Dielectric Metasurface Designs for Surface Enhanced Raman Scattering with Large Distances between Nanoparticles

In this thesis new dielectric metasurfaces in immersion were explored with a periodic distribution of unit cells with multiple silicon cylinder structures on a reflective gold slab with a fused quartz spacer in between. These new metasurfaces were designed with 60 nm and 130 nm gaps in order to improve manufacturability and enable larger...

Towards labonachip optical trapping and Raman spectroscopy of extracellular vesicles using multiwaveguide traps

Optofluidic lab-on-a-chips (LOCs) employing a dual-waveguide trap for optical trapping and Raman spectroscopy have proven to be attractive and potent tools for high throughput chemical fingerprinting of bio-particles for disease diagnosis. Among the relevant bio-particles are extracellular vesicles (EVs) which a been proven through recent...

Estimation of microtubule-generated forces using a DNA origami nanospring

Microtubules are dynamic cytoskeletal filaments that can generate forces when polymerizing and depolymerizing. Proteins that follow growing or shortening microtubule ends and couple forces to cargo movement are important for a wide range of cellular processes. Quantifying these forces and the composition of protein complexes at dynamic...

Subwavelength spinning of particles in vector cosine-Gaussian field with radial polarization

A new type of radially polarized (RP) cosine-Gaussian (CG) field is proposed. Through the analytical model, it is found that such RP CG beam exhibits completely different focusing properties from the reported RP plane waves. More importantly, a stable three-dimensional trap of Rayleigh particle accompanied by a subwavelength spin motion can...

Tightly Focused Spot Shaping and its Applications in Optical Imaging and Trapping

The Rayleigh criterion explains the diffraction limit and provides guidance for improving the performance of an imaging system namely by decreasing the wavelength of the illumination and/or increasing the aperture (NA) of the objective lens. If the wavelength and NA are set, is it possible to improve the spatial resolution further? This question...

Versatile Multilayer Metamaterial Nanoparticles with Tailored Optical Constants for Force and Torque Transduction

The ability to apply force and torque directly to micro- and nanoscale particles in optical traps has a wide range of applications. While full control of both force and torque in three dimensions has been realized using top-down fabrication of rod-shaped particles composed of birefringent crystalline materials, widespread usage of such...

Integrated photonics multi-waveguide devices for optical trapping and Raman spectroscopy: design, fabrication and performance demonstration

We realized integrated photonics multi-waveguide devices for optical trapping and Raman spectroscopy of particles in a fluid. In these devices, multiple beams directed towards the device center lead to a local field enhancement around this center and thus counteract the effect of light concentration near the facets, which is a disadvantage of...

Applications of Optical Birefringence: With Natural-Materials and Meta-Materials

The beauty of optical birefringence lies in the fact that it provides an independent control of light over different polarization directions, which leads to many important applications in today's optical systems. This thesis describes the applications of existing naturally-occurring birefringent materials as well as the engineered formed...

Raman based identification of on-chip trapped single micro-organisms: A feasibility study

An important aspect in increasing our health and safety is the development of new sensors for screening drinking water samples for the presence of microbiological contaminants.The main problem associated with the detection and identification of these microbial contaminants is the long process time. The majority of the time is required fortheir...

Single-Crystal Rutile TiO ₂ Nanocylinders are Highly Effective Transducers of Optical Force and Torque

Optical trapping of (sub)micron-sized particles is broadly employed in nanoscience and engineering. The materials commonly employed for these particles, however, have physical properties that limit the transfer of linear or angular momentum (or both). This reduces the magnitude of forces and torques, and the spatiotemporal resolution,...

Optical trapping and manipulation of bacteria with photonic crystal devices

In monitoring the quality of drinking water with respect to the presence of hazardous bacteria, there is a strong need for in-line sensors that allow quick identification of bacterium species at low cost. Raman spectroscopy is a very promising label-free optical technique capable of discriminating bacteria species based on their molecular...

On Electromagnetically Induced Fluid Flows in Water

It is well-known that charged particles feel a Lorentz force when an electromagnetic field is applied. When the field is applied not to a single particle but a piece of material this force leads to polarization. In a solid this will lead to local displacements and internal stresses, but not actual movement will occur. In this thesis we will...

Optical trapping at low numerical aperture

A theory of optical trapping at low Numerical Aperture (NA) is presented. The theory offers an analytical description of the competition between the stabilizing gradient and destabilizing scattering force. The trade-off can be characterized by a single dimensionless trapping parameter, which increases with bead size to wavelength ratio ?/?, m,...