Piotr Stepczak

Analysis of multiwavelength erbium-doped fiber ring source

In the presented work, we report the original numerical results of the properties of ring optical frequency comb generators employing the acousto optic frequency shifter (AOFS) and the single stable master laser (ML). A key element of the examined source is the AOFS controlled by the RF generator which determines frequency comb interval and stability. In each loop round-trip, AOFS splits the optical beam into two, where the deflected beam is frequency shifted. The multiple divisions, spectrum shifting and optical beam amplification in the ring configuration result in generating of an optical frequency comb. Performed numerical simulations allow spectral analysis of the generated optical frequency comb. We tested configurations with single and two cascaded AOFS operating at 1.5625 GHz. Calculations were carried out for a variety of input laser powers and different quantity of optical output frequencies whose number was controlled by an optical feedback filter bandwidth. It was shown that for different configurations and component parameters it was possible to obtain 20 - 30 uniform peaks with the amplitude difference of less than 0.5 dBm and OCNR in the range of 35-45 dB. We demonstrated that the main problem of the simultaneous multiwavelength fiber ring laser operation can be overcome by using a non resonant ring configuration with a quasi steady state operation. This method ensures generating of an optical comb with stable carrier frequency spacing. It allows diminishing the interchannel spacing and building up an ultra dense wavelength division multiplexing system.

Multifrequency source for UDWDM fiber systems

The numerical and experimental results of multifrequency optical source are presented. Up to 84 spectral lines with stable 1.5 GHz spacing ware obtained. The spectrum flatness was improved by equilizing polarization sensitivity of a frequency shifter.

Application of UDWDM technology in FTTH networks

In the paper we presented results of investigation of an original ultra dense wavelength division technology based on optical comb generator and its implementation for FTTH networks. The optical comb generator used a ring configuration with an acousto-optic frequency shifter (AOFS) which ensured obtaining very stable optical carrier frequency distances. Properties of an optical comb generator module determined stability of the UDWDM transmitter. Key properties of a selective components based on all fiber Fabry-Perot resonant cavity were presented. Operation of direct and coherent detection DWDM systems were shown. New configurations of FTTH UDWDM architecture have been proposed.

UDWDM system with optical multiwavelength source

In the presented paper we show a concept of the UDWDM system using multifrequency optical source with an acoustooptic frequency shifter as a key module. Original simulation results of the systems with very stable 3.125 and 6.25 GHz channel separation are presented.

Multifrequency erbium doped fiber source for UDWDM application

The original numerical and experimental results of multifrequency optical source, based on erbium doped fiber ring configuration are presented. Eleven spectral lines with very stable 1.5 GHz frequency separation were obtained. To achieve uniform amplitudes of optical frequencies, we propose an implementation of a polarization dependent diffraction efficiency equalizer of the acousto-optic shifter.

Properties of active fiber optical sources

In the paper, we presented the results of the research on the properties of erbium doper fiber optical sources. We discussed properties and presented results of investigating single mode lasers, focusing on the problem of a beam oscillations at the radio frequencies range. An original method leading to the increase of power efficiency was described. We presented some methods and problems concerning multiwave sources with a special respect to resonant and nonresonant ring structures. We demonstrated results of investigation of a non resonant loop configuration with a quasi steady state operation free of RF components. Results of measuring mode-locked erbium ring lasers were shown.

Ten years of optical communications laboratories in the Institute of Electronics and Telecommunications, Poznan University of Technology, Poland

For thirty years, the Institute of Electronics and Telecommunication has been teaching students in the field of telecommunications. In the academic year 1990/91, a course in optical communications was introduced. Currently, within electronics and telecommunication programs, we offer an undergraduate course entitled: Optotelecommunications, two courses for master level specialities: Optical Networks and Advanced Fiber Optic Systems, and finally, a course for extramural students. We also provide lab projects for Computer Science and Electrotechnics students and contribute to continuos education training. Over the last ten years, a number of students participating in our laboratories has increased seven times. At present, we have two laboratories, offering 40 projects, which fall into 5 categories: basics projects, fundamental projects, applied projects, advanced projects, optical systems. Such a variety of topics allows to offer a flexible choice to suit individual student interests.