Demonstration of the frequency upshifting of microwave radiation by rapid plasma creation

Abstract

A new technique for frequency-upshifting electromagnetic radiation is demonstrated. By ionizing azulene vapor contained in a resonant cavity using a laser pulse, the frequency of the incident RF wave at 33.3 GHz is upshifted by 5% with greater than 10% efficiency. Maximum frequency upshift of 2.3 times the source frequency is observed. There are two mechanisms thought to be operative in producing the observed frequency upshift: The time-dependent dielectric constant due to increasing plasma density, and rapid "Q-switching" of the cavity. This technique has the potential of being able to generate tunable and chirped radiation over a very broad (A f/f 2 1) frequency range.

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

“…Since the spatial homogeneity of the medium does not allow a change in the wavelength, the waves (both reflected and transmitted) must instantly increase their frequency to compensate for the change in the refractive index so as to satisfy the new dispersion relation, w = ( w i + w2)lj2, P where wo = cko is the initial frequency of the EM radiation and up is the plasma frequency corresponding to the newly created plasma. The value of wp can be controlled externally and consequently the suggested mechanism can be used for an effective control of the frequency upshift of the EM radiation [3]. Wilks et al [2] have also deduced an interesting additional consequence; the appearance of a time independent residual magnetic field with the characteristic wavelength equal to the vacuum wavelength of the passing radiation.…”

A transmission line filled with fast switched periodic plasma as a wide-band frequency transformer

“…These results clearly indicate that the effects of the magnetic field and periodic structure are additive to broaden the spectrum of the frequency transformed waves. For example, , which leads to (9) Equation (9) demonstrates the enhancing effect of the magnetic field on frequency upshift. The amount of plasma density change from one time interval to the next time interval varies with the time interval as can easily be seen in the piece-wise approximation.…”

Photonic energy lifters and event horizons with time-dependent dielectric structures

“…The conceptually simplest energy-shifting device would be, therefore, a single, homogeneous dielectric medium, with a time dependent . The physical mechanism of such device could be referred to as a "time refraction" [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. The light wave, indeed, gets refracted, by a continuous variation of the refractive index, similarly to what happens in a mirage.…”