Raman Cell and Wavelength Shifting
It is A "Light" of Choice




Key Benefits (e.g., for two-color Particle Imaging Velocimetry Application)

  • flexibility
  • size advantage 
  • cost effective 

Laser frequency conversion has been an active research field since the invention of laser. Harmonic generators only convert laser frequencies to their harmonics. Optical parametric oscillators (OPO’s) provide continuous tunability over a broad range (typically from 200 nm to 3 mm). OPO has recently been revitalized through the development of new nonlinear crystals.[1] Stimulated Raman scattering (SRS) can either up-shift or down-shift a single frequency line by multiples of the vibrational or rotational energy of the medium.

Stimulated Raman scattering is, in most cases, simpler than any other frequency conversion approach because phase matching is not required. The approach often leads to high conversion efficiency over a wide range of wavelengths, from the IR to the UV.[2] A Raman shift remains constant independent of the pump laser frequency. A Raman cell will not be damaged even if optical breakdown occurs in the medium. The recent report on obtaining high conversion efficiencies from some low gain Raman media will have its impact on the application of stimulated Raman scattering.[3]

Taitech, Inc. offers Raman cells for the following gases:

H2, D2, CH4, N2, O2, and CO2*     [* Contact Taitech for applications of gases other than those listed above.]

A typical energy-conversion efficiency to the first Stokes ranges from a few percent to higher than 70 percent depending upon the following factors: Laser wavelength, repetition rate, pulse width, gas or gases used, cell pressure, focusing f number, and number of passes

1. R. Danielius, A. Piskarskas, and A. Stabinis, "Traveling-wave parametric generation of widely tunable, highly coherent femtosecond light pulses," J. Opt. Soc. Am. B, 10, (11), 2222, (1993).

2. M. Noble, "Reaching those awkward wavelengths," Lasers & Optronics, November, 17, (1991).

3. B. Zhang, W. R. Lempert, R. B. Miles, and G. Diskin, "Efficient vibrational Raman conversion in O2 and N2 cells by use of super-fluorescence seeding," Opt. Lett., 18, (14), 1132, (1993).

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Copyright © 2002 Taitech, Inc.
Last modified: February 20, 2002