Advances in Plasmonic Technologies for Point of Care Applications

Demand for accessible and affordable healthcare for infectious and chronic diseases present significant challenges for providing high-value and effective healthcare. Traditional approaches are expanding to include point-of-care (POC) diagnostics, bedside testing, and community-based approaches to respond to these challenges. Innovative solutions utilizing recent advances in mobile technologies, nanotechnology, imaging systems, and microfluidic technologies are envisioned to assist this transformation.National Institutes of Health (U.S.) (RO1 AI093282)National Institutes of Health (U.S.) (RO1 AI081534)National Institutes of Health (U.S.) (U54EB15408)National Institutes of Health (U.S.) (R21 AI087107

Telekomünikasyon Aralığında Yenilikçi Optoelektronik Aygıtların Üretimine Yönelik Optik Malzemelerin Femtosaniye Lazer ile Mikro-Modifikasyonu

TÜBİTAK MFAG Proje01.03.20181,5 ?m dalgaboyunu kullanan telekomünikasyon teknolojilerinin hızlı gelişimi, bunlarıdestekleyen teknolojilerin de gelişmesine bağlıdır ki, bunların en kritik olanları önemlikızılötesi malzemelerden yapılan mikroaygıtların yüksek hassasiyetli üretim teknikleridir.Mikroaygıtların görünür bantta femtosaniye lazer ışını ile oluşturulması günümüze değin çokçalışılmış bir teknolojidir. Femtosaniye lazerlerin bazı özellikleri, dalga kılavuzları gibi mikroelemanların doğrudan veya kendiliğinden oluşumu alanında, bunlara diğer lazerlere göre ciddiüstünlükler sağlamaktadır. Bu projede, bu teknolojiyi, literatürde eksik olan 1,5 µm dalgaboyunda göstermek için disiplinlerarası ve uluslararası işbirlikli bir araştırmayı bildiriyoruz. 1,5?m civarında yüksek güçlü kısa atımlı ışık yayılımını ve telekomünikasyon dalga boyuaralığında çalışan optoelektronik malzemeler ile etkileşimini inceliyoruz. Projede başlıcahedefimiz, malzeme içine lazerle yazma işleminin temel fiziğini anlamak, özellikle desilisyumda optik etkileşimler sayesinde lazerle indüklenen malzeme modifikasyonunu /işlemeyi sağlamak ve lazerle telekominikasyon bant aralığında çalışabilecek optoelektronikelemanların doğrudan yazımı için pratik bir know-how yaratmaktı. Bu amaçla kompakt vedüşük maliyetli bir erbiyum fiber lazer sisteminden mikrojul seviyesi ve pikosaniye altı atımlarıveren yeni bir fiber lazer teknolojisi geliştirdik. Lazer sistemimizi literatürde ilk defa silikondaoptik dalga kılavuzu yapılarını doğrudan yazmak için kullandık. Kalkojenit camda doğrudanyazmayı ve yazılı yapıların silisyumdaki dalga kılavuzu özelliklerini doğruladık. Ayrıca, zamançözümlü bir görüntüleme düzeneği kurduk ve siisyumda pikosaniye altı 1.5 µm lazeratımlarının yayılımının görüntülenmesini ilk kez başardık. Ayrıca, yazılı yapıların kırılma indisiölçümleri ve görüntülemesi için gölgegrafi ve polarigrafi düzenekleri geliştirdik.Laser material processing, nonlinear optics, optoelectronics, microfabrication, siliconphotonicsRapid development of 1.5-μm wavelength-based telecommunication technologies requiresdevelopment of supporting technologies, most importantly new and/or improved low-cost,high-precision fabrication techniques for optoelectronic micro devices in important near-IRoptical materials. Femtosecond laser writing of optical micro devices in the visible spectralrange is an extensively studied technology. Unique properties of the femtosecond lasersprovide them significant advantages over other laser sources in the area of direct- or selfwriting of optical micro-elements. Here, we report on an interdisciplinary and internationallycooperative research to demonstrate this technology in the 1.5 µm wavelength which waslacking in the literaure. We study high-power short pulse light propagation around 1.5 μmand its interaction with optoelectronic materials of telecommunication wavelength range. Ourmain focus is to understand the basic optics and physics of these processes, but anadditional and main motivation is to generate practical know-how for laser-induced materialmodification and laser writing of optical elements in such materials. Towards this end, wedeveloped a novel fiber laser technology, delivering microjoule-level, sub-picosecond pulsesfrom a compact, low-cost Er-fiber laser system. We used our laser system fort he first time inliterature to directly write optical waveguide structures in silicon. We confirmed direct writingin chalcogenite glass and the waveguiding properties of the written structures in silicon. Wehave also built a time resolved imaging setup and applied for the first time on imagingpropagation of sub-picosecond 1.5 µm laser pulses in silicon. We have also developedshadowgraphy and polarigraphy setups fort imaging and index of refraction measurementsof the written structures

Development of a Selective Wet-Chemical Etchant for 3D Structuring of Silicon via Nonlinear Laser Lithography

Recently-demonstrated high-quality three-dimensional (3D) subsurface laser processing inside crystalline silicon (c-Si) wafers opens a door to a wide range of novel applications in multidisciplinary research areas. Using this technique, a novel maskless micro-pillars with precise control on the surface reflection and coverage are successfully fabricated by etching the laser processed region of c-Si wafer. To achieve this, a particular selective wet chemical etching is developed to follow subsurface laser processing of c-Si to reveal the desired 3D structures with smooth surfaces. Here, we report the development of a novel chromium-free chemical etching recipe based on copper nitrate, which yields substantially smooth surfaces at high etch rate and selectivity on the both laser-processed Si surface and subsurface, i.e., without significant etching of the unmodified Si. Our results show that the etch rate and surface morphology are interrelated and strongly influenced by the composition of the adopted etching solution. After an extensive compositional study performed at room temperature, we identify an etchant with a selectivity of over 1600 times for laser-modified Si with respect to unmodified Si. We also support our findings using density functional theory calculations of HF and Cu adsorption energies, indicating significant diversity on the c-Si and laser-modified surfaces

Portable Microfluidic Integrated Plasmonic Platform for Pathogen Detection

Timely detection of infectious agents is critical in early diagnosis and treatment of infectious diseases. Conventional pathogen detection methods, such as enzyme linked immunosorbent assay (ELISA), culturing or polymerase chain reaction (PCR) require long assay times, and complex and expensive instruments, which are not adaptable to point-of-care (POC) needs at resource-constrained as well as primary care settings. Therefore, there is an unmet need to develop simple, rapid, and accurate methods for detection of pathogens at the POC. Here, we present a portable, multiplex, inexpensive microfluidic-integrated surface plasmon resonance (SPR) platform that detects and quantifies bacteria, i.e., Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) rapidly. The platform presented reliable capture and detection of E. coli at concentrations ranging from ~105 to 3.2 × 107 CFUs/mL in phosphate buffered saline (PBS) and peritoneal dialysis (PD) fluid. The multiplexing and specificity capability of the platform was also tested with S. aureus samples. The presented platform technology could potentially be applicable to capture and detect other pathogens at the POC and primary care settings

In-chip microstructures and photonic devices fabricated by nonlinear laser lithography deep inside silicon

Silicon is an excellent material for microelectronics and integrated photonics1–3 with untapped potential for mid-IR optics4. Despite broad recognition of the importance of the third dimension5,6, current lithography methods do not allow fabrication of photonic devices and functional microelements directly inside silicon chips. Even relatively simple curved geometries cannot be realised with techniques like reactive ion etching. Embedded optical elements, like in glass7, electronic devices, and better electronic-photonic integration are lacking8. Here, we demonstrate laser-based fabrication of complex 3D structures deep inside silicon using 1 µm-sized dots and rod-like structures of adjustable length as basic building blocks. The laser-modified Si has a different optical index than unmodified parts, which enables numerous photonic devices. Optionally, these parts are chemically etched to produce desired 3D shapes. We exemplify a plethora of subsurface, i.e., “in-chip” microstructures for microfluidic cooling of chips, vias, MEMS, photovoltaic applications and photonic devices that match or surpass the corresponding state-of-the-art device performances

PHOTODISSOCIATION AND O(1D) REACTIONS OF NITROUS OXIDE

The focus of this dissertation is on the application of the velocity map imaging (VMI) technique to photodissociation and reaction dynamics. The multiplexing advantage of the VMI technique enables us to gather both angular and translational energy distributions simultaneously, with product quantum mechanical state selectivity. The first part of the thesis focuses on the ion-imaging experiments investigating the 130 nm dissociation of N2O and spectroscopic studies of its reactions with O(1D). The results are explained in conjunction with Hopper’s ab initio MCSCF calculations in the linear and bent configurations. Our analysis provide the spinorbit ratios, relative branching ratios and anisotropy parameters. We study the NO product channel of the O(1D)+N2O reaction with REMPI techniques and provide the first analysis of the rotational distribution of this channel. We will conclude the discussion of the full and half reactions of the N2O molecule by explaining the observed bimodal vibrational distribution in the NO channel. The second part focuses on the design and development of a dual-beam apparatus for the application of the VMI technique to reaction dynamics in a stateselective manner. We provide the ion-optics design considerations and ion trajectory simulations for satisfying the VMI conditions. Furthermore, a delayed extraction scheme will be described which will be important in future state-selective dual-beam VMI studies, allowing the critical low background environments for these type of experiments

In‐Volume Laser Direct Writing of Silicon—Challenges and Opportunities

International audienceLaser direct writing is a widely employed technique for 3D, contactless, and fast functionalization of dielectrics. Its success mainly originates from the utilization of ultrashort laser pulses, offering an incomparable degree of control on the produced material modifications. However, challenges remain for devising an equivalent technique in crystalline silicon which is the backbone material of the semiconductor industry. The physical mechanisms inhibiting sufficient energy deposition inside silicon with femtosecond laser pulses are reviewed in this article as well as the strategies established so far for bypassing these limitations. These solutions consisting of employing longer pulses (in the picosecond and nanosecond regime), femtosecond-pulse trains, and surface-seeded bulk modifications have allowed addressing numerous applications

High-Efficiency Multilevel Volume Diffraction Gratings inside Silicon

Silicon (Si)-based integrated photonics is considered to play a pivotal role in multiple emerging technologies, including telecommunications, quantum computing, and lab-chip systems. Diverse functionalities are either implemented on the wafer surface (“on-chip”) or recently within the wafer (“in-chip”) using laser lithography. However, the emerging depth degree of freedom has been exploited only for single-level devices in Si. Thus, monolithic and multilevel discrete functionality is missing within the bulk. Here, we report the creation of multilevel, high-efficiency diffraction gratings in Si using three-dimensional (3D) nonlinear laser lithography. To boost device performance within a given volume, we introduce the concept of effective field enhancement at half the Talbot distance, which exploits self-imaging onto discrete levels over an optical lattice. The novel approach enables multilevel gratings in Si with a record efficiency of 53%, measured at 1550 nm. Furthermore, we predict a diffraction efficiency approaching 100%, simply by increasing the number of levels. Such volumetric Si-photonic devices represent a significant advance toward 3D-integrated monolithic photonic chips

Optical Waveguides Written Deep Inside Silicon by Femtosecond Laser

Summary form only given. Photonic devices that can guide, transfer or modulate light are highly desired in electronics and integrated silicon photonics. Through the nonlinear processes taking place during ultrafast laser-material interaction, laser light can impart permanent refractive index change in the bulk of materials, and thus enables the fabrication of different optical elements inside the material. However, due to strong multi-photon absorption of Si resulting delocalization of the light by free carriers induced plasma defocusing, the subsurface Si modification with femtosecond laser was not realized so far [1, 2]. Here, we demonstrate optical waveguides written deep inside silicon with a 1.5-μm high repetition rate femtosecond laser. Due to pulse-to-pulse heat accumulation for high repetition rate laser, additional thermal lensing prevents delocalization of the light around focal point, allowing the modification. The laser with 2-μJ pulse energy, 350-fs pulse width, operating at 250 kHz focused in Si produces permanent modifications. The position of the focal point inside of the sample is accurately controlled with pumpprobe imaging during processing. Optical waveguides of ~20-μm diameter, and up to 5.5-mm elongation are fabricated by translating the beam focal position along the optical axis. The waveguides are characterized with a 1.5-μm continuous-wave laser, through optical shadow-graphy (Fig. 1 a-b, e) and direct light coupling (Fig.1 c-d, f). The measured refractive index change obtained by quantitative shadow-graphy is ~6×10 -4 . The numerical aperture of the waveguide measured from decoupled light is 0.05