An intense short laser pulse or a millimetre wave propagating through a plasma channel may act as a wiggler for the generation of shorter wavelengths. When a relativistic electron beam is launched into the channel from the opposite direction, the laser radiation is Compton/Raman backscattered to produce coherent radiation at shorter wavelengths. The scheme, however, requires a superior beam quality with energy spread less than 1% in the Raman regime.

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On account of nonlinear refraction, arising through the relativistic mass effect, a short intense laser pulse tends to accumulate its energy around the intensity maximum, leading to pulse compression over a length Zc≈ τ0c2ω2/ ω2pv, where τ0 and ω are the pulse duration and frequency of the laser, v is the oscillatory electron velocity and ωp is the plasma frequency. When the transverse extent of the laser is finite, nonlinear self-focusing interferes strongly with this process. The self-focusing occurs in a periodic manner on a shorter scale length. However, over long lengths of pulse propagation, pulse compression could be significant.

A large-amplitude Gaussian electromagnetic beam, propagating through a dusty plasma, heats the electrons nonuniformly. As the electron temperature rises, the rate of electron attachment to dust particles changes, modifying dust charge and free electron density. Further, the ambipolar diffusion of the plasma under thermal pressure gradient creates a plasma channel that guides the electromagnetic beam. At powers exceeding a threshold value, the beam becomes self-focused.

A high-power laser obliquely incident on a plasma produces a second-harmonic radiation in the reflected component. The second-harmonic reflected power P2 vanishes at normal and grazing incidence. P2 has a maximum, P2m, at an optimum value of the angle of incidence, θop, that depends on electron density. The harmonic generation occurs from subcritical to overcritical values of the electron density. P2m increases monotonically with electron density, attains a maximum around critical density then falls off at higher densities.