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Optical structures capable of concentrating electromagnetic radiation near a photosensitive medium are highly demanded in applications aiming to increase sensitivity of photodetectors and efficiency of photovoltaic devices. While spherical lenses or mirrors can be regarded as simplest optical field concentrators, a more efficient approach is to exploit sub-wavelength scale manipulation of optical...
Optical microscopy is one of the most important scientific achievements in the history of mankind, and it is the most widely used technique for exploring the small world. However, as is well known, traditional lens-based optical microscopes suffer from the low imaging resolution λ/2 due to the diffraction limit. To overcome this obstacle, multiple innovative methods have been proposed during the past...
Optical ring resonators have attracted great interests in integrated photonics, since they can be employed for a variety of applications, such as filters, multi/demultiplexers, true time delay lines, optical routers, optical signal processers, and so on. Here, we propose our recent progress on reflective-type ring resonators in both theoretical analysis and experimental results, which can be used...
Photoacoustic computed tomography (PACT) is an emerging computed imaging modality that exploits optical contrast and ultrasonic detection principles to form images of the absorbed optical energy density within tissue. The PACT reconstruction problem corresponds to a time-domain inverse source problem, where the initial pressure distribution is recovered from the wavefield recorded on a measurement...
In the follow paper I will discuss the recent progress in investigating the optical trapping dynamics of semiconductor nanowires and other high aspect-ratio nanoscale objects. Owing to their perculiar geometry, these objects present rich and complex behaviour that departs significantly from high-symmetry particles typically employed in tweezers experiments. Early work in the field focused on holographic...
Nanoscale local field sensing is a powerful technique for various applications in physical and biological studies. The performance critically depends on the high spatial resolving capability. Conventional protocols mainly make use of the scanning pointed tips with near field interaction, while the tips would introduce perturbation to the detected field at nanoscale and. Also the preparation of tips...
Plasmonic antennas have been investigated as potential sensing element since long, but great part of the efforts on the nanofabrication have been devoted to the 2 dimensional patterning. Many times the the “sensing or probing” processes require geometries of the probe that are more complicated than the simple flat surface. In this paper we are going to show some example of three dimensional structures...
Tip-enhanced Raman spectroscopy (TERS) witnesses its active development since more than 15 years. Based on the lightning-rod and plasmonic resonance effects, the generation of strongly confined electromagnetic field within a nanogap between a sharp tip apex and a sample surface under laser illumination even makes the visualization of single molecules possible [1–3]. Our group has actively contributed...
Synthetic optical holography (SOH) is an imaging technique, recently introduced in scanning microscopy to record amplitude and phase of a scattered field from a sample. In that approach, a point detector is employed, replacing CCD cameras, in order to record the mutual information between pixels and encode the phase across the whole image. The present work describes a SOH system implemented through...
Metal film materials have been widely used in optical devices, green energy field, biosensor technologies, and so on. In these applications, the properties of metal surface play the significant role. However, propagation characteristics of light in metal-based materials are still confusing. Wavelength-dependent refraction going from negative to positive at air/metal interface was reported in previous...
Solution-processed lead halide perovskites have shown very bright future in both solar cells and microlasers. Very recently, the nonlinearity of perovskites started to attract considerable research attention. However, the perovskite nonlinear devices are still absent. Here we demonstrate the two-photon pumped nanolasers from perovskite nanowires. The CH3NH3PbBr3 perovskite nanowires were synthesized...
Terahertz (THz) radiation has attracted a lot of attentions due to its fascinating potential applications. However, the traditional THz devices have relatively large size due to the long wavelength nature of the THz radiation. Several metasurface-based THz devices, including lens, computer generated holograms, spin selected focusing lens, as well as wavelength selected diffractive elements, have been...
A method to integrate the spectroscopic system of the push-broom scanning imaging spectrometer onto a single chip is proposed using echelle diffraction grating to split the light in the near infrared range according to different wavelengths. The on-chip spectrometer consists of an optical on-off switch array, a multi-input echelle diffraction grating (EDG) and a detector array. The designed EDG has...
The paper discusses the passive optical detection of small-sized targets moving through the air at overhead levels. An experimental module for a standalone locator to operate in real time is presented together with methods usable within the actual implementation of the underlying designer project. Within the supporting tests, an algorithm was developed to detect small particles in a video sequence,...
We address recent progress in large-area precise nanofabrication of metasurfaces using UV nanoimprint lithography. Metasurfaces for enhancing optical signals in molecules and for manipulating polarization of light are introduced.
Optical nanoantennas [1–4] formed by single or paired metallic nanoparticles have been recently demonstrated to efficiently couple the propagating light into and from deeply subwavelength volumes beyond the diffraction limit. The strong light-matter interaction mediated by collective oscillations of surface plasmons polaritons in metal may allow for manipulation of photon absorption, emission, and...
Gradient metasurfaces, or ultrathin optical components with engineered transverse impedance gradients along the surface have recently been demonstrated to provide control of the phase of scattered fields over sub-wavelength scale, enabling a broad range of linear optical components. More recently, sub-wavelength-thin nonlinear metasurfaces with tailored nonlinear responses have provided new degrees...
During cancer development, progression and therapy, tissues undergo enormous changes in their physiological and morphological properties, including angiogenesis, hypoxia, alterations in cell nuclear size and density, and denaturation. The ability to measure these biomarkers noninvasively has great clinical values in early detection of cancer and treatment evaluation. Quantitative optical spectroscopy...
The axial resolution of conventional confocal microscopy is usually larger than 600 nm. In super-resolution microscopy, although Stimulated emission depletion (STED) microscopy offers lateral resolution beyond the optical diffraction limit [1, 2], the axial resolution often remains the same, unless a special set of phase modulation is employed. With two opposing objectives in 4Pi microscopy, the interference...
The functionality of a traditional photonic device is usually realized by reshaping the wavefront of the light that relies on gradual phase changes along the optical paths, which are accomplished by either controlling the surface topography or varying the spatial profile of the refractive index. The thickness of photonic devices usually remains comparable to the wavelength of the light. However, further...
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