Power-Independent Microwave Instantaneous Frequency Measurement Based on Combination of Brillouin Gain and Loss Spectra

Photonics-assisted microwave instantaneous frequency measurement (IFM) is considered as a promising technique for detecting an unknown radio-frequency (RF) signal, which has advantages of broad range and fast processing speed. Up to date, there no photonics-assisted IFM system that can essentially measure RF signal time-frequency information with power fluctuating seriously. Moreover, the accuracy modulation recognition are not good those traditional electronic methods. Here, we propose scheme based on combination Brillouin gain spectrum (BGS) loss (BLS), RF-power-independent high efficiency. The BGS BLS construct amplitude comparison function (ACF) reduce influence fluctuation within 21.27 dB by single-shot measuring. When appropriate interval domain monotonous comb modulated pump lightwave, reaches about 1 MHz. After initial calibration system, it recognize variation single tone linear (LFM), nonlinear (NLFM), Costas signal. This will help promote application in field reconnaissance reception.