Offset-frequency locking of extended-cavity diode lasers for precision spectroscopy of water at 1.38 μm.

We describe a continuous-wave diode laser spectrometer for water-vapour precision spectroscopy at 1.38 μm. The spectrometer is based upon the use of a simple scheme for offset-frequency locking of a pair of extended-cavity diode lasers that allows to achieve unprecedented accuracy and reproducibility levels in measuring molecular absorption. When locked to the master laser with an offset frequency of 1.5 GHz, the slave laser exhibits residual frequency fluctuations of 1 kHz over a time interval of 25 minutes, for a 1-s integration time. The slave laser could be continuously tuned up to 3 GHz, the scan showing relative deviations from linearity below the 10{-6} level. Simultaneously, a capture range of the order of 1 GHz was obtained. Quantitative spectroscopy was also demonstrated by accurately determining relevant spectroscopic parameters for the 22,1→22,0line of the H2(18)O v1+v3 band at 1384.6008 nm.

[1]  Y. Kusumoto,et al.  Modification of Takaishi–Sensui formula for a diaphragm gauge system connected by an arbitrary length pipe , 2009 .

[2]  J. Hughes,et al.  A widely tunable laser frequency offset lock with digital counting. , 2008, The Review of scientific instruments.

[3]  Matthias Weidemüller,et al.  Simple scheme for tunable frequency offset locking of two lasers , 1999 .

[4]  R. Matthey,et al.  Laser offset-frequency locking up to 20 GHz using a low-frequency electrical filter technique. , 2008, Applied optics.

[5]  N. Coluccelli,et al.  Absolute frequency stabilization of an extended-cavity diode laser against Doppler-free H(2)O17 absorption lines at 1.384 microm. , 2009, Optics letters.

[6]  G. Lamporesi,et al.  Analog+digital phase and frequency detector for phase locking of diode lasers , 2005 .

[7]  R. Ciuryło.  SHAPES OF PRESSURE- AND DOPPLER-BROADENED SPECTRAL LINES IN THE CORE AND NEAR WINGS , 1998 .

[8]  P. Laporta,et al.  On the determination of the Boltzmann constant by means of precision molecular spectroscopy in the near-infrared , 2009 .

[9]  Gang Li,et al.  The HITRAN 2008 molecular spectroscopic database , 2005 .

[10]  P. Laporta,et al.  Primary gas thermometry by means of laser-absorption spectroscopy: determination of the Boltzmann constant. , 2008, Physical review letters.

[11]  Howard W. Yoon,et al.  Linearity of InGaAs Photodiodes , 2003 .

[12]  P. Laporta,et al.  Absolute frequency measurement of a water-stabilized diode laser at 1.384 μm by means of a fiber frequency comb , 2011 .

[13]  A Amy-Klein,et al.  Direct determination of the Boltzmann constant by an optical method. , 2007, Physical review letters.

[14]  Gunnar Ritt,et al.  Laser frequency offset locking using a side of filter technique , 2004 .

[15]  A. Merlone,et al.  Design and Capabilities of the Temperature Control System for the Italian Experiment Based on Precision Laser Spectroscopy for a New Determination of the Boltzmann Constant , 2010 .

[16]  E. Browell,et al.  Spectroscopy of water vapor in the 720-nm wavelength region - Line strengths, self-induced pressure broadenings and shifts, and temperature dependence of linewidths and shifts , 1989 .

[17]  Thomas M. Stace,et al.  DESIGN NOTE: Laser offset-frequency locking using a frequency-to-voltage converter , 1998 .