This PDF file contains the front matter associated with SPIE Proceedings Volume 11257, including the title page, copyright information, table of contents, and author and conference committee lists.

We will present surface enhanced Raman spectroscopy (SERS) detection of molecules using plasmonic nanoparticles that are embedded in agarose gel and in filter paper-integrated microfluidic channels, respectively. It has been known that, when SERS detection is performed in complex fluids such as cell culture media, a method to reduce interferences from a variety of molecules in the fluids on the detection results is very important. If continuous monitoring of molecules in cell culture media is needed, there should be a method to prevent large molecules such as proteins from reaching SERS substrates when sample solutions flow over the substrates. Since both agarose gel and filter paper can be used to separate molecules by size, in this study we have integrated them with plasmonic nanoparticles for SERS detection in complex fluids. We will report how to use filter paper-integrated microfluidic channels to detect melamine and sodium thiocyanate (NaSCN) in milk using SERS. In addition, we will demonstrate how to use plasmonic agarose gels to detect illegal drug in urine.

Surface Plasmon Resonance (SPR) biosensors are standard tools for chemical and biological sensing. They provide sensitive, real-time and label-free detection of biological species in fluids. However, their performance (time and detection threshold) is now close to the theoretical limit. In particular, at low target concentrations, sensitivity is limited by the diffusion of the target analyte to the sensor surface. To overcome the diffusion limit, non-uniform electric fields can be used to induce electrokinetic effects (dielectrophoresis and alternative-current electroosmosis) which attract analytes toward the surface sensing zone. This work proposes to pattern the gold film used for SPR detection and use it as electrodes for the electric field generation. The magnitude of the electrokinetic effects and resulting analyte trapping efficiency of different electrodes designs were studied numerically with COMSOL by modeling the dielectrophoretic and drag forces induced by the AC-electroosmotic flow. A biochip, which consists of a structured gold film on a glass substrate, was mounted in the SPR Kretschmann configuration in contact with a fluidic cell to enable the injection of analyte and rinsing solutions. SPR imaging allowed us to compare the spatial distribution of the SPR response both a planar metal zone similar to a conventional SPR sensor as well as on the electrodes. After microbeads injection into the fluidic cell and application an AC voltage (V=1V_pp, f=1kHz), a strong SPR signal jump was observed due to the analyte’s arrival on the sensing zone. As a result of the electrokinetic effects, the detection threshold of mass transport assisted SPR chips was improved by several orders of magnitude.

We have demonstrated, numerically and experimentally, that optimized nanostructured plasmonics substrates can generate new hybrid plasmonic modes that possess the spectral dispersion of propagating plasmon but with a much lower propagating length. The imaging performances of these nanostructured SPR chips were recently assessed by studying cellular responses following biochemical stimulation, in particular by real-time monitoring of integrity changes in confluent endothelial cell layer. Improvement in spatial resolution has resulted in an increase in detection sensitivity to cellular activity, with no detectable disturbances in cellular behavior due to the presence of nanostructures.

405 nm light is emerging as a safe alternative to UV light for light-based continuous inactivation of drug resistant bacteria in high risk environments (i.e., hospitals). LED manufacturers are introducing 405-nm room lighting solutions for this purpose. However, inactivation efficiencies of commercial 405-nm technologies are still few orders of magnitude lower than those of UV light. Here, we achieve light 500-fold increased inactivation efficiencies with 405-nm light using radiatively coupled aluminum plasmonic nanoantenna arrays and demonstrated nearly complete deactivation of bacteria (%99,995). Our inactivation scheme opens door to continously self-cleaning surface coatings killing multi-drug resistance bacteria using ambient/room lighting.

Non-invasive in vivo monitoring of the antioxidant level of human skin, e.g. by measuring carotenoid marker substances, can deliver significant data on human health status and can provide diagnostic data during medical treatments. Among others, resonance Raman spectroscopy is a promising contactless tool to detect carotenoids in human skin within the necessary nanomolar concentration range. Unfortunately, laser induced fluorescence and ambient light can obscure the Raman signals even when using the resonance Raman effect and exciting the carotenoids at wavelengths around 500 nm. Here, shifted excitation resonance Raman difference spectroscopy (SERRDS) is a powerful and easyto- use tool separating the wanted from the unwanted signals. For this purpose, a portable clinical diagnostic system including a compact Raman handheld probe and a miniaturized wavelength-tunable frequency-doubled diode laserbased 488 nm light source was developed. The diode laser can be tuned over 2 nm providing the two excitation lines with a flexible spectral distance for SERRDS, resulting fluorescence-free skin Raman spectra. For reliable and representative measurements of human skin, an excitation spot diameter of 3 mm was selected. An excitation power of 9 mW at the sample provides a power density of 1.3 mW/mm² meeting the laser safety regulations with a maximum permissible exposure of 20 mW/mm². A calibration procedure was performed using skin phantoms containing ßcarotene at selected concentrations and a limit of detection of 0.05 nmol g^-1 of β-carotene is achieved using the 3-sigma criterion.

Shifted excitation Raman difference spectroscopy (SERDS) has been successfully demonstrated for separating Raman signals from background interferences. This powerful tool has been applied for in situ applications such as in vivo diagnostics and outdoor investigations. Here, diode lasers are well suited excitation light sources and their compact size and electro-optical efficiency allows integrating them into portable devices such as handheld sensor systems. In the last decade our institute has developed and applied diode lasers for Raman spectroscopy and SERDS at 785 nm. Here, wavelength stabilization is realized using internal frequency selective elements such as distributed feedback (DFB) or distributed Bragg reflector (DBR) gratings. In this contribution, an overview of Raman spectroscopy and SERDS using our diode lasers and diode laser systems emitting at 785 nm will be given. DFB ridge waveguide (RW) lasers providing 0.2 W and wavelength tuning for SERDS via injection current will be discussed. DFB broad area devices with 1 W optical output power suitable for Raman spectroscopy are realized. Dual-wavelength Y-branch DBR-RW diode lasers are developed and show optical powers up to 0.2 W. The devices provide a flexible spectral distance between the two excitation lines via implemented heater elements. Recently, a micro-integrated diode laser based dual-wavelength MOPA at 785 nm with 0.5 W optical power suitable for SERDS has been developed. Laser characteristics and Raman experiments will be presented. The results demonstrate the suitability of these devices for SERDS improving Raman spectroscopy for various applications e.g. under in situ conditions.

In this work, we present surface enhanced Raman scattering (SERS) based sensor chips for applications in nanomedicine. Finite Difference Time Domain (FDTD) simulations in visible, infrared and near-infrared regimes were done to model electric field enhancement in the vicinity of plasmonic nanostructures. Some of the plasmonic nanostructures simulated were present bowtie nanohole arrays and bridged-bowtie nanohole arrays in a gold thin film. Surface enhanced Raman scattering (SERS) substrates based on these nanostructures exhibit large electromagnetic enhancement of SERS. We employ numerical simulations based on the finite difference time domain (FDTD) method to determine the electric field enhancement factors (EFs) and therefore the electromagnetic SERS enhancement factor for these SERS substrates. It was observed that the resonance wavelength of these arrays of nanoholes can be tuned by altering the size of the nanoholes. It was also observed that bridged-bowtie nanohole arrays exhibit very high electric field enhancement factors (EF) for multiple wavelengths. It was observed that bridged-bowtie nanohole arrays exhibit a highest electromagnetic SERS enhancement factor (EF) of ~ 10⁹, which is orders of magnitude higher than what has been previously reported for nanohole arrays as SERS substrates. Hence, these nanostructures can provide SERS enhancement suitable for a few-molecule detection.

Recent progress in microfluidics and optical systems has made enormous impact in the advancement of nucleic acid amplification and detection. However, commercial and currently reported microfluidic PCR devices have not yet found their utilization in point-of-care (POC) applications. This is due to long amplification time, high power requirement, and bulky size of commercial PCR machines or cost-inefficiency, complex fabrication and operation of microfluidic chips. In this work, we present a compact PCR device in which fast amplification is accomplished by photothermal heating of gold nanorods evenly dispersed in PCR reaction by a vertical-cavity surface-emitting laser (VCSEL). This thermocycler offers sub-ten-minute amplification time for 30 thermal cycles with high temperature stability and PCR products comparable to conventional bench-top machines. The proposed device is approximately 100mm×50mm×50mm in size, and its small footprint is obtained by hardware miniaturization. Retaining conventional sample volumes (20μL) makes our device more user-friendly in terms of sample loading and capable of more sensitive amplicon detection for on-site assays. Also, its cost-effectiveness due to disposable AuNRs and inexpensive light source outweigh surface plasmon heating methods utilizing embedded Au films with limited lifetimes and other previously presented plasmonic thermocyclers.

Novel, cost-effective and label-free Bloch surface plasmon biosensors are presented in this work. The biosensor chip consists of Au waveguides on a truncated 1D photonic crystal supporting Bloch long range surface plasmons (LRSPs) to form an optical biosensor. Gratings capable of coupling perpendicularly incident Gaussian beams are employed as the input-output means. The waveguides are covered with a low index fluoropolymer, etched to form the microfluidic channels and wafer bonded to seal and enable side fluidic interfaces. The devices are fabricated using wafer-scale processes and are capable of multichannel multimodal biosensing. Similar sensitivities to LRSPPs in the corresponding fluoropolymer/solution system are expected with Bloch LRSPPs.

In this work, we report a new SPR sensor configuration which enables a single-point detection strategy for 2D angular interrogated SPR sensor array. The single-point detection strategy for 2D SPR measurements is enabled by the cooperation of two digital micro-mirror devices (DMDs). Specifically, one DMD is used to conduct spatial scanning along the vertical direction of the sensor chip; and the other DMD is used to conduct spatial scanning along the horizontal direction. Thanks to the programmability of DMDs, arbitrary and instant access of interrogation angle and sensing site are achieved with no limitation in integration time. Besides, no mechanical scanning is required in the entire system. This configuration suffices a single-point detector for 2D angular interrogated SPR measurements that can be readily optimized for nearly ideal performance, increased sensing capacity without sacrificing the sensitivity.

Photoacoustic microscopy (PAM) is a novel and hybrid optical and acoustic technique for imaging. This modality can be used for label-free imaging of the retinal microvasculature with ultrahigh resolution and excellent image contrast. However, it is hard to distinguish newly developed microvasculature from native vessels. An exogenous photoabsorber contrast agent can boost the sensitivity and enhance the PAM image contrast. The focus of this study is to investigate the potential application of gold nanostars (GNS) as a contrast agent for multimodal PAM and OCT. GNS were validated on Rose Bengal laser-induced retinal vein occlusion choroidal neovascularization (CNV) rabbit model. Four New Zealand white rabbits were administrated with Rose Bengal (5 mg/kg) followed by laser illumination at a power of 300 mW. CNV developed at day 28 post laser illumination. The rabbit model before and after treatment was monitored by a multimodal imaging system including OCT, PAM, color fundus photographs, fluorescein angiography, (FA) and indocyanine green angiography (ICGA). At day 28 post laser treatment, the rabbits received an intravenous injection of 400 μL GNS at a concentration of 2.5 mg/mL. Multimodal PAM and OCT monitored the GNS at various time points: 1 h, 2 h, 8 h, 24 h, 48 h, 72 h, day 4, day 7, day 9, day 11 and day 14. The experimental results show that the PA signal was enhanced 24-fold and OCT intensity increased 184% 24 h post injection. Histological analysis and TUNEL assay show no evidence of any change in cell nuclear morphology suggesting no damage or cell death. In addition, the liver function tests showed normal liver and kidney function, indicating that GNS induced no toxicity in the rabbit at the treated concentration. Therefore, GNS may provide a safe and potential contrast agent for the detection of the microvasculature in the eye.

We present an all-optical, label-free technology for quantitative, real-time cancer tissue diagnostics on a single, clinically-compatible chip. Periodically-arranged sub-wavelength dielectric nanostructures, known as metasurfaces, are patterned into dielectric layers on glass microscope coverslips, where biopsied tumor tissue sections can be deposited following routine clinical procedure. We numerically and experimentally map the anisotropy and orientation of collagen fibers, a quantitative marker of cancer stage in tissue, onto metasurface structural color. Working at the interface of nanoscale optics and medicine, our colorimetric metasurface platform has the potential to set a new benchmark for rapid, quantitative and cost-effective cancer tissue diagnostics.

Infrared spectroscopy enables the investigation of conformational protein changes, associated with human diseases, such as Diabetes II or Alzheimer’s disease. However, the in-vitro investigation of individual molecules remains challenging, but could provide insight into mechanisms leading to structural changes. This is due to the lack of suitable light sources, among other things. Here, we detect polypeptide conformations at attomolar concentration within minutes, exploiting Fourier-transform infrared (FTIR) spectroscopy and the plasmonic enhancement of a single resonant nanoantenna, being enabled by using a highly brilliant, broadband mid-IR laser. We successfully determine polypeptide conformations and compare our results to Globar and synchrotron measurements.

Surface Plasmon Resonance (SPR) which is widely used to study interactions between different types of biomolecules, has emerged as a technique of choice for rapid and quantitative analyses. However, there are still some challenges on the use of the classical SPR optical configuration. The prism-based configuration setup requires precise alignment of light onto the sample surface and the oblique reflection angle plane yield optical aberration. In this work we have built, characterized and optimized a simple collinear transmission geometry plasmonic system for the detection of HIV-1. Here, a continuous wave laser at 785 nm with power output of 300 mW was used as light source and a 40X objective lens coupled to a CCD camera was used to collect and detect the transmitted intensity change. Furthermore, a white light source was used to study the wavelength dependency of the sample. We present our findings which may be useful to develop biomedical devices for point-of-care diagnostics and healthcare applications.

We investigate a way to detect images of surface plasmon scattering using deep learning approach. Unlike fluorescence imaging, the image of surface plasmon scattering shows much worse resolution due to propagation length of surface plasmon polariton. In this work, deep learning approach is taken to address this issue and to discriminate multiple target objects under complex and noisy environment. Conventional detection method based on fourier filtering and deconvolution was employed to compare the performance of the proposed method. It was shown that deep learning improves the accuracy by about six times, and especially more useful in noisy environment.

Our group has integrated surface-enhanced Raman scattering (SERS) silver coated gold nanostars on an optical fiber. Fiber-based sensors are an in-situ technology that can simultaneously bring the sensor and light to the sample without disturbing the environment. This technology is a multi-use method that does not require complex sample preparation. Fiber sensors or optrodes, enable the detection of analytes in samples that are difficult to access. Additionally, optrodes allow for specific detection while evading background signals from non-target regions. The fiber-optrode was used to detect miRNA and illegal food additives.

A surface plasmon resonance (SPR) based optical sensor is developed for real-time measurement of nano-scale binding events near a gold surface. The system, which we call confined optical field enhanced fluorescence emission (Cofefe), replaces the cw laser used in SPR devices by a femtosecond source, allowing for the generation and detection of optical non-linearities at the sensor surface. The binding events show up in the detector as diffraction limited spots against a dark background. We also demonstrate that the sensor can reliably register DNA hybridization adsorption events without any bright background or interference patterns that plague the traditional SPRI systems.

Harnessing the unprecedented spatiotemporal resolution capability of light to detect electrophysiological signals has been the goal of scientists for nearly 50 years. Advancements in this field could open new frontiers in neuroscience, cardiology and cellular biology. Yet, progress towards that goal remains elusive due to lack of electro-optic translators that can efficiently convert electrical activity to high photon-count optical signals. Here, we introduce an ultrasensitive and extremely bright nanoscale electric-field probe. Our electro-active plasmonic nanoantenna, offering ~3.25x10^3 times enhanced electric-field sensitivities than conventional plasmonic nanoantennas, overcomes the low sensitivity and photon-count limitations, and enables us to realize optical detection of electric-field dynamics with signal-to-shot-noise ratios (SSNR~ 60-220) from diffraction limited spots. We demonstrate label-free optical recording of field dynamics with sub-millisecond temporal resolution.

Nowadays, with various available choices of non-prescription medication it is quite easy when under illness instead advising with the specialist to self-medicate and try different types of pharmaceuticals at once in order to save time or money. Such unguided or incorrect self-diagnosis of one’s health often results in overdose and other serious health risks. In these cases when such life threatening events occur it is of the most importance to apply early medical treatment. However, specific treatment can be only chosen when the species of pharmaceutical is known. Thus, in order to prevent serious outcomes it is necessary to have a tool which would allow to diagnose the type of drug that was used as soon as possible. The fastest way to gather the required information is to analyze chemically biofluids like blood, saliva or etc. since the pharmaceuticals or their metabolites are contained and transported via biofluids. But the concentration of the molecules to detect is often very low thus the technique not only should be fast but also very sensitive. Of course, there are several clinically available drug screening methods which have already been used for decades and can identify chemical constituents with high sensitivity. Even though such conventional clinically used drug screening methods like liquid chromatography and mass spectroscopy, are sensitive enough, the sample preparation procedure and analysis is not easy and take time. Faster methods would be beneficial and could help avoid serious complications of unguided selfmedication. Vibrational spectroscopy is known to be a reliable tool for chemical composition and structure analysis. Be that as it may, the sensitivity of the conventional vibrational spectroscopy techniques is not sufficient for the detection of trace amounts of molecules. Surface enhanced Raman scattering (SERS) spectroscopy - one of the unconventional methods of vibrational spectroscopy is known to be very sensitive and chemically specific thus suitable for detection of low concentration substances in bodily fluids. This work presents the possible approach of label-free SERS and EC-SERS spectroscopies for application as a faster method for drug screening from biological fluids.

Vibrational spectroscopy is proved to be a reliable technique for biological tissue analysis and screening of pathological differences between healthy and cancerous tissues. Due to the ubiquity and inherent complexity of cancerous diseases together with existing challenges in diagnostic methods, the search for reliable separation of cancerous and healthy tissues is of great importance. In our previous works, we have shown that spectral differences between cancerous and healthy tissues of kidney can be found using FTIR–ATR and surface enhanced Raman scattering (SERS) spectroscopy. SERS allows identification and detection of molecules at low concentration and oversteps sensitivity limits of ordinary spectroscopic methods, thus is available for identification of cancerous tissues in cases where FTIR – ATR technique is not sensitive enough. For remote diagnostic applications (for example during surgeries) experimental configurations employing optical fibers are indispensable. In this work, we investigated the technical aspects of using optical fibers to accomplish SERS of biological tissues. For this purpose, we used commonly available optical fiber types: fused silica and acrylic glass (PMMA). One end of the fiber was coated with Ag nanoparticles. Different coating techniques were applied, such as formation of a self-assembled monolayer of the nanoparticles or drying of colloidal nanoparticle suspensions. Fiber-based SERS spectra of cancerous and healthy kidney tissues were analyzed. We found that reasonable quality fiberbased SERS spectra of normal and cancerous kidney tissue can be obtained through silica fiber with SERS activated tip. Furthermore, a distinction between cancerous and healthy kidney tissues from SERS spectra is found as cancerous kidney tissues contain spectral bands of glycogen which can be used as spectral markers of cancerous cells.

Surface-enhanced Raman spectroscopy (SERS) has enormous potential as a highly sensitive (to a single-molecular level) and molecular-specific analytical technique for biological imaging and sensing. For the reliable SERS sensing, fabrication of metal nanostructures bundle patterns with multiple narrow nano-gaps over the homogenous macroscale is important pre-requisite due to their enhanced properties. Unfortunately, the fabrication of dense and uniform nano-gaps without organic materials is rather difficult since they usually have required complicated and a number of synthetic steps. In this research, we propose a facile and efficient methodology for manipulation of nano-gap densities inside Ag bundle patterns (ABPs) by controlling the Ag nanostructure size over a large area. Especially, we successfully demonstrate the fabrication of high-density small nano-gaps (about 2.5 nm) between silver nanostructure array patterns. We generated uniform nano-hole patterns over the entire substrate through nano-imprint lithography and silver nanostructures were deposited via electrodeposition. The relative size of Ag nanostructure elements was controlled by the Ag precursor concentration. Finally, we fully demonstrate their application in the rapid detection of rhodamine 6G (R6G) molecules by SERS with a very low detection limit as well as excellent signal uniformity, indicating an extraordinary capability for single-molecule detection.

Surface-Enhanced Raman Scattering (SERS) has emerged as a powerful technique for sensitive detection of a wide variety of substances including drugs, pesticides, and biological molecules. Despite its potential as a broadly applicable detection strategy, quantitative studies using SERS have been hindered by substrate performance variability. We recently reported an in situ calibration method that merges inkjet dispense with SERS (ID-SERS), yielding quantitative measurements with Relative Standard Deviation (RSD) values below 2%. In this work, we provide a conceptual review of ID-SERS, highlighting the advantages of using inkjet to pattern microdroplets (28 pL) on the surface of a single SERS sensor and produce standard curves on a single SERS sensor. We subsequently explore the application potential of IDSERS by producing ID-SERS response curves for adenine and pyocyanin, two well-known metabolites that are biomarkers for bacterial detection. We then report preliminary results that suggest that ID-SERS can be harnessed to detect time-dependent changes in the spectra of metabolites released by bacteria under nutrient-deprived conditions. The ability to use ID-SERS to monitor the time-evolution in the SERS spectra of nutrient-deprived bacteria has implications for developing a SERS-based method for antibiotic susceptibility testing. More generally, we believe that the benefits afforded by ID-SERS will facilitate the development of reproducible plasmonic sensing for real-world applications.

Recently, the biological sensors based on surface plasmon resonance (SPR) have been highly investigated due to their versatile application in the field of medicine and pharmacy. In this study, we introduce a Kretschmann based sensor including a BK7 prism, gold, Pb₅Ge₃O₁₁ (PGO) and graphene layers. The special optical properties of the ferroelectric PGO layer plays a key role on improving the sensor performance. Initially the sensing sample is considered to be water where the sensor is sensitive to the refractive index changes of the sensing medium, Δn=0.005 (RIU), connected to outer layer. The structure sensitivity and the figure of merit (FOM) obtained as 228.22 (Deg/RIU) and 22.36 (1/RIU) at the wavelength of 632.8nm, respectively, which are higher than conventional structures properties. The main goal of the introduced sensor is to detect hypothyroidism caused by deficiency of thyroid hormones that is directly related to lack of hemoglobin level in the human body. According to the relationship between hemoglobin concentration and refractive index of blood, the sensor can be used to diagnostic tool. Also, by replacing blood profile of healthy people and patients into sensor structure some characteristics such as FWHM and reflectivity is obtained. Eventually, any impairment in refractive index of blood due to disease is recognizable with this group of sensors. For example, the achieved FWHM and reflectivity are 10.4308 (Deg) and 0.4739 (a.u) for healthy people and 10.3862 (Deg) and 0.4482 (a.u) for patients, respectively.

The discovery of new treatments for cancer is imperative. Recently, we showed in a proof-of-concept study that SYnergistic IMmuno PHOtothermal NanotherapY (SYMPHONY) is a powerful treatment for metastatic bladder cancer and brain tumor in mouse models. Our work has recently demonstrated that combining immunotherapy checkpoint inhibitors and gold nanostar (AuNS) photothermal therapy (PTT) is more effective in killing primary tumors and activating the immune system to eradicate tumors at distant sites, than each individual treatment alone. When the tumor is being ablated via PTT in mice models, using low intensity heat from a near infrared laser, the dying tumor releases proteins that trigger the immune system to destroy remaining tumor cells. Immune checkpoint inhibitors prevent the tumor cells from hiding from the immune system’s mechanisms; thus, the immune system becomes capable of attacking distant secondary tumors, after the primary tumor has been eradicated using AuNS mediated PTT. The data shows that after the cured mice were rechallenged with bladder cancer cells, no tumor formation was observed after 60 days; hence these results indicate that the SYMPHONY treatment can function as a cancer vaccine and lead to long-lasting immunity.

Further understanding of biomass producing associated metabolic pathways in plants can be used to increase the production of biomass. In vivo detection of these markers has proved to be limited due to complex sample preparation required by traditional methods. Recently the Vo-Dinh group has designed a platform to detect nucleic acid targets in biological systems called inverse molecular sentinels which utilize surface-enhanced Raman scattering. These multimodal probes were shown to detect and image key microRNA within whole plants in vivo. This work lays the foundation for detecting and imaging biological markers in plants with enhanced spatial and temporal resolution.

Raman spectroscopy provides vibration and rotation modes of the molecule, and directly reflects the molecular structure of the analyte. Surface enhanced Raman spectroscopy may be applied to practical applications because greater Raman scattering cross section. This paper proposed a large-area nanoslit array Surface Enhanced Raman Scattering (SERS) substrate which is cost effective. By exciting two resonance modes and coupling them together simultaneously, a strong local electromagnetic field was obtained. Up to 10⁸ Raman signals enhancement factor was achieved. Down to 10^-15 M minimum detection concentration was achieved. This substrate can be used as surface plasmonic resonance (SPR). Super-high electromagnetic field enhancement effect also can improve the sensitivity of SPR detection.

In this paper, we propose illumination beam shaping using azimuthal Walsh filters derived from azimuthal Walsh functions, in and around the focal plane of a rotationally symmetric imaging system and studied for finding out self-similar groups and sub-groups for different orders to examine self-similarity existing between them and their corresponding transverse intensity distributions at the far-field plane. The unique rotational self-similarities observed in 2D intensity distributions at the transverse far-field plane for adjacent orders of azimuthal Walsh filters are also presented. Practical implementations of these filters are achievable by the availability of high speed spatial light modulators (SLMs) which can be successfully used to code and control illumination in and around the tightly focused field and coupling of light into metamaterials, plasmonic structures and waveguides. Further scope of research is intended to develop a new photonics platform based on dielectric surface wave harvesting model controlled by the dynamically variable illumination using azimuthal Walsh filters. Surface waves such as Bloch Surface Waves (BSW) and Surface Plasmons (SP) can be considered as the future enabling tools using this concept for probable applications in Photonics Research as well as in Industrial sectors, namely, quantum optics, telecom, sensing, computing, security, imaging and medical applications.