Final PhD Seminar

Active photonic systems with balanced gain and loss

Mr Sergey Suchkov
Nonlinear Physics Centre

Active photonic systems with gain and loss are widely used for optical signal processing and amplification. Whilst generally such systems are described by non-Hermitian mathematical models, there is a particular type of pseudo-hermitian  systems attracting strong interest, with an important example of parity-time (PT) systems, due to a possibility of exact compensation between specially distributed gain and loss. The structure symmetry imposes specific mode geometry, which can facilitate non-reciprocal transmission, selective mode suppression or amplification, optical switching through phase transition, with applications in lasers and nonlinear optics.

In this talk, I will discuss different PT-symmetric and pseudo-Hermitian geometries such as dimers, trimers, chains of conservative waveguides with embedded non-Hermitian defects, and fiber ring resonators. I will outline their spectral properties and associated benefits for signal amplification, filtering, and lasing. I  will also consider a nonlinear bottle-type micro resonator in application to a frequency comb generation and signal transmission through reflectionless potentials.

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