Mindaugas Radziunas

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We investigate the longitudinal dynamics of multisection semiconductor lasers based on a model, where a hyperbolic system of partial differential equations is nonlinearly coupled with a system of ordinary differential equations. We present analytic results for that system: global existence and uniqueness of the initial-boundary value problem, and existence(More)
An in-depth theoretical as well as experimental analysis of the nonlinear dynamics in semiconductor lasers with active optical feedback is presented. Use of a monolithically integrated multisection device of submillimeter total length provides access to the short-cavity regime. By introducing an amplifier section as a special feature, phase and strength of(More)
Stripe-array diode lasers naturally operate in an anti-phase supermode. This produces a sharp double lobe far field at angles +/-alpha depending on the period of the array. In this paper a 40 emitter gain guided stripe-array laterally coupled by off-axis filtered feedback is investigated experimentally and numerically. We predict theoretically and confirm(More)
We propose and analyze a beam-shaping mechanism that in broad-area semiconductor amplifiers occurs due to spatial pump modulation on a micrometer scale. The study, performed under realistic parameters and conditions, predicts a spatial (angular) filtering of the radiation, which leads to a substantial improvement of the spatial quality of the beam during(More)
In the present paper a general technique is developed for construction of compact high-order finite difference schemes to approximate Schrödinger problems on nonuniform meshes. Conservation of the finite difference schemes is investigated. The same technique is applied to construct compact high-order approximations of the Robin and Szeftel type boundary(More)
High-power tapered semiconductor lasers are characterized by a huge amount of structural and geometrical design parameters, and they are subject to time-space instabilities like pulsations, self-focusing, filamentation and thermal lensing which yield restrictions to output power, beam quality and wavelength stability. Numerical simulations are an important(More)
The spatial modulation of pump in broad emission area semiconductor amplifiers has two important advantages in this kind of devices. A 2-dimensional periodic modulation of the pump profile introduces by one side, a filtering effect and an improvement of the beam quality. Moreover, the spatial modulation changes the effective diffraction inside the material(More)