Krassimir Panajotov

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We demonstrate the physical generation of random bits at high bit rates (> 100 Gb/s) using optical chaos from a solitary laser diode and therefore without the complex addition of either external optical feedback or injection. This striking result is obtained despite the low dimension and relatively small bandwidth of the laser chaos, i.e. two(More)
We show experimentally that polarization mode hopping in quantum dot vertical cavity surface emitting lasers (VCSELs) takes place between nonorthogonal elliptically polarized modes. In contrast to quantum well VCSELs the average dwell time decreases with injection current. This decrease is by 8 orders of magnitude: from seconds to nanoseconds and is(More)
We consider the paradigmatic Brusselator model for the study of dissipative structures in far from equilibrium systems. In two dimensions, we show the occurrence of a self-replication phenomenon leading to the fragmentation of a single localized spot into four daughter spots. This instability affects the new spots and leads to splitting behavior until the(More)
This work presents the application of the plane-wave admittance method (PWAM) to modeling the propagation of light and optical losses in photonic crystal waveguides. Both single- and multimode waveguides are analyzed and in the latter case the increase of losses due to the mode coupling is determined. As such mode coupling introduces a photonic mini stop(More)
We discuss how material anisotropy influences the modal birefringence of photonic crystal fibers. We introduce an efficient numerical method for the calculation of the modal structure which accounts for material anisotropy. The approach relies on solving the fully vectorial wave equation for the transverse magnetic field and the respective propagation(More)
Semiconductor-metal subwavelength grating (SMSG) can serve a dual purpose in vertical-cavity surface-emitting lasers (VCSELs), as both optical coupler and current injector. SMSGs provide optical as well as lateral current confinement, eliminating the need for ring contacts and lateral build-in optical and current confinement, allowing their implementation(More)
We report the experimental observation of two-dimensional vector cavity solitons in a Vertical-Cavity Surface-Emitting Laser (VCSEL) under linearly polarized optical injection when varying optical injection linear polarization direction. The polarization of the cavity soliton is not the one of the optical injection as it acquires a distinct ellipticity.(More)
We report on the method for monitoring of the modifications in Yb-doped optical fibers irradiated by gamma-rays with the doses 1, 2, 4 and 8 kGy. This method is based on the refractive index change (RIC) effect induced in the tested fibers by square modulated optical pump pulses of 1 ms duration at 980 nm with the power up to 100 mW. The applied in-situ(More)
We summarise the results of the COST MP0702 exercise on the sensitivity of metal-dielectric layered superlens to fabrication inaccuracies. The major results of this joint task have been already published in Ref. 1, Opto-Electronics Review, vol. 18(4), pp. 446–457, 2010. The numerical analysis of the superlens is based on the transfer matrix method,(More)