Sub-Picosecond Optical Pulse Generation with Repetition Rate of Several Tens of Gigahertz Using Electrooptic Standing-Wave Phase Grating with Periodic Domain Inversion

Abstract

We propose and demonstrate a novel electrooptic spatiotemporal modulator for sub-picosecond optical pulse generation with a repetition rate of several tens of gigahertz. The pulse generation is directly accomplished with an electrooptic standing-wave phase grating with periodic domain inversion that operates over 10 GHz. This device produces a phase distribution that is like a sinusoidal standing wave in the beam cross section. The output optical beam undergoes Raman–Nath diffraction with diffracted beams whose intensities vary temporally. When we extract a certain diffracted beam, we can obtain a pulse train. A near-Fourier-transform-limit pulse train with a repetition rate of twice the modulation frequency can be obtained using the zero-order undiffracted beam. In the experiment, we found that our new device operates as theoretically predicted and that we can obtain a pulse train with a pulsewidth of about 1 ps from the fabricated device at the maximum modulation power. By improving the modulation efficiency of the device or by further increasing of the modulation frequency, a sub-picosecond optical pulse train with a repetition rate of several tens of gigahertz can be generated by the new device.