Evolution of the spatiotemporal complexity in a phase-conjugate feedback laser system

Tushar Malica; Guillaume Bouchez; Delphine Wolfersberger; Marc Sciamanna

doi:10.1117/12.2559302

1 April 2020 Evolution of the spatiotemporal complexity in a phase-conjugate feedback laser system

Tushar Malica, Guillaume Bouchez, Delphine Wolfersberger, Marc Sciamanna

Proceedings Volume 11356, Semiconductor Lasers and Laser Dynamics IX; 113560Z (2020) https://doi.org/10.1117/12.2559302
Event: SPIE Photonics Europe, 2020, Online Only

Abstract

A semiconductor laser having an emission wavelength of 852 nm is subjected to phase-conjugated feedback. The phase conjugation is implemented using a Rh-doped BaTiO₃ photorefractive crystal of the dimension 5mm × 5mm × 5mm. A combination of several phenomena including light fanning, total internal reflection and four-wave mixing occur in tandem inside the crystal to generate the phase conjugate of the light entering the crystal. Our recent works have established that such configuration exhibits significantly enhanced chaos bandwidth with high spatiotemporal complexity at varied feedback strengths, compared to its conventional optical feedback counterpart in a long external cavity setup. The presented work studies the systematic progression of spatiotemporal complexity in a long-length (≈1.5 m) external cavity setup as a function of the feedback strength. System outputs at varied operating conditions are found to be highly complex with PE upwards of 0.9 and chaos BW in the order of several GHz. Such complex outputs have relevance for applications such as security-based communication and random-bit generation. These system outputs are shown to be dynamically diverse ranging from wide-band chaos to time-periodic oscillations of the output signal corresponding to a higher multiple of the external cavity frequency. The analyses performed in the temporal and frequency domain use several diagnostic tools including permutation entropy, continuous wavelet transform, and statistically calculated chaos bandwidth to unveil and dissect the evolution of the system's characteristic temporal signatures. Thus, we comprehensively determine the true chaotic nature of the system outputs in the spatiotemporal domain.

Conference Presentation

Citation Download Citation

Tushar Malica, Guillaume Bouchez, Delphine Wolfersberger, and Marc Sciamanna "Evolution of the spatiotemporal complexity in a phase-conjugate feedback laser system", Proc. SPIE 11356, Semiconductor Lasers and Laser Dynamics IX, 113560Z (1 April 2020); https://doi.org/10.1117/12.2559302

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