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Potasek M.J.,Simphotek, Inc. | Potasek M.J.,Courant Institute of Mathematical Sciences | Parilov E.,Simphotek, Inc.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

We describe a unique mathematical/numerical model to analyze ultrafast laser experimental data and obtain two-photon (TPA) and multi-photon (MPA) absorption parameter(s). The material used to demonstrate the numerical method is a hybrid organic-inorganic nano-structured semiconductor quantum dot-polymer composite. Chemical, biological and engineering studies require advancements in TPA/MPA absorbers for microscopy, fluorescence, imaging, and microprocessing of materials. We illustrate the numerical method by fitting data from the well-known z-scan experimental method. Often an analytical model is used to analyze data from such experiments, which is limited in scope with certain restrictions on laser intensity and material thickness. A more general mathematical/numerical method that includes TPA/MPA and can be extended to free carrier absorption and stimulated emission is described. Under certain circumstances, we can also calculate the electron population density on every electronic level to demonstrate physical effects such as saturation. Additionally, we include diffraction in our numerical calculation so that the TPA/MPA can be obtained even for thick optical samples. We use the numerical method to calculate published z-scan measurements on quantum-dot CdS-polymer composites, and show excellent agreement with published analytical results. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Parilov E.,Simphotek, Inc. | Potasek M.J.,Simphotek, Inc. | Potasek M.J.,Courant Institute of Mathematical Sciences
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

We have developed a mathematical/numerical framework based on computational transition modules and measured ultrafast laser light propagating through nonlinear materials. The numerical framework can be applied to a broad set of photo-activated materials and lasers, and can optimize photo-physical parameters in multi-photon absorbers. Two photon (TPA) processes are particularly useful in many applications including fluorescence imaging, optical data storage, micro-fabrication, and nanostructured quantum dots for optical limiters. Laser transmission measurements of the organic molecular chromophore, AF455-known TPA material-were taken with a 175 fs, λ 0=780nm, plane-polarized light pulses from Ti:S regenerative amplifier into a 5.1mm thick PMMA slab doped with the chromophore. The range of input energies (intensities) in this experiment was 0.01μJ (0.97 GW/cm 2) to 25 μJ (2.4 ×10 3 GW/cm 2). Experiments showed that for intensities beyond several μJ, the material did not saturate as predicted by traditional theory. We included excited-state absorption (ESA), as demonstrated by the absorption spectrum, which still could not account for the deviation. To understand this result we used our framework to show that an unexpected/unknown higher energy level was being populated. We calculated the entire experimental curve from 0.01μJ (0.97 GW/cm 2) to 25 μJ (2.4 ×10 3 GW/cm 2) and found excellent agreement with the experimental data. © 2012 SPIE.

Beeson K.,Simphotek, Inc. | Parilov E.,Simphotek, Inc. | Potasek M.J.,Simphotek, Inc.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

We describe a general numerical method for calculating short-pulse laser propagation in rare-earth-doped materials, which are very important as gain materials for solid-state lasers, fiber lasers and optical amplifiers. The split-step, finite difference method simultaneously calculates changes in the laser pulse as it propagates through the material and calculates the dynamic populations of the rare-earth energy levels at any position within the material and for times during and after the laser pulse has passed through the material. Many traditional theoretical and numerical analyses of laser pulse propagation involve approximations and assumptions that limit their applicability to a narrow range of problems. Our numerical method, however, is more comprehensive and includes the processes of single- and multi-photon absorption, excited state absorption (ESA), energy transfer, upconversion, stimulated emission, cross relaxation, radiative relaxation and non-radiative relaxation. In the models, the rare-earth dopants can have an arbitrary number of energy levels. We are able to calculate the electron population density of every electronic level as a function of, for example, pulse energy, dopant concentration and sample thickness. We compare our theoretical results to published experimental results for rare-earth ions such as Er 3+, Yb 3+, Tm 3+ and Ho 3+. © 2012 SPIE.

Beeson K.,Simphotek, Inc. | Potasek M.J.,Simphotek, Inc. | Parilov E.,Simphotek, Inc.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Using a novel numerical method we show how to optimize the resolution enhancement of stimulated emission depletion (STED) by simulating the entire process including the absorption, overlapping multiple beams and stimulated emission. We provide calculations showing that for fixed donut pulse energy, a longer donut pulse length can result in greater resolution enhancement than a shorter donut pulse length. These results show how it is possible to use our simulations to design the best experimental conditions for STED resolution enhancement and illustrate the importance of having a software program that includes both multiple beams and stimulated emission. © 2015 SPIE.

Potasek M.,Simphotek, Inc. | Parilov E.,Simphotek, Inc. | Hariharan A.,Simphotek, Inc.
Laser Focus World | Year: 2012

Simphotek has developed SimphoSoft, which models light interactions with active materials directly from the user interface. The basic concept reduces the billions of possible photoactivated phenomena to the least common denominator, Simphotek's Transition Modules (TM). The mathematical method links these TMs to the underlying equations used to describe photoactivated interactions in nearly unlimited numbers of configurations. Because the laser light is also changed by the photoactivated material, a mathematical method of coupled equations is also included to combine laser light changes due to the material and changes in the material due to the laser light. The algorithms can cover the entire electromagnetic spectrum. The software allows modeling complex interactions in real time by providing a graphical user interface (GUI) to build energy-level diagrams of arbitrary shape from graphical icons, representing the available TMs. The software automatically maps resulting diagrams to the underlying mathematical equations and solves them numerically with high accuracy.

Potasek M.,Simphotek, Inc. | Parilov E.,Simphotek, Inc. | Beeson K.,Simphotek, Inc.
Laser Focus World | Year: 2013

Simphotek has developed a new algorithm known as the active photonics building block (APBB) method to make calculations of photophysical interactions in materials a fast and straightforward process. The APBB method uses uniquely defined mathematical expressions to link icons on the user interface defining active photonic interactions to the main simulation engine. Material energy-level diagrams can be quickly revised or added, as their fragments are uniquely formulated in terms of building blocks, which provide links between input icons and the simulation engine. The algorithm, combined with well-known electromagnetic algorithms can be used for applications in fiber lasers, rare-earth amplifiers, solar cells, silicon photonics, solid-state lighting, displays, bioimaging, confocal microscopy, microlithography, and others.

Simphotek, Inc. | Date: 2011-06-14

Computer software for CAD-based modeling of photonic interactions of light with materials and devices, and for use in the design and optimization of photonic materials and devices.

Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 225.00K | Year: 2014

DESCRIPTION (provided by applicant): Photodynamic therapy (PDT) is used for treating a variety of medical conditions including cancer. Even after many years of PDT research and the large-scale use of PDT treatments by physicians, there are many aspects ofPDT, such as quantitative predictions for diffusive light propagation and the kinetics of the light-material interactions, that are not well understood. This can lead to a large variation in treatment results In particular, the dosimetry for treatments ischallenging and it is difficult to determine the lasr light energies and the photosensitizer (PS) concentrations that are optimal. In this Phase I SBIR, Simphotek (prime institution), Tech-X (subaward institution) and University of Pennsylvania School of Medicine, i.e. UPenn (subaward institution) will investigate the feasibility of experimentally (UPenn) and computationally (Simphotek/Tech-X) guiding novel and easy-to-use mathematical and numerical methods for PDT. The software product(s) that result

Agency: Department of Health and Human Services | Branch: National Institutes of Health | Program: SBIR | Phase: Phase II | Award Amount: 750.20K | Year: 2016

DESCRIPTION provided by applicant Photodynamic therapy PDT provides for standalone or intraoperative cancer treatment PDT provides a means to treat superficial and or residual disease while minimizing damage to underlying tissues and does not exhibit cumulative cell toxicities distinguishing it from radiation therapy As compared to radiotherapy treatment planning in PDT is often approached in a one size fits all fashion However patient and tumor specific factors such as tissue optical properties and photosensitizer PS levels are critical to the delivery of effective light doses The development of treatment dosimetry tools tha take into account these factors will fill an unmet clinical need and provide for individualized patient treatment An effective PDT treatment dosimetry system stands to improve therapeutic outcomes reduce the need for repeat PDT or additional cell killing therapy and could therefore reduce overall costs in the per patient delivery of cancer related therapy and care The major objective of this SBIR Phase II proposal is to develop and verify prototype software and hardware tools that combine simulations of PS photophysics with light propagation using fast Monte Carlo MC techniques The research of this Phase II SBIR will result in unique prototype dosimetry tools that will be further developed and commercialized in Phase III for use by PDT physicians and researchers to improve patient outcomes This Phase II SBIR has three major aims Aim is to develop prototype software for PDT dosimetry combining light transport using fast Monte Carlo MC techniques and patient PS variability The software should be fast enough for future clinical use in Phase III of this project At the foundation of this system will e Simphotekandapos s novel Active Photonics Building Blocks APBB algorithm with its simple graphical user interface for active photophysics The APBB breaks the computing problem for photophysics into a series of computational building blocks that the software automatically combines to generate the full numerical simulation To include light scattering in the analysis Simphotek has partnered with Tech X Corporation Tech X subaward a leader in the field of high performance computing Tech X has developed MC based scattering infrastructure and has adapted the code in Phase I to model light diffusion and absorption processes in biological tissue The Aim objective is for Tech X and Simphotek to develop a prototype PDT dosimetry tool combining both the software developed in Aim and specialized hardware for high speed simulations Aim is to verify the software hardware simulations by comparing the simulation results to phantom measurements done at the University of Pennsylvania School of Medicine Penn subaward by experts in PDT PUBLIC HEALTH RELEVANCE A critical barrier to continued progress in photodynamic therapy PDT cancer treatments is the general lack of effective treatment dosimetry tools that can provide for individualized patient treatments Our multidisciplinary team proposes to fill this unmet need by greatly improving the computational methods for PDT and subsequently developing unique prototype treatment dosimetry tools that can be easily utilized by PDT physicians and researchers An effective PDT treatment dosimetry system stands to improve patient outcomes reduce the need for repeat PDT or additional cell killing therapy and could therefore reduce overall costs in the per patient delivery of cancer related therapy and care

PubMed | Simphotek, Inc. and Roswell Park Cancer Institute
Type: Journal Article | Journal: Cancers | Year: 2017

Multiple clinical studies have shown that interstitial photodynamic therapy (I-PDT) is a promising modality in the treatment of locally-advanced cancerous tumors. However, the utilization of I-PDT has been limited to several centers. The objective of this focused review is to highlight the different approaches employed to administer I-PDT with photosensitizers that are either approved or in clinical studies for the treatment of prostate cancer, pancreatic cancer, head and neck cancer, and brain cancer. Our review suggests that I-PDT is a promising treatment in patients with large-volume or thick tumors. Image-based treatment planning and real-time dosimetry are required to optimize and further advance the utilization of I-PDT. In addition, pre- and post-imaging using computed tomography (CT) with contrast may be utilized to assess the response.

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