Recently, there has been growing interest in integrating metasurfaces with fiber-optic technology, which offers high functionality and design flexibility in handling optical properties. However, existing approaches of integrating optical fiber with Huygen’s metasurfaces are based on techniques such as Focused Ion Beam (FIB) or Multiphoton lithography which directly draw the desired metasurface on optical fiber, resulting in high fabrication complexity and difficulty in transferring multilayered metasurfaces for multifunctionality. In this study, we propose the punching-method, a simple technique to transfer prefabricated Huygen’s metasurfaces onto fiber apex.
With extreme field confinement in an ultrathin conducting layer, plasmons in 2D materials exhibit strong light-matter interactions, enabling the exploration of molecular vibration modes, specifically in infrared (IR) absorption spectroscopy. However, since high sensitivity in plasmons often results in a shorter resonant bandwidth, detecting molecular fingerprints across a broadband spectrum becomes fundamentally limited. Here, we demonstrate broadband surface-enhanced IR absorption (SEIRA) spectroscopy using a 2D materials-based gap plasmon resonator, specifically adopting Ti3C2Tx MXene. Within the MXene(Ti3C2Tx)-insulator(SiO2)-metal(Au) nanostructures, the MXene-based gap plasmon (MGP) modes are produced across the entire mid-IR spectrum. These modes exhibit a wavelength reduced by more than ten-fold compared to the wavelength in a vacuum, amplifying the light-matter interactions. Furthermore, using the MGP resonator, we demonstrate sensing of vibrational mode in polymethylmethacrylate (PMMA). This finding reveals that the MGP resonator can sensitively detect molecular fingerprints of the PMMA across the entire MIR range. Notably, the MGP resonator can also identify C-H bonding in the SWIR range, a detection that is challenging for other 2D material plasmonic devices. Our findings pave the way for developing sensitive sensors for the broadband spectrum and other optical applications in the SWIR range.
The hopping of a nanoparticle between two adjacent potential wells is a fundamental process in various physical, chemical, and biological phenomena. However, it is tricky to implement an experimental measure to study this process because handling a single nanoparticle is not a simple problem. We propose a 3D tapered metallic nanoantenna with a bow-tie-shaped hole illuminated by two lasers: a continuous-wave (CW) laser and a femtosecond laser. The CW laser produced a double-well potential inside the hole that trapped a single nanoparticle. The femtosecond laser generated a second harmonic signal by enhancing the nonlinear optical effect on the metal surface, which could be easily filtered and monitored. This two-laser platform provides the freedom to choose between the means for capturing a nanoparticle and the means for observing them. We controlled the landscape of the double-well potential by combining the gap size of a nanoantenna and optical pump power. The hopping of trapped nanoparticles over the central potential barrier was monitored and showed a maximum at the specific input laser power. This phenomenon agreed well with the theoretical prediction considering the thermal energy of a nanoparticle.
Recently several attempts by using transfer printing method for integration of on-chip laser into silicon circuit. These approaches can minimize wasted III-V areas but has the disadvantage of requiring high alignment tolerances. Here, we propose a new concept of hybrid silicon laser, which is high tolerable in alignment. Employing the whispering gallery mode laser in conjunction with III-V patch layer, designed hybrid micro-patch laser has high design flexibility, and lower the process difficulty in fabrication. We expect the hybrid micro-patch laser to be the next generation device of on-chip micro-lasers.
Thermal camouflage enables the object to be invisible from infrared detection system, by assimilating their thermal radiation (TR) signal into surroundings. While extremely low TR is required for thermal camouflage of a high temperature object, proposed materials is still limited in engineering emissivity, not controlling surface temperature for TR suppression. Here, we propose a titanium carbide (MXene) based selective emitter (SE) for suppression of TR. With reducing thermal conductivity of MXene, designed SE exhibits low surface temperature even for a few micron thickness. Additionally, with interference effects in multilayer systems, designed SE show radiative cooling effects for additional TR reduction.
KEYWORDS: Near field, Near field scanning optical microscopy, Near field optics, Nanostructures, Optical scanning systems, Optical microscopes, Wavefronts, Diffraction
Optical modes in subwavelength-scale nanostructures are hard to reach from conventional far-field optics because they mainly exist in the form of near-field. Here, we propose an experimental method that can map out the near-field optical modes of any arbitrary nanostructures. We set up a far- to near-field transmission matrix system by using near-field scanning optical microscope and wavefront shaping of incident wave. By applying the singular value decomposition of the measured transmission matrix, we could identify symmetric and antisymmetric modes of a pair of nano-antenna whose width and separation are well below the diffraction limit. Our method will help designing complex functional nanostructures by providing the experimental means of understanding their optical response.
Micro-disk resonators were fabricated using Er doped silicon-rich silicon nitride (SRSN:Er). SRSN:Er thin films are fully CMOS-compatible and show efficient Er3+ luminescence pumped off-resonantly via Si nanoclusters. The high refractive index of SRSN (>2.0 at 1.5 μm) allows freedom in designing compact micro-disk resonators. Micro-disks with two different contents of Er (0.2 at.%, 0.02 at.%) with a diameter of 25 μm were fabricated, and characterized using evanescent coupling using tapered fibers. Whispering gallery modes with Q-factors in excess of 13000 were obtained, and FDTD calculations indicate that much higher values should be possible. Finally, we demonstrate excitation of fundamental whispering gallery mode via off-resonant, top-pumping of the SRSN microdisk.
We propose and demonstrate reconfigurable microfiber-coupled photonic crystal (PhC) lasers. In this generic
configuration, the position of a PhC resonator can be defined (and redefined) repeatedly by simply relocating a curved
microfiber along the linear PhC waveguide. In the proximity of the PhC waveguide in contact with the microfiber, the
cutoff frequency (effective index) of the PhC waveguide becomes smaller (larger) than that of a bare PhC waveguide.
Accordingly, when a curved microfiber is in contact with the PhC waveguide, a linear PhC resonator having Gaussianshaped
potential well is formed. Experimentally we confirm the formation of the reconfigurable resonator by observing
laser operation slightly below three available band edges.
The influence of etching slope on cavity Q-factors in two-dimensional (2D) photonic crystal (PhC) slab is studied. Through FDTD simulation, it is confirmed that the Q-factor decreases with etching slope. The main loss comes from the horizontal coupling into propagating TM-modes. We designed three-lattice-long modified linear cavities having high Q-factors. However, the measured Q-factor was about 250. This small Q-factor is attributed to the non-vertical (13°) side wall.
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