No abstract available

No abstract available

No abstract available

[en] All-polarization maintaining, graphene-based passively mode-locked erbium doped fiber laser is presented. The laser consists of fully polarization maintaining (PM) fibers and components, providing linear output polarization state with degree of polarization (DOP) at the level of 93.5%. The saturable absorber was formed by mechanical exfoliation of graphene flakes from pure graphite and deposited on a fiber connector. Soliton pulses at 1555 nm were achieved with 45.88 MHz repetition rate with 590 fs duration

[en] In this work we demonstrate a high-power, high-repetition rate chirped pulse amplification system operating at 1560 nm center wavelength. The system consists of a mode-locked Er-fiber oscillator, a grating-based pulse stretcher, a two-stage amplifier and a grating compressor. The system provides over 2.5 W of average output power with nearly transform limited, linearly polarized 390 fs pulses and 12.6 nJ pulse energy at 200 MHz repetition rate. The whole design is based on single-mode fibers, which allows excellent beam quality to be maintained. (paper)

[en] In this work we demonstrate a single-frequency, single-mode all-fiber master oscillator power amplifier (MOPA) source, based on erbium–ytterbium co-doped double-clad fiber emitting 10 W of continuous wave power at 1565 nm. In the power amplifier stage, the amplified spontaneous emission from Yb³⁺ ions (Yb-ASE) is forced to recirculate in a loop resonator in order to provide stable lasing at 1060 nm. The generated signal acts as an additional pump source for the amplifier and is reabsorbed by the Yb³⁺ ions in the active fiber, allowing an increase in the efficiency and boosting the output power. The feedback loop also protects the amplifier from parasitic lasing or self-pulsing at a wavelength of 1 μm. This allows one to significantly scale the output power in comparison to a conventional setup without any Yb-ASE control. (letter)

[en] In this letter we present a passively mode-locked Yb:KGW oscillator pumped by a low power single-mode laser diode. Contrary to high power operation, single-mode pumping enabled us to suppress parasitic thermal effects, while keeping the setup compact and its alignment straightforward. Undisturbed mode-locking (ML) stability was achieved without active cooling of the gain medium and the laser was entirely self-starting. Pulses 59 fs in duration were obtained in a semiconductor saturable absorber mirror (SESAM)-assisted Kerr-lens mode-locked regime. The corresponding spectrum was 20.2 nm broad at a central wavelength of 1036 nm approaching the performance limit of the crystal. To the best of our knowledge, these are the shortest pulses generated from a Yb:KGW laser. (letter)

[en] This paper presents new solutions for laser vibrometry, which are based on fibre vibrometry in the third telecommunication window. The scattered laser beam from a vibrating object is guided by a fibre collimator and coherently detected through heterodyning it with an acousto-optical frequency-shifted reference beam. The concept of measuring vibration parameters from many points of the vibrating object has been inspired by wavelength division multiplexing (WDM) in fibre telecommunications. The N-independent WDM separated 15XX nm fibre-coupled laser diodes (used for optical fibre telecommunications) form a system of sources for multipoint vibration measurement according to the rule 'one wavelength–one point'

[en] One of the most important parts of a fiber-laser vibrometer is demodulation electronic section. The distortion, nonlinearity, offset and added noise of measured signal come from electronic circuits and they have direct influence on finale measuring results. Two main parameters of an investigated vibrating object: velocity V(t) and displacement s(t), influence of detected beat signals. They are: the Doppler frequency deviation f(t) and phase shift φ(t), respectively. Because of wide range of deviations it is difficult to use just one demodulator. That is the reason why we use three different types of demodulators. The first one is the IQ demodulator, which is the most sensitive one and its output is proportional to the displacement. Each IQ channel is sampled simultaneously by an analog to digital converter (ADC) integrated in a digital signal processor (DSP). The output signals from the two FM demodulators are proportional to the frequency deviation of heterodyne signals. They are sensitive directly to the velocity of the object. The main disadvantage of scattered light interferometry system is a ''speckle effect'', appearing in relatively large amplitude fluctuation of a heterodyne signal. To minimize ''speckle effect'' influence on quality of beat signals we applied the automatic gain control (AGC) system. Data acquisition, further signal processing (e.g. vibration frequency spectra) and presentation of results is realized by PC via USB interface.

[en] We demonstrate an all-polarization maintaining (PM), mode-locked erbium (Er)-doped fiber laser based on a carbon nanotubes (CNT) saturable absorber (SA). The laser resonator was maximally simplified by using only one passive hybrid component and a pair of fiber connectors with deposited CNTs. The repetition frequency (F_rep) of such a cost-effective and self-starting mode-locked laser was scaled from 54.3 MHz to 358.6 MHz. The highest F_rep was obtained when the total cavity length was shortened to 57 cm. The laser allows ultrashort pulse generation with the duration ranging from 240 fs to 550 fs. Because the laser components were based on PM fibers the laser was immune to the external perturbations and generated laniary polarized light with the degree of polarization (DOP) of 98.7%