Generation of cylindrical vector vortex beams using a biconical glass rod.

This Letter proposes a biconical glass rod for generating a cylindrical vector vortex (CVV) beam. Based on the principle of total internal reflection and the cylindrical symmetry structure of the glass rod, a circularly polarized incident beam with a constant phase distribution can be converted into a CVV beam, which possesses both a spatially inhomogeneous polarization and a helical phase distribution. The polarization azimuth of the CVV beam can be tuned with the aid of a polarization rotator composed of two cascade half-wave plates. The design theory is presented, and the feasibility of the design is demonstrated experimentally.

Using a Hexagonal Mirror for Varying Light Intensity in the Measurement of Small-Angle Variation.

Precision positioning and control are critical to industrial-use processing machines. In order to have components fabricated with excellent precision, the measurement of small-angle variations must be as accurate as possible. To achieve this goal, this study provides a new and simple optical mechanism by varying light intensity. A He-Ne laser beam was passed through an attenuator and into a beam splitter. The reflected light was used as an intensity reference for calibrating the measurement. The transmitted light as a test light entered the optical mechanism hexagonal mirror, the optical mechanism of which was created by us, and then it entered the power detector after four consecutive reflections inside the mirror. When the hexagonal mirror was rotated by a small angle, the laser beam was parallel shifted. Once the laser beam was shifted, the hitting area on the detector was changed; it might be partially outside the sensing zone and would cause the variation of detection intensity. This variation of light intensity can be employed to measure small-angle variations. The experimental results demonstrate the feasibility of this method. The resolution and sensitivity are 3 × 10(-40) and 4 mW/° in the angular range of 0.6°, respectively, and 9.3 × 10(-50) and 13 mW/° in the angular range of 0.25°.

Small-angle measurement with highly sensitive total-internal-reflection heterodyne interferometer.

In this paper, a high-sensitivity total-internal-reflection (TIR) heterodyne interferometer is proposed for measuring small angles. In the proposed interferometer, a half-wave plate and two quarter-wave plates that exhibit specific optic-axis azimuths are combined to form a phase shifter. When a rhomboid prism is placed between the phase shifter and an analyzer that exhibits suitable transmission-axis azimuth, it shifts and enhances the phase difference of the s- and p-polarization states at double TIR. The enhanced phase difference is dependent on the incident angle; thus small angles can be easily and accurately measured by estimating the phase difference. The experimental results demonstrate the feasibility of this method. Angular resolution and sensitivity levels superior to 1.2×10⁻4 deg (2.1×10⁻6 rad) and 100 (deg/deg), respectively, were attainable in a dynamic range of 0.5 deg.

Multiport optical circulator by using polarizing beam splitter cubes as spatial walk-off polarizers.

Optical circulators are necessary passive devices applied in optical communication systems. In the design of optical circulators, the implementation of the function of spatial walk-off polarizers is a key technique that significantly influences the performance and cost of a device. This paper proposes a design of a multiport optical circulator by using polarizing beam splitter cubes as spatial walk-off polarizers. To show the feasibility of the design, a prototype of a six-port optical circulator was fabricated. The insertion losses are 0.94-1.49 dB, the isolations are 25-51 dB, and return losses are 27.72 dB.

Determination of the refractive index and the chiral parameter of a chiral solution based on chiral reflection equations and heterodyne interferometry.

This study develops a method for determining the chiral parameter and the refractive index of an isotropic chiral medium using chiral reflection equations and critical angle phenomena. Linearly polarized light propagates back and forth in a parallelogram prism between two parallel compartments with chiral solutions. A beam splitter then divides the light that emerges from the prism into a reflected light beam and a transmitted light beam. The two beams pass through a compensator and an analyzer, respectively, to cause phase compensation and interference of s and p polarizations. The phase difference between the two interference signals are initially optimized by a suitable optical arrangement and subsequently measured by heterodyne interferometry. Additionally, the refractive index of the solution is determined from the critical angle that occurred at the discontinuity of the phase difference between the two interference signals. These results are substituted into derived equations to calculate the chiral parameter. The approach has the merits of both common-path interferometry and heterodyne interferometry.

Optical method for measuring optical rotation angle and refractive index of chiral solution.

Based on the phenomena of Brewster's angle and the principles of common-path heterodyne interferometry, we present an optical method for measuring the optical rotation angle and the refractive index of a chiral solution simultaneously in one optical configuration. A heterodyne light beam and a circularly polarized heterodyne light beam are separately guided to project onto the interface of a semicircle glass and a chiral solution. One of the beams is transmitted through the solution, and the other is reflected near Brewster's angle at the interface. Then the two beams pass through polarization components respectively for interference. The phase differences of the two interference signals used to determine the rotation angle and the refractive index become very high with the proper azimuth angles of some polarization components, hence achieving an accurate rotational angle and a refractive index. The feasibility of the measuring method was demonstrated by our experimental results. This method should bear the merits of high accuracy, short sample medium length, and simpler operational endeavor.

Improved N-port optical quasi-circulator by using a pair of orthogonal holographic spatial- and polarization- modules.

Based on the flexibilities of light beam propagation in three dimensions, we propose an improved N-port optical quasi-circulator by using a pair of orthogonal holographic spatial- and polarization- modules. All optical elements are located in parallel planes that are perpendicular to the optical axis. The number of optical elements is decreased, and a higher performance optical quasi-circulator without crosstalk and polarization mode dispersion can be easily achieved. A prototype of 5-port polarizationindependent optical quasi-circulator operating at a wavelength of 1300nm was assembled and tested to show its validities.