Four-wave mixing, heterodyne-detected

Diffractive Optics-Based Four-Wave Mixing with Heterodyne Detection... 

Dadusc, G., Ogilvie, J. R, Schulenberg, R, Marvet, U., and Miller, R. J. D. 2001. Diffractive optics-based heterodyne-detected four-wave mixing signals of protein motion From protein quakes to ligand escape for myoglobin. Proc. Nat. Acad. Sci. USA 98 6110-6115. 

V. Extension to Heterodyne-Detected Four-Wave Mixing Appendix A Time- and Frequency-Gated Autocorrelation Signals Appendix B The Signal and the Optical Polarization... 

V. EXTENSION TO HETERODYNE-DETECTED FOUR-WAVE MIXING... 

The description of pump-probe signals presented in the preceding section can be immediately generalized to heterodyne-detected transient grating spectroscopy as well as to other four-wave mixing techniques. Heterodyne detection involves mixing the scattered field with an additional heterodyne field 4(r). The signal in the ks direction can then be written in terms of the polarization Ts(t) as... 

A new technique to measure low-frequency spectra is optical-heterodyne-detected Raman-induced Kerr-effect spectroscopy (OHD-RIKES). A recent publication by Chang and Cast-ner contains references to previous work within this field [18]. OHD-RIKES is based on a four-wave mixing of femtosecond laser pulses. Spectra obtained by OHD-RIKES reflect the anisotropic part of the Raman polarizability. Thus, the information obtained by OHD-RIKES is very similar to that obtained by low-frequency Raman scattering in an scattering configuration. From a theoretical point of view, the spectral representation obtained from OHD-RIKES measurements corresponds to the I v) representation given in Eq. (3). In Fig. 4 is shown an OHD-RIKES spectrum of liquid A-methylformamide (NMF). In Fig. 5 are shown low-frequency Raman spectra of liquid NMF together with the R(i>),... 

Four wave mixing via the third order nonlinear susceptibility of the medium produces two new waves of frequencies 03+6, travelling collinearly with the probe. A photodiode detects the resulting intensity modulation of the probe. The original probe beam serves thus as the local oscillator for sensitive heterodyne detection. 

Before going into the details of various materials and their third-order NLO properties, it would serve well to have an idea of the characterization techniques used for their study. To study the effect of the real part of third-order susceptibility, Z-scan measurements, degenerate four-wave mixing (DFWM), optical heterodyne detection of optical Kerr effect (OHD-OKE), and differential optical Kerr effect (DOKE) detection are employed. For the study of TPA, techniques such as nonlinear transmission (NLT) method, two-photon excited fluorescence (TPEF) method, and Z-scan measurements are used. The observables from the above-mentioned techniques vary depending on the inherent limitations of the technique. The nature of the light source employed like the central wavelength of the laser. 

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