Holographic-current study in laser and photorefractive crystals

Smart photogalvanic running-grating interferometer

“…Such a trapping was already demonstrated in both photosensitive laser materials 17 and semiconductors 18 through photoelectron holes and molecular fragments motion. This trapping ͑sometimes defined as holographic trapping͒ of charged particles through the generation of holographic photo-emf ͑Refs.…”

The role of polymers in random lasing

“…However, for the real materials, fast gain saturation determines the dynamics of laser emission with characteristic oscillations at the beginning of material excitation, and its stabilization in time. [27][28][29][30] Light Localization-Coherent Feedback Light diffusion is obviously a simplified physical situation that can take place in random media with gain, but in general the interference effects cannot be neglected at all. As it was shown by Cao et al in 1998 23,31 random media excited with strong pump light can produce unusual emission spectra composed of several narrow emission lines, like in regular lasers.…”

Energy structure and micromechanism of photo-EMF effect in adaptive IR-detectors based on CdTe:V crystals

“…The phase modulation on the signal beam causes a lateral vibration of the periodic free carriers grating. It induces an ac current (holographic current) in the crystal, that is proportional to the modulation amplitude and to the total power of the laser beams [13,15,16]. The photocurrent signal was registered in short circuit regime by a synchronous detector.…”

“…The phase modulation of laser signal beam causes some vibrations of interference pattern, which leads to the creation of non-steady-state photoelectromotive force in the photorefractive crystals. It causes the appearance of transient holographic current through a short-circuited sample of a photorefractive crystal illuminated by a vibrating interference pattern [15,16,23]. This current is proportional to the interference pattern displacement from the stationary space field pattern.…”

“…In recent years there was a noticeable progress in the following fields: comprehensive study of different physical properties of the CdTe-based semiconductors, the engineering construction of their defect structure, optimization of the physical parameters of the crystals, advances in high technology of growth of novel highly sensitive in the near IR region (0.9-1.6 µm) photorefractive materials based on the semi-insulating (ρ ≈ 10 7 -10 9 Ω×cm) CdTe:Ti and Cd 1-At present, among the applications of photorefractive materials, a special focus is applied to the development of adaptive photodetectors for laser systems to perform remote ultrasonic inspection of the quality of different industrial goods (metal, alloys, composites, weld joints etc) [11,12,13,14]. It should also be noted that the adaptive photodetectors included into the laser interferometer form a laser ultrasonic receiver based on photo-EMF detection, and are the powerful tool for the semiconductor material parameters investigation [15,16,17]. At the same time the adaptive photodetectors can be used to develop the highly sensitive laser vibrometers for the detection of vibration in the wide frequency spectrum [18] .…”