A. Budnicki

Investigation of passively mode-locked erbium doped fiber ring laser due to nonlinear polarization rotation

Passively mode-locked erbium doped fiber ring laser was investigated. We present optimization of laser configuration where nonlinear polarization rotation was used for modes synchronization. Simulations of pulse propagation inside a laser cavity were applied in order to confirm the optimisation technique. Experimental results are presented and more than 32-nm spectral width of the output frequency comb was obtained.

Discretely tunable and multiwavelength erbium doped fibre lasers with Fabry-Perot etalon

Modern WDM telecommunication systems require stable and calibrated laser sources. In this paper we present examples of such lasers based on erbium-doped fibres: discretely tunable and multiwavelength ring lasers. For the first case tuning is possible due to tunable Bragg grating overlapping spectrally the third telecommunication window (1550 nm). When a Fabry-Perot etalon is inserted into the cavity, discrete tunable operation with appropriate spacing between operating wavelengths is possible. Different free spectral ranges (FSR) of applied etalons ensured operation at wavelength spacing 0.4 nm, 0.8 nm or 1.6 nm, respectively. When an acoustooptic Bragg frequency shifter was inserted together with the Fabry-Perot etalon, the stable simultaneous multiwavelength operation covering the erbium-doped gain range was achieved.

EDF laser with double-Bragg grating selection

We present a new configuration of ring erbium doped fiber laser with specific way of wavelength selection. The fiber circulator with a novel configuration of two Bragg gratings was applied. The wavelength selectivity of the ring laser can be substantially improved when the transmission characteristics of both gratings are partly overlapped. Additional element improving the stability of the laser can be obtained when its state of polarization is controlled.

Multiwavelength fiber laser with acoustooptical Bragg frequency shifter

There is a necessity of development a stable and calibrated laser sources for modern WDM telecommunication systems. Additionally simultaneous oscillations of many wavelength are required for testing and diagnostic of such systems. This regime of operation is possible in Frequency Shifted Feedback Lasers (FSFL). The multiwavelength erbium doped fiber laser is presented in this paper. The acoustooptical Bragg frequency shifter (AOFS) in the laser cavity ensures stable and multi-frequency operation by preventing steady-state regime. The wavelengths forced by Fabry-Perot filter cover part of third window (1550 nm).

Laser Fiber Vibrometry Gained by Fiber Amplifiers

Fast development ofthe fiber optotelecommunications in the infrared band 1550nm has caused quite large price drop ofsuch elements like: single mode fibers, fiber couplers, fiber isolators, laser sources, photodetectors, fiber Bragg gratingsetc. The laser fiber vibrometry or interferometry up till now have dealt rather with the red range of visible bandwidth

Technological development of the erbium doped fibers for L-band

We report on the erbium doped low numerical aperture (NA) fibers for L-band EDFA, obtained in the Laboratory of Optical Fibres Technology, Marie Curie Sklodowska University. The gain and noise properties of doped fibers were investigated by a diagnostic system developed in the Laser & Fiber Electronics Group, Institute of Telecommunications and Acoustics, Wroclaw University of Technology. Their basic characteristics are presented, especially in the 1580 nm to 1620 nm spectral range.

Sub-picosecond fiber laser source at 1550 nm

We present investigations on passive mode-locked fiber lasers with different states of soliton oscillation. A bound state of solitons was obtained by introducing additional bidirectional loop into NALM (nonlinear amplifying loop mirror) passive mode-locked fiber laser configuration.

ASE source at 1550 nm

The source of ASE around 1550 nm based on double clad erbium-ytterbium doped fiber is presented. Such source can be much cheaper alternative comparing to tuneable semiconductor lasers.

Multiwavelength polarization maintaining erbium doped fiber lasers

In this paper simultaneous multiwavelength lasing in fiber ring laser using PM EDF (polarization maintaining erbium doped fiber) is presented. Experimental results indicate that multiwavelength lasing is connected with the elliptical polarization state of the output signal. By changing the polarization state of both the lasing signal and the pump signal and their placement towards each other we can obtain linear polarization with the maximal value and stability of fiber laser signal. It is important that the direction of lasing signal vibrations be consistent with one of the major PM fiber axes.

Phase-locking of two coupled EDF ring lasers

The phase synchronization (phase-locking) of two lasers occurs in generating the same frequency (they can differ only in phase). The phase-locking effect can by forced by mutual radiation coupling between lasers. We investigated experimentally that phenomenon in two erbium doped ring fibre lasers. They were strongly coupled by using a 50/50 fibre coupler. Both lasers had the same resonator lengths in order to keep their free spectral ranges equal. The phase-locking state was diagnosed by observing the spectrum of the beat signals. Using a tuneable fibre Bragg grating, the locking range was investigated. One laser operated at 1551.91 nm, the second one was tuned around. Due to frequency pulling effect, the common frequency of both synchronized lasers changed from 1551.26 to 1552.22 nm. That locking range was about 225 GHz (1.8 nm). Although the lasers are not single-frequency ones, we showed, that proper designing, careful alignment and phase control, can give effective phase-locking effect.