Terahertz-frequency-interval dual-wavelength optical pulse generation with semiconductor lasers

Generation of automatically synchronized dual-wavelength optical pulses was successfully demonstrated by using a combination of semiconductor lasers and a four wave mixing device. These dual-wavelength optical pulses have a terahertz interval frequency, and thus they are useful for investigating nonlinear optic processes in terahertz region.

INTRODUCTION

Recent increasing interests in electromagnetic wave generation or nonlinear spectroscopy in terahertz frequency region also stimulate the development of coherent light sources for these applications [1]. Among these light sources, high-repetition synchronized dual-wavelength picosecond pulse lasers, that have a terahertz frequency interval, can provide an excellent performance because their moderate peak power and average power features avoid degradations in specimens. In general, however, instrumental configurations for synchronized two different ultarashort lasers are not simple and are large-scaled. In this paper, we demonstrate a very simple scheme with a combination of semiconductor lasers and a four wave mixing (FWM) device.