Space-time analogy and its application to design schemes borrowed from Fourier optics for processing ultrafast optical signals

Square-wave pulse generation with a variable duty ratio can be realized with the help of ideas of Talbot array illuminators formulated for binary phase gratings. A binary temporal phase modulation of CW laser field propagating through a group-delay-dispersion circuit of the fractional Talbot length $P/Q$ results in a well defined sequence of square-wave-form pulses. When $P=1$ a duty ratio of the pulses $D$ is $1/2$ for $Q=4$ and $1/3$ for $Q=3$ and 6. Maximum intensity of the pulses doubles and triples compared to the CW intensity for $D=1/2$ and $1/3$, respectively. These pulses can be used for return-to-zero laser field modulation in optical fiber communication. For $D=1/3$ extra features between the pulses are found originating from a finite rise and drop time of phase in a binary phase modulation. Similar effect as a benefit of the time-space analogy is predicted for binary phase gratings and interpreted as gleams produced by imperfect edges of the components of the rectangular phase gratings

Increasing efficiency of quantum memory based on atomic frequency combs

A protocol, which essentially increases the efficiency of the quantum memory based on the atomic frequency comb (AFC), is proposed. It is well known that a weak short pulse, transmitted trough a medium with a periodic structure of absorption peaks separated by transparency windows (AFC), is transformed into prompt and delayed pulses. Time delay is equal to the inverse value of the frequency period of the peaks. It is proposed to send the prompt pulse again through the medium and to make both delayed pulses to interfere. This leads to the essential increase of the efficiency of the AFC storage protocol.Comment: 23 pages, 8 figure

Conversion of recoilless gamma-radiation into a periodic sequence of ultrashort pulses in a set of dispersive and absorptive resonant media

An efficient technique to produce a periodic sequence of ultrashort pulses of recoilless gamma-radiation via its transmission through the optically thick vibrating resonant absorber was demonstrated recently [Nature, 508, 80 (2014)]. In this work we extend the theoretical analysis to the case of a set of multiple absorbers. We consider an analytical model describing the control of spectral content of a frequency modulated gamma-radiation by selective correction of amplitudes and initial phases of some spectral components, using, respectively, the resonant absorption or dispersion of nuclei. On the basis of the analytical solutions we determine the ultimate possibilities of the proposed technique.Comment: 16 pages, 6 figure