High-RF-Frequency Analog Fiber-Optic Links using Optical Signal Processing Techniques

摘要

Wide band phase modulators used with high power laser carriers convert high-frequency RF signals to phase-modulated optical signals. Higher laser optical power to the modulator produces larger RF signal sidebands. A carrier attenuation filter passes the attenuated carrier and non-attenuated RF modulation sidebands. Carrier attenuation leaves the larger RF signal sidebands. A demodulation filter used with a photodetector or a balanced photodetector pair converts the phase-modulated optical signal back to an electrical signal. Carrier-only attenuation allows high power laser use, avoids photodetector damage or saturation, and provides increased RF link gain, low noise figure (NF) and high spurious-free dynamic range (SFDR). Filtered-out carrier power fed back to the laser source increases to overall system efficiency. An additional optical delay filter with dual outputs used with a polarization multiplexer or a coherent combiner coupler combines signal power to a single photodetector to further increase electro-optic signal conversion efficiency.

主权项

1. A method comprising:
providing an analog optical link, providing an optical laser source, providing an optical frequency spectrum power signal from the laser source, providing an optical phase modulator, providing the optical frequency spectrum power to the optical phase modulator, providing a high frequency electric signal source, providing a high frequency electric signal from the electric signal source to the optical phase modulator, phase modulating the optical frequency spectrum power with the high frequency electric signal in the optical phase modulator, providing a phase modulated optical signal with the frequency spectrum power and RF modulation sidebands from the optical phase modulator, providing a filter combination having a first carrier attenuation filter and a second demodulation filter, providing the phase modulated optical signal to the first carrier frequency attenuation filter, attenuating a carrier frequency in the phase modulated optical signal, providing the carrier-attenuated optical signal to the second demodulation filter, demodulating the carrier-attenuated phase-modulated signal, providing a photodetector, providing the demodulated carrier-attenuated optical signal to the photodetector, and changing the demodulated carrier-attenuated optical signal to an electric signal.