Polarization holography has been extensively applied in many fields, such as optical science, metrology, and biochemistry, due to its property of polarization modulation. However, the modulated polarization state of diffracted light corresponds strictly to that of incident light one by one. Here, a kind of tunable polarization holographic grating has been designed in terms of Jones matrices, and intensity-based polarization manipulation has been realized experimentally. The proposed tunable polarization holographic grating is recorded on an azobenzene liquid-crystalline film by a pair of coherent light beams with orthogonal polarization states and asymmetrically controlled intensities. It is found that the diffracted light can be actively manipulated from linearly to circularly polarized based on the light intensity of the recording holographic field when the polarization state of incident light keeps constant. Our work could enrich the field of light manipulation and holography.

In this Letter, an all-optical logic sequence generator based on two different polarization holographic gratings has been proposed and demonstrated, which has one input port and four output ports. The polarization state of input light signal determines logic output signals. It can produce four kinds of logic sequence output signals: 1000, 0100, 0010, and 0001, corresponding to the input light signal of four different polarization states: the p-linear, s-linear, left-handed circular, and right-handed circular. The two polarization gratings have been fabricated, and the working principle of the logic sequence generator has been proved by diffraction pattern analysis of polarization gratings.

Through anisotropic Ag overgrowth on the surface of Au nanobipyramids (AuNBPs), high-purity and sizecontrolled Ag nanorods (Au/AgNRs) are obtained by a simplified purification process. The diameters of the Au/AgNRs are determined by the size of the as-prepared AuNBPs, and the lengths of the Au/AgNRs are tunableusing different amounts of Ag precursor in the growth solution. Surface-enhanced Raman scattering (SERS) studies using Rhodamine-6G (R6G) as a test molecule indicate that the Au/AgNRs have excellent sensing potential. The tunable optical properties and strong electromagnetic effect of the Au/AgNRs, along with their superior SERSsignal enhancement, show that Au/AgNRs are promising for further applications in plasmon sensing and biomolecular detection.of Nanjing Institute of Technology (CKJB201411, QKJB201409, YKJ201538); Qing Lan Project and Priority Academic Program Development of Jiangsu Higher Education Institutions.

A polarization holographic grating, which integrates the functions of a grating and a wave plate and is called a diffractive wave plate, is recorded by two beams (left and right circularly polarized) of a 532 nm laser in an azo polymer with a liquid-crystal structure. The polarization conversion characteristics of the diffractive wave plates are investigated with a detecting light of 650 nm by metering the polarization state of first-order diffracted light. It is confirmed that the diffractive wave plates convert the incident linear polarization into circular polarization for a linearly polarized probe laser and reverse the sense of rotation of the circular polarization when the detecting light is circularly polarized light.