Decrease In Light Intensity Research Articles

Laser diode optical output dependence on junction temperature for high-power laser systems

Laser diode optical output is studied and modeled. Four major diode parameters (threshold current, slope efficiency, central wavelength of output, and full-width half maximum of output), which are dependent on diode junction temperature, determine the optical output. The physics and equations representative thereof for each parameter are presented and incorporated into a multiphysics model of a high-power laser system (HPLS) to study the optical power/thermal interactions. Simulations are compared to show how optical power output of an HPLS changes when the temperature dependence of parameters are and are not accounted for in the model. The decrease in laser light intensity out of the HPLS as junction temperature changes is also studied. Intensity is sometimes a more important consideration than optical power because for most applications, laser light is only effective when the output power is focused over a very narrow wavelength range. The research provides higher fidelity diode modeling for effectively understanding optical/thermal interactions and the price to be paid for improper diode thermal management. The research supports our main goal of more accurately representing the thermal loads from the individual components of an HPLS.

Cultivation of early life history stages of Porphyra dioica from the British Isles

Bladed Bangiales of the genus Porphyra/Pyropia are highly valuable red algae and extensively farmed in South East Asia. Interest is rising in cultivating species local to the North East Atlantic but the control of the heteromorphic life cycle of native species remains difficult as previous studies reported high inter- and intraspecific variability in required cultivation conditions. Here, working with Porphyra dioica from a UK source population, we conducted a series of experiments investigating the influence of substrate, temperature, photoperiod and light intensity on the development of early life history stages (conchocelis (filamentous sporophyte) and young thalli (gametophyte)). Special focus was the influence of temperature and photoperiod on mature conchocelis to induce a conchospore mass release—the current bottleneck of European Porphyra cultivation. Sporophytes grew largest on an oyster shell substrate and under long day conditions at 18 °C. A decrease in temperature from 18 to 9 °C initiated a mass conchospore release (498 ± 146 spores mL−1) from a P. dioica conchocelis culture grown in suspension. Released conchospores germinated into small thalli on nylon ropes, with best growth (7.2 ± 0.9% day−1) at low temperatures of 9 °C. Conchospore germination increased with decreasing light intensity but germination success was generally very low (< 5%), indicating the cultivation protocol needs further improvement. Our results reflect the adaptation of P. diocia to seasonal environmental conditions in temperate regions and the importance of these conditions for the successful cultivation. We are the first to describe a mass conchospore release for P. diocia growing in suspension which has important implications for commercial production.

Light intensity affects leaf morphology in a wild population of Adenostyles alliariae (Asteraceae)

Low light conditions can impose environmental stress on plants, and plants often respond adaptively by increasing their leaf area. Light stress on plants can also result in developmental instability, which can manifest as increased fluctuating asymmetry in leaves or other organs. The relationship between light conditions and fluctuating asymmetry has been documented in experimental populations, but has been less frequently observed in the wild. Here, we studied how leaf surface area and fluctuating asymmetry correlate with light intensity in a wild population of Adenostyles alliariae (Asteraceae). We found strong evidence that leaf surface area increases and weak evidence that fluctuating asymmetry increases as light intensity decreases. Our results help to elucidate the relationship between light stress and developmental instability under naturally occurring conditions.

Effect of light intensity on survival and photosynthetic efficiency of cultured corals of different ages

In this present study, we investigated the effects of increase and decrease of light intensity and photoperiods on growth, survival, and photosynthetic efficiency in three different corals, Pocillopora damicornis (Linnaeus, 1758), Acropora millepora (Ehrenberg, 1834) and Platygyra sinensis (Milne Edwards and Haime, 1849) with different ages (6-, 12-, and 24-month old). All experimented corals were cultured from sexual propagation. In light intensity trials, juvenile corals were transferred and exposed to different treatments (0, 21, 42, 85, and 169 μmol m−2 s−1 provided by 400-W metal halide lamps or equal to daily light integrals (DLI) of 0, 0.95, 1.89, 3.8, and 7.6 μmol m−2 s−1) for 2 weeks, while in the photoperiod experiment, the coral colonies were exposed to 5 different treatments (24/0, 18/6, 12/12, 6/18, and 0/24 h light-and-dark cycle). The results from the light intensity experiment showed that 2-year old Platygyra sinensis survived (100%) under all light intensity levels, while the survival rates of other coral species decreased, ranging between 20 and 80%, when the light intensity levels changed from the ambient light condition. For the photoperiod experiments, the results showed that 2-year old Platygyra sinensis and 1-year old Acropora millepora survived (100%) under all photoperiod levels. However, there was no significant difference on the growth of corals between different light intensity levels and different photoperiods. From this study, Platygyra sinensis seemed to have more tolerance to wider ranges of light intensities and photoperiods than other coral species. In addition, the results implied that corals were able to acclimate to a prolonged light period and light intensity, which can be feasible for future coral aquaculture.

Effects of light intensity on growth and content of active components of Uncaria rhynchophyll

The aim of this study was to study the effects of different light intensity on the growth,biomass accumulation and distribution,chlorophyll content and effective components of Uncaria rhynchophylla seedlings,and explore the suitable light intensity conditions for artificial cultivation of U. rhynchophylla seedlings. Three-year-old U. rhynchophylla seedlings were used as experimental materials. Four light intensity levels( 100%,70%-75%,30%-35%,5%-10%) were set up with different layers of black shading net. With the decrease of light intensity,the results showed that the plant height,basal diameter and biomass( root,stem,leaf and hook) of U.rhynchophylla seedlings exhibited the trend of &quot; increase-decrease&quot;. Under 70%-75% light intensity,the plant height,basal diameter,biomass( root,stem,leaf,hook) of U. rhynchophylla seedlings were significantly higher than those of other treatments( P&lt; 0. 05);under 5%-10% light intensity,the plant height,basal diameter and biomass( root,hook) of U. rhynchophylla seedlings were significantly lower than those of other treatments( P&lt;0. 05). With the decrease of light intensity,the chlorophyll content of U. rhynchophylla seedlings increased gradually: under 100% light intensity,the chlorophyll content of U. rhynchophylla seedlings were the smallest,while under 100% light intensity,its chlorophyll content was the highest. With the decrease of light intensity,the contents of rhynchophylline and isorhynchophylline in different organs of U. rhynchophylla seedlings varied: under 30%-35% light intensity,the contents of rhynchophylline and isorhynchophylline in hooks and rhynchophylline content in stems were the highest; under 5%-10% light intensity,the contents of rhynchophylline and isorhynchophylline in leaves and stems of U. rhynchophylla were the highest. In conclusion,70%-75% light intensity is suitable for seedling growth and biomass accumulation,and 30%-35% light intensity is suitable for the accumulation of effective components in U. rhynchophylla seedlings.

Film formation and mechanical properties of an opaque titanium dioxide and transparent polyvinyl alcohol composite films

AbstractMechanical, optical, and film formation properties of titanium dioxide/polyvinyl alcohol (TiO2/PVA) composites were studied. Two identical experimental sets of % TiO2 content were prepared that one set is in the range of 1, 3, 5, 7, 10, 13, and 20 wt% for the film formation and the second set is 5 and 50 wt% for the mechanical measurements. Photon transmission technique (PT) at room temperature was used for the film formation process after annealing for 10 min at the temperatures changing from 100 to 270°C. The increase and decrease in the transmission light intensity (Itr) from the composite films were attributed to void closure and interdiffusion models, respectively. The results were consistent with the data obtained from the film formation processes and mechanical measurements that the addition of TiO2 in PVA had remarkable improvement on mechanical properties, for example, increment in the Young's modulus and the rigidity as TiO2 content increased from 5 to 50 wt%, and it had also good film forming especially above 10 wt% TiO2 for the void closure processes leading to lower the activation energy. It was observed that for the lower content of TiO2 such as 5 wt%, the tensile strength and Young's modulus increased remarkably for heating temperature increased up to 150°C. However, with the increase of TiO2 content, the maximum values of the mechanical strength and modulus were shifted to 180°C for 50 wt% TiO2 from 150°C for 5 wt% TiO2 because of the thermal stability of TiO2.

Melatonin and corticosterone profiles under polar day in a seabird with sexually opposite activity-rhythms

The 24 h geophysical light-dark cycle is the main organizer of daily rhythms, scheduling physiology and behavior. This cycle attenuates greatly during the continuous light of summer at polar latitudes, resulting in species-specific and even individual-specific patterns of behavioral rhythmicity, but the physiological mechanisms underlying this variation are poorly understood. To address this knowledge gap and to better understand the roles of the hormones melatonin and corticosterone in rhythmic behavior during this ‘polar day’, we exploited the behavior of thick-billed murres (Uria lomvia), a charadriiform seabird with sexually opposite (‘antiphase’) activity-rhythms that have a duration of 24 h. Melatonin concentration in the plasma of inactive males was unexpectedly high around midday and subsequently fell during a sudden decrease in light intensity as the colony became shaded. Corticosterone concentration in plasma did not vary with time of day or activity in either sex. While the reasons for these unusual patterns remain unclear, we propose that a flexible melatonin response and little diel variation of corticosterone may be adaptive in thick-billed murres, and perhaps other polar birds and mammals, by stabilizing glucocorticoids’ role of modulating energy storage and mobilization across the diel cycle and facilitating the appropriate reaction to unexpected stimuli experienced across the diel cycle while attending the colony.

Fabrication of Milk Fat Sensor based on Plastic Optical Fiber

The research about milk fat content based on plastic optical fiber sensor using gamma and spiral spring without cladding configurations has been reported. LED light transmitted through the plastic optical fiber to be received by the phototransistor. Changes in milk fat content affect the light intensity received by the phototransistor. Sensor output voltage amplified by a differential amplifier and then the analog signal converted into the digital signal by the Arduino Uno microcontroller furthermore, the output voltage read on a computer. The milk fat content sample with a percentage of 0.773 % to 4.473 % affect the propagation of light in the core of plastic optical fiber results in power losses that occur so that the light intensity decreases and the output voltage measured becomes smaller. The results showed that the higher the milk fat content, the sensor output voltage decreases. The best measurements obtained on the spiral spring configuration with 4 windings produce value range 0.044 V, sensitivity 11.887 mV/%, and a resolution of 0.084 %. This method is effective as well as efficiently used as milk fat sensor because it has good sensitivity and resolution.

Responses of seed germination and seedling growth of Cunninghamia lanceolata and Schima superba to different light intensities.

Light is a key factor affecting seed germination and seedling growth. In this study, seed germination and seedling growth of Cunninghamia lanceolata and Schima superba were compared under controlled conditions with five light treatments (100%, 60%, 40%, 15% and 5% of full sunlight). The results showed that light intensity significantly impacted seed germination and seedling growth of both species. With decreasing light intensity, the germination rate and germination index of C. lanceolata increased, while those of S. superba showed a trend which increased first and then decreased, with the maximum at 40% light intensity. The seedling survival rate of both species was 0 under full sunlight, while significantly decreased with decreasing light intensity from 60% to 5%. Root length, basal stem diameter and height showed a consistent trend with the change of light availability in both species. Root length significantly decreased, basal stem diameter and height increased first and then decreased with decreasing light intensity, with the minimum at 5% light intensity. With decreasing light intensity, root biomass, stem biomass, leaf biomass and total biomass of C. lanceolata seedlings declined, while high biomass accumulation of S. superba seedlings were observed in 15%-60% light intensities, and lowest at 5% light intensity. Biomass accumulation in each organ of S. superba seedlings was greater than that of C. lanceolata seedlings under the same light intensity. High stem biomass and leaf biomass, low root biomass and root to shoot ratio were a phenotypic response to low light intensity in C. lanceolata and S. superba seedlings grown under poor light condition. The growth of C. lanceolata is better under relatively high light intensity than S. superba. Whereas S. superba is moderately shade-tolerant at the seedling stage, thus is more suitable for planting under closed canopy.

Strong optical absorption of a metallic film to induce a lensing effect in the visible region

In this work, the two-dimensional profile of the light transmission through a prism-like metallic film sample of Au was measured at a wavelength of 632.8 nm in the visible intraband transition region to verify that, beyond the possible mechanisms of overcoming the diffraction limit, a strongly nonuniform optical absorption path length of the light traveling in the metal could induce a lensing effect, thereby narrowing the image of an object. A set of prism-like Au samples with different angles was prepared and experimentally investigated. Due to the nonuniform paths of the light traveling in the Au samples, lens-effect-like phenomena were clearly observed that reduced the imaged size of the beam spot with decreasing light intensity. The experimental measurements presented in the work may provide new insight to better understand the light propagation behavior at a metal/dielectric interface.

Seed germination traits shape community assembly along a hydroperiod gradient.

Hydroperiod drives plant community composition in wetlands, resulting in distinct zonation patterns. Here, we explored the role of seed germination traits in shaping wetland community assembly along a hydroperiod gradient. Specifically, we tested the hypothesis that seeds of reed, mudflat, swamp, shallow- and deep-water communities only germinate under a specific set of environmental factors characterized by the community-specific optimal conditions for seedling survival and growth. In a three-factorial experiment, we tested the seed germination response of 50 species typical for temperate wetlands of Europe to temperature fluctuations (constant vs. fluctuating temperature), illumination (light vs. darkness) and oxygen availability (aerobic vs. hypoxia). Phylogenetic principal component analysis, cluster analysis and phylogenetic linear regressions were used to confirm the community-specific seed germination niches. Our study revealed the presence of five distinct, community-specific seed germination niches that reflect adaptations made by the study communities to decreasing light intensity, temperature fluctuations and oxygen availability along the hydroperiod gradient. Light as a germination trigger was found to be important in mudflats, swamps and shallow water, whereas the seeds of reed and deep-water species were able to germinate in darkness. A fluctuating temperature is only required for seed germination in mudflat species. Germination of species in the communities at the higher end of the hydroperiod gradient (reed and mudflat) demonstrated a strict requirement for oxygen, whereas swamp, shallow- and deep-water species also germinated under hypoxia. Our study supports the recent argument that the inclusion of seed germination traits in community ecology adds significant insights to community response to the abiotic and biotic environment. Furthermore, the close relationship between seed germination adaptations and community assembly could help reach a better understanding of the existing patterns of wetland plant distribution at local scales and wetland vegetation dynamics, as well as facilitate nature conservation measures and aquatic habitat restoration.

Designing A Low-Cost Surface Plasmon Resonance (SPR) Instrument For Monitoring Degradation Of Milk Quality

A design of a low-cost SPR instrument has been made to monitor the degradation of milk quality. The cost-production of the SPR instruments is much more economical, namely around IDR 10,000,000 where the price of commercial SPR instruments such as nanoSPR6 is $ 9,950. The main components of the instrument are consist of an Arduino Uno microcontroller, red laser, polarizer, stepper motor, prism, gold chip, and a cell phone camera. The light detection system of the instruments is using image processing that utilizes recorded data from the cell phone camera programmed with python software. The sample in this research used is pasteurized milk. The measurement results obtained from the SPR instruments are compared with nanoSPR6. The sensorgram result from the monitoring of pasteurized milk using both SPR instruments for 12 hours and nanoSPR6 for 4 hours has experienced a decrease in light intensity. The light intensity had decreased up to 8 hours from the time of observation and remained flat for the next 4 hours. This decreased intensity states that there is a shift in the angle dip during the monitoring process. This explanation is supported by track mode measurement data by nanoSPR6 that run for 2 hours, showing a change in the angle dip from 67.34° to 67.6°. The increase in angle dip during the monitoring process is because of increasement in the dielectric constant and the density of the milk during the process of quality degradation. In addition, it is also suspected to be due to the appearance of fatty deposits in milk which results in an increase in the milk refractive index. The change of the milk refractive index within 2 hours is 0.0023 obtained by a fitting process using the Winspall software.

Influence of water depth and season on the photodegradation of micropollutants in a free-water surface constructed wetland receiving treated wastewater

Micropollutants such as pharmaceutical products and pesticides are still present in treated wastewater. Several of these compounds are photoactive, either by direct or indirect photodegradation. An innovative on-site experimental protocol was designed to investigate the contribution of photodegradation processes to eliminate micropolluants in constructed wetland (CW). The solar photodegradation of 23 organic micropollutants was studied using in situ photoreactors at different depths. A CW-photodegradation model was designed and calibrated to further scrutinize the contribution of direct and indirect photodegradation processes in the elimination of micropollutants.The results show that photodegradation is most effective in the first 10 cm of the water column. A classification of micropollutants in 3 groups was developed to characterize their photodegradation. A significant increase of the half-life by direct photodegradation was observed in winter compared to summer due to a lower light intensity in winter. On the opposite, for direct + indirect photodegradation, no significant difference was observed between seasons. The decrease in light intensity in winter was compensated by higher nitrates concentration which promoted the formation of hydroxyl radicals and increased indirect photodegradation.The CW-photodegradation model successfully simulated the measured concentrations for direct and indirect photodegradation for 23 micropolluants. Nonetheless, it overestimated the indirect photodegradation with hydroxyl radicals when using default parameter values derived for surface waters. Hence, the consumption of hydroxyl radicals was increased by a factor of 20 for treated water. This model highlighted the predominance of direct photodegradation in the elimination of all micropollutants, except sotalol for the winter campaign.

A Portable and Efficient Solar‐Rechargeable Battery with Ultrafast Photo‐Charge/Discharge Rate

AbstractThe solar‐rechargeable electric energy storage systems (SEESSs), which can simultaneously harvest and store solar energy, are considered a promising next‐generation renewable energy supply system. However, the difficulty in meeting the demands of higher overall photoelectric conversion and storage efficiency (PCSE) with both high power density and large energy density in the current SEESSs severely limit their practical application. Herein, a new class is demonstrated of portable and highly efficient SEESS that uniquely integrates a perovskite solar module (PSM) and an aluminum‐ion battery (AIB) directly on a bifunctional aluminum electrode without any external circuit. Such nanostructural design in the SEESS not only exhibits fast photo‐charge/discharge rate (less than one minute) with high power density (above 5000 W kg−1), but also delivers a high energy density (above 43 Wh kg−1). By rationally matching the maximum power point voltage of PSM with AIB charging voltage, an excellent solar‐charging efficiency of 15.2% and a high PCSE of 12.04% are achieved, which is among the best in all reported portable SEESSs. Moreover, enhanced PCSE is observed as the light intensity decreases, which makes such SEESS immune from the geographical location and climate limitations for diverse practical applications.

Video recording and light intensity change analysis during cataract surgery using an animal model.

To estimate light exposure changes during cataract surgery through intraoperative images simulated from the "patient's perspective" using an animal model. In this experimental study, a 3-mm maculostomy was performed through the posterior globe's surface of 15 porcine eyes. Eyes were fixated to a glass slide and placed over an iPad camera. Video footage of a cataract surgery was obtained through the maculostomy for each eye, keeping light exposure parameters and focus constant. Seventy-five images, five from each eye, were extracted at pre-determined points, and mean gray value (MGV), a light intensity measure, was calculated. Differences in MGV between discrete surgical steps were evaluated using multiple one-sample t-tests. This technique allowed for the capture of a full-length cataract surgery through a 3-mm maculostomy. MGV range was 14.21-132.51. Light intensity was similar across surgeries and varied greatly through each procedure. A 24% decrease in MGV between post-hydrodissection and post-phacoemulsification stages was noted (difference - 18.36; 95% CI - 30.50 to - 6.22; p value = 0.006). A 22.4% decrease in light intensity was noted after phacoemulsification in comparison to the starting image (MGV difference - 16.78; 95% CI - 32.45 to - 1.12; p value: 0.0375). Light intensity was similar at the start and end of surgery (difference - 7.15; 95% CI - 19.35 to + 5.05; p value = 0.229). Light intensity changes through different steps of cataract surgery and may be minimal after phacoemulsification completion. This video and data may serve as informational and educational tools for surgeons and patients.

Effects of different light conditions to the structure and biomass of Emmenopterys henryi seedlings

Emmenopterys henryi is a unique genus of Rubiaceae in China. It belongs to the national precious tree species announced by the Ministry of Forestry. Shading net was used to set 20%, 40%, 60%, 80% shading and natural light (full light) respectively to measure the structure and biomass changes of E. henryi seedlings under different shading conditions. The results showed that the length, dry weight, wet weight and diameter of trunk decreased linearly with the increase of shading degree, and the difference was significant under different light conditions (p < 0.05). With the increase of shading degree, the length, dry weight and wet weight of the first branch of the main trunk of E. henryi seedlings increased first and then decreased. The diameter of the first branch of the main trunk of E. henryi seedlings decreased linearly, and the difference was significant under different light conditions (p < 0.05). With the increase of shading degree, the length and diameter of the main roots of E. henryi showed a linear downward trend, while the dry weight and wet weight showed a wavy trend of first decreasing, then rising and then decreasing, with significant differences under different light environments (p < 0.05). In general, with the decrease of light intensity, the biomass increment of E. henryi seedlings decreased significantly. The result implies that light affects the morphological composition and biomass synthesis of E. henryi seedlings.

The vertical distribution of maraena whitefish (Coregonus maraena) early juveniles in different times of day in a newly created oligotrophic lake

Diel vertical distribution of strictly pelagic juvenile (23–47 mm total length) maraena whitefish Coregonus maraena (Bloch, 1779) was repeatedly investigated in spring primarily using hydroacoustics in the artificial post-mining Most Lake in the Czech Republic. At the same time, an ichthyoplankton trawl was used to identify acoustical targets. During the day, fish performed extensive shoaling behaviour in depths between 2 and approximately 40 m and were not accessible for trawling. By evening, with decreasing light intensity, shoals started to disintegrate and at night fish were relatively homogeneously distributed in the water column from the surface down to a depth of 40 m. Juvenile maraena whitefish could be caught by trawl as the only fish species at night. Shoaling behaviour started again approximately 1.5 h before sunrise. The data showed steep decreases in fish density between the two surveys in spring which indicates significant mortality of early juvenile coregonids as a result of poor availability of zooplankton in a highly oligotrophic post-mining lake.

Effects of light intensities on growth,physiological characteristic and chemical composition of Viola yedoensis

The study is aimed to investigate the effects of light intensities on growth,photosynthetic physiology,antioxidant systems and chemical composition of Viola yedoensis and provide cultivation references for V.yedoensis.Five groups of V.yedoensis were planted under five light intensities conditions,namely 100%,80%,50%,35%,5%of full sunlight,and then morphological index,growth,chlorophyll fluorescence parameters,photosynthetic parameters and antioxidant enzyme system indexes were measured during harvest.The results showed that there was no significant difference in the biomass of V.yedoensis among 35% -100%full sunlight,but the biomass of those were significantly higher than that in the 5%full sunlight treatment(P<0.05).The net photosynthetic rate,transpiration rate,stomatal conductance,intercellular CO_2 concentration and water use efficiency increased firstly and then decreased with the decrease of light intensity;F_m,F_v/F_mand Yield in 5% full sunlight treatment were significantly lower than those in the other four groups(P<0.05).The structure of chloroplast was normal under light intensity ranged from 50%to 100% full sunlight.The lamellar concentration of chloroplast matrix decreased and the starch granules decreased in 35% full sunlight treatment,and the margin of lamellar layer of chloroplast and substrate were blurred,and the starch granules were small and the number of starch granules decreased significantly under 5% full sunlight.MDA content in 5%full sunlight treatment was significantly higher than those in the other four groups(P<0.05).The total coumarin content and total flavonoid content decreased with the decrease of light intensity.In summary,the light in-tensity range suitable for the growth of V.yedoensis is wide(ranging from 35% to 100% full sunlight).The content of flavonoids and coumarins is positively correlated with light intensity.

Dynamic leaf energy balance: deriving stomatal conductance from thermal imaging in a dynamic environment.

In spite of the significant progress made in recent years, the use of thermography to derive biologically relevant traits remains a challenge under fluctuating conditions. The aim of this study was to rethink the current method to process thermograms and derive temporal responses of stomatal conductance (gsw) using dynamic energy balance equations. Time-series thermograms provided the basis for a spatial and temporal characterization of gsw responses in wheat (Triticum aestivum). A leaf replica with a known conductance was used to validate the approach and to test the ability of our model to be used with any material and under any environmental conditions. The results highlighted the importance of the co-ordinated stomatal responses that run parallel to the leaf blade despite their patchy distribution. The diversity and asymmetry of the temporal response of gsw observed after a step increase and step decrease in light intensity can be interpreted as a strategy to maximize photosynthesis per unit of water loss and avoid heat stress in response to light flecks in a natural environment. This study removes a major bottleneck for plant phenotyping platforms and will pave the way to further developments in our understanding of stomatal behaviour.

Interface electric field confinement effect of high-sensitivity lateral Ge/Si avalanche photodiodes

A novel lateral Ge/Si avalanche photodiode without a charge region is investigated herein using device physical simulation. High field is provided by the band-gap barrier and build-in field at the Ge/Si interface in the vertical direction. Modulating the Si mesa thickness (0-0.4 μm) and impurity concentration of the intrinsic Si substrate (1 × 10 16 -4 × 1016 cm -3 ) strengthens the electric field confinement in the substrate region and provides a high avalanche multiplication in the Si region. When the Si mesa thickness is 0.3 μm, and the impurity concentration of the Si substrate is 2 × 10 16 cm -3 , the Lateral Avalanche PhotoDiode (LAPD) exhibits a peak gain of 246 under 1.55 μm incident light power of -22.2dBm, which increases with decreasing light intensity.