Level Of Optical Losses Research Articles

Ultra-low noise meta-mirrors with optical losses below 500 ppm

Interferometric experiments are often limited in sensitivity by the thermal noise of the mirrors. In particular, interferometric gravitational wave detectors and laser stabilization resonators can benefit from reduced mirror noise. We present results of experimental investigations on micro-structured mirrors (meta-mirrors) and hybrid etalon mirrors (meta-etalons) promising particularly low thermal noise. We show the first characterization of meta-etalons scattering and absorption losses, demonstrating optical losses below 500 ppm. This level of optical losses is sufficient for planning direct thermal noise measurement in dedicated optical cavity experiments. These measurements would be very important for validating the thermal noise predictions. We present our development toward the integration of meta-etalons in ultra-stable optical cavities.

Submicron surface relief fabrication technology for epitaxial GaAs structures with thin AlGaAs stop layers

Basic technology for the fabrication of submicron surface reliefs in epitaxial GaAs structures with thin AlGaAs stop layers has been developed using electron-beam lithography. High sensitivity of the characteristics of vertical-cavity surface-emitting lasers (VCSELs) with respect to the level of optical losses allows this technology to be used for controlling the mode composition and stabilizing the polarization of VCSEL radiation.

Recent advances in preparation of high-purity glasses based on arsenic chalcogenides for fiber optics

The processes of production of high-purity glasses based on arsenic chalcogenides and optical fibers with low optical losses in the middle IR have been analyzed. Physical–chemical, technological and methodological factors determining the degree of purity of glasses and the level of optical losses in optical fibers are considered. Dominant factors, rational actions and approaches optimizing the manifestation of these factors in glasses formed by arsenic chalcogenides are discussed. Vitreous As 2S 3 is produced with the content of hydroxyl groups not more than 1 ppb wt, of hydrogen in the form of SH-groups — 75 ppb mol, of silicon — 0.2 ppm wt. From this glass a multi-mode optical fiber was manufactured with optical losses of 12 and 14 dB/km at 3.0 and 4.8 μm, respectively, which is the best result published in literature for chalcogenide glass optical fibers.

Preparation of optical fibers based on Ge–Sb–S glass system

Unclad optical fibers based on Ge–Sb–S glass systems were prepared by preform drawing. It was shown that optical losses in fibers depend on the content of limiting impurities in glass. The correlation between the level of optical losses in fibers and the content of gas-forming dissolved impurities and heterophase inclusions in glasses was established. The minimum optical losses were equal to 300 dB/km at 5.35 μm wavelength in fiber from Ge 25Sb 10.5S 64.5 glass prepared using chemical-distillation melt purification.

Static multislit dispersive optical spectrometer based on complementary Golay sequences

A high-transmission multislit spectrometer free of moving elements is described, the main parts of which are the multislit entrance aperture, collimator, dispersive element, objective, multichannel matrix detector, processor, and spectrum output device. The proposed instrument differs from the known analogs in that its operation is based on the use of complementary Golay sequences, which makes it possible to use a relatively simple multislit entrance aperture involving only four parallel horizontal rows of slits at an arbitrarily large length of these rows. In practice, this design provides a decrease in the level of optical losses on nontransparent bands separating the rows and simplifies manufacturing of the spectrometer.

Radiation-hard KS-4V glass and optical fiber, manufactured on its basis, for plasma diagnostics in ITER

Transmission spectra and optical losses before and after γ-irradiation (60Co) at a dose up to 11 MGy in 1 cm thick glass plates and in “all-silica” type optical fibers were examined. KS-4V, KU-1, KUVI, Suprasil F-300 glasses and fluorine-doped glass (vapor-phase axial deposition (VAD) technology, Japan) were used as a core material in the fibers. Comparison tests of four types of high purity fused silica (HPFS) showed that the highest ORR is characteristic of KS-4V (the lowest chlorine content). Optical Radiation Resistance (ORR) testing of “all-silica” type fibers (KS-4V glass, Japan VAD glass, Suprasil F-300 and KU-1 glasses as a core material) showed that the highest ORR is characteristic of KS-4V glass, which contains minimum of impurities. The level of optical losses in the visible band of the KS-4V spectrum is twice lower than the level of fluorinated glass (VAD), and 4–5 times lower as the level of losses of Suprasil F-300 and KU-1 respectively.

Propagation and transformation of light waves in magnetically active periodic structures

The influence of an external magnetic field applied to a magnetoactive periodic structure on the specific features of formation of the photonic band gaps is established. It is shown that abrupt (stepwise) changes in the polarization of the radiation transmitted by the periodic structure and reflected from it exist near the band gap edges. The possibility of a substantial enhancement of the Faraday effect at a low level of optical losses in the magnetoactive periodic structure with a large number of periods and a dielectric contrast and without a defect layer is substantiated.