Miniaturized Optical Microwave Source Using a Dual-Wavelength Whispering Gallery Mode Laser

We report on the observation of a compact optical microwave source based on a whispering gallery mode (WGM) laser. The use of a single 160-¿m diameter erbium-doped glass microsphere and two half fiber tapers allows a dual single-mode laser emission around 1550 nm to be obtained. The generated beat note at 10.86 GHz has a linewidth of 22 kHz. This preliminary experimental demonstration shows the potentialities of erbium-doped WGM resonators for microwave generation.