High-refractive-index nanoparticles (NPs), such as silicon NPs, were considered as effective carriers in their response to a magnetic field at optical frequencies. Such NPs play an important role in many state-of-the-art technologies in nano-optics. Although the resonance properties of these NPs when varying their structural parameters have been studied intensely in the past few years, their interaction with the underlying substrate has seldom been discussed, in particular, when the substrate is a waveguide structure that significantly modulates the optical responses of the NPs. We proposed and studied a selective magnetic coupling system comprising a Si-NP on a metal-dielectric waveguide (MDW). The MDW structure supports either a transverse electric (TE) or a transverse magnetic (TM) mode that induces a large polarization dependence in the magnetic resonance. A new manifestation of the optical spin Hall effect was demonstrated in which a vertical rotating magnetic dipole excites a TE-type waveguide mode with a specific unidirectional emission. Making use of this polarization response, we developed a scanning imaging system that can selectively map the transverse or longitudinal magnetic field component of a focused beam depending on the type of MDW used in the system. This selective magnetic resonance coupling system is expected to be valuable for studying the fundamental interactions between the magnetic field and matter and for developing related nano-applications.A scheme is proposed to generate stable light bullets (LBs) in a cold Rydberg atomic system with a parity-time (PT) symmetric potential, by utilizing electromagnetically induced transparency (EIT). Using an incoherent population pumping between two low-lying levels and spatial modulations of control and auxiliary laser fields, we obtain a two-dimensional (2D) periodic optical potential with PT symmetry. Based on PT symmetry potential and the long-range Rydberg-Rydberg atomic interaction, the system may support slow LBs with low light intensity. Further, it is found that the local and non-local nonlinear coefficients and PT-symmetric potential can be tuned and used to manipulate the behavior of LBs.Based on measuring the polarimetric parameters which contain specific physical information, polarimetric imaging has been widely applied to various fields. However, in practice, the noise during image acquisition could lead to the output of noisy polarimetric images. In this paper, we propose, for the first time to our knowledge, a learning-based method for polarimetric image denoising. This method is based on the residual dense network and can significantly suppress the noise in polarimetric images. The experimental results show that the proposed method has an evident performance on the noise suppression and outperforms other existing methods. Especially for the images of the degree of polarization and the angle of polarization, which are quite sensitive to the noise, the proposed learning-based method can well reconstruct the details flooded in strong noise.The d1-d2-d3-d4-d5 gradient-type spoof surface plasmons (SSP) grating was designed and found to exert an obvious effect on electric field localization. Two gradient-shaped planar ports were added to the bottom of this grating to form a gradient-type slotted SSP grating and achieve tight focusing and local electric field enhancement for a terahertz wave. The size of the focal spot was optimized to 0.01λ. The single-gradient-type slotted SSP grating was considered as a unit and arranged in one and two dimensions to generate a longitudinal focal line and square focal spots array. This did not only improve the resolution of terahertz imaging, but also simultaneously scan multiple focal spots to increase the speed of terahertz imaging. This work makes the manipulation of terahertz wave more flexible and efficient which has great potential in terahertz high-resolution near-field scanning imaging.Bound states in the continuum (BICs) can be derived from a generalized waveguide condition in which the total internal reflection is substituted by coherent perfect reflection. Coherent perfect reflection can occur in the truncated photonic crystal (PhC) due to the interference of different Bloch modes. Based on the coherent reflection, BICs can be constructed by the bulk Bloch modes of PhC slabs. In contrast to the determination of BICs from the topological vortices of far-field radiation, this interpretation from coherent reflection can give the spatial field profile in detail in the near field. We show that the BICs can be characterized by the indices (or number of nodes) of their constituent Bloch modes. Moreover, all the guided resonances in addition to BICs can also be labelled by these mode indices. It is found that for the guided resonances the mode indices can change suddenly on the same frequency band. Our results may have potential applications in guided-wave optics and enhanced light-matter interaction.A polydimethylsiloxane film patterned by a self-assembled array has been demonstrated as a strain sensor. A monolayer of 580 nm polystyrene spheres prepared by convective deposition was the template to transfer a periodic pattern to a polydimethylsiloxane (PDMS) film. Optical diffraction through the stretched PDMS film, enabled strain sensing perpendicular and parallel to the stretching direction, with sensitivities of 1.7 nm/% strain and 4.0 nm/% strain, respectively. The PDMS film was used as a vibration sensor at 50 Hz.The distance and velocity measurement can be obtained by the round-trip time and Doppler effect on the down-chirp and the up-chirp of the linear frequency-modulated waveform (LFMW), but false targets will appear in a multi-target situation, resulting in erroneous detection. Here, we report a photonics-assisted approach to realize unambiguous simultaneous distance and velocity measurement in multi-target situations utilizing a dual-band symmetrical triangular LFMW. Dual-band observation invariance is proposed, to effectively resolve the false targets. The de-chirped signals can be obtained from parallel de-chirping processing to the dual-band echoes. By measuring and calculating the beat frequencies of the de-chirped signals in the two frequency bands, the actual parameter measurements can be acquired according to the authenticity criterion. In the experiments, detections to three targets are performed, and the distance and velocities are acquired without false targets. The absolute measurement errors of the distance and the velocity are less than 9 mm and 0.16 m/s, respectively. These results show the feasibility of the proposed approach.Optical tweezers find applications in various fields, ranging from biology to physics. One of the fundamental steps necessary to perform quantitative measurements using trapped particles is the calibration of the tweezer’s spring constant. This can be done through power spectral density analysis, from forward scattering detection of the particle’s position. In this work we propose and experimentally test simplifications to such measurement procedure, aimed at reducing post-processing of recorded data and dealing with acquisition devices that have frequency-dependent electronic noise. In the same line of simplifying the tweezer setup we also present a knife-edge detection scheme that can substitute standard position sensitive detectors.Conventional models of Er/Yb co-doped fibers assume all ytterbium ions are equally involved in the energy transfer with erbium ions, governed by a singular transfer rate. This would predict output power clamping once ytterbium parasitic lasing starts, contrary to the observations that the output continued to grow albeit at a slower rate. One study explained this using elevated temperature at high powers. Our study, however, shows that elevated temperature and mode-dependent effects only play insignificant roles. A new model is developed based on the existence of isolated ytterbium ions, which can explain all the observed experimental behaviors.During the past few years, a lot of efforts have been devoted in studying optical analog computing with artificial structures. Up to now, much of them are primarily focused on classical mathematical operations. How to use artificial structures to simulate quantum algorithm is still to be explored. In this work, an all-dielectric metamaterial-based model is proposed and realized to demonstrate the quantum Deutsch-Jozsa algorithm. The model is comprised of two cascaded functional metamaterial subblocks. The oracle subblock encodes the detecting functions (constant or balanced), onto the phase distribution of the incident wave. Then, the original Hadamard transformation is performed with a graded-index subblock. Both the numerical and experimental results indicate that the proposed metamaterials are able to simulate the Deutsch-Jozsa problem with one round operation and a single measurement of the output eletric field, where the zero (maximum) intensity at the central position results from the destructive (constructive) interference accompanying with the balance (constant) function marked by the oracle subblock. The proposed computational metamaterial is miniaturized and easy-integration for potential applications in communication, wave-based analog computing, and signal processing systems.In this paper, a new method combining carrier transport in semiconductors with an RF equivalent circuit was put forward to simulate the frequency response of an avalanche photodiode (APD). The main trade-off between the gain-bandwidth product (GBP) and the dark current was analyzed to optimize the structure of an APD; and a separated absorption, grading, charge, multiplication, charge, transit (SAGCMCT) structure with 120 nm balanced InAlAs multiplication layer was proposed to reduce the dark current and improve the frequency response. The fabricated triple-mesa type back-illuminated InGaAs/InAlAs APD achieved the properties of low dark current of 6.7 nA at 0.9Vb and high GBP over 210 GHz.Modeling techniques for light-shaping systems with freeform surface are presented from a physical-optics point of view. We apply the modeling techniques to different light-shaping systems with freeform surfaces designed by „ray mapping method”. The simulation results show that the design is not always valid. Diffraction effects occur, especially in paraxial situations. We discuss the accuracy of the design via physical-optics simulation, and find an explanation in the geometric-optics assumption of the design algorithm being sufficient only if the optical system results in homeomorphic behavior for the electric field between the input and target.Continuous wave optically detected magnetic resonance (CW-ODMR) is a practical way to study the sensitivity of the DC magnetic field. However, in large ensemble nitrogen-vacancy (NV) defects, the simultaneous excitation of microwave and laser will deteriorate the parameters of the ODMR spectrum and some unwanted sideband excitations caused by P1 electron spins will also bring challenges to further improve the sensitivity and signal quality. Here, we first achieve the CW-ODMR and acquire DC photon-shot-noise-limited magnetic sensitivity of 12nT/Hz. Different from the conventional method, we take advantage of pulsed quantum filtering (PQF) technology to eliminate such impacts above and demonstrate a sensitivity of about 1nT/Hz, which an order of magnitude enhancement over CW-ODMR. We find this method provides simple but effective support for relevant high-sensitivity DC magnetometry and obtains pure resonance signal when using large ensemble NV- defects.