SIMULTANEOUS AMPLIFICATION OF TERAHERTZ DIFFERENCE FREQUENCIES BY AN INJECTION-SEEDED SEMICONDUCTOR-LASER AMPLIFIER AT 850 NM

Two-frequency operation of an 850 nm semiconductor optical amplifier w as achieved by simultaneously injection seeding it with two diode lase rs. The two frequencies could be independently amplified without stron g interference when they were separated by more than 10 GHz, and the s pectral purity was preserved by the amplification process. At frequenc y differences below 10 GHz, unbalanced two-frequency output was observ ed, which can be explained by a two-mode interaction driven by the ref ractive index modulation at the beat frequency. The laser system is su itable for the difference-frequency generation of coherent terahertz r adiation in ultra-fast photoconductors or nonlinear optical media.