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Title: Frequency modulation upon nonstationary heating of the p - n junction in high-sensitive diode laser spectroscopy

Abstract

A special type of modulation of the injection current of a diode laser is proposed at which the frequency modulation of radiation is not accompanied by the residual amplitude modulation. This method considerably reduces the influence of the diode laser radiation instability on the recorded absorption spectra. This allows a prolonged monitoring of small amounts of impurities in gas analysis by retaining a high sensitivity. Prolonged measurements of absorption spectra are performed at a relative absorption of 8x10{sup -7}. By using a 50-cm multipass cell with the optical length of 90 m, the absorption coefficient of 1.2x10{sup -10} cm{sup -1} was detected. As an example, the day evolution of the background concentrations of NO{sub 2} molecules was measured in the atmosphere. (laser applications and other topics in quantum electronics)

Authors:
; ; ; ; ;  [1]
  1. P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
Publication Date:
OSTI Identifier:
21466655
Resource Type:
Journal Article
Resource Relation:
Journal Name: Quantum Electronics (Woodbury, N.Y.); Journal Volume: 37; Journal Issue: 4; Other Information: DOI: 10.1070/QE2007v037n04ABEH013311
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ABSORPTION SPECTRA; AMPLITUDES; BEAM CURRENTS; DIODE-PUMPED SOLID STATE LASERS; FREQUENCY MODULATION; GAS ANALYSIS; HEATING; INSTABILITY; LASER RADIATION; LASER SPECTROSCOPY; MOLECULES; NITROGEN DIOXIDE; P-N JUNCTIONS; SENSITIVITY; CHALCOGENIDES; CURRENTS; ELECTROMAGNETIC RADIATION; LASERS; MODULATION; NITROGEN COMPOUNDS; NITROGEN OXIDES; OXIDES; OXYGEN COMPOUNDS; RADIATIONS; SEMICONDUCTOR JUNCTIONS; SOLID STATE LASERS; SORPTION; SPECTRA; SPECTROSCOPY

Citation Formats

Andreev, Sergei N, Nikolaev, I V, Ochkin, Vladimir N, Savinov, Sergei Yu, Spiridonov, Maksim V, and Tskhai, Sergei N. Frequency modulation upon nonstationary heating of the p - n junction in high-sensitive diode laser spectroscopy. United States: N. p., 2007. Web. doi:10.1070/QE2007V037N04ABEH013311.
Andreev, Sergei N, Nikolaev, I V, Ochkin, Vladimir N, Savinov, Sergei Yu, Spiridonov, Maksim V, & Tskhai, Sergei N. Frequency modulation upon nonstationary heating of the p - n junction in high-sensitive diode laser spectroscopy. United States. doi:10.1070/QE2007V037N04ABEH013311.
Andreev, Sergei N, Nikolaev, I V, Ochkin, Vladimir N, Savinov, Sergei Yu, Spiridonov, Maksim V, and Tskhai, Sergei N. Mon . "Frequency modulation upon nonstationary heating of the p - n junction in high-sensitive diode laser spectroscopy". United States. doi:10.1070/QE2007V037N04ABEH013311.
@article{osti_21466655,
title = {Frequency modulation upon nonstationary heating of the p - n junction in high-sensitive diode laser spectroscopy},
author = {Andreev, Sergei N and Nikolaev, I V and Ochkin, Vladimir N and Savinov, Sergei Yu and Spiridonov, Maksim V and Tskhai, Sergei N},
abstractNote = {A special type of modulation of the injection current of a diode laser is proposed at which the frequency modulation of radiation is not accompanied by the residual amplitude modulation. This method considerably reduces the influence of the diode laser radiation instability on the recorded absorption spectra. This allows a prolonged monitoring of small amounts of impurities in gas analysis by retaining a high sensitivity. Prolonged measurements of absorption spectra are performed at a relative absorption of 8x10{sup -7}. By using a 50-cm multipass cell with the optical length of 90 m, the absorption coefficient of 1.2x10{sup -10} cm{sup -1} was detected. As an example, the day evolution of the background concentrations of NO{sub 2} molecules was measured in the atmosphere. (laser applications and other topics in quantum electronics)},
doi = {10.1070/QE2007V037N04ABEH013311},
journal = {Quantum Electronics (Woodbury, N.Y.)},
number = 4,
volume = 37,
place = {United States},
year = {Mon Apr 30 00:00:00 EDT 2007},
month = {Mon Apr 30 00:00:00 EDT 2007}
}
  • For the first reported time, high-frequency optical heterodyne spectroscopy has been performed with tunable lead-salt diode lasers. N/sub 2/O transitions at 1259.2 cm/sup -1/ were observed by modulating the injection current at 50--200 MHz and detecting the heterodyne beat signal generated by the frequency- and amplitude-modulated light. By proper adjustment of the rf phase in the phase-sensitive detection circuitry, the background contributions due to laser amplitude modulation could be completely suppressed. The sample induced signal is measured against zero background and detected at radio frequencies at which diode lasers have little noise.
  • Tunable diode laser absorption measurements at high pressures by use of wavelength-modulation spectroscopy (WMS) require large modulation depths for optimum detection of molecular absorption spectra blended by collisional broadening or dense spacing of the rovibrational transitions. Diode lasers have a large and nonlinear intensity modulation when the wavelength is modulated over a large range by injection-current tuning. In addition to this intensity modulation, other laser performance parameters are measured, including the phase shift between the frequency modulation and the intensity modulation. Following published theory, these parameters are incorporated into an improved model of the WMS signal. The influence of thesemore » nonideal laser effects is investigated by means of wavelength-scanned WMS measurements as a function of bath gas pressure on rovibrational transitions of water vapor near 1388 nm. Lock-in detection of the magnitude of the 2f signal is performed to remove the dependence on detection phase. We find good agreement between measurements and the improved model developed for the 2f component of the WMS signal. The effects of the nonideal performance parameters of commercial diode lasers are especially important away from the line center of discrete spectra, and these contributions become more pronounced for 2f signals with the large modulation depths needed for WMS at elevated pressures.« less
  • Frequency-modulation (FM) spectroscopy has been performed on the D/sub 2/ transitions of rubidium atoms with an AlGaAs diode laser at 780 nm. Doppler-broadened hyperfine-structure transitions of /sup 85/Rb and /sup 87/Rb were resolved with no residual amplitude-modulation-induced background signal by modulating the injection current of the laser diode at a low frequency (20--50 MHz) compared with the Doppler width. To obtain Doppler-free spectra, we combined FM spectroscopy with saturation spectroscopy. The results show that the FM spectroscopy technique is sensitive and should be useful for high-resolution spectroscopy, although the resolution was instrument limited and unusual double peaks were observed.
  • A p-n junction diode of cubic boron nitride was made by growing an n-type crystal epitaxially on a p-type seed crystal at a pressure of 55 kilobars and a temperature of about 1700/sup 0/C. A temperature-difference solvent method was used for the crystal growth, and beryllium and silicon were doped as acceptors and donors, respectively. Formation of the p-n junction was clearly confirmed at 1 bar by rectification characteristics and by existence of a space charge layer of the junction as observed by electron beam induced current measurement. This diode operated at 530/sup 0/C. 14 references, 2 figures.
  • The model scheme of the nonlinear mechanism of transformation (decreasing) of the spatial coherence of a pulsed laser field in an extended multimode optical fibre upon nonstationary interaction with the fibre core is theoretically analysed. The case is considered when the spatial statistics of input radiation is caused by phase fluctuations. The analytic expression is obtained which relates the number of spatially coherent radiation modes with the spatially energy parameters on the initial radiation and fibre parameters. The efficiency of decorrelation of radiation upon excitation of the thermal and electrostriction nonlinearities in the fibre is estimated. Experimental studies are performedmore » which revealed the basic properties of the transformation of the spatial coherence of a laser beam in a multimode fibre. The experimental results are compared with the predictions of the model of radiation transfer proposed in the paper. It is found that the spatial decorrelation of a light beam in a silica multimode fibre is mainly restricted by stimulated Raman scattering. (fiber and integrated optics)« less