We apply Fourier-transform spectral interferometry to complete phase and intensity characterization of a chirped filter engraved in a persistent spectral hole-burning (PSHB) material. The conjugated transfer function of a grating pair compressor is stored in a PSHB material as an accumulated spectral hologram that behaves as a pulse stretcher. By directing the diffracted pulse back through the compressor, we verified that the PSHB stretcher’s transfer function is indeed conjugated to that of the grating pair compressor. We have extended the spectral phase analysis to regions where the engraved structure is much narrower than the spectrometer’s resolution.
We apply Fourier-transform spectral interferometry to complete phase and intensity characterization of a chirped filter engraved in a persistent spectral hole-burning (PSHB) material. The conjugated transfer function of a grating pair compressor is stored in a PSHB material as an accumulated spectral hologram that behaves as a pulse stretcher. By directing the diffracted pulse back through the compressor, we verified that the PSHB stretcher’s transfer function is indeed conjugated to that of the grating pair compressor. We have extended the spectral phase analysis to regions where the engraved structure is much narrower than the spectrometer’s resolution.
In a series of experiments we explore various aspects of femtosecond pulse shaping by coherent filters engraved in a persistent spectral hole burning (PSHB) material. We have in mind the coherent control of quantum systems, with high resolution and large number of addressable spectral points. We examine the phase correction efficiency of this approach, relying on Fourier transform spectral interferometry techniques to characterize the coherent filter. Two different PSHB materials are considered, with two different setups, involving different values of repetition rate, fluence, wavelength, spectral width and pulse duration.
Persistent spectral hole burning (PHSB) provides a unique possibility of controlling, by means of illumination with high spectral resolution, optical properties, the coefficient of absorption and the index of refraction in the impurity absorption band of doped solid materials. New versions of holography are the most successful application of PSHB data storage and processing. It utilizes both distributed storage and parallel processing and demonstrates the advantages and potentials of PSHB in this field. An interesting property of time and space-domain holograms occurs in connection with external electric fields: the pseudo-Stark splitting of narrow spectral holes due to the linear Stark effect in an external electric field manifests itself as an additional modulation of holographically stored signals in the time domain. The idea of PSHB time- and space-domain holography is simple. When a PSHB sample is illuminated by a pulse of light, the intensity (more precisely, the doses of illumination), in dependence of the frequency, is stored in the hole profile.
The persistent spectral hole-burning (PSHB) phenomenon has been known since 1974. It is still an important research area for the study of the intimacy of complex molecular systems in the solid state, revealing high-resolution spectra, photophysics, photochemistry, and dynamics of molecular doped amorphous media, organic as well as inorganic. From another point of view, PSHB allows the engraving of any spectral structures in the inhomogeneous absorption band profile of molecular doped amorphous hosts or ion doped crystals cooled down to liquid helium temperatures. Therefore, a PSHB material is programmable in the spectral domain and consequently it can be transformed in an optical processor capable of achieving user-defined optical functions. Some aspects of both fields are illustrated in the present paper. Concerning the search for efficient PSHB materials, the hole-burning performances and the photophysics of polymer and xerogel based systems are compared. The problem of high-temperature persistent spectral hole-burning materials and the search for new frequency selective photosensitive systems for fast optical pulse processing at 800nm are considered. Regarding the points treated, inorganic hosts based on silicate xerogels or porous glasses have shown the best results. Moreover, by combining inorganic and organic capabilities or by grafting organic species to the host, hybrid xerogels have not yet revealed all possibilities. Also, the interest of two-photon materials for engraving spectral features with near-infrared or infrared light is developed. As an introduction to possible applications of PSHB material, the basics of spectro-temporal holography are remembered and a demonstrative experiment using a naphthalocyanine-doped polymer film is described, proving that the temporal aberration free recompression of ultrashort light pulses is feasible, therefore opening a way for applications in ultrashort light pulse shaping. Aspects for a comparison between cw hole-burning and femtosecond spectro-temporal experiments are considered, and prospects for coherent control of light fields or photochemical processes are also evoked.
Spatio-temporal holography using persistent spectral hole-burning in dye molecules embedded in plastic films is promising for applications such as femtosecond pulse shaping, data storage or phase conjugation. In addition to the common 2 spatial dimensions of classical holograms, each point in the sample plane can be used to store spectral informations such as the shape of a femtosecond pulse. On each point of the sample, spectral interferences between a reference pulse and an object pulse (for example chirped) are recorded via spectral hole-burning in the absorption band of the dye molecule. As early as 1983, photon echo and time-reversal experiments using persistent spectral hole-burning were performed in porphyrazine styrol solutions at 630 nm [1]. Then several developments, like the reconstruction of the polarization state of object pulses [2], time and space holography [3,4], image holograms using a single pair of femtosecond pulses [5] were demonstrated in different photosensitive media.
Persistent spectral hole burning (PSHB) in organic molecules doped in a polymer matrix at low temperatures allows optical recording of information in the dimensions of frequency and time, as well as in space and externally applied electric field. We use this special property to demonstrate new types of holograms, which extend conventional spatial-domain optical data storage into the new dimensions. Basic aspects of recording and playback of holograms by persistent spectral hole burning, including relation between frequency- and time-domain response function, is discussed. This paper is elucidating inherent relations between the time- and frequency-domain versions of PSHB holography. We show that by multiplexing holograms in the frequency dimension, we can store a large number (up to 12 000) of image holograms using a single spectral hole burning sample. In the time domain, we show storage and reproduction of ultrashort time-space images on the scale of 10 -12 −10 -13 s. Experiments demonstrating unusual hologram properties, such as causality-related asymmetry of diffraction, inversion of time coordinate, and ultrafast processing, are presented.
Persistent spectral hole burning [1] in conjunction with holography (PSHB) opens new prospects for high density optical information storage and processing. In the holographic approach, hole burning is carried out with two -crossed coherent laser beams which bleach out a narrow frequency domain hole in an inhomogeneously broadened absorption band recording, at the same time, a spatial holographic fringe pattern. During read out of the hologram diffraction from this spatial fringe pattern occurs, and a holographic image is reconstructed, reflecting the changes of the absorption coefficient and the refractive index introduced by the spectral hole [2].