Optical polarization

About: Optical polarization is a research topic. Over the lifetime, 13992 publications have been published within this topic receiving 244284 citations.

Polarization discrimination in a phase-sensitive optical time-domain reflectometer intrusion-sensor system

Abstract: A distributed sensor system for detecting and locating intruders based on a phase-sensitive optical time-domain reflectometer (phi-OTDR) that utilizes polarization discrimination is described. The sensing element is a single-mode telecommunications fiber in a 3 mm diameter cable buried along a monitored perimeter in a 20-46 cm deep, 10 cm wide trench in clay soil. Light pulses from a continuous-wave Er fiber Fabry-Perot laser with a narrow (< 3 kHz) instantaneous linewidth and low (a few Kilohertz per second) frequency drift are injected into one end of the fiber, and the orthogonal polarizations of the backscattered light are monitored with separate receivers. Localized phase changes in the optical carrier are sensed by subtraction of a phi-OTDR trace from an earlier stored trace. In field tests with a monitored length of 12 km, detection of intruders on foot as far as 4.5 m from the cable line was consistently achieved.

A vector finite element method with the high-order mixed-interpolation-type triangular elements for optical waveguiding problems

Abstract: A vector finite element method with the high-order mixed-interpolation-type triangular elements is described for the analysis of optical waveguiding problems. It is a combination of linear edge elements for transverse components of the electric or magnetic field and quadratic nodal elements for the axial one. The use of mixed-interpolation-type elements provides a direct solution for propagation constants and avoids spurious solutions. This approach can yield more accurate results compared with the conventional approach using the lowest order mixed-interpolation-type elements, namely, constant edge elements and linear nodal elements. The accuracy of this approach is investigated by calculating the propagation characteristics of optical rib waveguides. Results obtained for both E/sup x/ and E/sup y/ polarizations are validated using benchmark results produced by established methods. >

Experimental observation of polarization instability in a birefringent optical fiber

Abstract: We present the first experimental demonstration of spatial instability in the nonlinear evolution of the state of polarization of an intense light beam in a birefringent Kerr‐like medium. As the peak power crosses the threshold for the instability, we observed strong intensity‐dependent power transfer between the two counter‐rotating circularly polarized waves propagating along a birefringent optical fiber. The experimental results agree well with the theory.

High extinction ratio in-fiber polarizers based on 45° tilted fiber Bragg gratings

Abstract: We report a near-ideal in-fiber polarizer implemented by use of 45° tilted fiber Bragg grating structures that are UV inscribed in hydrogenated Ge-doped fiber. We demonstrate a polarization-extinction ratio of 33?dB over a 100-nm operation range near 1550?nm. We further show an achievement of 99.5% degree of polarization for unpolarized light with these gratings. We also theoretically investigate tilted grating structures based on the Green's function calculation, therein revealing the unique polarization characteristics, which are in excellent agreement with experimental data.

Integrated mode-evolution-based polarization splitter.

Abstract: A mode-evolution-based polarization splitter suitable for high-index-contrast systems and directly integratable with a recently reported on-polarization rotator is described and its performance verified through both finite-difference time-domain and eigenmode expansion simulations. For a device length of 200??m, greater than 22?dB of extinction is obtained across a 1.45–1.75-?m bandwidth.