The extraordinary properties of second harmonic generation in negative-index metamaterials, where the Poynting vector and the wavevector have opposite directions are investigated. The ”backward” phase-matching condition results in significant changes in the Manley-Rowe relations and in spatial distributions of the field intensities of the coupled waves. 0 0 z RHM

We suggest a novel approach for generating the second-harmonic radiation in subwavelength graphene waveguides. We demonstrate that the quadratic phase matching between plasmonic guided modes of different symmetries can be achieved in a planar double-layer graphene structure when conductivity of one of the layers becomes spatially modulated. We predict theoretically that, owing to graphene nonlo...

A compact endomicroscope is the only solution for transferring second harmonic generation (SHG) imaging into in vivo imaging and real time monitoring the content and structure of collagen. This is important for early diagnoses of different diseases associated with collagen change. A compact nonlinear endomicroscope using a double clad fiber (DCF) is newly employed in SHG imaging. The experiment...

We demonstrate mid-infrared second-harmonic generation as a highly sensitive phonon spectroscopy technique that we exemplify using α-quartz (SiO2) as a model system. A mid-infrared free-electron laser provides direct access to optical phonon resonances ranging from 350 cm−1 to 1400 cm−1. While the extremely wide tunability and high peak fields of an free-electron laser promote nonlinear spectro...

We present studies of the optical properties of the new nonlinear material BiB3O6 for second harmonic generation from the visible to infrared. We have determined the phase-matching conditions and effective nonlinear coefficients in the three principal optical planes, acceptance bandwidths, spatial and temporal walkoff, group velocity dispersion and double phase-matching behaviour. We also repor...

We demonstrate coherent driving of a single electron spin using second-harmonic excitation in a Si/SiGe quantum dot. Our estimates suggest that the anharmonic dot confining potential combined with a gradient in the transverse magnetic field dominates the second-harmonic response. As expected, the Rabi frequency depends quadratically on the driving amplitude, and the periodicity with respect to ...

The process of second harmonic generation (SHG) has a unique property of forming a sharp optical contrast between noncentrosymmetric crystalline materials and other types of material, which is a highly valuable asset for contrast microscopy. The coherent signal obtained through SHG also allows for the recording of holograms at high spatial and temporal resolution, enabling whole-field four-dime...

this paper proposes a new method for parameter estimation of distorted single phase signals, through an improved demodulation-based phase tracking incorporated with a frequency adaptation mechanism. the simulation results demonstrate the superiority of the proposed method compared to the conventional sogi (second-order generalized integrator)-based approach, in spite of the dc-offset and harmon...

The pulse inversion averaging (PIA) method is introduced to the shadowgraph imaging system to visualize the second-harmonic component of the ultrasonic field. The principle of the PIA method is summarized and the method is customized for observing an second-harmonic ultrasonic field. An experiment of a shadowgraph with PIA using a 1-MHz concave focused transducer is conducted to evaluate the sy...