In this work, efficient light coupling into a microdisk capable of sustaining whispering gallery modes is thoroughly investigated, in order to understand the effect of polymer coating on the coupling efficiency. Light coupling within the microdisk from a tapered single mode optical fiber (SMF) is modelled and simulated, in presence and absence of a 100 nm thick polystyrene (PS) shell. The critical coupling parameters, such as the optical fiber distance to the microresonator (dx) as well as the fiber optical properties such as cladding material (nclad) are altered in order to achieve an efficient coupling and accordingly a high-quality factor QF in the microresonator. Results show that the QF of the resonators can exceed 104 only by tuning the geometrical parameter such as coupling distance dx where the ideal dx for uncoated and PS-coated microresonator is 0.55 μm and 0.40 μm respectively. Additionally, the sensitivity of the surrounding medium including the variation of the SMF cladding layer can be improved via using thin PS coatings on the surface of the microresonators.
In this work, the protein content alteration in cancerous versus healthy exosomes is used as the figure of merit in an early stage, label-free, non-invasive, liquid biopsy based cancer diagnosis biosensing method. To do so, an anisotropic effective refractive index is assigned to the exosome, which determines its protein content, according to a minute 3D model of the exosome based on the mean field theory. The modeled exosomes are then positioned in the vicinity of a polymer coated spherical microresonator, capable of distinguishing such slight refractive index alteration. Such ultra-sensitivity is achieved due to adding the shell as it reduces the radiation loss together with the mode volume. Results show that, increasing the amount of protein content in the exosome by even 1%, as a potential cancer biomarker, concludes to 3.5fm wavelength shift in the whispering gallery resonance of the microresonator, and accordingly facilitating early stage cancer diagnosis in a label-free manner.
Gold nanoparticle-mediated hyperthermia is a non-invasive, target-based cancer treatment with significantly reduced side effects compared to conventional treatments. In this work a simulation model for gold nanoparticlemediated hyperthermia is set up and used to investigate the case of a liver tumor located in the vicinity of a hepatic vein. Gold nanorods with optimized size and aspect ratio are embedded within the liver, and the temperature raise under CW laser illumination is calculated, while taking into account the convective heat transfer through blood perfusion. For this purpose, an analytical model based on the Navier-Stokes equation is used. Results show that due to the heat drain in the blood stream, an effective temperature raise is not achievable when the tumor is located in the vicinity of the hepatic vein. Additionally it is shown that even in the case of a 90% occluded vein, the temperature raise with such nanoparticle arrangement is still not enough for tumor ablation.
KEYWORDS: Absorption, Optical design, Remote sensing, Binary data, Teeth, Thin film solar cells, Solar cells, Active optics, Plasmonics, Integrated optics
We propose the use of one-dimensional semiperiodic front and back gratings based on Thue–Morse, Fibonacci, and Rudin–Shapiro (RS) binary sequences as promising photon management techniques for enhancing ultra-broadband optical absorption in thin-film solar cells. The semiperiodicity allows an aggregate light in-coupling into the active layer within the range of the solar spectrum that is less weak compared to an inherently broadband random grating, but has a much larger bandwidth than the strong in-coupling via a periodic grating configuration. The proper design procedure proposed here deviates from a canonical double grating synthesis as it adheres to an ultra-broadband design where the spectrally integrated absorption in the active material is the proper subject to optimization, leaving the grating perturbations just a measure to perturb and mold the trapped light field in the active layer accordingly. It is shown that by using a well-defined RS double grating in a 400-nm thick crystalline silicon solar cell, a 110.2% enhancement of the spectrally integrated optical absorption can be achieved relative to the reference case without grating.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.