There is described the possibility to use a special optical system based on using a powerful semiconductor continuous wave laser as a power source.

In this paper, some results of experimental investigations of conditions of the mode-locked regime obtained by microwave pumping in a diode laser with an external cavity are presented. It was observed that the mode-locked regime is achieved at certain power levels of the microwave oscillator at pumping currents close to the generation threshold.

Dynamics of a semiconductor laser coupled to a fiber Bragg grating is analyzed thanks to a map, which indicates the existence of low frequency fluctuations when the reflectivity and the bandwidth of the Bragg grating are varied. The influence of these parameters is detailed and we show how the filter can be used to control the laser dynamics.

It has been found that acousto-optical modulator (AOM) operating in a Raman-Nath diffraction mode can be used as an external phase modulator in Pound-Drever FM sideband technique converting the single mode laser diode input into a pure frequency-modulated (FM) spatially separated optical spectrum. With the use of Pound-Drever FM sideband technique and negative electrical feedback, wide-bandwidth frequency noise suppression and stable frequency locking of the external cavity laser diodes (ECLD) to the sub-Doppler resonances within caesium D₂ spectral line is achievable.

Polaritons appears as the complex excitations in semiconductors via the interaction between electrons, holes and photons. There are the over-zone and sub-zone polaritons in the case of a semiconductor’s contact with a metal. The difference between the optical properties of the over- and sub-zone polaritons are expressed in terms of the difference between the commutation relations of the subzone and overzone polariton creation and annihilation operators. Polariton energy spectrum depends on the photon and exciton energies similarly to the exciton spectrum dependence on the electron and a hole energies.

Intensity noise of mode-locked hybrid soliton pulse source (HSPS) with linearly chirped uniform fiber Bragg grating (FBG) is reported using by coupled-mode equations. Mode-locking is difficult to achieve for some value of rf and dc bias currents because of increasing noise. Hence, transform-limited pulses are not generated over a wide tuning range although these pulses are obtained over a wide tuning range without any noise.

Midterm (1 - 1000s) stability of the traveling-wave Er-doped fiber ring laser has been experimentally studied as a function of laser parameters: the pump power, the doped fiber length and type, the total laser cavity length, polarization control, and the exit coupler ratio. In all cases the total cavity length over ten meters resulted in a multi-wavelength generation with the comb central wavelength, defined by a 1.12 GHz-band tunable Fabry-Perot filter with a 3.1 THz free spectral range. We have found that the key parameters defining the laser stability are the cavity length and the out-coupling ratio, while the polarization control seems not very important for our multi-wavelength regime. Output power variations are less than 0.02dB on a 10 min interval were obtained.

In a two-stage phosphosilicate Raman fiber laser (1.26/1.53μm) pumped by Yb-fiber laser (1.08μm), a temperature tuning of FBGs forming Raman cavities has been performed by means of thermoelectric modules based on Peltier elements. Output power and spectral profiles at 1.26μm and 1.53μm have been monitored during such T⁰-tuning in the range of ±25C corresponding to the FBG wavelength shift of ±0.2nm. The most pronounced effect is that the observed spectral profile at 1.26μm corresponding to the first-stage highly-reflective cavity consists of two splitting components, which become strongly asymmetric while independent T⁰-tuning of cavity FBGs. A simple model considering spectral broadening with increasing pump power and T⁰-induced shift between central wavelengths of the FBGs has been developed. The model takes into account wavelength-dependent Raman gain saturation and qualitatively describes the observed effects of the splitting and asymmetry with T⁰-tuning. It is also demonstrated, that the studied spectral broadening and shift lead to the effective “bleaching” of the highly-reflective cavity, so estimated integral transmission may increase by order of magnitude from minimum transmission ~ 1%, corresponding to central FBG wavelength.

In the present work we have developed an analytical model which takes into account power distribution along the fiber in the two-stage Raman fiber laser thus enabling both qualitative and quantitative comparison with performed experiment. The model describes pump power depletion and intensity interactions in cascades that seem important in the experiment. It is shown that the cascade generation saturates (depletes) sequentially: depletion of residual pump power begins when the first Stokes generation starts, then the first Stokes power saturates when the second Stokes generation starts etc. We have also compared the results of calculations with measurements of intensities in cascades and residual pump power which confirm the model qualitatively. Good quantitative coincidence with the experiment is also reached but for this we have to take into account spectral broadening of the first Stokes wave with increasing pump power. The presented model adequately describes the thresholds, the differential efficiency for the first and the second Stokes waves generation, the saturation levels for the residual pump and the first Stokes wave powers.

Numerical simulations are used to study temporal characteristics of supercontinuum (SC) generated in tapered and photonic crystal fibers. The dependence of SC temporal characteristics on pumping parameters (pulse duration, peak power, and wavelength) is investigated. The correlation between the SC spectrum and temporal structure is studied. This correlation is shown to be caused by fiber dispersion. An easy way to estimate SC pulse duration by spectrum width is proposed. It is shown that using specially designed fibers with flattened dispersion one can obtain shorter SC pulses.

We performed numerical simulations in order to demonstrate that Rayleigh scattering - stimulated Brillouin scattering cooperative process (RS-SBS) can lead to generation of second-order SBS in standard telecom fibers. We give a clear physical insight into the RS-SBS mechanism and built 1-D model describing dynamics of first two SBS cascades. To our knowledge for the first time, we theoretically determine the threshold of the second-order SBS generation in the RS-SBS process and reveal how the SBS spectra, phase portraits and power distributions along the fiber evolve as the pump power grows leading to growth of the second-order SBS. Recently published experimental observations of low-threshold second order SBS in 4.4-km-long optical fiber [e.g., J.Opt.Soc.Am.B 19, 2341-2345 (2002)] are completely reproduced by our simulations.

We report a self-starting gigantic pulse generation observed during steady state stimulated Raman scattering (SRS) process in 10 km long telecom fiber. In our rather specific experimental configuration, the fiber was pumped by radiation from a 2.4 W continuous wave (CW) fiber laser source operating at 1455 nm. This pump provided the generation of light at Raman shifted wavelength around 1555 nm. At pumping face, the fiber was spliced with a broadband fiber loop mirror that reflected ~80% of Stokes power back into the fiber. Reflection from the far fiber end face was strongly prevented by the use of an optical isolator. The configuration provided ~30% power conversion from pump to Stokes radiation. Pulsations were observed from both ends of the fiber and occurred in rather stochastic manner with repetition rates in the range from hundreds kilohertz to several megahertz. Gigantic pulses with duration down to ~1 ns and peak power estimated to be above ~1 kW were recorded from the far fiber end. Smaller pulses with duration down to ~50 ns were observed from the pumping side of the fiber. Using a digital oscilloscope we investigated the fine structures of the pulses and determined some consistent patterns of their mutual dynamics. The RF spectrum measurements highlighted the stimulated Brillouin scattering that is suspected to be a main dynamical mechanism initiating pulsations. We observed also other different nonlinear effects caused by propagation of the intensive pulses through the fiber. Corresponding optical spectra were recorded and interpreted. Reported experimental data indicate that Rayleigh, Brillouin and Raman scatterings are all involved in the process of gigantic pulse generation in the fiber.

We report new class of steady-state periodic solutions of the nonlinear Schroedinger equation perturbed by the cubic dispersion term and present their basic properties including the existence areas. Possibility of formation of periodic pulse trains with high contrast and high repetition rates in the spectral region close to the point of zero group-velocity dispersion is demonstrated.

We report the results of analytical and numerical studies of the reflection of N -soliton bound states at the interface formed by a Kerr nonlinear medium and a linear dielectric. A variety of effects are shown to occur, including bistability and soliton filtering, with applications to all-optical soliton switching concepts.

We report theoretically the existence, classification and basic properties of families of stationary two-dimensional cnoidal-type waves in bulk Kerr-type saturable nonlinear media. This is the first known example of families of two-dimensional cnoidal-type wave solutions, which in addition are shown to exhibit richer features than their known one-dimensional counterparts. At low and high energy flows the cnoidal patterns are predicted to be robust enough to be observable experimentally.

The results of studying the steady states for bright picosecond dissipative optical solitons, appearing in single-mode semiconductor laser waveguides structured in a direction of passing those pulses, is presented. This type of solitons occurs due to reshaping the incoming optical pulses via the passive mode-locking process in traveling-wave regime. The relations between the pulse parameters and the waveguide's properties are chosen in such a way that the mode-locking process is incoherent in behavior that leads to the phase decay of the incoming pulses. The analysis performed demonstrates that bright optical solitons can be supported by the waveguides with slowly saturable gain and fast relaxing saturable absorption.

The approximate analysis performed shows that in spite of a non-Hamiltonian character of the perturbation, associated with the intrapulse Raman scattering, the optical solitons in their conventional understanding are able to exist in Kerr media with weakly illocal nonlinear response. A pair of the bright background-free solitons with asymmetrical shapes of envelopes has been revealed in the anomalous dispersion regime. In the normal dispersion regime, the effect of the intrapulse Raman scattering leads to shaping even a triplet of the bright and flashing solitons on a background.

Nonlinear optical wave packets with the second Painleve transcendent shape of envelope are revealed in Kerr media, manifesting weakly focusing cubic nonlinearity, square-law dispersion, and linear losses. When the state of nonlinear optical transmission is realized, two possible types of boundary conditions turn out to be satisfied for these wave packets. The propagation of initially unchirped optical wave packets under consideration could be supported by lossless medium in both normal and anomalous dispersion regimes. At the same time initially chirped optical waves with the second Painleve transcendent shape in low-loss medium and need matching the magnitude of optical losses by the dispersion and nonlinear properties of that medium.

We present the results of our investigation on the spectral dynamics of dissipative solitons in passive mode-locked lasers with non-instantaneous saturable absorbers. Mechanisms for temporal periodically repeated drift of carrier frequency and for chaotic temporal changes in spectrum of ultrashort pulses have been established. These results are applicable to communication fiber lines with non-instantaneous saturable absorbers.

We demonstrate all-optical label encoding and updating for an orthogonally labeled signal in combined IM/FSK modulation format utilizing semiconductor lasers, semiconductor optical amplifiers and electro-absorption modulators. Complete functionality of a network node including two-hop transmission and all-optical label swapping is also experimentally demonstrated with overall penalty of less than 2 dB, proving the orthogonal IM/FSK labeling scheme to be a feasible solution for future optically labeled networks.

An increase in the data-carrying abilities of modern communication systems is the most important scientific and technical challenge, requiring further studies of the physical effects involved. The possibility to increase in the data-carrying abilities of optical communication systems by waveguide modes (both longitude and transverse) multiplexing by diffractive optical elements (DOEs) is considered.

Integrated optical unit operating as a selective mode launcher/detector matched with a multimode fiber is described. The unit is capable to perform an independent launch of fiber modes of different orders, and each excited mode represents an independent informational channel. Hence total informational capacity of fiber system can be increased by several times. The key element of the launcher/detector is full planar selective mode coupler. The fabricated experimental samples of the developed selective coupler demonstrate a serviceability of the device.

New type of gain equalization filter for WDM systems is proposed. It is based on the employment of nonlinear Fabry-Perot interferometer as a pump controlled mask in the layout of Fourier-synthesis of short optical pulses. Results of numerical simulation show that the flat gain spectrum of EDFA can be achieved over the whole C-band in the equalization scheme proposed at moderate pumping power and small additional losses.

For the first time the multi-gratings holographic recording has been obtained in novel class of liquid crystals namely in ionic lyotropic metal-organic smectics formed on the base of metal alkanoates. It was shown that alkali metal alkanoates form smectic structures. They self-organized in hydrophobic bi-layers of alkanoate chaines with electrostatic conductive layers. The gratings are recorded by the action of pulsed laser radiation both picosecond and nanosecond duration from double frequency Nd-YAG laser. The multi-gratings formation can be connected with the recording process in micro-domains of smectic matrix.