Microwave Photonics
Understanding Microwave Photonics
Microwave photonics overcomes fundamental limitations of electronic signal processing by exploiting the enormous bandwidth of optical systems. An optical fiber can carry an RF signal from DC to 100+ GHz with the same low loss (~0.2 dB/km at 1550 nm), far better than any coaxial cable or waveguide.
Key Microwave Photonic Functions
- RF-over-fiber: Analog transmission of RF signals over optical fiber. Ultra-low loss over long distances.
- Optical beamforming: True-time-delay beamforming using optical delay lines. Wideband, squint-free.
- Photonic signal generation: Ultra-low-phase-noise microwave signals from optical frequency combs.
- Photonic ADC: Optical sampling for ultra-high-speed analog-to-digital conversion.
Frequently Asked Questions
What is microwave photonics?
Microwave photonics uses optical components to generate, process, and distribute RF signals. It enables ultra-wide bandwidth (100+ GHz), low-loss RF distribution over fiber, and frequency-agile signal generation impossible with electronics alone.
What is RF-over-fiber?
RF-over-fiber modulates an optical carrier with the RF signal and transmits it over fiber optic cable. The RF signal is recovered at the remote end by a photodetector. Fiber loss is ~0.2 dB/km regardless of RF frequency vs 10-100+ dB/km for coaxial cable.
Where is microwave photonics used?
Satellite ground stations (RF distribution to remote antennas), radar (true-time-delay beamforming), cellular (fronthaul: RF-over-fiber from central to remote antenna), electronic warfare (wideband signal distribution), and metrology (photonic frequency synthesis).