Date of Graduation

5-2017

Level of Access

Restricted: Campus/Bates Community Only Access

Degree Name

Bachelor of Science

Department or Program

Physics and Astronomy

Number of Pages

85

First Advisor

Lin, Hong

Abstract

We study polarization dynamics of vertical-cavity surface-emitting lasers (VCSELs) subject to optical injection, optical feedback, or a combination of the two. First, dynamics of the VCSEL in single mode operation under single beam injection alone are studied for both parallel and orthogonal injection. Observed behaviors include period 1 (P1) and period 2 (P2) dynamics, polarization switching, and injection locking. The response of the VCSEL to feedback alone is also investigated in the isotropic and polarization-rotated cases. Fluctuations in each polarization of the VCSEL are analyzed through power spectrum measurements and calculations of correlation coefficients and permutation entropies. Isotropic feedback generally triggers dynamics with periods equal to the feedback delay times, while dynamics associated with the rotated feedback exhibit a doubled period. The y-polarized output power of the VCSEL was enhanced, and an anti-correlation between lasing polarizations for periods corresponding to the feedback delay time was recorded. Finally, we studied the dynamics when the VCSEL is subject to polarized injection and polarized feedback simultaneously. We observe that orthogonal injection can enhance or suppress feedback dynamics, while parallel injection is responsible for fluctuations with a higher number of discrete frequencies in the power spectrum. The polarization of the feedback does not directly influence the type of dynamics observed, but the rotated case still exhibits period-doubled fluctuations.

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