Light Pulses Research Articles

Intense pulsed light versus pulsed dye laser in the treatment of nail psoriasis: Intra-patient left to right comparative controlled study.

Background Until now, the management of psoriatic nails has not been satisfactory. Pulsed dye laser (PDL) as well as intense pulsed light (IPL) have been evaluated separately for the management of psoriatic nails and proved to be effective. Aim This study aimed to measure and compare the usefulness as well as the safety of intense pulsed light versus pulsed dye laser for the management of psoriatic nails. Methods The psoriatic fingernails of 20 patients were managed using intense pulsed light on one hand and pulsed dye laser on the other. Two to three psoriatic nails were left without treatment as controls. The therapeutic sessions were conducted monthly for a period of 6 months. Evaluation of the clinical outcomes was assessed by a blinded dermatologist depending on the total, nail bed, nail matrix, modified and target NAPSI scores. Patient global assessment, in addition to Nail Psoriasis Quality of Life (NPQL10), was performed to assess the response to the therapy. Results A significant reduction in the total, target and modified NAPSI scores from baseline to the end of the study was detected, but no significant differences were detected between the two treatments. The responses of the nail matrix and bed lesions to both modalities were nearly the same. All patients stated that the two devices were efficient and improved their quality of life. The intense pulsed light treatment was more painful. Complete clearance of nail lesions was not obtained. Limitations Lack of long-term follow-up of cases and preset laser parameters were the major limitations of this study. Conclusion Intense pulsed light, like pulsed dye laser, is safe and efficient in treating nail psoriasis; however, the former is more painful. Dermoscopy had an additive function in analysing the response of nail psoriasis to therapy.

Optical solitons for 2D-NLSE in multimode fiber with Kerr nonlinearity and its modulation instability

This paper deals with the soliton solutions for beam movement within a multimode optical fiber featuring a parabolic index shape. It is considered that a Two-Dimensional Nonlinear Schrödinger Equation (2D-NLSE) with an instantaneous Kerr nonlinearity of the kind can represent the beam dynamics. Nonlinear Multimode Optical Fibers (MMFs) of this kind are gaining popularity because they provide novel approaches to control the spectral, temporal, and spatial characteristics of ultrashort light pulses. We gain the optical soliton solutions for the nonlinear evolution beam dynamics using the Jacobi Elliptic Function Expansion (JEFE) method. The exact analytical solution of Nonlinear Partial Differential Equations (NLPDEs) can be achieved with wide application using the effective JEFE approach. These solutions are obtained in the form of dark, bright, combined dark–bright, complex combo, periodic, and plane wave solutions. Additional solutions for Jacobi elliptic functions, encompassing both single and dual function solutions, have been acquired. This approach is based on Jacobi elliptic functions, which will provide us the exact soliton solutions to nonlinear problems. Additionally, we will analyze the Modulation Instability (MI) for the underlying model. Moreover, we show the physical behavior of the beam propagation in a multimode optical fiber the three-dimensional, two-dimensional, and their corresponding contour plots are dispatched using the different values of parameters.

Soliton unveilings in optical fiber transmission: Examining soliton structures through the Sasa–Satsuma equation

The exploration of higher-order and multicomponent extensions of the nonlinear Schrödinger equation holds significant importance across diverse applications, notably within the field of optics. Among these equations, the integrable Sasa–Satsuma equation stands out for its captivating soliton solutions. The Sasa–Satsuma equation serves as a mathematical representation for describing the propagation of femtosecond light pulses through optical fibers. The breather, multiwave, combined dark–bright, singular, dark, bright and periodic singular optical soliton solutions are derived in this paper by using the 1φ(ϑ),φ′(ϑ)φ(ϑ) and multivariate generalized exponential rational integral function approach. Furthermore, the paper emphasizes the essential fiber parameters essential for the emergence of these structures and offers visual representations of chosen solutions to elucidate their physical characteristics. The novelty of this work lies in the inaugural application of these methods to the Sasa–Satsuma equation and gives a significant advancement in the understanding of optical phenomena. This study not only opens avenues for further research but also introduces a fresh perspective on the Sasa–Satsuma model in the field of nonlinear physics with its applications in optical systems.

Electronic Coherences Excited by an Ultra Short Pulse Are Robust with Respect to Averaging over Randomly Oriented Molecules as Shown by Singular Value Decomposition.

We report a methodology for averaging quantum photoexcitation vibronic dynamics over the initial orientations of the molecules with respect to an ultrashort light pulse. We use singular value decomposition of the ensemble density matrix of the excited molecules, which allows the identification of the few dominant principal molecular orientations with respect to the polarization direction of the electric field. The principal orientations provide insights into the specific stereodynamics of the corresponding principal molecular vibronic states. The massive compaction of the vibronic density matrix of the ensemble of randomly oriented pumped molecules enables a most efficient fully quantum mechanical time propagation scheme. Two examples are discussed for the quantum dynamics of the LiH molecule in the manifolds of its electronically excited Σ and Π states. Our results show that electronic and vibrational coherences between excited states of the same symmetry are resilient to averaging over an ensemble of molecular orientations and can be selectively excited at the ensemble level by tuning the pulse parameters.

Suppression of Thermally Induced Surface Traps in Colloidal Quantum Dot Solids via Ultrafast Pulsed Light.

Thermal annealing (TA) of colloidal quantum dot (CQD) films is considered an important process for recent high-performing CQD solar cells (SCs) due to its beneficial effects on CQD solids, including enhanced electrical conductivity, denser packing of CQD films, and the removal of organic residues and solvents. However, the conventional TA for CQDs, which requires several minutes, leads to hydroxylation and oxidation on the CQD surface, resulting in the formation of trap states and a subsequent decline in SC performance. To address these challenges, this study introduces a flashlight annealing (FLA) technique that significantly reduces the annealing time to the millisecond scale. Through the FLA approach, it successfully suppressed hydroxylation and oxidation, resulting in decreased trap states within the CQD solids while simultaneously preserving their charge transport properties. As a result, CQD SCs treated with FLA exhibited a notable improvement, achieving an open-circuit voltage of 0.66V compared to 0.63V in TA-treated devices, leading to an increase in power conversion efficiency from 12.71% to 13.50%.

Photodynamic therapy with redaporfin activated by pulsed laser light

SignificanceRedaporfin is a photosensitizer under clinical trials for head and neck cancer. In previous work, a continuous light source was used in several tumor models, either in vitro or in vivo. However, the use of pulsed light (PL) sources can bring advantages to photodynamic therapy, such as higher penetration depths. ApproachTo study the influence of the light source in the efficacy of redaporfin-PDT, balb/c mice were inoculated with subcutaneous CT26 tumors. Redaporfin was activated using a PL source at 750 nm, with a repetition rate of 20 Hz and an energy per pulse of 24 mJ/cm2. Illumination time ranged from 5 to 15 min. ResultsThe results show an acute inflammatory response followed by a fast shrinkage and necrosis of the tumors and no significant side effects. ConclusionsThe activation of redaporfin with PL leads to good response of the tumors and further studies are being held to optimize the treatment conditions.

OLED-Pumped Organic Laser Diode

A theoretical analysis is presented for a recently proposed high-speed µ-OLED optically pumped organic laser. We confirm that for this configuration, the laser threshold is reached at a lower current density than in the case of a direct-electrically pumped organic laser diode while generating pulses of order 15 ns duration. With a validated model for the electrically pumped organic light-emitting diode (OLED), we simulate the generation of light pulses. This light is fed into the organic laser section, where it optically pumps the emitting organic medium. The full model includes field-enhanced Langevin recombination in the OLED, Stoke-shifted reabsorption in both the OLED and organic laser, and an optical cavity in the latter. We numerically demonstrate 2 GHz modulation and conjecture the feasibility of ~0.025 Mb/s data transmission with this device.

Spatial extension of the transient gain drop in a microchannel plate for a single-pulse irradiation

It is widely recognized that a microchannel plate gain drops temporarily after a particle initiates an electron avalanche and that a large amount of charge is extracted from the channel. Electron multiplication is expected to deplete the charges from the microchannel and produce depleted charges (wall charges), and this gain drop is known to persist until charges are replenished. In addition, it was reported that a gain drop occurs not only in the activated channels, where the electrons are multiplied, but also in the surrounding channels. A proposed mechanism for this phenomenon is suggested that the wall charges in the activated channels change the electric field in the surrounding channels, which affects the electron multiplications. In this study, the spatial extent of the gain drop of a chevron microchannel plate detector was evaluated by measuring gains as a function of distance from an activated channel. The experiment used two ultraviolet pulses with different beam sizes, which initially activated one channel and the six neighboring channels with carefully focused laser light, and then applied another light pulse to the surrounding 900 μm × 30 μm area. The gain of each channel was measured using a charge-coupled device camera, and the change in gain as a function of the output charge for the laser pulse was analyzed. A gain drop of 20% was observed at a channel located 110 μm far from the initial activated channel when the output charge was 4 pC. The obtained relationship between the radius of gain drop area and the output charge for the laser pulse was in good agreement with that predicted from the transverse electric field due to the wall charges by computational analysis.

Light-induced electronic polarization in antiferromagnetic Cr2O3.

In a solid, the electronic subsystem can exhibit incipient order with lower point group symmetry than the crystal lattice. Ultrafast external fields that couple exclusively to electronic order parameters have rarely been investigated, however, despite their potential importance in inducing exotic effects. Here we show that when inversion symmetry is broken by the antiferromagnetic order in Cr2O3, transmitting a linearly polarized light pulse through the crystal gives rise to an in-plane rotational symmetry-breaking (from C3 to C1) via optical rectification. Using interferometric time-resolved second harmonic generation, we show that the ultrafast timescale of the symmetry reduction is indicative of a purely electronic response; the underlying spin and crystal structures remain unaffected. The symmetry-broken state exhibits a dipole moment, and its polar axis can be controlled with the incident light. Our results establish a coherent nonlinear optical protocol by which to break electronic symmetries and produce unconventional electronic effects in solids.

Using an intense pulsed light (IPL) module for the treatment of pigmented lesions.

Pigmented lesions are largely benign and may lead to extreme distress. Various light and lasers may be used to treat pigmentation, often Q-switched lasers are considered the method of choice, while intense pulsed light (IPL) devices may offer a less invasive treatment with a shorter downtime. The purpose of this study is to evaluate the safety and efficacy of a narrowband IPL module for the treatment of pigmented lesions. A retrospective study of 20 patients with pigmented lesions underwent treatment with an IPL module. Treatment was assessed by blinded evaluation of clinical photographs using a GAIS scale of 0-10, as well as through patient satisfaction ratings on a scale of 0-10. Throughout the treatment, pain levels and adverse events were monitored. The mean GAIS score was 7.55 ± 1.15 (mean ± SD), and the mean patient satisfaction score was 7.3 ± 1.26 (mean ± SD). There was a strong positive correlation between GAIS and patient satisfaction scores (r = 0.83), and no significant difference between them (p-value = 0.516). The number of treatments did not significantly affect GAIS and patient satisfaction scores (p-values 0.364 and 0.126). Additional positive unexpected outcomes were improved skin firmness and reduced wrinkles. The results of the study indicate that the IPL module is both safe and effective in treating pigmented lesions and may have the potential to stimulate collagen production.

Human and animal cells under influence of different lighting and stimulus

Circadian rhythms, are the basis of homeostasis of organisms like human and other mammals. Violation of circadian rhythms leads to the development of pathological conditions and severe course of preexisting pathologies. For example some work with B16-F1O cells (B16) has shown that molecules like opsins, Circadian Locomotor Output Cycles Kaput (CLOCK) and clock genes are changed after a white light pulse (WLP). Like this, melanopsin (OPN4) and rhodopsin (OPN2) through UVA irradiation induced B16 pigmentation. Thus, heat shock reduces secreted rhodopsin expression in normal Melan-a melanocytes, while the opposite effect is found in malignant B16 cells. In both cell lines UVA radiation increases the expression of melanopsin and melanin, interfering with several clock genes, and also increasing the DNA repair enzyme xeroderma pigmentosum, complementation group A (XPA). Furthermore, B16 are more responsive to UVA radiation when compared to normal cells. Thereby, opsins are involved in animal camouflage. And their functions in humans involve different wavelengths, for example in skin the keratinocyte differentiation by (410 nm) involved cone opsin (OPN1) and rhodopsin (OPN2), like this in epidermal keratinocytes irradiation by (447 nm) accelerates closure in wound-healing and violet light (415 nm) induced hyperpigmentation. Furthermore, in B16 cell culture certain wavelengths induce proliferation or inhibition like signs of apoptosis and necrosis. Finally understanding the response of opsins and clock genes to different wavelengths in the skin, we could attribute a therapeutic of photobiomodulation (PBM) to approach various dermatological conditions, such as psoriasis, atopic dermatitis, hair growth, wound healing and tissue regeneration.

Intense pulsed light as an alternative treatment for erythematotelangiectatic rosacea: a case report

Intense pulsed light as an alternative treatment for erythematotelangiectatic rosacea: a case report

Femtosecond pulsed laser photodynamic therapy activates melanin and eradicates malignant melanoma

Photodynamic therapy (PDT) relies on a series of photophysical and photochemical reactions leading to cell death. While effective for various cancers, PDT has been less successful in treating pigmented melanoma due to high light absorption by melanin. Here, this limitation is addressed by 2-photon excitation of the photosensitizer (2p-PDT) using ~100 fs pulses of near-infrared laser light. A critical role of melanin in enabling rather than hindering 2p-PDT is elucidated using pigmented and non-pigmented murine melanoma clonal cell lines in vitro. The photocytotoxicities were compared between a clinical photosensitizer (Visudyne) and a porphyrin dimer (Oxdime) with ~600-fold higher σ2p value. Unexpectedly, while the 1p-PDT responses are similar in both cell lines, 2p activation is much more effective in killing pigmented than non-pigmented cells, suggesting a dominant role of melanin 2p-PDT. The potential for clinical translational is demonstrated in a conjunctival melanoma model in vivo, where complete eradication of small tumors was achieved. This work elucidates the melanin contribution in multi-photon PDT enabling significant advancement of light-based treatments that have previously been considered unsuitable in pigmented tumors.

Analysis of the Efficacy of Intense Pulsed Light Combined with Doxycycline in the Treatment of Rosacea

Objective: To investigate the clinical efficacy of intense pulsed light combined with doxycycline in the treatment of rosacea. Methods: A sample of 60 patients with rosacea admitted to our hospital from January 2021 to December 2023 were selected and grouped into the observation group (n = 30) and the control group (n = 30) by using the randomized numerical table sampling method. The patients in the control group were treated with doxycycline, and the patients in the observation group were treated with intense pulsed light combined with doxycycline. The clinical effective rate and recurrence rate, clinical symptom score, skin barrier function indexes, and the incidence of adverse reactions in the two groups were compared. Results: The clinical effective rate of the observation group was higher than that of the control group, and the recurrence rate was lower than that of the control group (P < 0.05); the clinical symptom score of the observation group was lower than that of the control group after treatment (P < 0.05); the water content of the stratum corneum of the observation group was higher than that of the control group after treatment, and the amount of transepidermal water loss was lower than that of the control group (P < 0.05); the incidence of adverse reactions of the two groups did not have any significant difference in comparison (P > 0.05). Conclusion: The treatment effect of intense pulsed light combined with doxycycline in rosacea patients is remarkable. It can alleviate clinical symptoms and improve the skin barrier function, with a lower recurrence rate after treatment and higher therapeutic safety, which is suitable for popularization and use in healthcare institutions.

Photonic curing for innovative fabrication of flexible metal oxide optoelectronics

Flexible optoelectronics, based on non-planar substrates, hold promise for diverse applications such as wearables, health monitors, and displays due to their cost-effective manufacturing methods. Despite the superior properties of metal oxides, the challenge of processing them at high temperatures incompatible with plastic substrates necessitates innovative annealing approaches. Photonic curing, which delivers microsecond to millisecond broadband (200–1500 nm) light pulses on a sample, emerges as a viable solution. Depending on the optical properties, the targeted film absorbs the radiant energy resulting in rapid heating while the transparent substrate absorbs a minimal amount of light and remains at ambient temperature. The light intensity can be high, but since the light pulse is short, the total energy absorbed by the sample remains low and will not damage the plastic substrate. This perspective explores the innovative application of photonic curing to fabricate flexible metal oxide optoelectronics, including thin-film transistors, metal–insulator–metal devices, solar cells, transparent conductors, and Li batteries, emphasizing the conversion of sol–gel precursors to metal oxides. However, this technique was initially developed for sintering metal nanoparticles to conductive patterns and poses intriguing challenges in explaining its mechanism for metal oxide conversion, especially considering the limited absorption of visible light by most sol–gel precursors. The review delves into UV-induced photochemistry, common flexible metal-oxide optoelectronic components, and non-intuitive distinctions between photonic curing and thermal annealing. By elucidating the distinctive role of photonic curing in overcoming temperature-related challenges and advancing the fabrication of flexible metal oxide optoelectronics, this perspective offers valuable insights that could shape the future of flexible optoelectronics.

Dual Mode Optoelectronic Devices Based on 2D Single Crystalline VO2 Films with Controlled Metallic Domain Regime Induced Variable Hysteresis

AbstractThe multimode optoelectronic operation in a single component device is an attractive design strategy for future optoelectronics, which demands unique and complex multifunction. Here, a novel dual‐mode optoelectronic device with both memory and switching functionalities by utilizing alternating metallic stripe domain regime‐induced controllable hysteresis of two dimensional (2D)‐crystalline VO2 films is reported. It is found that the formation and disappearance of tensile strain‐induced metallic stripe domain arrays are susceptible to temperature‐induced thermal energy, allowing controllable hysteresis in electric field‐induced metal‐insulator transition (E‐MIT) by tuning the total region of aligned metallic stripe domains within the VO2 films through current flow‐induced thermal energy. Based on the tunable hysteresis in E‐MIT, the 2D‐crystalline VO2 film‐based device exhibits successful multimode optoelectronic memory and switching operations. The device with a large hysteresis width exhibits high‐performance optoelectronic memory behavior with a high on/off ratio of up to ≈55% and a long retention time over 5000 s response to a light pulse optically triggering MIT. On the other hand, the 2D‐crystalline VO2 film device with a narrow hysteresis width exhibits high performance of photodetection with a responsivity of 316 mA W−1 and response times of ≈1.2 and ≈2 µs at rise and fall, respectively.

Wireless pulsed nanophotoelectrochemical cell for the ultrafast degradation of organic pollutants

An urgent demand exists for advanced-technologies to efficiently remove persistent organic pollutants from water, while minimizing energy consumption. Here, we introduce an innovative wireless nanophotoelectrochemical (nPEC) cell using pulsed light for the ultrafast degradation/mineralization of organic pollutants. The nPEC cell comprises a nanostructured Si-pn photodiode that monolithically integrates: (i) a Si-n/Au nanowire-based-photocathode for effective light absorption and photovoltage generation, and (ii) a Si-p/mesoporous-NiPt photoanode serving as catalyst to wirelessly amplify the sulfate radical production by low-intensity light without any bias voltage. The efficacy of the nPEC cell was shown by ultrafast degradation (>99 %) and mineralization (>98 %) of three emerging pollutants (tetracycline, levofloxacin and anatoxin-A). Notably, reaction kinetics were boosted by more than one order of magnitude when exposed to light intensities ca. 5-fold lower than sunlight. Remarkably, pulsed light beams in the 100–500 Hz range provided an additional enhancement in the degradation/mineralization efficiencies, reducing energy-input by half, while enhancing the catalyst's oxidation state and durability.

Fully visible light controlled neuro-synaptic ReRAM device based on metal oxide heterojunction

Photoelectric synaptic devices as a combination of electronic synapse and photodetector are considered as emerging bio-inspired device technologies. These devices have immense potential to conquer the bottleneck of von Neumann architecture based traditional computing systems. In this Letter, we propose an all-oxide based photoelectric neuro-synaptic resistive random access memory device with the structure of ITO/Ga2O3/ZnO/ITO/Glass, in which the conductance states are reversibly tuned by two different wavelengths (405/522 nm) of visible light spectrum. The strength of light pulse is altered to investigate the learning and forgetting phases of the photoelectric response of the device. A basic biomimetic function “learning-forgetting-rehearsal” behavior is imitated up to 20 cycles. Moreover, emulation of some typical synaptic functions such as associative learning and switching between short and long term plasticities indicate the wavelength awareness of the device. Based on the pure optically induced potentiation/depression characteristics, convolutional neural network simulation achieves an overall test accuracy of 82.5% for the classification of Zalando's article images. The noise tolerance capability of neural network is also examined by applying “salt and pepper” noise in high proportion (75%) to corrupt the images. This work may provide a promising step toward the development of transparent electronics in optogenetics-inspired neuromorphic computing.

Nonlinear Photodetector Based on InSe p–n Homojunction for Improving Spatial Imaging Resolution

AbstractAn efficient nonlinear photodetector (NLPD) is demonstrated with quadratic response based on a few‐layer InSe p–n homojunction, which is beneficial from the strong second harmonic generation (SHG) process in InSe and effective harvest of photocarriers actuated by the high‐quality homojunction. The NLPD can sense light with photon energy smaller than InSe's electronic bandgap because the SHG process in InSe doubles the frequency of incident light, extending InSe's photodetection wavelength range to 1750 nm. The InSe p–n homojunction, which is electrostatically doped by two split back gates, presents a rectification ratio exceeding 106 with a dark current down to 2 pA and a high normalized responsivity of 0.534 A W−2 for the telecom‐band pulsed light at 1550 nm. The photocurrents of the SHG‐assisted photodetection have a quadratic dependence on the optical powers, making the NLPD highly sensitive to light intensity variation with improved spatial resolution. As examples, the NLPD is employed to precisely determine the localization point of a focused laser beam waist and implement spatial imaging with an improved resolution compared with the linear photodetector. These features highlight the potential of the proposed NLPD in developing advanced optical sensing and imaging systems.

Foveal Retinal Ganglion Cells Develop Altered Calcium Dynamics Weeks After Photoreceptor Ablation

Objective or purposePhysiological changes in retinal ganglion cells (RGCs) have been reported in rodent models of photoreceptor (PR) loss but this has not been investigated in primates. By expressing both a calcium indicator (GCaMP6s) and an optogenetic actuator (ChrimsonR) in foveal RGCs of the macaque, we reactivated RGCs in vivo and assessed their response in the weeks and years following PR loss. DesignWe used an in vivo calcium imaging approach to record optogenetically evoked activity in deafferented RGCs in primate fovea. Cellular scale recordings were made longitudinally over a 10 week period following photoreceptor ablation and compared to responses from RGCs that had lost photoreceptor input more than two years prior. ParticipantsThree eyes received photoreceptor ablation, OD of a male Macaca mulatta (M1), OS of a female Macaca fascicularis (M2) and OD of a male Macaca fascicularis (M3). Two animals were used for in vivo recording, one for histological assessment.Methods: Cones were ablated with an ultrafast laser delivered through an adaptive optics scanning light ophthalmoscope (AOSLO). A 0.5 s pulse of 25Hz 660nm light optogenetically stimulated RGCs, and the resulting GCaMP fluorescence signal was recorded using AOSLO. Measurements were repeated over 10 weeks immediately after PR ablation, at 2.3 years and in control RGCs. Main Outcome measuresThe calcium rise time, decay constant and sensitivity index of optogenetic mediated RGC were derived from GCaMP fluorescence recordings from 221 RGCs (Animal M1) and 218 RGCs (Animal M2) in vivo. ResultsFollowing photoreceptor ablation, the mean decay constant of the calcium response in RGCs decreased 1.5 fold (1.6±0.5 s to 0.6±0.3 s SD) over the 10 week observation period in subject 1 and 2.1 fold (2.5±0.5 s to 1.2±0.2 s SD) within 8 weeks in subject 2. Calcium rise time and sensitivity index were stable. Optogenetic reactivation remained possible 2.3 years after PR ablation. ConclusionsAltered calcium dynamics developed in primate foveal RGCs in the weeks after photoreceptor ablation. The mean decay constant of optogenetic mediated calcium responses decreased 1.5-2-fold. This is the first report of this phenomenon in primate retina and further work is required to understand the role these changes play in cell survival and activity.