Nonlinear optical techniques are widely used to study energy transport in nanoscale objects. In particular photon echo spectroscopy can be used to determine if the energy transport is coherent or not. In this project a novel phase sensitive nonlinear technique is proposed. The main feature of this technique is the application of two phase-locked pulses. The relative phase and the delay between the two pulses is set electronically by a pulse shaper based on a spatial light modulator (SLM). The use of an SLM ensures phase stability. The proposed method is tested on a model system of solutions of the dye molecule DTTCI in ethylene glycol and acetonitrile. The obtained results demonstrated that the parameters from the experimental data agree with those from previous studies. Hence, the proposed technique can be further developed for energy transport studies.
Two-pulse photon echo electron-nuclear double resonance (or PENDOR) has been used to measure the second-order hyperfine splittings in the ground state and the lowest component of the excited 1D2 state of YAlO3:Pr3+. The excited-state splittings are 0.923 and 1.565 MHz and are significantly different from previous hole-burning results because of greatly increased resolution. The mechanism for two-pulse PENDOR involves a modulation of the photon echo decay at the rf Rabi frequency. This modulation has been observed directly. A brief theoretical analysis is given which shows that the echo modulation is a result of phase and amplitude changes in the oscillating opitical dipole moment which are indirectly produced by the rf field.