Abstract
We propose a photonic mixer with image rejection capability using a broadband optical source (BOS) and polarization processing. Intermediate frequency (IF) signals with image rejection are generated from the local oscillator-modulated and the time-delayed radio frequency (RF)-modulated BOS light. The RF operating frequency is flexibly tunable over a wide range by simply adjusting the time delay. In addition, the proposed system is free from dispersion-induced mixing power fading and bias drift problem. Experimental results exhibit an image rejection ratio of more than 44.6 dB for RF signals from 2 to 18 GHz, while the IF signal is fixed at 800 MHz. Image rejection mixing operation at different IF frequencies and signal power is also confirmed.
Highlights
Frequency down-conversion of radio frequency (RF) signals is of critical importance for signal processing in microwave systems such as electronic warfare, wireless communication and radar [1]–[3]
We propose a photonic mixer with image rejection capability using a broadband optical source (BOS) and polarization processing
A BOS light provided by an amplified spontaneous emission light source (Lightcomm) was filtered by a WS (Finisar 4000S), which was programmed as a Gaussian filter with a center wavelength of 1555 nm and a full width at half maximum (FWHM) of 8 nm
Summary
Frequency down-conversion of radio frequency (RF) signals is of critical importance for signal processing in microwave systems such as electronic warfare, wireless communication and radar [1]–[3]. A Fabry–Perot filter has been employed to accurately remove the image-modulated sidebands without affecting the RF-modulated sidebands [21], which may not be suitable for relatively low IF band due to the limited roll-off factor of the optical filter In this context, stimulated Brillouin scattering (SBS) gain and loss spectrum with wide tunability and narrow bandwidth has been utilized in photonic mixing operation to process optical sidebands induced by RF or LO signals [22]–[24]. It is noted that most of previous laser-based photonic image rejection schemes require SSB modulation, which is implemented by optical filters or electrical hybrids in conjunction with complicated bias control [10]–[19]. A proof-of-concept experiment confirms an effective image suppression across a wide frequency range
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