Femtosecond echo-processing in a dye-doped polymer film at room temperature

Abstract

Abstract:The possibility to mechanize at room temperature a logical function of bit-to-bit parallel multiplication for optical echo-processor based on the third-order nonlinear optical response of a resonant medium is experimentally studied. The polyvinilbutural film doped with phthalocyanine dye was used as an operating medium in our experiments. The time needed to realize the logical operation, the result of which is presented in the spectrum of the nonlinear optical response of the medium after action of the two spectrally coded pumping pulses, is less than 1 ps. The values of a homogeneous broadening of S 0 -S 1 line Γ hom = 89 cm −1 and Γ hom = 44 cm −1 are established at T = 300 K and T = 77 K respectively. The laser excitation parameters needed for effective operating of optical processor are defined. The maximum word length achievable under current experimental conditions is estimated. The exciting pulses k1, k2 and the optical response kS1 spectra measured at τ 12 = 30 fs

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

“…The factor F (v z ) contains the dependence of the echo amplitude on the areas θ n (14) of the exciting pulses. This factor depends on the Z projection v z of the atomic velocity through the dependence on v z of Rabi frequencies n (14).…”

“…This factor depends on the Z projection v z of the atomic velocity through the dependence on v z of Rabi frequencies n (14). In case of short exciting pulses (kuT n 1) F (v z ) does not depend on v z and provides a familiar echo dependence on the exciting pulse areas:…”

“…Here f (v z ) is the Maxwell distribution function in the Z projections of the atomic velocity, while factor F (v z ) is determined by (12)- (14). However, in case of orthogonal polarizations of the exciting pulses (l 2 l * 1 = 0) the two signals formed on the transitions m a = 0 → m b = −1 and m a = 0 → m b = 1 interfere destructively, so that the ordinary echo ultimately disappears.…”

“…The expression for this function contains the integrals over the velocity angle θ and over the velocity magnitude v: (12)- (14) and u is the atomic thermal velocity. As follows from (21), the intensity of the collision-induced echo depends on the ellipticity α of the exciting pulses, it obtains its maximum with the linear (α = π/4) orthogonal polarizations of exciting pulses, and it becomes zero with their circular (α = 0) orthogonal polarizations.…”

“…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]. Photon-echo applications for quantum memory [12,13] and for echo-based optical processors [14,15] seem to be very topical.…”