What is it about?
In this paper, we demonstrate experimentally that a vertical cavity surface emitting laser (VCSEL) exhibits an enhancement of nonlinear polarization dynamics, i.e., antiphase chaos synchronization and mode hopping with optical feedback (OF). Rotating orthogonal polarization of a VCSEL is used as an external parameter to generate chaotic signal when it is reflected back with a fixed bias current and a strong OF signal. The intensity of the two linear polarizations modes of VCSEL is measured for a range of bias current, which provides a detailed investigation for its dynamics dependence.
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Why is it important?
The results show that, the antiphase chaotic synchronization enhances with increasing the angle of orthogonal polarization of OF. Polarization modes are oscillated entirely in the chaotic regime in antiphase synchronization with no time delay at the bias currents of 1.2 (low) and 1.7 mA (high). However, the synchronization quality of the two modes is completely deteriorated when the bias current is increased to 1.7 mA at a polarization angle of 70o, where power modes differences are increased. The result shows that, the power mode difference affects antiphase synchronization dynamics and thus destroys the mode computation effects. In addition, polarization switching take place at the polarization angles of 60o and about 33o at low and high bias currents, respectively. Polarization mode hopping is also observed, which is associated with improvement of the antiphase synchronization dynamics.
Perspectives
In this paper we experimentally investigate the antiphase dynamic dependency on both the bias current and the rotating polarization angle for fixed and strong OF levels. The bias current is a key parameter, which effects the VCSEL’s dynamics, therefore we can anticipate that the chaos behaviors under different bias currents and OF strength will be more complex and interesting. Increasing current destabilizes the self-pulsing characteristics of the VCSEL thus leading to chaos , where the chaos bandwidth is strongly dependent on the bias current
Assist Prof. Salam Nazhan AL Zaidi
University of Diyala
Read the Original
This page is a summary of: Antiphase chaotic synchronization enhancement in a vertical cavity surface emitting laser, Applied Optics, December 2019, Optical Society of America (OSA),
DOI: 10.1364/ao.58.009491.
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