the visible and near-ultraviolet portions of the spectmm, tunable dye lasers have commonly been used as the light source, although they are being replaced in many appHcation by tunable soHd-state lasers, eg, titanium-doped sapphire. Optical parametric oscillators are also developing as useful spectroscopic sources. In the infrared, tunable laser semiconductor diodes have been employed. The tunable diode lasers which contain lead salts have been employed for remote monitoring of poUutant species. Needs for infrared spectroscopy provide an impetus for continued development of tunable infrared lasers (see Infrared technology and RAMAN spectroscopy). 

Semiconductor lasers, also known as diode lasers, obtain population inversion between the conduction band and the valence band of a p -junction diode. Various compositions of the semiconductor material can be used to give differ ent output wavelengths. Diode lasers can be tuned over small wavelength inter vals. Such lasers produce outputs in the IR region of the spectrum. They have become extremely useful in CD players, CD-ROM drives, laser printers, and spectroscopic applications, such as Raman spectroscopy. 

Monkman G (2000) Monomolecular Langmuir-Blodgett films— tomorrow s sensors Sensor Rev 20 127-131 Morrison SR (1987) Mechanism of semiconductor gas sensor operation. Sens Actuators 11 283—287 Moseley PT, Norris JOW, Williams DE (eds) (1991) Techniques and mechanisms in gas sensing. Adam Hilger, Bristol Moskalenko KL, Nadezhdinskii AI, Adamovskaya lA (1996) Human breath trace gas content study by tuneable diode laser spectroscopy. Infrared Phys Technol 37 181-192... 

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