To solve inverse problems, in particular, the recovery of optically active substances from hydro-optical measurements, it is necessary to clearly understand the nature of these dependencies. The work analyzes such relationships between the fluorescence of dissolved organic matter, chlorophyll-a fluorescence and the beam attenuation coefficient at a wavelength of 660 nm based on direct measurements performed in Lake Teletskoye in August 2023. It is shown that the waters of Lake Teletskoye belong to the so-called waters of the second type (CASE2) according to the Morel classification, i. e. optically complex waters.

The sunlight spectral composition, penetrating to different depths in the upper water layer, on the one hand, depends on the optically active components contained in the water, on the other hand, it is important for the functioning of phytoplankton, and therefore plays an important role in the functioning of the aquatic ecosystem in general. When studying the spectral composition of light at different depths, a new instrument was used, made on a modern elemental basis. Analysis of the obtained spectra of the vertical attenuation coefficient made it possible to identify regional features of the penetration of natural sunlight characteristic of Lake Teletskoye.

—A method is proposed for constructing a regional algorithm to calculate the thickness of the euphotic zone from in situ measurements of the vertical profiles of the beam attenuation coefficient under the condition of one-parameter optical properties of water (Case-1 water). Using the proposed methodology, a regional algorithm for determining the thickness of the photic zone was developed based on the results of synchronous measurements of the beam attenuation coefficient and photosynthetically active radiation, performed in January 2022 as part of cruise 87 of the R/V Akademik Mstislav Keldysh for the northwestern Weddell Sea. For this region, an equation was obtained that can estimate the depth of the photic zone with a relative reconstruction error of 18%.

This work precedes the field experiment on Lake Teletskoye, which is scheduled for August 10-20, 2023. The main goal of the work is to get an information of the regional features and seasonal variability of the optically active characteristics of the water upper layer of Lake Teletskoye based on the Level-2 standard products of the OLCI optical scanner.

Based on the analysis of long-term measurements by bio-argo floats, characteristic features are described and quantitative characteristics of the distribution of the light backscattering coefficient by suspended particles in the upper 1000-meter layer of the Black Sea are obtained.

A method is proposed for constructing a regional algorithm for calculating the thickness of the euphotic zone from in situ measurements of the vertical profiles of the beam attenuation coefficient under the condition of one-parameter optical properties of water (Case-1 water). Using the proposed methodology, a regional algorithm for determining the thickness of the photic zone was developed based on the results of synchronous measurements of the beam attenuation coefficient and photosynthetically active radiation, performed in January 2022 as part of the 87th cruise of the R/V Akademik Mstislav Keldysh for the northwestern part of the Weddell Sea. For this region, an equation was obtained that makes it possible to estimate the photic zone depth with a relative reconstruction error of 18%.

The use of satellite scanners of medium resolution to study inland water regions, such as lakes and large reservoirs, is an important task. In this paper, using the example of Lake Baikal, the limitations of the new HawkEye medium-resolution satellite scanner for studying the optical characteristics of lakes are identified and described. A technique for adaptation the regional algorithm for recovering the vertical light attenuation coefficient obtained for the OLCI bands ratio to the the HawkEye bands ratio is tested.

Использование спутниковых сканеров среднего пространственного разрешения для изучения внутренних водоёмов, таких как озера и крупные водохранилища, является актуальной задачей. В данной работе, на примере о. Байкал, выявлены и описаны ограничения возможностей нового спутникового сканера среднего разрешения HawkEye для изучения оптических характеристик озер. Опробована методика адаптации регионального алгоритма восстановления показателя вертикального ослабления света, полученная для спектральных каналов сканера OLCI, на спектральные каналы сканера HawkEye.

Aspects of silicon photonics process technologies intended for high volume production in a traditional silicon electronics-driven foundry environment are discussed. Both technological and economical challenges associated with this juxtaposition of a complex, non-standard process technology, inside of a factory geared for producing thousands of standardized electronics-based wafers per month, are described in detail.

It is noted that the high instrumental accuracy of modern marine spectrophotometers for reflectance measurements is difficult to implement due to large methodological errors caused by the sea surface waves by weather conditions and illumination geometry. A two-beam spectrophotometer based on the use of a multi-channel photomultiplier eliminating the disadvantages is proposed. The design and operation principle of a spectrophotometer, developed on the basis of a compact high-aperture monochromator and a photometric unit, in which the channels of the upwelling radiation and the irradiance of the sea surface are located, are described. In the instrument, instead of absolute measurements, the light fluxes are compared in a differential photometer instead of absolute measurements in order to reduce methodological errors. The use of a differential photometer, which measures the spectral reflectance of water, can significantly increase the measurement accuracy, because does not require absolute calibration of optical channels. The use of a multichannel photomultiplier leads to an additional decrease in methodological errors by reducing the time of measurements of the seawater spectral reflectance and makes it possible to select a sufficient number of spectra in a large volume of data without interference from waves and lighting conditions. The photomultiplier signals are digitized using a compact USB ADC/DAC module with digital input/output functions. Amplified signals from photocathodes are received at the module input, the module output is connected to the USB input of a computer recording signals and controlling the spectrophotometer work.

We study the quantum properties of light propagating through an array of coupled nonlinear waveguides and forming a discrete soliton. We demonstrate that it is possible to use certain types of quasi-solitons to form continuous variables entanglement between the certain pair of waveguides. Moreover, there is a possibility to entangle several pairs of waveguides independently. We show that the entanglement is generated for arbitrary high intensity of the input laser field, so it does not require a special material with an extremely high nonlinearity coefficient. Also, absorption in the waveguide media does not influence the discussed process too much.

Using the results of the 4D IOPs model, an estimate of the lower boundary of the photosynthesis zone in the deep water region of the Black Sea was obtained. For the year warm period, its value significantly differs downward (by 5–10 m) from that obtained in earlier paper. At the cold period, this difference in estimates is smaller and amounts to 2–3 m. The main reason is the more correct consideration of the light absorption profile of dissolved organic matter, which increases with depth.

Используя результаты 4D IOPs модели [1], получена оценка нижней границы зоны фотосинтеза в глубоководной части Чёрного моря. Для тёплого периода времени её величина существенно отличается в меньшую сторону (на 5-10 м) от той, которая получена ранее в работе [2]. Для холодного периода эта оценка меньше и составляет 2-3 м. Основная причина состоит в более корректном учёте профиля поглощения света растворённым органическим веществом, которое увеличивается с глубиной.

The purpose of the work was to build a regional algorithm for reconstructing the vertical diffuse attenuation coefficient at 380, 443, 490, 510, 555, 590 and 620 nm for Lake Baikal based on quasi-synchronous in situ measurements and the standard ocean color Level-2 OLCI product. For the first time, the spatial distribution of the diffuse attenuation coefficient was obtained at seven wavelengths in the upper layer of Lake Baikal.

В настоящей работе рассмотрены результаты гидрологических, гидрооптических и гидробиологических исследований, выполненных в фотической зоне северной части Чёрного моря в октябре 2016 г. Выявлены основные особенности формирования биооптической структуры и ее связь с гидрологическим режимом. Показано, что в зоне Севастопольского и Феодосийского антициклонов, параллельно с заглублением верхнего квазиоднородного слоя, отмечается и заглубление слоя максимальных значений концентрации общего взвешенного вещества. В южной части съемки, ближе к центру основного циклонического круговорота Чёрного моря, где глубина нижней границы верхнего квазиоднородного слоя минимальна, отмечается подъем слоя максимума концентрации общего взвешенного вещества. Установлено, что в октябре 2016 г. отмечалась аномально высокая прозрачность вод с малым диапазоном пространственной изменчивости. Показано, что в этот период наблюдались заметно более низкие связи между вертикальными распределениями концентрации общего взвешенного вещества и температурой, соленостью и плотностью по сравнению с летним периодом 2016 г. В пробах воды идентифицированы микроводоросли девяти отделов, типичных для данного сезона. Выявлено, что величины метаболически активной биомассы микропланктона в открытой части моря соответствовали значениям, характерным для олиго-мезотрофных вод, в то время как в прибрежье Крыма они были близки к эвтрофным характеристикам. Стадия продукционно-деструкционной сукцессии микропланктона - развивающаяся, с прогнозом на рост биомассы в последующем.

С целью проведения экологического мониторинга и получения оперативных данных о состоянии исследуемой акватории был создан зондирующий спектральный измеритель флюоресценции и рассеяния света. Он позволяет одновременно проводить измерения флюоресценции фитопланктона, растворенного органического вещества и рассеяния света в морской воде, в спектральном диапазоне, охватывающем область от ближнего ультрафиолета до красной границы видимого спектра. Получение спектров указанных параметров производятся в одном и том же измерительном объеме, что избавляет от необходимости согласовывать полученные сигналы по объёму флюоресцирующего вещества. Результаты проверки функционирования прибора в лабораторных условиях на образцах монокультур фитопланктона, обитающего в водах Чёрного моря, показали хорошее совпадение измерений с литературными данными. В ходе испытаний прибора во время 106-го рейса на НИС «Профессор Водяницкий» весной 2019 г. были произведены измерения на 77 гидрологических станциях следующих параметров: профилей вертикального распределения флюоресценции фитопланктона; растворённого органического вещества и упругого рассеяния света. В результате были получены сведения о вертикальном распределении измеряемых параметров на исследованных акваториях Чёрного моря. Результаты проведённых испытаний представленного измерителя позволили апробировать техническое исполнение и методологию работы с данным измерителем.

This work demonstrates the spectral measurements of underwater irradiance in the surface water layer of Lake Baikal. These measurements allowed us to obtain spectra of the vertical light attenuation coefficient, restore the spectral structure of the incident solar radiation, including changes of photosynthetically active radiation with depth, and calculate some primary bio-optical characteristics of water: spectra of the CDM absorption coefficient and the light backward scattering coefficient as well as the chlorophyll a concentration. We compare the results of measurements of underwater irradiance with the data obtained by the MODIS-Aqua/Terra colour scanners.

Propagation of soliton-like structures along a one-dimensional nonlinear Kerr waveguide array has been studied taking into account quantum effects. Generation of entanglement between waveguides with maximal intensity has been shown for solitons of certain shape.

The information capabilities of spectral measurements of underwater irradiance in the upper layer of Lake Baikal were demonstrated. It allowed to obtain the spectra of the vertical light attenuation coefficient, to restore the spectral structure of the incident solar radiation, including changes of photosynthetically active radiation with depth, and to calculate a number of primary bio-optical characteristics of water: spectra of the CDM absorption coefficient and the light backscattering coefficient, as well as the chlorophyll-a concentration.

The profiles of the light attenuation coefficients, reconstructed using a model based on statistics of bio-argo floats and regional satellite product, as well as measured under natural conditions in the Black Sea, were compared. Additionally, we compared the values of the attenuation coefficient of photosynthetically active radiation – Kd(PAR), obtained on the basis of spectral measurements of horizontal irradiance, with the results of direct measurements of Kd(PAR) on the shelf and the deep-sea parts of the Black Sea. The effects of meteorological conditions, cloudiness on PAR attenuation in the upper and lower the sea layers are demonstrated.