Robert Frankowski

Spectral density matrix of a single photon measured.

We propose and demonstrate a method for measuring the spectral density matrix of a single photon pulse. The method is based on registering Hong-Ou-Mandel interference between a photon to be measured and a pair of attenuated and suitably delayed laser pulses described by a known spectral amplitude. The density matrix is retrieved from a two-dimensional interferogram of coincidence counts. The method has been implemented for a type-I down-conversion source, pumped by ultrashort laser pulses. The experimental results agree well with a theoretical model which takes into account the temporal as well as spatial effects in the source.

Statistics of multiphoton events in spontaneous parametric down-conversion

We present an experimental characterization of the statistics of multiple photon pairs produced by spontaneous parametric down-conversion realized in a nonlinear medium pumped by high-energy ultrashort pulses from a regenerative amplifier. The photon-number-resolved measurement has been implemented with the help of a fiber loop detector. We introduce an effective theoretical description of the observed statistics based on parameters that can be assigned direct physical interpretation. These parameters, determined for our source from the collected experimental data, characterize the usefulness of down-conversion sources in multiphoton interference schemes that underlie protocols for quantum-information processing and communication.

An optical method for the time-to-digital converters characterization

Measurement of the distribution random error describing a high precision multi-tapped delay lines with coding registers module is important from the perspective of construction high-resolution time-to-digital converters. Knowledge of this distribution allows to optimize the process of implementation Multi-Tapped Delay Lines in programmable structures, thus obtaining the converters with much improved processing performance. In this article a new method for optical measuring of the delay line characteristics is presented. Using this method, the distributions of probabilities of counts in each time-channels are also executed. Finally, the experimental results obtained from optical and widely used a statistical code-density test method were also compared.

A Sub-Channel method for the time-intervals histogram calculation

One of the methods used for presenting the results of the time-interval measurement is a two-sample-difference of quantized data histogram calculation method. The proposed Sub-Channel method allows to increase the precision and minimizes the influence of nonlinearity and quantization error during the time-interval histogram calculation. It is possible to achieve, thanks to the information obtained by an optical method, from the matrix of the probabilities of counts in particular delay cells. Using this matrix, the appropriate envelope functions and their parameters is possible for obtainable. This information is useful in the preparation of the time-intervals histogram with any resolution, independent of the real time-interval-module resolution. This paper describes a methodology of creation an envelope function and explains the process of applying a Sub-Channel method for the time-intervals histogram calculation.

Selected methods of thin films deposition and their applications

Modern technologies requires thin films for different applications. Thin film materials are important elements of technological progress made in the fields of optoelectronic, photonic, photovoltaic and magnetic devices. The processing of materials into thin films allows easy integration into various types of devices. The properties of material significantly differ when studied in the form of thin films. Technologies of the thin films makes use of the fact that the properties can be easy controlled by the thickness of the layer. Thin films are formed mostly by deposition with physical or chemical methods. Obtained layers, both crystalline and amorphous, are important for the modern technology. In this paper, we present the selected methods of thin films depositions (Pulsed Laser Deposition, Physical Vapour Deposition, Dip coating and spin coating) and examples of their application. All of these methods are implemented in the Laboratory of Physical Foundations of Microelectronics, Institute of Physics, Nicolaus Copernicus University [1-6].

Non-invasive TDC based temperature method for the local interconnects properties identification

Application of various types Cu/Low-k materials improve on CMOS FPGA structure a quality of high-speed data transferred between all of their embedded parts. An effective combination of the specialized fast interconnections and high performance logic elements introduces the possibility of implementation in these structures a high-resolution delay cells. The delay cells temperature parameters strongly depends on the type of materials which are used for FPGA construction. In this paper, based on TDC a non-invasive methodology of the multi-level interconnects properties measurement by the optical direct method are described. The proposed method allows us to obtain a complete temperature description for everyone of the delay segments. This information has been useful for temperature optimization of the sub-picosecond delay line implementation process.