We propose a prism-hologram-prism sandwiched recording method for the fabrication of polarization-selective substrate-mode volume holograms with a large diffraction angle. In fabrication, the C-RT20 photopolymer is sandwiched between two 45°-90°-45° prisms and the interference fringes can be easily recorded in the recording material. The experimental results are in good agreement with the theoretical predictions. The proposed method features of a reflection-type recording setup for a transmission element and belongs to a technique of longer-wavelength construction for shorter-wavelength reconstruction. In addition, the method is much easier than the traditional recording method of two incident beam interference and has application potential in holographic photonics.
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.
In this demonstration, an erbium-doped fiber (EDF) based laser with stable, wide and wavelength-selectable single-longitudinal-mode (SLM) performances is designed and demonstrated. Here, to achieve SLM oscillation, a compound-ring scheme is constructed in the EDF laser cavity serving as a mode-restriction-filter for densely side-mode suppression. Moreover, the continuous-wave tunability can be scaled from 1520.0 to 1582.0 nm by using the proposed compound-ring scheme and commercial C-band EDF amplifier. In the measurement, the output stability and 3 dB Lorentzian linewidth of each lasing wavelength in the proposed EDF compound-ring laser have also been discussed.
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