Photonic envelope logarithmic processor and its application demonstration

Similar to their electronic counterparts, logarithmic operation processors are fundamental building blocks for all-optical circuits used in ultrafast signal processing and computing. In this paper, we propose and experimentally demonstrate a new approach for performing logarithmic operations on signals. The logarithmic operation is constructed through a combination of reciprocal, differential, multiplication, and integral operations. Detailed theoretical analysis and simulations are developed. In the experiments, as sinusoidal, square, and triangular waveforms are used as inputs, the corresponding logarithmic results are successfully obtained. Logarithmic operations with different bases are readily achieved through power scaling, and operations with bases less than 1 are easily realized with simple adjustments to the system. Furthermore, a potential application of the proposed logarithmic system is also demonstrated. By taking the time-domain Fourier transform result of a square pulse as the input signal, the full spectral information is effectively visualized on a logarithmic scale in the time domain.