Increased Performance of Single-Channel Analog Photonic Links Enabled by Optical Wavelength-Division Multiplexing

Laser-intensity noise often sets the limitation to the performance of an analog photonic link. In particular, optimization of the all-important noise figure requires reduction of the laser's relative-intensity noise (RIN) in the spectral band of interest. In this paper, we build on earlier work and analyze an approach for RIN reduction using multiple wavelengths. We extend the analysis and calculate all the important link parameters with no assumptions on modulator bias, RIN spectra, or signal power strength. We then impose constraints that conform with various practical situations and we calculate the performance tradeoffs among the three link parameters: 1) direct current photocurrent; 2) number of wavelengths; and 3) ratio of RIN-to-non-RIN noise. An experiment was performed with five lasers, and the results are in excellent agreement with theory.