Ultrafast Four-Wave Optical Parametric Amplification in Transparent Condensed Bulk Media

Figure 3

Near-field intensity profiles of the pump beam: (a) at the input and at the output of 40-mm-long water cell; (b) in the absence; (c) in the presence of the seed signal launched at the phase-matching angle; (d) measured FWHM diameter of the pump beam (circles and solid curve) versus propagation distance 𝑧 within the nonlinear medium and calculated diffraction spreading of the Gaussian beam of the same diameter (dashed curve).

(a)

(b)

(c)

(d)