Detection of Low-Power RF Signals Using a Two Laser Multimode Optoelectronic Oscillator

We present a two laser, multimode optoelectronic oscillator (OEO) for detecting unknown low-power RF signals. By switching between one or two lasers, the OEO cavity will become sensitive to an interleaved set of frequencies. The system has an input sensitivity of -78.4 dBm, which is only 14.2 dB higher than the thermal limit for a 140-MHz bandwidth. In addition, mode spacing has been increased to 100 MHz, a 20 times increase from previous demonstrations.