Adam Kujawski

Diffractive patterns of small cores generated by interference of Bessel beams.

The characteristic dimensions of Bessel beams are fully determined by the corresponding Bessel functions. We consider a way of obtaining a narrower diameter of the central core of a diffractive pattern generated by the Bessel beams. The method relies on superposition of two or more Bessel beams with appropriately chosen amplitudes and widths. The disturbing influence of the apertures edges can be eliminated by addition of the proper amplitude filter.

Propagation Effects in Liquid Crystal-Core Optical Fiber Waveguides

Abstract Propagation effects in liquid crystal-core optical fiber waveguides have been investigated. In theory, propagation properties of the TE01 and TM01 modes in the waveguide composed of a low-birefringence nematic liquid crystal acting as an optical-fiber core have been analyzed. For smaller diameters of the liquid crystal-core, the TE01 mode is guided and TM01 is the leaky mode, but for larger diameters differences between both modes decrease. The paper presents initial experimental transmission characteristics of the liquid crystal fiber subjected to the influence of selected external perturbations. The experimental results have been compared with the theory in view of some typical optical fiber parameters suggesting a great potential of the liquid crystal-core fibers for environmental sensing.

Influence of the position of the gain medium on the excess noise factor.

An exact analysis of the excess noise in a two-mirror laser that takes into account the intracavity elements and the position of the active medium is presented. The influence of the active mediums position and length of the laser cavity on the excess noise factor is shown.

Analysis of Waveguide Ring Lasers with Nonlinear Directional Outcoupler

Abstract The waveguide ring laser with the light outcoupled through the nonlinear directional coupler is analysed theoretically. The influence of the characteristic system parameters on the laser radiation for two configurations of the laser is presented. In particular, the stability of the laser radiation is studied in details.

Polarimetric fiber optic sensors with partially polarized laser sources

The degree of light polarization propagating in a birefringent optical fiber diminishes along the propagating distance. This effect is of particular interest in optoelectronics since the quasi-monochromatic semiconductor sources are not perfectly coherent. Therefore, measurement of the degree of polarization of light propagating along the fiber can be directly applied to determine the coherence characteristics of laser diodes. The issue concerns also applications in polarimetric sensing with birefringence fibers. The paper analyzes the problem of polarizations degree fading in polarimetric fiber optic sensors in view of optimizing the performance of real polarimetric sensors with highly birefringent fibers. The influence of degree of polarization of partially polarized light passing through highly birefringent optical fiber on metrological parameters of polarimetric sensors is presented.

Model of the nonlinear operation of a laser with a gaussian mirror

In this paper a semi-classical model of the nonlinear operation of a laser is extended to describe a laser with a Gaussian mirror. Modified nonlinear self-consistent equations including transverse and longitudinal field dependence, gain saturation, spatial hole burning and nonlinear dispersion effects are derived. With the help of an energy theorem an approximate solution for steady-state single mode operation is presented, which relates the small signal gain to the output power and the laser system characteristic parameters. The laser output power characteristics are presented for various cavity configurations, especially, revealing an influence of the Gaussian mirror parameter on the power efficiency of the laser.

Polarimetric Fiber Sensors for Partially Polarized Laser Source

Polarimetric fiber sensors have for several years been successfully applied in high hydrostatic pressure, stress and strain measurements [1]. Increasing numbers of applications result in growing demand for improved sensors accuracy and reliability. The principle of operation of the Polarimetrie fiber sensor is based on measuring the state of polarization at the birefringent fiber end and therefore the degree of light polarization influences the measurement quality.

INFLUENCE OF THE POSITION OF THE GAIN MEDIUM ON LASER OUTPUT POWER

Abstract A one-dimensional model of a laser in which the position of the active medium in the laser cavity is taken into account, is considered. If the distributed losses outside the active medium equal zero the output power does not depend on the position of the active medium. Dependence of the output power on distributed losses and position of the active medium in the cavity is discussed in detail.

Nonlinear Operation of Lasers with a Saturable Absorber

Abstract An approximate method of the modelling of the nonlinear operation of the segment laser containing a saturable absorber beyond mean field approximation is presented. An analytical condition for the bistable operation as a function of the system parameters is derived. The influence of the output mirror reflectivity, the linear losses, the saturable losses, the ratio of the active medium length to the total length of the structure on hysteresis loop is investigated. The results are compared to the predictions of the exact solutions, and they are found to be in qualitative agreement as well as in good quantitative agreement. Moreover, the laser characteristics revealing the optimal output mirror reflectivity are presented.

Statistical Properties of Light From a Real Laser with Saturation Effect

To characterize the statistical fluctuations of the laser light, an additive white noise (representing spontaneous emission source) is included in the conventional laser theory, that adds phase and amplitude fluctuations to the optical field. However, the conventional laser models used in the previous analysis1 only contains cubic nonlinearities and orthogonality of the laser modes. Recently, the cubic model of the statistical properties of light from a laser at steady-state have been developed to take into account the nonorthogonal nature of the laser modes2.