Femtosecond photon echo and four-wave mixing studies on GaAs/AlGaAs heterostructure at room temperature

Abstract

We report femtosecond photon echo and fourwave mixing measurements performed on GaAs/AlGaAs heterostructure at room temperature. In femtosecond photon echo experiment the dephasing time was obtained, found to vary between 40 and 55 fs depending on carrier density. The dependence showed a power-law behavior T2 ∝ N −0.22 , which indicates that major phase coherence loss is due to screened Coulomb electron-electron interaction. Transient grating experiments yielded the electron diffusion coefficient value of 200 cm 2 /s and electron relaxation time equal to 3 ns.Intensity, a.u.

Collision-induced photon echo at the transition0↔1in ytterbium vapor: Direct proof of depolarizing collision anisotropy

“…where L is the length of the gaseous medium, n 0 is the concentration of resonant atoms, f (v) is the Maxwell velocity distribution function, while the atomic density matrixρ(t ) at the instant of time t is determined by (9). Vector e e (t ) may be presented as a sum of two components: e e (t ) = e e 1 (t )s 1 + e e 2 (t )s 2 , where s n (n = 1,2) are the two arbitrary unit orthogonal (s n s * m = δ nm ) vectors in the plane XY .…”

“…Then, after the successive substitution of Eqs. (6)- (9) in (10) with an account of the formulas for the matrix elements of the evolution operators (A4) and (A5) we obtain for the two echo polarization components e e n (t ) = e e (t )s * n the following expression:…”

“…After the first experiment in a solid [1], the prediction of photon echoes in gases [2,3], and the first photon-echo observation in molecular gas [4], photon echo became of great importance in basic and applied research. Today the applications of photon echo concern the structure and dynamics of macromolecules [5], high-resolution spectroscopy of solids [6], local vibrations in disordered solids [7], and other fundamental research [8][9][10]. Photon echo generated by shaped femtosecond pulses of tunable radiation is one of the most promising tools for the investigation of ultrafast relaxation in condensed media [11].…”

Femtosecond photon echo and four-wave mixing in dye-doped polymer films, semiconductors and heterostructures

“…Later on, due to the femtosecond technique, methods of optical echo spectroscopy were used for investigation of other media (such as polymers, liquids and glasses). In recent years, our echo experiments have been aimed at room temperature studies of dye-doped polymer films [6], semiconductors [7] and heterostructures [8]. The present paper gives a review and detailed discussion of the obtained results.…”

Theory of cavity-enhanced spontaneous four wave mixing

“…In addition, if implemented in a fiber, SFWM has a number of important advantages including the possibility of very long interaction lengths and straightforward integration with existing fiber optic networks. Recently, in the context of classical optics there have been important experimental demonstrations of four wave mixing (FWM) [14] and the implementation of nonlinear optical devices, such as wavelength converters and multi-wavelength fiber lasers, which are based on FWM [15][16][17][18][19]. While the use of a guided-wave configuration constrains the transverse spatial properties of emitted photon pairs, the spectral properties can vary widely.…”