Broadband Brillouin slow light based on multifrequency phase modulation in optical fibers

We theoretically analyze and experimentally demonstrate broadband Brillouin slow light using multiple equalamplitude spectral lines generated by multifrequency phase modulation. The theoretical analysis shows that 4n-l equal-amplitude spectral lines can be obtained if the modulation signal comprises the fundamental frequency and the odd harmonic waves, where n denotes the number of frequency components in the modulation signal. In experiment, 7 and 11 equal-amplitude spectral lines are obtained and Brillouin bandwidths of 340 and 570 MHz are gained, respectively. The experimental results also indicate that the slope of the broadening factor for the delayed signal decreases in the case of broad and flattened Brillouin gain spectrum.