Modulator Enables Nanowatt Reception

Photonic microwave receivers have improved dramatically with the recent advent of higher-sensitivity electro-optic modulators. Now researchers from the Jet Propulsion Laboratory at California Institute of Technology in Pasadena have designed and demonstrated a microphotonic receiver with a sensitivity that is improved orders of magnitude over existing technology.

As described in the November issue of IEEE Photonics Technology Letters, they fabricated a 2.4-mm-radius spheroidal LiNbO₃ optical cavity demonstrating highquality whispering-gallery modes. They directed light from a 1550-nm distributed feedback laser into the cavity and studied the dependence of light modulation on the frequency of the microwave signal power directed to the same cavity.

The researchers reported a minimal detectable microwave power of approximately 2.5 nW. Previous technologies based on light-microwave interactions in an optic whispering-gallery resonator provided microwave sensitivity of only 160 µW.