Transmission measurements of Q-switched Er:YAG laser radiation, through cyclic olefin polymer-coated silver hollow glass waveguides, were performed under straight and bent conditions and the beam quality at the output of the waveguide was studied.

Operational characteristics of highly integrated picrosecond Nd:glass laser system are presented. The laser harmonic generation involves novel frequency conversion techniques, enabling powerful femtosecond pulse generation with picosecond laser output. High contrast widely tunable pulses are generated in picosecond and femtosecond regimes by traveling wave optical parametric generator/amplifier.

In order to compensate for the thermally induced lenses in high-power laser rods we investigate self-adaptive techniques based on thermo-optical processes. Recently we have demonstrated that the influence of the thermal lenses in high-power lasers can be reduced significantly by means of thin layers of either liquids or gels. After a short review of the past developments we discuss the limits of lasers with intra-cavity thermo-optically self-compensated amplifiers (TOSCA). It is shown that for Nd:YAG typically one compensating layer is needed for every 6 cm of rod length.

We report the experimentally measured polarized small signal gain for Ce:LiLuF at 309 nm and 327 nm. The gain was found to be anisotropic and temperature dependent. Using a rate equation based model we have simulated the affect of excited state absorption (ESA) on the small signal gain in Ce:LiLuF. As a result we report the polarized emission and ESA cross-sections for Ce:LiLuF at 309 nm and 327 nm. We show the ESA to be temperature dependent and consequently demonstrate that ESA is the cause of the change in small signal gain with temperature in Ce:LiLuF. Further, we experimentally show the decrease, with temperature, of the ESA cross-sections at 309 nm causes a 70% increase in the laser output at 309 nm. We demonstrate how the introduction of a σ-biased loss into the cavity suppresses σ-polarized lasing at 327 nm. This counteracts the decrease in laser output below ~10°C caused by the anisotopic nature and temperature dependence of the ESA in Ce:LiLuF at 327 nm.

We report on the use of a compact Er-Yb:glass laser Q-switched by an AOM for seeding two-stage optical parametric amplifier realized in a single PPKTP crystal. We have generated 5 ns long pusles with a pulse energy exceeding 0.5 mJ. The parametric signal generation efficiency in the second amplification stage was 27%, while the pump depletion reached 39%. The two-stage OPA peak power gain was 30.1 dB for the seeding peak powers of 100W, while the gain reached 81 dB for the lowest seed peak powers of 0.7 mW. The OPA generated a diffraction-limited signal beam while maintaining the original spectral width of the seen.

Operation of Cr:LiSAF laser pumped by 670 nm high brightness single stripe (width of 50 μm) laser diode with pump-threshold as low as 650 μw is reported. The lasing threshold was observed simultaneously with threshold of operation of laser diode. For short pulse generation we designed and tested different multiple quantum well saturable absorbers. The continuous mode-locked operation was achieved with tunability from 846 to 875 nm.

Cr²⁺-doped chalcogenide crystals have shown to be efficient and broad band tunable solid state lasers for the infrared spectral range between 2μm and 3μm. Pulsed, continuous wave, mode-locked and diode pumped laser operation have been demonstrated in the recent years. Possible application of these mid-infrared lasers include scientific research, remote sensing, trace gas analysis, medicine, biology, materials processing, and ultrashort pulse generation. An overview about the research in the field of lasers based on the tetrahedrally coordinated Cr²⁺ as active ion will be given. Recent results on the laser characteristics in different host materials will be presented.

Diode-pumped 1.3μm Nd:YVO₄ and Nd:KGd(WO₄)₂ lasers passively Q-switched with the PbS- and PbSe-doped phosphate glasses were demonstrated. Pulses of 110 ns in duration for both types of materials and average output power of 23 mW from Nd:YVO₄ laser were obtained. Absorption recovery time of the PbS-doped glass was measured to be 27±4 ps. Numerical simulations of lasers operation were presented and analysis for more efficient use of PbS- and PbSe-doped glasses as passive shutters for diode-pumped lasers was made.

We discuss the latest achievement on passively mode-locked high-power lasers, delivering tens of watts of average power in sub-picosecond pulses. The most promising concept is that of the passively mode-locked thin disk Yb:YAG laser which can so far generate up to 50 W of average power in sub-picosecond pulses.

The new laser crystals BeAl₆O₁₀:Cr³⁺ were grown, spectral-luminescence and CW laser properties were investigated and compared with those of well-known laser medium-alexandrite (BeAl₂O₄:Cr³⁺). CW laser generation on vibronic transition ⁴T₂-⁴A₂ of Cr³⁺ ions in BeAl₆O₁₀ crystals was realized in the range of 800-880 nm under Ar⁺ laser pumping. The emission cross-section of laser transition was estimated about 6×10^-20 cm². We confirmed these crystals are perspective for generation of femtosecond pulses in the near IR region under LD pumping.

Femtosecond pulse generation in Al₂O₃:Ti³⁺ laser with some types of laser cavity configuration with semiconductor saturable absorber mirror (SESAM), based on semiconductor quantum well low temperature (LT) GaAs/AlAs, Ga_xIn_1-xAs/Al_yGa_1-yAs saturated absorbers and metal mirrors have been investigated.

The technique of operating picosecond modelocked laser systems quasi-CW is presented. Higher modelocked output power results at the expense of reduced effective pulse repetition rate. Passively modelocked quasi-CW lasers at 1.0 and 1.3 μm with high 'on-time' powers (~65W) are described. Active stabilization of these systems is demonstrated via negative feedback using an intracavity loss modulator. Stabilization suppresses relaxation-oscillation driven spiking on reaching threshold and prevents Q-switching of the laser caused by the presence of a saturable absorber for modelocking. In this way, the usable parameter range of a saturable absorber for stable CW modelocking is extended such that stable Q-switch free modelocking of a quasi-CW laser with pulse repetition rates over 900MHz, is possible. Numerical modeling confirms the flexible nature of stabilization via negative feedback applied to unstable laser systems incorporating saturable absorbers.

Raman lasers on barium nitrate crystal pumped with the radiation of nanosecond LiF:F₂ laser and its second harmonic have been developed and optimized. As a result, using simple and cheap all-solid-state laser technique the continuously tunable radiation of the first, second, and third Stokes components of stimulated Raman scattering of LiF laser radiation with maximum conversion efficiencies of about 35, 28, and 10%, respectively, was obtained in the spectral range between 1240 and 1800 nm. Using the second harmonic radiation for pumping barium nitrate allowed us to generate the continuously tunable radiation of its first and second Stokes components in 594-682 nm range with maximum conversion efficiencies of approximately 40-45 and 10-15%, respectively.

Growth and annealing technology for Cr⁴⁺-doped garnets is developed. We show the influence of preparation technology for Cr⁴⁺-crystals to operation characteristics as passive Q-switches of Nd-lasers.

We present an analysis of the performance of backward-pumped discrete Raman amplifier modules designed for simultaneous amplification and dispersion and/or dispersion slope compensation, both in single-channel and in multi-channel systems. Optimal module parameters are determined within a realistic range of pump and signal powers.

Passive Q-switching in fiber lasers can be caused by cooperative dynamics of linear Rayleigh backscattering (RS) and Stimulated Brillouin Scattering (SBS) in a fiber configuration. We give a clear physical insight into the RS-SBS mechanism and present new experiments with low- and high-power self-Q-switched fiber lasers. A 15-ns self-stating periodic pulse generation with a peak power up to 40-300 W has been investigated with an Er-doped fiber laser pumped at 20-160 mW from a laser diode. The generation of Q-switched pulses occurs with a perfect pulse shape performance without emitting any parasitic pulse. We have also realized a self Q-switched double-clad Yb-doped fiber laser. For this laser an average/peak power as high as 1.4 W/5 kW has been achieved at a pulse repetition rate in a range of 5-50 kHz and a pulse duration of 5-10 ns.

Signal-to-noise for a coherent laser source and a mixture of a laser source with a narrow band amplified spontaneous emission source are directly measured using a digital sampling oscilloscope. The measurement for a coherent source is found unreliable due to the low level of shot-noise compared to the thermal noise. On the other hand, the measurement for a mixed source is found in good agreement with theoretical predictions within 1dB error.

We have demonstrated a Tm-Ho-codoped silica fiber laser pumepd by a third-stokes Raman Fiber Laser (RFL) at 1212 nm. RFL consists of Yb-double clad fiber laser (DCFL) as a pump, 1-km Single mode fiber (SMF) and cascated cavities made with fiber Bragg gratings (FBG). For the 30-cm-long Tm-Ho-codoped silica fiber, the output power of 400 mW is obtained at wavelength of 1790 nm (due to the laser radiations of Tm³⁺ ions). The optical-optical conversion efficiency and the slope efficiency are 18% and 23%, respectively. For the 270-cm-long Tm-Ho-codoped silica fiber, the output power of 450 mW is obtained at 1970 nm; this is the laser emission from Ho³⁺ ions. The optical efficiency is 18% and the slope efficiency is measured to be 31%. This is the highest output power ever reported for a Tm-Ho-codoped silica fiber laser.

A comparison between phase characteristics of the laser multimode beam and random light fields is carried out theoretically. It is shown that probability density of phase distribution has considerable distinctions. The peculiarities of the wavefront dislocation structure in investigating fields are considered.

Theoretical propositions of powerful technological CO₂ laser operation with selection and correction of phase of high order cross models have been experimentally studied. The effective transformation with the help of phase corrector of the high order mode oscillations field to the narrow directed beam at the level of output power up to 1kW is reported for the first time. The physical nature of intra-cavity aberrations with negative influence on the beam quality is analyzed. It is shown that the most significant aberrations such as optical wedge arise when we use the cross pumping of active medium and the cross discharge. The prospect of the considered method application to obtain narrow directed radiation is considered at higher power values.

Preliminary investigations into the potential for automatic spatial-mode optimization in tehrmally distorted soild-sate lasers using deformable mirrors are presented. A 37 element adaptive optic mirror has been used intracavity to control the oscillation mode profile of a diode-laser pumped Nd:YVO4 laser. Spatial mode and output power optimization are demonstrated by closed loop computer control of the deformable mirror using a modified hill-climbing algorithm.

A non-steady-state theoretical and mathematical model and a complex of computer codes have been developed for modeling a high-power double-pass explosively pumped photo-dissociation iodine laser (EPDL) with phase conjunction (PC) at SBS. The model and the complex of codes taking into account 3D of space consist of two blocks. The first block is devoted to detailed modeling of the SBS mirror consisting of an angular selector of Stokes radiation, an ordered raster of small diffraction lenses, a main focusing lens, and a SBS cell. The second block describes the dynamics of radiation in the laser system as a whole with using SBS mirror parameters calculated in the first block. The model takes into account parasitic reflections of laser radiation from the elements of the optical scheme, intrinsic amplified spontaneous emission of the amplifiers, radiation losses in the optical path, non-uniformity of gain, and radiation refraction on optical non-uniformaties of gain, and radiation refraction on optical non-uniformities of the active medium caused by a shock wave. As a result of calculations an optimal configuration of the SBS mirror has been determined, possessing unique properties if compared to the existing specimens of the SBS mirrors. It stably gives a nearly ideal quality of PC at any level of SBS saturation, i.e. any reflection coefficient that is confirmed by experimental laboratory investigations. Modeling of the laser system as a whole at working mixture 25 Torr C₃F₇I+125 Torr Xe and amplifier aperture 15 cm has been shown a good agreement of calculated results with available experimental data in energy, time dependence of power and Strehl number of output radiation. The considered EPDL has output energy of about 400 J and brightness of about 10¹² J/ster. It is shown that parasitic reflections of laser radiation from the ends of amplifiers and elements of the optical scheme with a coefficient exceeding 10^-7 considerably decrease the brightness of EPDL.

The Laguerre-Gaussian (LG) beam is an optical beam with a phase singularity that propagates along its axis. We have studied the effect of astigmatnic aberration on LG beams through numerical simulation and experiment. An LG beam with astigmatic aberration can undergo various transformations. An LG beam with astigmatic aberration can be expanded in terms of Hermite-Gaussian (HG) beams whose horizontal and vertical axes are aligned with the axes of the astigmatism. By redefining the expansion coefficients to include the Gouy phase of the HG beams, the coefficients can be reduced to a single parameter that depends on the propagation distance. It can be shown that the various transformations of the LG beam is governed by this parameter. This presents us with a simple method of estimation the beam profile and positions of the split phase singularities at any given propagation distance. The estimations show good agreement with intensity and phase distributions calculated with the angular spectrum method.

We have implemented on one beam of the LULI six-beam high-energy (6×100 J, 1 ns) Nd:glass laser facility a closed-loop Adaptive Optics (AO) system to compensate for thermal distortions onto the wave front. Using the AO system composed of a dielectric coated deformable mirror and of a wave front sensor, we are able to improve the wave front quality in order to obtain a focal spot close to the diffraction limit. This allows not only to improve the reproducibility of the experiments but also to increase by at least two orders of magnitude the peak intensity as compared with what usual laser smoothing techniques can achieve.

We have implemented on the LULI 100 TW laser facility a closed-loop Adaptive Optics system composed of a large aperature dielectric coated deformable mirror and a home-made shearing interferometer. Significant results have been obtained with this system: not only the beam focusability has been improved to a Strehl ratio of 0.9 but it has also been kept at this level for a sequence full-energy shots, with a repetition rate of 20 minutes, through systematic compensation of the cumulative thermal load generated in the large disk amplifiers.

For the first time, experimental samples of adaptive liquid-crystal lenses that require no additional lighting for wave front shaping by the wave's intensity variation are presented. Both spherical and cylindrical lenses are fabricated and investigated.

High thermal conductivity intra-cavity crystalline heatspreaders are used to control the pump-induced temperature increase limiting the power scaling of vertical external-cavity surface-emitting lasers (VECSELs). Pump-power-limited output of greater than 0.4 W was achieved from a GaAs-based VECSEL at room temperature with the use of a silicon carbide heatspreader bonded to the surface of the gain element and 0.5 W by water-cooling the system to 7.5°C.

Abnormal modulation characteristics of a DBR-type dual-frequency laser diode will be reported. Applying strong but relatively low frequency (less than 3.5GHz) microwaves on a dual-frequency LD, average output power of the short-wavelength oscillation of the LD was enhanced, and the long-wavelength oscillation line was suppressed. With increasing microwave injection frequency up to 4GHz, the situation was reversed; namely the short-wavelength oscillation was suppressed and the long-wavelength oscillation was enhanced. Much higher frequency (over 4.5GHz), the situation was reverted to the low-frequency area.

Laser and optical properties of InGaN/GaN multiple quantum well heterostructures were investigated as functions of temperature (T=80-450 K) and excitation intensity (I_exc=10-1100 kW/cm²) of the N₂ laser radiation. Laser action was achieved in all types of the MQWs from the violet up to the blue spectral region (λ_las=405-470 nm). The laser threshold at room temperature was 35-100 kW/cm² and 70-150 kW/cm² for the 'violet' and 'blue' lasers, correspondingly. The characteristic temperature in the temperature range of 80-220 K was T₀=180 K for the 'violet' and T₀=530 K for the 'blue' lasers. The T₀ was lower for all types of lasers at T>250 K. It was shown that the overheating of the active region under high excitation intensities can reach 40-100 K and it is due to inherent laser radiation.

The spectra of the optically pumped ZnMgSSe/ZnSe multiple quantum well separate confinement heterostructure lasers and the PL spectra of the heterostructures were investigated as functions of temperature (T=80-500 K), excitation intensity (I_exc=0.001-1000 kW/cm²) and number of excitation pulses (N=106). The laser threshold temperature dependence was investigated and explained by alternation of the spontaneous emission efficiency and spectral broadening with temperature rise. It was shown that at room temperature the active region overheating value does not exceed 10 K at high I_exc. It was established that the degradation of the heterostructures under high levels of excitation is due to the inherent laser emission interaction with the heterostructure leading to the appearance of intrinsic defects and to the inherent light stimulated interdiffusion at ZnMgSSe/ZnSe interfaces.

A wide aperture (120 cm²) electron beam generator with peak current density up to several A/cm² based on the small-gap barrier discharge was developed. The stability of generator operation at pressure up to 1 atm was observed. Fast electrons with energy up to 20 keV were produced and injected into neutral gas. The efficiency of electron beam excitation of gas volume and the laser operation at infrared transitions of atomic Xe were investigated.

In the present paper a gas kinetic temperature change of active medium of high-power TEA CO₂ laser that is conditioned by a self-influence of laser radiation on plasma parameters, is investigated. The active medium was pumped by a self-sustained transverse glow discharge. The gas kinetic temperature T_g of plasma has been deduced from the half-width of rotationally unresolved spectral bands of the (2+)N₂. It is shown that the laser radiation propagation through the inverse medium causes a cooling of the active medium. The degree of the gas mixture cooling δTg≈5K at W~2.2 W/2.2 W/cm³ and δTg≈60 K at W~4.4 W/cm³. We suppose that the effect of the active medium cooling is connected with the change of a kinetic of V-T relaxation in asymmetrical mode of the active medium cooling is connected with the change of a kinetic of V-T relaxation in asymmetrical mode of the active medium cooling is connected with with the change of a kinetic of V-T relaxation in asymmetrical mode of vibrationally-excited CO₂ molecule when the lasing takes place in the laser resonator. Analytical estimation of light-induced temperature change δT*_g of fast-flow TEA CO₂-laser active medium are compared with the experimental ones.

The report reviews the results of developments of the perspective excimer lasers which has been carried out in Pulsed Laser System Laboratory at TRINITI. We present parameters of XeCl laser (λ=308 nm) with average power up to 500 W and ArF laser (λ=193 nm) with a pulse repetition rate ≥6 kHz.

An experiment for increasing the relaation rate of the lower laser level in a CuBr-He laser has been carried out by applying a variable axial external magnetic field. A homemade CuBr-He was employed. The effect of an axial external magnetic field on the output power of the laser under different charging voltages and buffer gas pressures has been studied. The results show that the laser output power increases about 400 percent at 0.19 Tesla, 7 Torr of He gas pressure, 10 Kv charging voltage, and 14 KHz repetition rate frequency.

An experomental study of stimulated Raman conversion of high-coherent XeCl laser radiation in H₂ has been carried out. About 50 vibrational-rotational components were realized with a circularly polarized laser beam pump. High spatial and temporal coherence of conversed radiation was obtained. Quantum efficiency of conversion in first vibrational Stokes was achieved 95%.

We demonstrate the use of an Nd:YAG laser to optically pump an HBr gas laser, a concept combining the advanctages of solid-state and gas-laser technologies. A Q-switched Nd:YAG laser, tuned to 1.34 μm and frequency-stabilized, excites the v=3, J=5 state of HBr in a third-overtone transition. A diode laser locked to the HBr transition provides the seed signal for the Nd:YAG laser. Higher efficiencies than previously obtained for similar systems are expected in this concept because of the possibility of cascade lasing, which we have observed in our experiments and predicted in our simulations. Pump pulses of approximately 400-ns duration and 20-mJ energy are directed along the axis of a 1-m containing 15-torr HBr. In the currently unoptimized configuration, approximately 6 laser lines at about 4 μm are observed. The observed laser spectrum suggests collisional pumping for some lines and that intracavity atmospheric CO₂ is a factor. We have developed and used a kinetic model, which shows good agreement with the experimental results. There is evidence of pure rotatioal lasing. Amplifiers are being added to increase the pump energy to 1 J.

Optimization of parameters of the 4-component gas mixture in CO₂ laser is carried out using the method of simplex-lattice planning of experiment. The cubic radiation power model, the cubic small-signal gain model, the cubic power saturation model and the cubic optimum pressure model are obtained. Radiation power for obtained CO₂, N₂, He and Xe optimal concentration is 10% higher than that for the standard (CO₂:N₂:He:Xe=1:1:3+5%).

We offer the simple and clear analytical mode of quasi-steady mode of active media and optimal resonator of CO-laser (COL), giving in an evident form all basic characteristics of COL. This model is similar to known (classical) model of "optimal resonator" for 4th-level media, but with essentially important differences for this new media. In this paper the new definition of unsaturated gain factor and saturation intensity is given. After that the new fundamental dependence of relative gain factor from relative resonator intensity is deduced. This dependence is essentially distinguished from the known Rigrods-formula for 4th-level meida. And at last, the new theory of the optimal resonator of COLis constructed. As the result, very simple and physically transparent dependences of characteristics COL from electrical power and other parameters were received. The model was successfully checked in experiments and showed the high efficiency. The important role of the induced (abnormal) losses in active media, resulting to the essential decrease of COL efficiency in most experiments, is revealed.

Performance of a planar cw CO₂-laser excited by RF waves at two fixed frequencies of 40 and 125 MHz is studied. A laser output power of 100 W and efficiency about 10% have been achieved, and the influence of the excitation frequency has been studied. The hybrid waveguide-unstable optical resonators were used in the planar laser.

A breadboard model of a planar CO₂ laser excited by a wide-aperture microwave discharge of size 2×20×250 mm was elaborated and constructed. Test experiments were carried out with a repetitive uniform microwave discharge with pulse duration of 10-50 μs, repetition frequency of 0.1-10 kHz at a level of the input microwave power of 1.8 kW per pulse and an average power up to 300 W. The spatial structure of the microwave discharge at pressures up to 50 Torr of the laser gas mixture is studied.

Amplitude-temporal and spectral paramters of laser radiation and electric discharge parameters in gas mixtures of SF₆ with hydrogen and hydrocarbons in the high efficiency operation mode are studied. The laser effiency with respect to deposited energy up to ηdep ~10% is obtained using both inductive and capacitor generators. It was shown that maximal efficiency of the HF-laser is reached under high E/p parameter value across the laser gap during excitation pulse (where E is the electric field strength, p is the gas mixture pressure). Application of profilated electrodes along with UV preionization allows to obtain specific output of the non-chain HF-laser of about 140 J/l×atm and total laser efficiency η0~4.5%. It was found that output spectra of the laser in the high efficiency operation mode significantly widen and cascade laser action on some rotational lines of HF molecule vibrational transitions v(3-2) → v(2-1) → v(1-0) is observed.

An effective mode selection method for square waveguides is proposed. One has to cut up the waveguide and turn the parts around optical axis. Nearly round fundamental mode is almost indifferent to such asymmetry while the mirror modes suffer great losses. The "turn" losses evaluation through the mode overlap integral confirms the method effectivenss. Lasing experiments were performed for an RF-pumped CO₂ laser with a folded U-type resonator. To introduce asymmetry, waveguide channels were shifted so that the waveguide end fold mirrors image is turned axially. The laser beam quality was tested with "ModeMaster" coherent beam propagation analyzer. M² value equal to one within the device tolerance is measured.

Over the last decade excimer lasers have been broadly used for technological and medical processes. One of the most widespread applications of excimer laser is the clinical use for refractive surgery. Refractive surgery with excimer lasers is the prevalent method for the eye acuity correction. Operation at 193 nanometers, the excimer laser is able to precisely sculpt the corneal surface to correct refractive errors. Both the increase in the accuracy of sculpturing and the predictability of procedures are the key elements of the excimer laser designed for refractive surgery. The novel excimer laser for refractive surgery is offered for small aberration treatment. The excimer laser with both a full aperture Gaussian beam and fly spot system is described. The comparison of different systems of laser correction is reviewed.

The comprehensive results are presented on the behavior of high purity synthetic CaF₂, MgF₂, quartz glass and Al₂O₃ under the action of intensive ionizing radiation (x-rays and energetic electrons) and UV laser radiation with 248-nm wavelength. They are concerned to the application of e-beam-pumped large-size KrF-laser as a driver in the Inertial Fusion Energy.

Fast-flow lasers with controllable dynamical regimes were analyzed. Generator-amplifier resonator system considered in the paper was found to possess particular physical mechanism of self-modulated pulsing. The mechanisms lie in the generator and amplifier interaction due to the feedback supplied with the flow. One of the mechanisms is the inversion saturation in the amplifier, which determines the gain of the medium entering the generator. At the same time spatial modulation of the gain profile, as a result of the edge effects in non-stationary optical field, can also affect the regime of lasing. Methods of a regime control based on mechanisms mentioned above are proposed.

We illustrate some of the applications of coherent infrared spectrometers based on frequency conversion by difference frequency generation. We show that very high sensitivity molecular detection can be performed as well as sub-Doppler saturated spectroscopy. Moreover, we describe a setup that allows absolute frequency measurements in the infrared wtih metrological grade uncertainties.

We describe a lwo frequency noise laser system conceived for the readout of small mechanical vibrations. The system consists of a Nd:YAG source stabilized to a high Finesse Fabry-Perot cavity and achieves the best performance in the range 1-10 kHz, with a minimum residual noise of 4×10^-3 Hz√Hz. We perform an extended characterization of the frequency stability by means of an independent optical cavity and we also measure the residual fluctuations after transmission through an optical fiber. Our apparatus is optimized for the use in an optical readout for the gravitational wave detector AURIGA, where a laser system with the characteristics here reported will allow an improvement of one order of magnitude in the detector sensibility.

We present experimental results of the frequency stabilization of a Nd:YAG laser at 946 nm to the Hertz-level. The laser will be used for ultra-high resolution spectroscopy of the 5s²¹S₀-5s5p³P₀ transition at 237 nm in In⁺ (natural linewidth 0.82 Hz) and will ultimately serve as a local oscillator of an optical frequency standard based on a single traped Indium ion. The frequency stability of the laser is obtained by locking it onto an external reference cavity of high finesse, placed on an active vibration isolation platform.

Theoretical and experimental investigation of the light shift in optical pumping and coherent population trapping based gas-cell atomic frequency standards is reported. A possibilty for realization of a minimial (possibly zero) light shift configuration is discussed.

A 445-THz (674nm), ⁸⁸Sr⁺ trapped and laser cooled single ion reference transition has been used at the National Research Council of Canada (NRC) to extend precision frequency measurements to other points in the electromagnetic (EM) spectrum. We are currently refining the single ion experiment to approach the uncertainty limited spectral resolution of 1×10^-15. Connected with these developments is the use of frequency grids based on mode-locked femtosecond lasers. A band of reference modes extending from 520 nm to beyond 1060 nm has been recently obtained femtosecond lasers. A band of reference modes extending from 520 nm to beyond 1060 nm has been recently obtained at NRC and has been applied to the absolute frequency measurement of the widely used 633 nm I₂ stabilized HeNe laser standard. Excellent agreement was obtained between the measurements determiend via ion an comb based measurements. With such devices, the possibility of accurate, stable and compact sources at any wavelength is coming into being.

The iodine vapor cell is an important element of metrological stabilized lasers. The presence in the cell of foreign gases cases the frequency shifts of hyperfine components of iodine molecule. In this paper we pay the particular attention for the influence of irrelevant iodine isotopes on frequency shifts of hyperfine components and show that cell testing should include the additional sensitive detection of irrelevant iodine isotopes presence.

Basic advantages and limitations of ultrafast photoelectronic imaging are overviewed. Presented are recent experimental results on recording of Ti: sapphire laser radiation with 200-fs time resolution and 30-line pairs/mm spatial resolution. Some peculiarities in displaying of utlrafast optical events onto the photocathode with femtosecond precision are shortly mentioned. Special emphasis is given to creation of ultra high (10-100 kV/mm) electrical field strength nearby the photocathode surface, as well as to manufacturing various types of femtosecond image converter tubes. To break the femtosecond barrier, a new technique for generation the attosecond bunches of tens keV electrons in quasistationary electromagnetic fields is proposed.

Integrated optical waveguide sensors based on optical interaction into waveguide structures are still of great importance. Due to their minimal sizes, low driving power level, delicate sensitivity for processed signals and other advantages the devices are widely used in photonic systems. The original method (based on changing of propagation conditions for guided optical waves) for pressure and acceleration measuring has been developed, computer simulated and tested at Institute for Microprocessors of Russian Academy of Science.

We describe experimental investigations on an optical frequency standard based on a single laser cooled ¹⁷¹Yb⁺ ion confined in a radiofrequency Paul trap. The 435.5 nm electric-quadrupole transition from the ²S_1/2(F=0) groudn state to the ²D_3/2(F=2) state is probed using a diode laser system whose short-term frequency stability is derived from an environmentally isolated ULE cavity. The transition is resolved with a Foruier-limited full halfwidth of approximately 30 Hz. The absolute optical transition frequency is determined using a femtosecond frequency comb generator and a Cs fountain clock as the frequency reference. The measured frequency value is 688 358 979 321 Hz at an ambient blackbody radiation field of 300 K. The 1σ fractional uncertainty of this frequency measurement is 1×10^-14.