arXiv subjects

Xianfeng Chen

Publications and source records attributed to Xianfeng Chen.

113 records · Page 7Linked to original sources

arXiv2010

Coherently superposed efficient second harmonic generation by domain wall series in ferroelectrics

A novel mechanism of efficient second harmonic generation in domain wall series is reported. By employing angle modulation, obvious intensity peaks of second harmonic appear at specific incident angles utilizing the continuous laser source of 200mW, and the single-pass conversion efficiency comes up to 5%/W only through dozens of domain walls. It can be shown that the phenomenon is caused by coherent superposition of Cherenkov second harmonics (CSH) generated by different domain walls, which is a novel mechanism totally distinguished from Quasi-phase-matching (QPM).

physics.optics↗

arXiv2010

Single domain wall effect on parametric processes via Cherenkov-type phase matching

We report on important influence of single domain wall (DW) of electrically poled ferroelectric crystal on parametric processes via Cherenkov-type phase matching. It shows that the effective nonlinear polarization is confined in DW and its phase velocity can be modulated when incident light is off domain wall's direction. These effects lead to novel Cherenkov second harmonic generation (CSHG) which has no analogue in bulk ferroelectrics. Complex DW-modulated parametric process via Cherenkov-type phase matching, such as Cherenkov sum frequency generation (CSFG), is also demonstrated in DW. We propose that nonlinear coefficient in DW is significantly enhanced.

physics.optics↗

arXiv2010

Significantly enhanced second order nonlinearity in domain walls of ferroelectrics

Significantly enhanced second order nonlinearity resulting from local symmetry breaking in domain walls is reported. By this new giant nonlinearity, novel hexagonally, conically and trigonally distributed second harmonic beams closely related to domain wall patterns are generated without contribution of reciprocal vectors. Experimental results show that such nonlinearities have made important impact on quasi-phase-matching technique and electro-optic Solc filter, which needs careful reconsiderations.

physics.optics↗

arXiv2006

Simulation of optical microfiber loop resonators for biochemical sensing

Based on the basic theory of the microfiber loop resonator, we exploit the application of microfiber loop resonators in biochemical sensing. We set up a reliable theoretical model and optimize the structural parameters of microfiber loop resonators including the radius of the microrfiber, the radius of the loop and the length of the coupling region for higher sensitivity, wider dynamic measurement range, and lower detection limit. To show the convincible and realizable sensing ability we perform the simulation of sensing an extreme small variation of ambient refractive index by employing a set of experimental datas as the parameters in the expression of intensity transmission coefficient, and the detection limit reaches to a varation of ambient refractive index of 10-5 refractive index unit(RIU). This has superiority over the exsiting evanescent field-based subwavelength-diameter optical fiber refractive index sensor.

physics.optics↗

arXiv2004

Recovery of graded index profile by cubic spline function

We present in this paper a method to recover the refractive index profile of graded waveguide from the effective indices by cubic spline interpolation function. It is proved by numerical analysis of several typical index distributions that the refractive index profile can be reconstructed closely to its exact profile with the presented interpolation model. This method can reliably retrieve index profile of both more-mode (more than 4 guiding mode) and fewer-mode (2-4) waveguides.

physics.optics↗