Abstract
A photomixed laser beam of two 1.55 μm lasers is used to obtain interband photoexcitation at the difference frequency and at room temperature in suvmicron gate length INAIA/InGaAs transistors. Results show the clear excitation of plasma oscillation modes in the transistors channel Fundamental plasma resonant frequency and its add harmonics can be tuned with the applied gate voltage. Numerical simulation have also been performed using a hydrodynamic approach coupled to a pseudo-2D Poisson equation. Numerical results are in qualitative agreement with experiments and confirm optical beatin detection at terahertz frequencies.