Frequency up-conversion and trapping of ultrashort laser pulses in semiconductor plasmas

Propagation of Optical Pulses in Dynamic Media: A Time Transformation Method

“…A soluble quantum theory model for the interaction of an electromagnetic field with a time-dependent dielectric medium was given by Cirone et al, and the electromagnetic field and photon statistics were found [18]. In a theoretical work, Berezhiani et al showed that the interaction of a laser pulse with a nonstationary semiconductor plasma can lead to a variety of interesting phenomena, including the controlled upshifting of the laser frequency, which could lead to the possibility of tunable lasers over a wide range of frequencies, and the trapping (nonpropagation) of a substantial part of the incident pulse [19]. The propagation of an electromagnetic wave along a planar wave-guiding structure containing time-varying plasma was considered by Bakunov et al They found some quantities (adiabatic in-16 variants) that relate the energy of the wave and its frequency to be conserved during the process of the plasma density variation on condition that the time scale of the variation is much greater than the wave period (adiabatic approximation) [20,21].…”

“…A clue is found by noting that the two sets of transmission and reflection coefficients are not independent, rather they can be related as 19) where n i = i µ i ( 0 µ 0 ) with i = 1 or 2. The same ratio n 1 n 2 was also found to occur in Eq.…”

Dc to ac field conversion due to leaky-wave excitation in a plasma slab behind an ionization front

“…The results indicate the possibility of using such converters based on planar photoconductive antennas to create sources of microwave and terahertz radiation with controllable waveforms that are transformed from video to radio pulse when the angle of incident ionizing radiation is tuned. laser pulse on a photoconductive material flat boundary [5,6,20,21]. In this case, the speed of the generated ionization front is greater than the speed of light and is determined by the incident angle of the ionizing radiation, which makes it easy to control the front speed through the adjustment of the angle.…”

“…Available femtosecond laser systems are capable of securing the propagation of such fronts over sufficiently long distances and the formation of subsurface plasma over sufficiently large areas (tens of square centimeters) [24][25][26][27]. Photoconductive devices (including large-area ones) that use ultrafast ionization have been used for generation, detection, frequency conversion, phase shifting, and fast switching of terahertz or microwave radiation (see, e.g., [5][6][7][20][21][22][23][24][25][26][27][28][29][30][31]). Since the speed of propagation of ionization fronts is greater than the speed of light, fast leaky polarization waves are excited behind the front and radiate energy through the transverse plasma boundaries at an angle to the direction of front propagation.…”

Picosecond pulse frequency upshifting by rapid free-carrier creation in ZnSe

“…2 The particular case of a transverse propagating front ͑infinite velocity with respect to the wave͒ means an instantaneous change of the properties of the medium in which the waves are propagating. Berezhiani et al 6 calculated the case of an ultrashort pulse propagating in a semiconductor crystal, which is rapidly ionized ͑on the order of ten optical cycles͒. 3 Lampe et al 4 and Wilks et al 5 proposed this method to upshift frequencies of radiation considering the availability of ultrashort laser pulses to induce such rapid ionization.…”