Superluminal-source-induced emission.
Raman emission by an axicon-generated superluminal source is demonstrated. The anti-Stokes radiation is emitted at an angle defined by a Cerenkov-type condition. This technique of superluminal-source generation has advantages in both low pump self-phase modulation and compensation of temporal walk-off caused by group-velocity dispersion, rendering the scheme useful for efficient Raman conversion, pump-probe measurements, and harmonic and optical parametric generation with ultrashort intense pulses.
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