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Organochlorine (OC) contaminant concentrations in tissues and lipid profiles in blubber are summarised for 101 gray whales (Eschrichtius robustus) from the eastern North Pacific stock. Samples were obtained from presumably healthy gray whales during a 1994 subsistence hunt in the Russian Arctic (n = 17) and also from biopsy sampling of live animals from the Washington coast (n = 38). In addition, tissues were collected from two groups of animals (1988-1991, n = 22; and 1999, n = 24) that stranded along the west coast of the USA. These whales represent a diverse group of animals with respect to lipid stores, age, gender, health and reproductive status. Information about these biological factors is necessary before contaminant concentration data can be properly interpreted. Differences in blubber lipid levels and profiles were examined among these groups of whales. Significantly higher lipid levels were found in the blubber of subsistence animals that were sampled following summer feeding in the Bering and Chukchi Seas, compared to lipid levels in the biopsied and stranded animals. Lipid class profiles from blubber of presumably healthy gray whales (i.e. from subsistence and biopsy sampling) contained primarily triglycerides and were very different from those of stranded animals that showed lipid decomposition (increased proportions of free fatty acids, cholesterol and phospholipids). Furthermore, lipid class profiles were found to be a means of estimating the quality of a blubber sample from stranded cetaceans. An examination of how biological factors (e.g. gender, reproductive status, age) contribute to interpreting the differences found in contaminant concentrations among the gray whales was also undertaken. Although not statistically significant, higher (OC) concentrations were found in males compared to females, thus suggesting the tendency of the mother to shift her contaminant burden to her calf during gestation and lactation. Results also indicated that there was no significant increase in concentrations of contaminants in the blubber with increase in length (surrogate for age). Higher concentrations of OC contaminants were found in stranded juvenile gray whales, compared to juvenile subsistence whales, and were thought to result from retention of OCs in blubber of the stranded animals as lipid stores are mobilised for energy and total lipid levels decrease, rather than from a difference in diet or feeding areas. OC concentrations in various tissues (blubber, liver, kidney, muscle, brain) were similar on a lipid weight basis, except for brain, which had lower lipid-adjusted OCs because the blood-brain barrier limits contaminant transfer.

The optical characteristics of vertical cylindrical micropillars with AlGaAs distributed Bragg reflectors and InAs/GaAs quantum dots, which are designed for the fabrication of single-photon sources, have been studied. The effect of parameters such as the inclination angle of sidewalls, partial oxidation of AlGaAs layers, and deviation of quantum dots from the central axis of a micropillar on the Purcell factor and the radiation extraction efficiency has been numerically simulated by the finite-difference time-domain method. The allowable ranges of the listed parameters have been determined for cylindrical vertical 920-nm micropillars. The comparison of the calculations performed with the refined refractive indices of the used materials at cryogenic temperatures with the measured characteristics of the fabricated micropillar structures has confirmed the adequacy of the used models.

Gallium nitride (GaN) is one of the most promising materials for high-frequency devices owing to its prominent material properties. We report on the fabrication and study of a series of Schottky diodes in the ground-signal-ground topology based on individual GaN nanowires. The electrical characterization of I–V curves demonstrated relatively high ideality factor value (about 6–9) in comparison to the planar Au/GaN diodes that can be attributed to the nanowire geometry. The effective barrier height in the studied structures was defined in the range of 0.25–0.4 eV. The small-signal frequency analysis was employed to study the dependency of the scattering parameters in the broad range from 0.1 to 40 GHz. The approximation fitting of the experimental data indicated the record high cutoff frequency of about 165.8 GHz.

An investigation has been performed of 1.55-μm vertical-cavity surface-emitting lasers based on heterostructures with a buried tunnel junction (BTJ) with a height difference of 15 nm. The devices are obtained by wafer fusion of heterostructures grown by molecular beam epitaxy and provide single-mode lasing at a BTJ diameter of up to 8 μm. A decrease in the BTJ size leads to a sharp increase in the threshold current, the output optical power, and the resonance frequency at the lasing threshold. Stable single-mode lasing takes place due to the smoothed boundary of the buried surface relief, which induces a gradual change in the profile of the effective refractive index in the lateral direction with the effective current confinement retained. This makes it possible to reduce significantly the transverse optical confinement factor for the higher-order modes even at a large BTJ size. However, at a small BTJ size, it leads to the formation of a saturable absorber in unpumped parts of the active region.

A design of a tunnel junction (TJ) based on n++-InGaAs/p++-InGaAs/p++-InAlGaAs layers for vertical-cavity surface-emission lasers (VCSELs) for the 1.55-μm spectral range fabricated by wafer fusion of an InAlGaAsP/InP optical cavity and wafers with AlGaAs/GaAs distributed Bragg reflectors has been suggested and tested. The presence of the oxidation-resistant InGaAs layers makes it possible to employ the molecular-beam epitaxy in all stages of the fabrication technology of VCSELs, including the overgrowth of the surface profile in the TJ layer. Owing to the Burstein–Moss effect and to the thickness minimization of the p++-InGaAs layer, it was possible to avoid a buildup of the internal optical loss. As a result, the characteristics of the thus fabricated devices are comparable with those of VCSELs having an n++-/p++-InAlGaAs TJ and a similar level of the mirror losses.

A high-electron-mobility transistor (HEMT) based on InAlAs/InGaAs/InP heterostructures possessing higher breakdown characteristics is developed. An InGaAs composite channel structure, combined with completely selective forming of the double recess structure, is used in the devices. HEMTs with a T‑shaped gate 120 nm in length consist of four fingers, each 30 μm in width, exhibit a maximum transconductance of 810 mS/mm, 460-mA/mm maximum density of drain current and 8- to 10-V drain-to-gate breackdown voltage. The current-amplification cut-off frequency of transistors is over 115 GHz. Due to the enhanced breakdown voltage and the forming of a double recess structure by selective etching, the elaborated transistors are promising for application in the monolithic integrated circuits of the millimeter-wave medium power amplifiers.

The results of a study of internal optical losses and current injection efficiency in vertical-emitting lasers of a spectral range of 1.55 µm obtained by sintering plates of high-q Bragg reflectors and the active region on the basis of thin strained InGaAs/InAlGaAs quantum wells have been presented. It has been shown that the proposed design of the laser provides a record low level of internal optical losses (less than 6.5 cm–1) and high efficiency of current injection (more than 90%) at room temperature, which allows the realization of submilliampere threshold currents. As the temperature rises to 85°C, the current injection efficiency drops to 70% due to the thermal emission of charge carriers from the active region, accompanied by an increase in internal optical losses to 9.1 cm–1 because of an increase in absorption on free carriers and/or intersubband absorption in the valence band.

We propose a hybrid microcavity design of a 1.3 μm range electrically driven single-photon source (SPS) consisting of two high-contrast dielectric distributed Bragg reflectors which surround a 3λ-thick semiconductor cavity with two intra-cavity contact layers and four 40-nm-thick oxide-confined apertures. According to 3D finite-difference time-domain modelling, the overall photon-extraction efficiency of ~74% and the Purcell factor of ~13 can be obtained by properly adjusting the position of oxide-confined apertures relative to the electric field of the fundamental optical mode. The studied SPS design also demonstrates a coupling efficiency of up to 13% within numerical aperture 0.12 in contrast to ~5% reached for a conventional semiconductor micropillar.

Results of investigation of 1550 nm range stripe semiconductor lasers fabricated from heterostructures with different designs of the gain medium are presented. It is shown that the proposed designs of the gain medium allow obtaining the effective lasing at high level of total optical losses, comparable with the typical optical losses in the vertical-cavity surface-emitting lasers. The evaluation of modal gain in different types of the gain mediummade it possible to estimate the possible frequencies of the small-signal modulation of vertically emitting lasers and proposed the ways to increase them up to 20 GHz or more.

Vertical-cavity surface-emitting lasers (VCSELs) of 895 nm spectral range, with fixed direction of output polarization have been developed. These lasers provide single-mode output power of over 1 mW at an operational temperature of 60°С, at orthogonal polarization suppression ratio (OPSR) about 20 dB. The designed VCSELs were used in a laser source for a perspective compact nuclear magnetic resonance gyroscope. The designed laser source provides precise tuning of wavelength to the Cs133 D1 spectral line, and formation of collimated output beam.

The main problems of providing a high-speed operation semiconductor lasers with a vertical microcavity (so-called “vertical-cavity surface-emitting lasers”) under amplitude modulation and ways to solve them have been considered. The influence of the internal properties of the radiating active region and the electrical parasitic elements of the equivalent circuit of lasers are discussed. An overview of approaches that lead to an increase of the cutoff parasitic frequency, an increase of the differential gain of the active region, the possibility of the management of mode emission composition and the lifetime of photons in the optical microcavities, and reduction of the influence of thermal effects have been presented. The achieved level of modulation bandwidth of ∼30 GHz is close to the maximum achievable for the classical scheme of the direct-current modulation, which makes it necessary to use a multilevel modulation format to further increase the information capacity of optical channels constructed on the basis of vertical-cavity surface-emitting lasers.

Vertical-cavity surface-emitting lasers (VCSELs) with an aperture limited by an oxide and a resonance cavity based on GaAlAs with high Al content provide a maximum γ factor (λ/2 design) and suppression of optical power beyond the aperture. A VCSEL with two coupled cavities provides additional sharp growth of the loss of high-order lateral modes by leakage to the oxidized region and provides single-mode laser generation for an aperture diameter of up to 5 μm. Single-mode antiwaveguiding VCSELs provide ultrafast data transmission with a rate of up to 160 Gbit/s. The structure in which the active medium is placed in the lower distributed Bragg reflector and the cavity and the upper distributed Bragg reflector are dielectric, reducing the temperature shift of the radiation wavelength by a factor of 2 (to ∼0.03 nm/K).

The results of studies on fabrication of vertical-cavity surface-emitting 1.55-μm lasers by fusing AlGaAs/GaAs distributed-Bragg-reflector wafers and an active region based on thin In0.74Ga0.26 As quantum wells grown by molecular-beam epitaxy are presented. Lasers with a current aperture diameter of 8 μm exhibit continuous lasing with a threshold current below 1.5 mA, an output optical power of 6 mW, and an efficiency of approximately 22%. Single-mode lasing with a side-mode suppression ratio of 40–45 dB is observed in the entire operating current range. The effective modulation frequency of these lasers is as high as 9 GHz and is limited by the low parasitic cutoff frequency and self-heating.

The studies of the emission linewidth for single-mode near-IR vertical-cavity surface-emitting lasers with an active region based on InGaAs/AlGaAs quantum wells and different optical microcavity design. For low mirror loss, lasers with a 1λ cavity and carrier injection through distributed Bragg reflectors demonstrate a linewidth of 70 MHz and its growth to 110 MHz with increasing mirror loss (corresponding differential of efficiency ∼0.65 W/A). The design of the optical cavity with carrier injection through intracavity contacts and low-Q composition Bragg lattices reduces the linewidth to 40 MHz in spite of high mirror loss (corresponding differential efficiency of ∼0.6 W/A).

We have studied characteristics of a 23-μm-diameter microdisk laser operating in a regime of direct high-frequency modulation at a stabilized heat-sink temperature of 18°C. It is found that the minimum energy consumption in this regime amounts to ~1.6 pJ/bit and is achieved at a modulation frequency of 4.2 GHz. The maximum modulation frequency is 6.7 GHz, at which the minimum energy consumption is 3.3 pJ/bit.

We demonstrate noise characterization of novel 894.4 nm vertical-cavity surface emitting lasers with intracavity contacts and a rhomboidal oxide current aperture (IC-VCSELs), dedicated to 133Cs D1 line compact optically pumped atomic magnetometers (OPM). The laser relative intensity noise, measured to be -139 dB/Hz at 10 kHz frequency in 1 Hz bandwidth for a laser optical power of 0.8 mW, is decreased with optical power growth. The IC-VCSELs polarization-resolved relative intensity noise is 143 dB/Hz at 10 kHz frequency in 1 Hz bandwidth for 0.8 mW. The emission linewidth of the VCSEL is about 55 MHz. The IC-VCSEL parameters are determined, such as emission linewidth ~ 50-60 MHz, optical power ~ 0.5-1.0 mW, at which the polarization-resolved RIN becomes close to the RIN, which makes it possible to use these lasers in various OPM Mz and Mx schemes. The ultimate sensitivity of OPM was estimated by the ratio of the magnetic resonance to the signal to noise level. It is shown that a OPM based on the IC-VCSELs, assuming magnetic resonance FWHM ~ 1 kHz, can achieve a shot noise-limited sensitivity around 20 fT in 1 Hz bandwidth without any polarization improvements by polarizer or polarization beam splitter cube (PBC). Developed IC-VCSELs is acceptable for use in compact OPM for magnetoencephalography.

The paper presents the results of studies of the conditions for the formation of A3B5 compound semiconductors heterointerfaces including InP, InGaAsP and GaAs layers. The heterostructures were grown by molecular-beam epitaxy and were fused by wafer fusion technique. Improvement of planarity and homogeneity over the thickness of heterointerface due to using optimized preliminary preparation of semiconductor wafer surfaces was demonstrated. No additional extended defects such as dislocations were found.

Vertical-cavity surface-emitting lasers of 1.3 μm spectral range with the active region based on the InGaAs/InGaAlAs superlattice were studied. VCSEL heterostructure was formed by a wafer-fusion of the heterostructure with an active region and two DBRs grown by molecular-beam epitaxy on InP and GaAs substrates respectively. Fabricated VCSELs have shown threshold current below 1.6 mA and frequency of small signal modulation near 9 GHz at 20°C.

The quality of heteroboundaries and optimal conditions for epitaxial growth are critical parameters for obtaining low leakage currents of heterobarrier varactors in the InGaAs/InAlAs/AlAs material system. Grown by molecular-beam epitaxy, three-barrier heterobarrier varactor structures adjacent to InAlAs/AlAs/InAlAs barrier layers by additional mismatched InGaAs layers subjected to compressive stress show, under optimal epitaxy conditions, extremely low levels of leakage current density (not more than 0.06 A/cm2 at a voltage of 5 V and 85°C) with relatively thin AlAs inserts (with a thickness of 2 nm).

Vertical-cavity surface-emitting lasers with an active region based on submonolayer InGaAs quantum dots with an oxide-aperture diameter of ~1 μm have been studied. It is established that peaking of the output optical pulses to 50–100 ps can be achieved by pumping these lasers with 10–100 ns electric pulses at a repetition frequency of 10–100 kHz.

We demonstrate the possibility of using vertical-cavity surface emitting lasers with intracavity contacts and a rhomboidal oxide current aperture for creating compact optically pumped 133Cs atomic magnetometer operating in non-zero magnetic fields, which is promising to use in magnetoencephalographic systems. The magnetic resonance parameters were studied in a two-beam MX optically pumped magnetic field sensor scheme based on the effect of the magnetic resonance line narrowing at high laser pumping and high concentrations of alkali-metal atoms. The ultimate sensitivity of OPM was estimated by the ratio of the magnetic resonance steepness to the probe light shot noise level. It is shown that a magnetic sensor based on the vertical-cavity surface emitting lasers and a compact (0.125 cm3 volume) Cs vapor cell can achieve a shot noise-limited sensitivity better than 15 fT in 1 Hz bandwidth. Developed intracavity contacted VCSELs suitable for use in compact atomic magnetometers for magnetoencephalographic systems.

Studies aimed at optimization of the design of a dielectric distributed Bragg reflector (DBR) produced by the reactive magnetron sputtering method for applications in near-IR vertical-cavity surface-emitting lasers with intracavity contacts (ICC-VCSELs) are carried out. It is shown that the reflectivity of the dielectric DBRs based on SiO2/TiO2 decreases due to the polycrystalline structure of the TiO2 layers, which causes diffusive scattering of light. In contrast, amorphous Ta2O5 layers is characterized by a low surface roughness and low fluctuation in the refractive index. Single-mode ICC-VCSELs in the 980-nm spectral range with dielectric DBR based on SiO2/Ta2O5 with a threshold current less than 0.27 mA, electric resistance of less than 200 Ω, and differential efficiency of more than 0.8 W/A are demonstrated.

The fundamental possibility of achieving temperature stability of laser emitters of 1.3-μm spectral range exhibiting a vertical microcavity and an active region based on InAs/InGaAs quantum dots (QDs) is investigated. It is demonstrated that using an undoped hybrid vertical optical microcavity formed by a lower undoped semiconductor and an upper distributed dielectric Bragg reflectors allows obtaining laser oscillation up to a temperature of ~100°C at nearly constant threshold optical pump power for an active region consisting of QD layers under optimal spectral mismatch between the position of maximum gain of the QD ground state and the resonance wavelength.

The polarization characteristics of 850-nm vertical-cavity surface-emitting lasers (VCSELs) with intracavity contacts and a rhomboidal oxide current aperture are studied. It is found that radiation polarization is always directed along the minor diagonal of the rhomboidal aperture (along the [ $$\overline 1 $$ 10] direction) for all single-mode VCSELs. The numerical simulation of carrier transport does not reveal the significant anisotropy of carrier injection to the active region. Furthermore, an analysis of the spatial distribution of the fundamental mode for two orthogonal polarizations within an effective waveguide model shows close transverse optical-confinement factors. Optical loss anisotropy in the asymmetric microcavity and/or gain anisotropy in the strained active region are the most likely mechanisms responsible for fixing the polarization.

Microdisk injection lasers on GaAs substrates, with a minimum diameter of 15 μm and an active region based on InAs/InGaAs quantum dots, are fabricated. The lasers operate in the continuous-wave mode at room temperature without external cooling. The lasing wavelength is around 1.27 μm at a minimum threshold current of 1.6 mA. The specific thermal resistance is estimated to be 5 × 10–3 °C cm2/W.

The paper presents the results on fabrication technique of a 1,55 μm wafer-fused vertical-cavity surface-emitting lasers (VCSELs) based on the InAlGaAsP/InP optical cavity and AlGaAs/GaAs distributed Bragg reflectors (DBRs) grown by solid-source molecular beam epitaxy. The optical cavity InAlGaAsP/InP containes an active region based on multiple InGaAs quantum wells, n++/p++-In (Al)GaAs buried tunnel junction (BTJ), InGaAsP intracavity contact layers and n-InP spreading layers. The top and bottom AlGaAs/GaAs DBRs were grown on GaAs substrate, while the optical cavity InAlGaAsP/InP was grown on InP substrate. The main fabrication proceseses of 1,55 μm VCSELs such as: BTJ fabrication, dry etching of first mesa on top DBR, wet etching of second VCSEL mesa, forming of the ohmic contacts and passivation of the VCSEL structure were described in details.

The study was aimed at assessing the role of chemokines in inflammatory changes in tissue following abdominoplasty. The levels of neutrophil-coupled chemokines and their receptors in the serum and blood cells, as well as in cells isolated from the subcutaneous adipose tissue sampled during abdominoplasty were compared in patients with obesity and normal body weight. The levels of chemokines CCL3, CCL3, and CCL5 in blood serum and expression of chemokine receptor CXCR2 and CXCR6 on blood neutrophils were significantly higher (p

Detail measurements and full-vector three-dimensional FDTD technique were used to analyze anomalous mode behavior in double-aperture oxide-confined 850 nm VCSELs with large gain-to-cavity detuning.

This work was devoted to analysis of the efficiency of the application of a “Geron” hydraulic drive as an alternative to a beam pumping unit. The issue of replacement old drives for new one was considered in the context of economic profitableness taking into account field conditions of Russia and neighbor countries. To prepare this scientific article, different data about field experience of usage the machines in different countries and fields were asked for and obtained. Thanks to information got general characteristics of both machines with their advantages and disadvantages based generally on technological, energetical and economic data were composed. After this the drives were compared with each other. As a result, hydraulic drive “Geron” was taken to be a good alternative of traditional pumping unit.

Miniature laser source based on intracavity-contacted vertical-cavity surface-emitting laser with rhomboidal oxide current aperture was investigated for coherent population trapping (CPT) resonance excitation in microfabricated 133Cs gas cell filled with Ne buffer gas under the pressure of 300 torr. The cell operation temperature was 90°C. The laser output power was 550 μW at bias current of 3.2 mA and 65°C. The short-term stability of ∼2.5·10-11 at the measurement time of 1 sec was estimated from CPT resonance signal measurements.

The effect of the spectral detuning between the spectral gain maximum of an active region based on AlInGaAs nanoheterostructures and vertical microcavity resonance (gain-cavity detuning) on the steady-state- and dynamic characteristics of high-speed vertical-cavity surface-emitting lasers (VCSELs) for the 850-nm spectral range with two selectively oxidized current apertures is studied. For multimode devices with gain-cavity detuning exceeding 20 nm and a comparatively large current aperture (>6 μm), anomalous lasing onset via higher order modes is observed, with subsequent switching to lower order modes at high currents. Simultaneous lasing via both types of transverse modes, observed at intermediate pumping levels, leads to a nonclassical dependence of the maximum effective-modulation frequency on the pump current. An increase in the working temperature, as well as a decrease in the size of the current aperture of a VCSEL, leads to classical multimode lasing behavior. The observed phenomena are to be taken into account when optimizing the design of high-speed VCSELs.

The effect of the photon lifetime in an optical microcavity on the characteristics of 850-nm vertical-cavity surface-emitting lasers (VCSELs) with fully doped distributed Bragg reflectors (DBRs) and an oxide current aperture is studied. The photon lifetime in the microcavity is controlled by varying the upper DBR reflectance. It is found that the speed of VCSELs with a current-aperture diameter of 10 μm is mainly limited by the self-heating effect, despite an increase in the relaxation-oscillation damping coefficient with increasing photon lifetime in the microcavity. At the same time, the higher level of internal optical loss in lasers with a current-aperture diameter of 1.5 μm leads to dominance of the effect of relaxation-oscillation damping independently of the radiation output loss. In the case of devices with a current-aperture diameter of 5.5 μm, both mechanisms limiting the speed operate, which allow an increase in the VCSEL effective modulation frequency from 21 to 24 GHz as the photon lifetime decreases from 3.7 to 0.8 ps.

We have studied the possibility of determining the actual thicknesses and compositions of separate layers in AlGaAs heterostructures with vertical-cavity optical microresonators by the combined use of optical reflectance spectroscopy and X-ray diffraction. It is established that a self-consistent solution of two inverse problems with the aid of a special test heterostructure partly removes the problem of solution ambiguity and increases the absolute accuracy of determination of the parameters of individual epitaxial layers.

Highly efficient fast vertical-cavity surface-emitting lasers (VCSELs) for the 850-nm spectral range, promising for the development of optical interconnections with a data transmission rate of 25 Gbit/s per channel, are fabricated and studied. Lasers with a selectively oxidized current aperture 6 μm in diameter demonstrate multimode lasing with a quantum efficiency of 35–45% and a threshold current of 0.5–0.7 mA in the temperature range 20–85°C. According to the results of small-signal frequency analysis, the maximum modulation frequency of the lasers exceeds 17 GHz, with the rate of its increase with current exceeding 9 GHz/mA1/2, which provides VCSEL operation at a rate of 25 Gbit/s in the entire working temperature range. Endurance tests for 3000 h did not reveal any sudden degradation of the lasers. The optical power at working point and the threshold current changed relative to that at the beginning of the tests by no more than 5 and 10%, respectively.

An electro-optic medium based on the type-II semiconductor superlattice is proposed. Electrooptic modulation of the intensity of optical reflectance of the electro-optic medium integrated into a vertical Fabry-Perot cavity is studied by the optical-reflectance-spectroscopy method. The experimental data are approximated using an oscillator model of exciton absorption. The efficiency of the electro-optic medium in the case of detuning from the absorption peak by 50 meV in electric fields of 0–50 kV/cm is 10−9 m/V at a medium filling factor of 100%.

The effect of the level of internal and external optical losses on the dynamic characteristics of vertical-cavity surface-emitting lasers (VCSELs) in the spectral region of 850 nm is studied. It is shown that an increase in optical losses leads to a decrease in the speed of laser response and to the predominance of thermal effects, while a decrease in losses for the output of radiation brings about an increase in the response speed of the laser and the dominance of damping of the effective modulation frequency. Linear matrix emitters with the 1 × 4 format based on fast-response VCSEL with individual element addressing are produced and studied. Individual laser emitters with a current-aperture diameter of 5–7 μm provide lasing in the continuous-wave mode at room temperature in the region of 850 nm with threshold currents no higher than 0.5 mA, a differential efficiency no lower than 0.6 W/A, a modulation frequency as high as 20 GHz, and a MCEF factor of ∼10 GHz/mA1/2.

The high-frequency electrical properties of a vertical-cavity surface-emitting laser with a monolithically integrated electro-optical modulator are studied using small-signal modulation analysis of the electroreflectance. The experimental data obtained are approximated using the suggested equivalent electrical circuit, which accounts for the formation of a nonequilibrium space charge in the carrier-depletion region of the modulator. The bandwidth of the high-frequency electrical-signal transfer to the electro-optical region, determined for the suggested equivalent electrical circuit of the modulator, is shown to be 3GHz.

A concept of passive cavity surface–emitting laser is proposed aimed to control the temperature shift of the lasing wavelength. The device contains an all–semiconductor bottom distributed Bragg reflector (DBR), in which the active medium is placed, a dielectric resonant cavity and a dielectric top DBR, wherein at least one of the dielectric materials has a negative temperature coefficient of the refractive index, dn/dT < 0. This is shown to be the case for commonly used dielectric systems SiO 2 /TiO 2 and SiO 2 /Ta 2 O 5 . Two SiO 2 /TiO 2 resonant structures having a cavity either of SiO 2 or TiO 2 were deposited on a substrate, their optical power reflectance spectra were measured at various temperatures, and refractive index temperature coefficients were extracted, dn/dT = 0.0021 K -1 for SiO 2 and dn/dT = –0.0092 K -1 for TiO 2 . Using such dielectric materials allows designing passive cavity surface–emitting lasers having on purpose either positive, or zero, or negative temperature shift of the lasing wavelength dλ/dT. A design for temperature–insensitive lasing wavelength (dλ/dT = 0) is proposed. Employing devices with temperature–insensitive lasing wavelength in wavelength division multiplexing systems may allow significant reducing of the spectral separation between transmission channels and an increase in number of channels for a defined spectral interval enabling low cost energy efficient uncooled devices.

Food compositions in 82 individuals of the gray whale Eschrichtius robustus from Mechigmen Bay in the Bering Sea were analyzed in 2007–2009. Animals of 12 taxonomic groups were revealed in the food boluses of whales; amphipods and polychaetes prevailed by biomass and frequency of occurrence. The average specific biomass of amphipods was 54.2–71.7% and the frequency of occurrence reached 96.3–100%; those of polychaetes were 19.5–37.2 and 85.2–100%, respectively. The comparison of the feeding of E. robustus in 2007–2009 and 1998–1999 displayed that the taxonomic composition of the eaten animals remained the same, but the sizes of the groups changed. In 2007–2009, 68 species of amphipods were recorded in the whale stomachs; the input to biomass was counted for six species, Anonyx nugax (31.7%), Ampelisca macrocephala (22.3%), Psammonyx kurilicus (15.3%), Ampelisca eschrichti (9.1%), Hippomedon denticulatus orientalis (4.3%), and Pontoporeia femorata (4.6%). As in 1998–1999, the first two species prevailed. In percentage terms, the greatest portion of the whale bolus was based on most abundant benthic species.

Results of a comparative study of the structural parameters and the static and dynamic characteristics of vertical-cavity surface-emitting lasers (VCSELs) with microresonators based on Al0.15Ga0.85As and Al0.8Ga0.2As are presented. It is established that the vertical oxidation of layers in the Al0.8Ga0.2As microresonator during formation of the current aperture leads to a significant increase in the oxide thickness. This leads to a considerable decrease in parasitic capacitance of the device and a 1.7- to 2-fold growth in the cut-off frequency of a low-frequency filter formed by parasitic elements of the equivalent electric scheme of the device.