NIL Technology (NILT) is an optical solutions company designing, developing, and manufacturing flat optical elements and components with nanoscale features such as diffractive optical elements (DOEs) and meta optical elements (MOEs). NILT’s MOE lenses have recently demonstrated a groundbreaking 94% absolute efficiency at 940 nm. This major milestone, in combination with other efforts such as the subsequent module integration and enabling of mass production of MOE elements, are among the key development areas for successful adoption of MOE lenses in various markets, ranging from consumer to automotive and applications such as sensing and machine vision systems. Here, we report our recent achievements with a camera module based on an MOE lens. We have successfully designed and manufactured camera modules using a single MOE lens showing excellent performance compared to refractive lens counterparts. The design has a low f-number and extremely high relative illumination. Prototypes are prepared using e-beam lithography, whereas MOE lenses in mass production are manufactured using nanoimprint lithography. The characterization of the MOE lenses reveals full agreement with the simulated nominal design. Image artifacts can appear due to higher orders of diffraction if the MOE lenses are not designed and manufactured properly. To illustrate the promise for volume production, a tolerance analysis has been performed, where the system tolerance analysis shows yield versus performance. At the module level, a straylight study, including ghost image and finally, thermal stability has been analyzed. The tolerance and thermal analysis are not presented in this manuscript. These results show the advantages of using 'NILT's high-efficiency meta optical elements compared to traditional optical systems.
The optical efficiency of metalenses is extremely important for practical applications. With only limited efficiency, useful light is lost. This can for example result in reduced sensitivity. Even worse, the light, will appear as straylight that can result in ghost images, reduced resolution, reduced contrast etc. depending on the specific application.
Here, metalenses optimized for a wavelength of 940 nm are experimentally demonstrated with an absolute focusing efficiency of up to 94% measured as the optical power transmitted to the focal spot divided by the power incident on the lens element.
The function of the highly efficient metalenses is demonstrated in a camera module. The resulting images are sharp, crisp and artefact free.
Optical manipulation of metallic nanoparticles has numerous applications including nano-architectural control, enhancement of spectroscopic signals or photothermal treatment. Due to their large absorption cross sections, metallic nanoparticles, made of gold or platinum, generate significant heat upon irradiation and together with their large scattering cross sections, they can be challenging to optically trap and control. We demonstrate that strongly absorbing individual platinum nanoparticles can be optically trapped in three dimensions using a single focused continuous wave near infrared laser beam. Moreover, via direct measurements and finite element modeling, we show that platinum nanparticles have extraordinary thermoplasmonic properties and a single NIR irradiated platinum nanparticle with a diameter of 70 nm can reach surface temperature increases as high as 700°C in repeated heating cycles, thus demonstrating an exceptional thermal stability. Also, in comparison to the larger NIR resonant gold nanoshells, currently used for photothermal therapy, we show that the platinum nanparticles exhibit similar photothermal heating capacity and similar low toxicity. However, as the platinum nanoparticles exhibit better thermal stability than the gold nanoshells, they are quite promising for bioengineering and biomedical applications.
Due to their unique properties, magnetic nanoparticles, often made of iron oxides, have received significant attention in chemistry, solid state physics, and the life sciences. Although a magnetic field is the most obvious mean by which one can manipulate magnetic nanoparticles, we here demonstrate that magnetic nanoparticles can be individually controlled by optical manipulation. We quantify the interaction of optically trapped individual magnetic nanoparticles with the electrical field by determining the spring constant. Also, by finite element modeling we determine the extinction, scattering and absorption cross sections of magnetic nanoparticles as well as the real and imaginary parts of their complex polarizability. In comparison to magnetic manipulation, optical manipulation has the advantage, due to the tight focusing of the laser beam, that it allows for manipulation of a single particle at a time. Also, one can imagine applications where it is advantageous to employ both magnetic and optical manipulations simultaneously.
In typical colloidal suspensions, the corresponding optical polarizability is positive, and thus enhanced scattering takes place as optical beams tend to catastrophically collapse during propagation. Recently, light penetration deep inside scattering suspensions has been realized by engineering dielectric or plasmonic nanoparticle polarizibilities. In particular, we have previously demonstrated two types of soft-matter systems with tunable optical nonlinearities - the dielectric and metallic colloidal suspensions, in which the effects of diffraction and scattering were overcome, hence achieving deep penetration of a light needle through the suspension.
In this work, we show that waveguides can be established in soft matter systems such as metallic nanosuspensions through the formation of plasmonic resonant solitons. First, we show that, due to plasmonic resonance, a 1064nm laser beam (probe) would not experience appreciable nonlinear self-action while propagating through 4cm cuvette containing the metallic nanosuspension of gold spheres (40nm), whereas a 532nm laser beam (pump) can readily form a spatial soliton due to nonlinear self-trapping. Second, we demonstrate effective guidance of the probe beam, which would otherwise diffract significantly through the nanosuspensions, due to the soliton-induced waveguide from the pump beam. Such guidance was observed when the power of the probe beam was varied from 20mW to 500mW at constant pump beam power, with more pronounced guidance realized from lower to higher probe beam power. Interestingly, due to the presence of the probe beam, the pump beam undergoes self-trapping at an even lower power. These results may bring about the possibility of engineering plasmonic soliton-based waveguides for many applications.
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