Experimental Demonstration of the Doppler Frequency Conversion in a Slot Line

Frequency conversion from microwaves to millimetre waves using the Doppler effect in a slot line on an optically excited silicon-on-insulator (SOI) substrate has been experimentally demonstrated. Laser pulses with a wavelength of 532 nm and duration of 33 psec have generated electron-hole plasma periodically at the intervals of 1.2 mm and of 13.6 psec on the SOI surface along the slot line. The plasma acts as an rf-short which effectively moves at a relativistic velocity. The rf-short reflects counter propagating microwaves and up-shifts their frequency through the double Doppler effect. Experiments have shown that microwaves at the frequencies between 10 GHz-18 GHz in the slot line have been successfully converted to millimetre waves with a frequency up-ratio of about 3.9.