Properties of the polymer-filled nanoporous glass (PFNPG) doped with different family dyes are reviewed in this paper. They include mechanical, optical, and thermo-optical properties of PFNPG as a host material for lasing and nonlinear absorbing dyes. Data on lasing and nonlinear absorption characteristics of dye-doped PFNPG are presented. From an analysis of these characteristics it is concluded that PFNPG is a new optical material perspective for creation of highly efficient solid-state dye lasers and laser radiation control elements including Q-switchers, mode selectors, and laser radiation power limiters.

Frequency doubling in a 4-mirror Z-type cavity with BBO crystal and a large-bore argon discharge tube has been simulated and tested experimentally. Power of the second harmonic as dependent of the position of focusing mirror and crystal, fundamental laser power is measured. The measured dependences satisfactory agree with the calculated ones. Cavity optimization results in achievement of ~1 W output power at 244 nm.

PbS-quantum dot-doped glasses have been demonstrated as saturable absorber Q-switches for 2-pm holmium lasers. Q-switched pulses of 50 ns in duration, 2.4 mJ in energy from a Cr,Tm,Ho:Y₃Sc₂A₁₃0₁₂ laser at 2092 nm and Q-switched pulses with 70 ns in duration, 4.5 mJ in energy from a Cr,Tm,Ho:Y₃A₁₅0₁₂ laser at 2097 nm are obtained.

Q-switched operation of a novel transversely-diode-pumped bulk 1.65μm Er:Yb:YAG laser is demonstrated using a piezoelectric "FTIR" type of Q-switch. Typical output pulses of approximately 12mJ energy and 4011s duration have been obtained, suitable for telemetry and other applications. The material is transversely pumped using quasi-cw 960-nm laser-diode arrays. In Q-switched mode, lasing threshold lies in the range of 0.5-1.4J, depending on pumping conditions and output coupling, while optical slope efficiencies in the order of 1% were measured with respect to the incident pump energy. The reported system represents a rare-earth crystalline laser with superior active material and optical qualities, to challenge the established glass-host materials in the 1.6μm eyesafe wavelength region.

Transverse beam dynamics in photonic crystal fibre laser is studied numerically. The field decomposition in terms of Laguerre-Gaussian functions is used for simulations. The few-mode photonic crystal fibre laser is considered. Symmetry breakdown due to the competition of transverse modes is demonstrated. In the photonic crystal fibre with broad gain region the resulting beam structure is shown to depend strongly upon the initial conditions.

The influence of high-energy (2 1MeV) electrons irradiation on spectroscopic properties of both undoped and chromium doped forsterite (Mg₂Si0₄) crystals, as well as the corresponding extent of radiation-resistance of the crystals has been studied for the first time. It was found that such kind of irradiation results in formation of the induced additional absorption (AA) in both undoped and chromium-doped crystals, independently of crystal growth atmosphere. This AA is broad, structureless band in the range 300-1 100 nm with flat maximum at -450nm. Simultaneously the strong AA in UV part of spectrum appears. The shape of the band with maximum at 450 nm is practically the same for e-irradiated and previously studied y-irradiated forsterite crystals. It is also insensitive to Cr³⁺/Cr⁴⁺ ratio in crystals, as well as to additional codoping of crystals by Li⁺-ions. On the contrary to the shape, the intensity of the AA substantially depends on all above mentioned factors. Meanwhile, the irradiation had not led to change of the ratio of concentrations Cr⁴⁺:Cr³⁺:C²⁺. Thus, like in other oxide crystals observed induced absorption in the visible spectral range is caused, apparently, by point defects formation in the host. Possibly, these defects are hole 0 centers (ionized oxygen). The AA in UV belongs, apparently, to metal-to-ligand (oxygen ion) change transition.

A study of the Relative Intensity Noise (RIN) of an optically injected semiconductor laser is presented versus the injected power. The seeded laser is then operating from an amplifying regime towards a locking one, at the same wavelength than that of the master one. It is shown that when the Master is more coherent than the slave, a reduction of the RIN of the slave is progressively observed along with an increase of the injected power. In the converse case, no significant modification of the RIN is experimentally observed.

Efficient lasing of Fe:ZnSe was demonstrated with a 2.94 pm Er:YAG pump laser. Output energy of 130 mJ, an absorbed energy slope efficiency of 44% and continuous tunability from 3.8 to 4.4 pm at 85 K were obtained. Laser efficiencies were determined for temperatures ranging from 85 to 253 K.

We develop and investigate InGaAs/GaAs/InGaP-based heterolasers with asymmetrically grown quantum wells of two types which are capable of dual-wavelength operation and second-harmonic generation at room temperature over a wide range of injection currents: from 0.2 A in CW mode up to 10 A in injection with 200-ns-long pulses. Previously unknown special features of such a dual-wavelength generation are experimentally revealed and interpreted in terms of the competition and coexistence of short- and long-wavelength TE modes, including the "whispering-gallery" modes.

A numerical model of rate equations for a four level solid state laser with Cr⁴⁺:YAG Saturable absorber including excited state absorption ESA is presented. Simultaneous mode-locked and Q-switched pulses are obtained by the solution of this model. The pulse width is estimated to be 100 ps.

The results of experimental investigations of different regimes of laser diode oscillation at active mode-locking are presented. The regimes at which the minimum beat spectrum width (-3.5 kHz) is achieved were observed. Investigations of the dependence of the optical mode spectrum on different work regimes and feedback factors were carried out. The maximum width of the optical spectrum was 3.7 THz, which corresponds to a pulse width of 0.3 psec. The results of investigations of intermode frequency stability are presented.

An estimation of conditions of regime of lasing self-oscillations arising in cw-pumped injection laser due to light field spectrum linewidth broadening is carried out at assumption of the sub-micrometer planar nonlinear film presence in the laser cavity.

The present work presents the study of an ultrashort pulse high quality laser source. This source is based on Gain Switching diode lasers and pulse compression schemes. Gain switching is one of the most interesting methods used to obtain short pulses from diode laser. This technique is easy to implement, cheap and does not require any specific fabrication. It also offers repetition rate tunability. Pulse compression is also studied as a means of shortening and improving the shape and quality of the pulses obtained from Gain Switching sources. Several compression techniques are evaluated. Linear pulse compression phenomenon is studied, as well as compression devices based on nonlinear optical pulse propagation. A comparative study of these compressors is performed in order to develop a monolithic source based on InP semiconductor technology.

Highly transparent Nd- or (Nd,Yb)-doped Sc₂0₃ ceramics are produced by the method of solid-state mixing of oxides. High-resolution spectroscopy indicates the spectroscopic and structural properties of the doping ions in these ceramics are similar with those of single crystals, although the maximum doping could be much higher. Very efficient Nd-to-Yb energy transfer is observed, which can be used for sensitisation of Yb laser emission.

The high resolution and polarized spectroscopic investigation of Nd³⁺ in Mg-compensated strontium lanthanum aluminate Sr_l-xLa_x-yNd_yMg_xAl_12-x0₁₉ (Nd: ASL) function on composition makes possible the elucidation of the nature of non- equivalent centers and enables the selection of composition and pumping conditions that grant the efficient quasi-three-level laser emission around 900 nm. Based on a proper selection of these conditions, 900 nm laser emission with slope efficiencies of 0.74 and 0.84 at 792 nm ⁴F_5/2 and respectively 865 nm ⁴F_3/2 pumping of Nd³⁺ is demonstrated.

For the purpose of creation of a source of stimulated UV radiation investigations of UV radiation of powders and disordered films of zinc oxide manufactured by different methods were conducted. The samples were pumped by the 3rd harmonics of two-stage Nd: YAG-laser with pulse duration -10 ns. Maximum density of energy of pumping pulses was about 480 mJ/cm². Spectra of spontaneous emission were registered at 300 and 77K. With some of our powdered samples we achieved lasing at 300K. The threshold values of pumping energy density occurred to be higher than that under picosecond pumping for more than two orders of magnitude. Peculiarities of different samples lasing are demonstrated and discussed. Unfortunately we did not yet achieve lasing in the samples of disordered films investigated.

We present experimental diode-pumped Yb:GdCOB laser performance using gain elements with a range of Yb-doping levels and thicknesses to optimize broadband amplification around 1053 nm.

New Yb:YVO₄ and Yb:Gd_xY_1-xVO₄ (x=0.6) laser crystals were grown by the Czochralski methods. The experimental spectroscopic properties of trivalent ytterbium ions in tetragonal vanadates have been performed. Polarized absorption and fluorescence spectra were investigated and stimulated emission cross sections were estimated for both crystals at room (RT) and liquid nitrogen (LN) temperatures. On the absorption and fluorescence data, excited states lifetimes the energy of electronic levels of ytterbium in crystalline hosts were calculated and the lasing parameters of broadband transitions of doped ions were studied. The investigation shows these crystals are perspective for femtosecond pulses generation in NIR region near 1000 nm under laser diode pumping.

In this work the opportunity of realization of laser action on vibronic transitions of Cr³⁺ ions in new crystal - hexaaluminate of beryllium-lanthanum (BeLaAl₁₁0₁₉:Cr) is investigated. The thermodynamic and physical parameters of host crystal were studied. The experimental spectroscopic and relaxation properties of Cr³⁺ ions have been performed. Absorption and fluorescence spectra are characteristic for octahedral coordinated trivalent ions. The emission cross-section of broadband ⁴T₂-⁴A₂ transition is determined (~2•1O^-20CM²). In configuration curves model the basic features of fluorescence and perspective of lasing in the 700-1000 nm range are considered. The new laser crystals BeLaAl₁₁O₁₉:Nd were grown by the Czochralski methods. This material has broad absorption bands at 580, 740 and 790 nm, the latest can be used for LD pumping. The broadest emission lines at 1050 and 1080 nm are perspective for ultrashort laser pulses generation. The intensity parameters, spontaneous emission probabilities, the inter-manifold branching ratios and fluorescent lifetime have been calculated by means of Judd-Ofelt theory and compared with the experiment. The CW generation was realized under Ar-laser pump and laser properties were investigated. The investigation shows that the BeLaAl₁₁O₁₉ is a promising host for a creature the new solid state laser media.

The lowest pumping threshold of 0,3 W for the LiF:F²_- laser has been achieved. The parameters of the Lyot filter used for tuning the LiF:F₂^- laser have been calculated using the analytical method developed by authors in which the optic path difference in air between incident rays from which the extraordinary and ordinary rays are split off and also the extraordinary ray declining from the incidence plane are taken into consideration.

Mathematical modelling is used to study laser emission in an Er(0.5 at.%):YAG active medium on the transition ⁴S_3/2 → ⁴1_15/2 for various pump wavelengths. The emission regimes corresponding to each pump wavelength are investigated. For upconversion pumping, we find an optimum pump wavelength and optimum conditions for lowering of the emission threshold.

Continuous wave and Q-switched diode-pumped laser operation of Yb³⁺ :NaLa(MoO₄)₂ single crystal was demonstrated for the first time to our knowledge. A cw output power of 220 mW and slope efficiency of 46% were obtained. Q-switched laser operation was achieved with pulse duration of 60 ns. An average output power and slope efficiency were 70 mW and 22% respectively.

Here spectral-kinetic properties of Ce³⁺ ions and UV pumping induced color centers in KY₃F_I0 (KYF) crystals are reported and discussed. The efficiency of crystal-chemical approach of UV pumping induced solarization processes inhibition in these crystals was shown. Laser oscillation was achieved on the Ce:KYF crystals which were considered earlier as unpromising as active medium due to its photochemical instability.

Excitation of the active media of lasers by the induction of a magnetic field is proposed. Possibilities of creation of various gas and solid-state inductive lasers in a range of a spectrum from IR up to D W area are analyzed. For the first time inductive lasers on the He, N₂, He:F₂, He:Xe:F₂, He:Xe:HCl are created and parameters of pumping and emission are described.

A vortex kinoform mode converter which transforms a zero order Hermite-Gaussian laser mode to first order Laguerre-Gaussian mode with screw phase dislocation has been demonstrated. The kinoform element imitating mathematical helicoid surface has been fabricated in fused silica substrate with using wet chemical etching. Conversion efficiency >90% for high power laser beams has been achieved in testing experiments.

Saturable absorbers on the base of lead sulfide QDs for lasers emitting at 1, 1.3, 1.5, 2.1 microns are introduced and characterized. It is demonstrated that these SAs can be used both for mode-locking and Q-switching of near IR lasers.

We demonstrate that insertion of a simple diffractive optical element in the cavity of a self-Q-switched Cr³⁺ : LiSAF laser can speed up its dynamics so that the laser output pulse is shortened and its energy is increased.

Design of a high-power femtosecond laser system based on hybrid chirped pulse amplification (CPA) technique developed by us is presented. The goal of the hybrid principle is the use of the parametric and laser amplification methods in chirped pulse amplifiers. It makes it possible to amplify the low-cycle pulses with a duration of ≤ fs to terawatt power with a high contrast and high conversion efficiency of the pump radiation. In a created system the Ti:Sapphire laser with 10 fs pulses at 810 nm and output energy about 1-3 nJ will be used like seed source. The oscillator pulses were stretched to duration of about 500 ps by an all-reflective grating stretcher. Then the stretched pulses are injected into a nondegenerate noncollinear optical parametric amplifier (NOPA) on the two BBO crystals. After amplification in NOPA the residual pump was used in a bow-tie four pass amplifier with hybrid active medium (based on Al₂0₃:Ti³⁺ and BeAl₂O₄:Ti³⁺ crystals). The final stage of the amplification system consists of two channels, namely NIR (820 nm) and short-VIS (410 nm). Numerical simulation has shown that the terawatt level of output power can be achieved also in a short-VIS channel at the pumping of the double-crystal BBO NOPA by the radiation of the fourth harmonic of the Nd:YAG laser at 266 nm. Experimentally parametric amplification in BBO crystals of 30-50 fs pulses were investigated and optimized using SPIDER technique and single-shot autocomelator for the realization of shortest duration 40 fs.

We discuss basic concepts of the frequency-shifted feedback (FSF) laser and of our approach to modeling the physics of this device. Such apparatus offers potential for measuring incremental heights of surfaces with micrometer accuracy over meter or kilometer distances. We present experimental results, obtained using a Yb³⁺ fiber ring laser, that demonstrate the usefulness of such a device.

Spiral beams while propagating and focusing, keep their intensity structure unchanged neglecting scale and rotation. One of the experimental ways to obtain spiral beams is the astigmatic transformation method. It allows producing spiral beams by means of structurally one-dimensional amplitude-phase elements and simple cylindrical optics. The paper is dedicated to modeling of spiral light fields formed with one-dimensional spatial light modulators. The effect of the ultimate resolution of the modulator and ultimate accuracy of the intensity and phase choice on the quality of the synthesized field in a far-zone of diffraction has been estimated in this work. The results can be of interest for various laser applications including the laser manipulation with micro-objects.

A polymer-filled nanoporous glass composite (PFNPG) has been shown recently to be a very attractive host material for solid-state dye lasers. In particular, a high-conversion (lasing) efficiency, up to 70%, has been demonstrated for pyrromethene-family dyes impregnated to PFNPG, in a visible spectral range at 2-nd harmonic nanosecond pulse duration Nd:YAG laser excitation. For development of PFNPG-based dye lasers it is important to investigate lasing characteristics of this type matrices at various excitation (pump) wavelengths. In this context we have investigated the conversion efficiency, η, and emission spectra, f_em, of phenolemine 512 (Ph 512) and pyromethene 580 (PM 580) dyes impregnated into PFNPG, at excitation wavelengths, λ_p, varied in a range of their main absorption bands. A microsecond pulse duration liquid solution dye laser was used in our experiments as a pump source. The conversion efficiency, η=32% and 47%, has been observed at λ=525 nm for Ph 512 and PM 580 respectively with output energy as high as 250 mJ. "Anomalous" dependencies of η and f_em upon λ_p have been revealed for both dyes. In particular, two-frequency lasing has been observed for Ph 5 12 at λ=535 nm. Mechanism of the lasing anomalies is supposed to be related to photoinduced absorption in lasing dyes.

The original excitation system of electro-discharge laser is considered. The excitation system represents the LC-invertor on basis of artificial storage lines. Results of computer calculation of excitation system working characteristics are discussed. An advantage of this system is the possibility of time dependence control of energy input in discharge. These results are compared with experimental data.

Simplified method of eigenmodes simulation in random media based on numerical solution of the stationary wave equation for two-dimensional (2D) medium with a random distribution of dielectric permittivity is suggested. By means of discretization the wave equation can be reduced to the system of homogeneous linear equations that includes parameter α=(2πb/λ)², where b is the spacing between the nodes of discretization, λ - the wavelength. The values of a (and corresponding b/λ) for every mode were determined from condition of zero value of the system determinant. The relative field amplitudes in all discretization nodes were calculated with this a. 2D random medium was simulated by matrix whose elements randomly take on two different values. One of them corresponds to dielectric permittivity of the material particles, the other - to permittivity of the spacings between them. Under the assumption made, elements of such matrix represent material particles and spacings between them correspondingly, quantity b - particles size. All calculations were made using MATLAB. Different variants of disordered (and ordered) media were examined. It was shown that localized modes exist only in disordered systems with sufficiently large filling ratio and in a limited range of ratio b/λ .

The small signal intensity modulation (IM) of a hybrid soliton pulse source (HSPS) utilizing Gaussian apodized fiber Bragg grating is described using electric field approach. The HSPS is modeled by a time-domain solution of the coupled-mode equations. It is shown that type of external cavity is important effect on resonance peak spectral splitting (RPSS) in IM response as well as effect of laser and fiber Bragg grating (FBG) parameters. The RPSS can be suppressed by using linearly chirped Gaussian apodized FBG as an external cavity insted of Gaussian apodized FBG.

In the report questions of influence of broadbandness and structure of a spectrum of pumping radiation on optical parametric oscillator efficiency are considered. The results of experiment are in accordance with conclusions of the theoretical analysis and estimations.

The analytical expressions for the changes of the coherence degree and the thickness of the coherence layers while propagation of the dispersed light beams are obtained. It is established, that the larger the angle between the coherence layers and the phase fronts the faster the deterioration of the spatial coherence with a distance occurs. The comparison with a case of the nondispersed beams is made. It is shown, that the decrease of the coherence degree while the beam propagation is accompanied by the rise of its spatial fluctuations. The change of mutual correlation of two dispersed beams with the parallel correlated coherence layers is investigated.