📝 SummarXiv

Abstract

The diode-pumped Nd: Vanadate laser is one of the most widely used lasers in the near-infrared range. Using passive Q-switching with a Cr:YAG saturable absorber (SA), it generates nanosecond pulses at tens of kilohertz. It is well known to display either regular pulsing or low-dimensional deterministic chaos, depending on the absorber's position within the cavity. However, to our knowledge, a strange nonchaotic attractor (SNA) has never been reported in this system. Our experiments provide the first evidence that, for a specific absorber position, the laser dynamics correspond to a strange nonchaotic attractor. SNAs exhibit complex dynamical behavior that is neither periodic nor chaotic, positioning them as a valuable resource for applications requiring high spectral diversity while preserving predictable dynamics. By experimentally obtaining time series of two laser variables, we reconstruct the underlying attractor. For a certain position of the SA, we find that all Lyapunov exponents are negative and that the energy spectra exhibit a broad frequency range, indicating that the attractor is nonchaotic and lacks periodicity. Using Higuchi's method, we estimate the fractal dimension (df) and find that 13 percent of the nonchaotic time series exhibit a well-defined df, confirming the presence of an SNA.