Recent advances in Nd-doped phosphate laser glasses for high-peak-power and high-average-power applications are reviewed. Compositional studies have progressed to the point that glasses can be tailored to have specific properties for specific applications. Non-radiative relaxation effects can be accurately modeled and empirical expressions have been developed to evaluate both intrinsic (structural) and extrinsic (contamination induced) relaxation effects. Losses due to surface scattering and bulk glass absorption have been carefully measured and can be accurately predicted. Improvements in processing have lead to high damage threshold (e.g. Pt inclusion free) and high thermal shock resistant glasses with improved edge claddings. High optical quality pieces up to 79 x 45 x 4cm3 have been made and methods for continuous melting laser glass are under development.
Photochromism is a specific example of photosensitivity in which the absorption spectrum of a material is altered by exposure to electromagnetic irradiation and in which the sample reverts to its original condition after cessation of the irradiation. This phenomenon has been observed in a variety of glasses and crystals. In addition to photochromism, photosensitivity is exemplified by permanent changes in absorption, refractive index, chemical durability or in other properties. Photosensitive materials provide a convenient means of producing spatial modulation of properties.
A review of physical properties of the materials used in manufacturing real acousto-optic cells for optical and RF signal processing is presented. The overall design of acousto-optic cells requires the knowledge of not only the elastic modulii of the second order, but those of higher orders also, as they determine the acoustic nonlinearity and the dynamic range of any device. The parameters of elastic anisotropy determine the near zone of cell's transducer and directly affect cell's time aperture and number of resolvable spots, and interchannel cross-talks in multichannel devices. The requirements to the properties of crystal materials used in cells with anisotropic and collinear interaction are discussed.
Dielectric coatings have been in use for a very long time, yet today they represent a steadily growing world-wide industry. A wide range of materials, and applications from the near ultraviolet into the infrared are in use, or under development. This paper is a brief survey, including references to the literature, and a discussion of materials diagnostics. Discussed is the microstructure, optical constants and their relationship as determined especially by optical measurements. This paper emphasizes the materials science aspects rather than applications.
This paper surveys available transparent infrared optical materials, their applications, selection criteria, and physical properties. Crystalline, polycrystalline, and amorphous (glassy) materials are considered. A few representative materials (KBr, KRS-5, MgF2, BaF2, A1203, Si02, ZnS, ZnSe, GaAs, Diamond, Ge, ZBLAN glass, As2S3 glass and Ge28SbI2Se60 glass) are discussed in detail and a complete and consistent set of property data are provided. Applications for these materials include bulk optics (lenses, prisms, beam splitters, etc.), windows, optical fibers, thin-film coatings (spectral and neutral density filters, protective and anti-reflective coatings), and opto-electronic devices.
The properties that are important for the application of optical glasses are specified. It is described which regions of optical properties are realized today. In the last 15 years the improvement of existing glass types has been priority over the development of new glass types. Logistic actions on the availability have been useful for producers and users and will be continued. Scientific investigations of new glass systems give indications to new regions of refractive indices and dispersion behaviour which may be received. But glasses with extreme optical properties may have disadvantages (e.g., lower chemical resistance, lower transmission) or other limitations. A patient and consequent development - also concerning glass-type-specific production methods - may yield interesting new glass types.
Compact and efficient tunable solid state UV sources are highly desirable for a variety of optoelectronic and medical applications. During the past decade single crystals with certain types of boron-oxygen anionic groups have been identified as providing excellent short wavelength transmission and nonlinear properties which allows them to efficiently convert longer wavelength laser light to the UV and vacuum UV regions. In this review the properties, crystal growth methods, defect issues and device applications for the most important of these materials are discussed.
High-power/high-energy laser (HEL) systems include an optical train consisting of mirrors and windows, which must be capable of transporting and directing the beam without seriously degrading the nominal performance. Since catastrophic failure modes are not a major threat at beam-power levels of current interest, the system's performance as measured in terms of achievable target irradiances may degrade as a result of thermal lensing, that is, the wavefront distortion caused by thermally induced phase aberrations. The purpose of this paper is to review and update analytical investigations that address the problem of evaluating die nature of laser-driven mirror/window distortions; in this context, it is shown how to obtain simple figures of merit (FoM) for rating the thermal lensing performance of mirror-substrate materials as well as window-material candidates. The performance of cooled HEL mirrors reflects their ability to minimize irradiance-mapping wavefront distortions, which leads to defining a thermal distortion coefficient % that controls the out-of-plane growth of the faceplate. It is then straightforward to derive equations for characterizing the RMSsed surface deformation and to assess the merit of mirror-faceplate materials in a pulsed or a CW environment. Since state-of-the-art heat exchangers exhibit relatively modest Biot numbers, the thermal conduction is not a critical parameter but the modulus of elasticity must be properly factored into the FoM for CW operation. Window-induced wavefront deformations require special attention because they involve not only position-dependent variations of the window thickness but also position- and polarization-dependent variations of the refractive index. This situation leads to introducing a symmetric and an anti-symmetric distortion coefficient, which can be combined into an effective optical distortion coefficient x that specifies the relative weight of birefringence compared to all other sources of distortion and shows that zero distortion can only be achieved with stress-birefringence free material having a negative dn/dl'. As in the case of mirror-faceplate materials, FoM’s for the pre-diffusion and the steady-state regimes emerge in a direct manner and demonstrate that fluoro-zirco-aluminate glass by far outperforms other window-material candidates in implementing the zero-distortion goal.
The photorefractive(PR) materials offer the real-time, erasable, high capacity, and parallel accessible capabilities, that warrant applications to variety of photonics devices. In this paper, we reviewed some of the material processing aspects and their optical properties. The thermal influence on the PR materials, dynamics of PR holographic process as well as applications of PR fiber holograms are discussed. The major obstacle and fundamental limitations of the PR materials that prevent the wide-spread applications are also described.
In this paper, we shall briefly review some recent works done at The Pennsylvania State University on the photorefractive(PR) fibers and their applications. There are three major parts. First, we shall briefly review the growing process of single crystal fiber by using the laser heated pedestal growth (LHPG) technique. Second, a brief discussion on the theory of the holographic grating recording in the PR crystal fiber will be provided. Finally, the applications of PR crystal fibers to the holographic storage, fast speed wavelength tunable filter, and fiber optic true time delay line will be discussed.
The physical mechanisms of the light interaction with different materials are discussed. The modulation of refractive index and conductivity gives a physical basis for the different applications: Information Storage, Image Processing, Material Characterization and Control. A concept of the dual-use devices is formulated, based on the simultaneous use of the light-induced modulation of the optical and electrical material parameters. The latest results in the high-contrast dynamic holography are presented with emphasis on nonlinear interaction of the optical and space-charge waves.
A review of the current status, understanding and trends in the field of oxide-glass fiber-optics. It discusses separately the linear and nonlinear optical properties of fibers, with a focus on doped-silica compositions. Applications and devices covered include communications fibers, dispersion control, rare earth and Raman fiber amplifiers and lasers, fiber gratings, filters, isolators, switches, sensors, hollow and birefringent fibers, frequency doublers and soliton generation.
Non-oxide glasses1-5 find an increasing use in fiber optic applications. Most of the current research activity is in the halide glass fibers used as active hosts for rare-earth ion doping. These include, 1.3 and 1.5 μm optical amplifiers, frequency upconversion devices, fiber lasers, permanent gratings, etc. Other non-oxide glasses, chalcogenides and mixed chalcogenide halide glasses have potential in fiber applications in IR laser power deliverers, image-guides and sensors. Some of the important issues that require further research include, the glass purification, stable glass compositions, hermetic coatings for fibers, better methods for preform and fiber fabrication.