We report on techniques used to manufacture IR diffractive elements in chalcogenide glasses and on measurements of the materials properties relevant to the performance of these elements. The characteristics of the elements produced are also presented and compared with theoretical predictions. The fabrication process used is based on photodarkening of amorphous As-S films. Low loss, refractive index modulated and surface relief structures have been made, both binary and analogue.

Nonlinear materials offer a wavelength-agile means of protecting sensors against damage by pulsed lasers. The paper reviews the study and development of nonlinear protection materials within DERA. Materials under study include nonlinear absorbers, scatterers, and refractors, and a powerful suite of diagnostic techniques has permitted fundamental study of the underlying nonlinear processes.

Fused taper single-mode fiber couplers are readily fabricated with specific spectral properties, including 3 dB splitting in the 1310 and 1550 nm windows, and 1310/1550 nm wavelength division multiplexing (WDM) and demultiplexing. The specific functionality of the coupler is achieved through precise control over the heating and drawing processes. A possible alternative approach to obtaining the required functionality is to use UV- trimming or post-tuning. The spectral response of single-mode fused taper fiber couplers can be shifted by exposing the entire coupler to intense UV light. Furthermore this occurs without any prior hydrogenation, and there is also no discernible increase in excess loss in the exposed couplers. Results will be presented showing the effect of varying both the fluence and the wavelength of the UV-source on the spectral shift of these and other types of couplers. Wavelength shifts of over 100 nm are possible with the 1310/1550 nm WDM couplers, using sufficient fluence. A simple slab model of the complete tapered coupler confirms that the major contribution to the wavelength shift due to the change in the core index originates mainly in the down- and up-taper regions and, to a lesser extent, in the central waist region. This model explains the greater sensitivity of the spectral shift of the more-tapered WDM couplers to UV-irradiation compared to the shift in the 3 dB couplers.

A vectorial coupled mode theory is used to analyze sol-gel ridge waveguides with UV-light imprinted Bragg grating. The effect of device parameters on grating reflectivity is investigated. It is shown that 100% reflectivity for both TE and TM modes can be achieved using short (1 - 2 mm) gratings. The measured reflectivity in a ridge waveguide with grating agrees with the theoretical predictions for TE and TM modes.

Photosensitive glasses are very attractive because they permit the fabrication of gratings by UV exposition and gratings are key elements in many active and passive components used for communication and sensing applications. At present, most of these devices (particularly the passive ones) are fiber-based, but there is an evident interest in the integration of gratings with complex waveguide structures on a glass substrate to increase compactness and mechanical stability. With this aim, a new photosensitive glass has been developed. Furthermore the glass composition has been chosen so that it is possible to make waveguides with the inexpensive ion exchange technique. Preliminary results on the fabrication and characterization of channel waveguides in this new glass are given.

An optical chemical bench is a nanostructured integrated optics structure--usually a waveguide circuit--where chemistry and spectroscopy can be combined for the purpose of studying chemical reactivity in thin films and at interfaces. In this paper, we describe how glass waveguide surfaces can be decorated with Rayleigh-limit (sub-20 nm dia.) silver and gold colloid particles by covalent bonding to an organothiolate adhesion layer attached to the glass. The step-by-step assembly of the heterostructure is monitored by X-ray photoelectron spectroscopy.

Integrated optical devices can be deposited by photolithography in hybrid organic-inorganic glass films prepared by solution sol- gel processing. The latter are made from a generic matrix of methacryloxypropyltrimethoxysilane, methacrylic acid and zirconium oxide. An optical phase mask and pulsed 6.4 eV light were used to deposit 1.5 mm Bragg gratings in ridge waveguides. The gratings are polarization insensitive and show very high reflectivity at 1.55 micrometers . The photoresponse that give rise to the grating in the nanocomposite are complex. They express themselves simply as an increase in the material refractive index n. To understand the way in which the underlying photochemistry and physical changes contribute to the refractive index change, we chose to follow structural changes in the polymer and silica framework by combinations of electronic and vibrational spectroscopy. Photoinduced polymerization of the organic methacrylate monomer upon UV irradiation triggers a cascade of structural changes within the inorganic matrix. The process is akin to photo-induced sintering. Reduction in non-bonded interactions due to bond formation following polymerization precipitates a localized structural relaxation in the silica network. Collateral densification of the silicate matrix is evident by the shifts to lower energy in the transverse optical phonon mode associated with antisymmetric stretching and decreased Si-O-Si bond angles in the matrix.

The brief review of solid-state interface interaction between systems of metal-metal, metal-semiconductor is given with results for laser and thermal annealing of systems, forming simple eutectic pairs. A conclusion was postulated about an opportunity of their use as recording media for the optical disks.

Hydropolysilane copolymers have been synthesized by the Wurtz- type reductive coupling of mono and diorganodichlorosilane comonomers with sodium dispersion in a refluxing toluene medium. Post-synthetic modifications of the copolymers have been carried out to improve their photosensitivity to UV/Vis energy, by the substitution of electron-withdrawing groups such as acetate (from mercuric acetate), p-nitrophenol, p-cyanophenol, and p- chlorocinnamic acid. The modified and unmodified copolymers, have been extensively characterized by various spectroscopic techniques such as GPC, FTIR, H-NMR, C-NMR, UV/VIS, etc. The results reveal that, the properties as well as the reactivities of hydropolysilanes are strongly dependent on the types of substituent groups on the Si-Si main chains.

Thin films of cadmium selenide were prepared for the first time by spray pyrolysis technique using non-toxic selenosulphate on clean glass, titanium and conducting glass substrates, at substrate temperature in the range of 300 to 500 degree(s)C. The films were characterized by X-ray diffraction, optical absorption, photo conductivity and photo electro chemical studies.

This study examines the optical response and physical properties of the homologous series 4-n-butyl-4'-n-alkoxyazobenzene. The members of this series all exhibit liquid crystalline phase behavior, and have also been used as dopants in 4-cyano-4'- n'pentylbiphenyl (5CB), a room temperature nematic liquid crystal. The guest-host system and the azobenzene series have been characterized using optical microscopy and UV-vis spectrophotometry. Illumination of these systems with light of a suitable wavelength induces a trans-cis isomerization of the azo- dye molecules which results in a reorientation of the liquid crystal director, often to such an extent that the liquid crystal phase is disrupted, causing an in situ isothermal phase transition. The response of the liquid crystal system to a linearly polarized beam of exciting radiation is examined with the use of a probe He:Ne laser. Changes in light transmission are then detected with a photodiode. Responses are discussed in terms of homologue, cell thickness and temperature.

The photochemical behavior of dichromated gelatin and of different aminoacids-chromium (VI) systems was investigated. The photoredox process that takes place between chromium (VI) (complexed or not) and the organic moiety leads to the formation of chromium (V) which is then reduced to chromium (III) likely complexed in the medium. In chromium (VI)-aminoacids systems, the quantum yield (Phi) , that measures the efficiency of a photon at a given wavelength, strongly depends on the reductive properties of the aminoacid. (Phi) is proportional to aminoacid concentration. In irradiated DCG films, the formation of chromium (V) is observed and this intermediate species appears to be surprisingly stable in the polymeric matrix. For the first time, we were able to quantitatively measure the formation of Chromium (V) in dichromated photosensitive materials.

The paper contain the results of investigation of new registration medium based on thin films for optical data storage. Thin compositive polymer films doped with Sb and Pd are the high effective registration media with thermal mechanism of digital recording by means of pulsed laser irradiation of visible and infrared spectral regions. The investigation of the optical properties had been carried out by laser ellipsometry method and Raman spectroscopy in these films.

A computer model has been developed to calculate the optical properties (reflection and absorption coefficient) for various dye thicknesses between 20 and 300 nm for situation various reflecting layer Au or Al (Si). For a high k dye to power absorption being very critically dependent on dye thicknesses. In the less absorbing dye the situation be more extreme, with oscillatory interference effects causing considerable variations in absorption (reflection) from a maximum to a minimum every 50 - 70 nm (Au) and 100 - 120 nm (Al), and 150 nm (Si). A series of calculations are presented on a number of different layer structures and materials in an attempt to optimize the storage medium.