Phase-Sensitive Optical Probe for Surface Acoustic Wave Soliton Investigation

Abstract

The interference optics of analytical ultracentrifuges can be greatly improved by the installation of a laser. This will not only give a short exposure time and quite a few clearly discernible fringes in the interference pattern, but will also offer the possibility of achieving stroboscopic behaviour through the modulation of the emission by a multiplexer.In this paper we deal with the Beckman Model E, since it is the ultracentrifuge most widely used. Should it not already be equipped with a multiplexer, it can easily be retrofitted and utilised to modulate the laser. Special care, however, has then to be taken to suppress the contrastreducing background illumination that comes from two satellite orientations of the rotor at each passage of a cell. Suitable electro-optical devices are described.

Excitation of higher harmonics in transient laser gratings by an ablative mechanism

“…For the optical probing of harmonic generation usually the variation of the first and higher order diffracted probe laser intensities have been monitored as a function of acoustic power. [10][11][12][13] In the present experiments we launched coherent SAWs with picosecond laser pulses and demonstrated that in the nonlinear excitation regime SRWs with higher harmonics can easily be excited. For optical recording outside the source we used a probe beam deflection technique for detection in the time domain.…”