Rądio-photonic microwave receiving channel with optical heterodyning

 

Sergey F. Boev¹, Victor V. Valuev^1,2, Victor V. Kulagin^1,2,3, Vladimir A. Cherepenin²

¹Joint Stock Company «RTI»

²Kotel’nikov Institute of Radio-engineering and Electronics of RAS

³Sternberg Astronomical Institute of Lomonosov Moscow State University

 

The paper is received on December 15, 2014

 

Abstract. The use of continuous wave (cw) stable laser together with amplitude modulators and narrow band optical filters to convert radar signal to low (envelope) frequencies is considered. An amplitude modulation of the cw optical carrier with microwave signal results in creation of the signal sidebands. Then, the optical carrier can be suppressed by filtering one sideband using optical band-pass filter based on, e.g., microresonators or fiber Bragg gratings. Part of the laser beam should be amplitude-modulated with the radar carrier and filtered as well to suppress the optical carrier. After that, optical signals containing radar signal and radar carrier can be mixed at a photodetector and digitized with a slow electronic ADC. Performance capabilities for receiving channel using optical heterodyning are estimated. Parameters for optimal system operation are derived. It is shown that, for modern optical elements, signal-to-noise ratio at the output can be about 60-70 db and more for a microwave signal with a carrier frequency of tens of gigahertz and bandwidth of 100 MHz and higher.

Keywords: microwave photonics, rądio-photonic receiving channel, optical heterodyning.