Spatial-frequency response of holographic gratings photodeposited from inorganic colloids.
Surface photodeposition is a photon-assisted process by which thin films are formed on substrates immersed in colloid solutions. We experimentally evaluate the resolution capabilities of the photodeposition process with amorphous selenium colloids by recording holographic gratings at different spatial frequencies, up to 2200 lines/mm. The experimental diffraction efficiencies are analyzed in terms of a theoretical model, which relates the spatial-frequency response to optical recording parameters and colloid particle sizes. The maximal experimental diffraction efficiency reaches 13% with a spatial frequency of f = 1100 lines/mm. The diffraction efficiencies decrease monotonically with spatial frequency, and drop to half of the maximal diffraction efficiency at f ≈ 1500 lines/mm. These resolution capabilities are achieved with colloid particle sizes extending up to 80 nm. The theoretical derivation indicates that to obtain spatial frequencies above 3000 lines/mm, one should restrict the colloid particle size to a(max) ≤ 30 nm.
Optical Photorecording By The Surface Photodeposition Effect
The basic properties of the surface photodeposition effect are described. The process can be used as an imaging and optical recording method realizable with various light sources such as laser, discharge, or even conventional incandescent white light sources. Since the photo-process is controlled by the dose of light delivered to the photosystem, films of required thicknesses can be obtained in the range 50 to 2000 nm. This makes possible the preparation of various optical devices such as coatings, filters, phase retardation plates, holograms, gratings, and optical patterns for recording data. The optical resolution and contrast were tested by projection and mask contact methods. With both methods, the recorded linewidth resolution of the imaged patterns was about 1000 nm. This figure, however, was the basic resolution of the optical projection system or that of the original mask used for imaging. Theoretical arguments lead us to assume that the effect can provide better resolution due to its special feature of a one-step photographic process involving adsorption on a flat surface without a scattering emulsion on it.
Third order nonlinear distortion of SAW duplexers in UMTS system
Nonlinearity distortion characterization and accurate modeling techniques for leaky surface acoustic wave (LSAW) devices have been desired in the recently years due to the applications of the Radio Frequency (RF) SAW duplexers in the third-generation (3G) telecommunication system, such as Universal Mobile Telecommunications System (UMTS). In the work, we first discuss the approaches to measure and characterize the 3rd order harmonic generation of the resonators on lithium tantalate YXl42° wafer and YXl48° wafer, with resonance frequency of 800MHz to 900 MHz; Second, we present an effective nonlinear Butterworth-van-Dyke (BVD) model to simulate the multi-tone 3rd order intermodulation effects of a band 5 duplexer; simulation result vs. measurement of 3rd order harmonic generation, 3rd order intermodulation (IMD3) and triple beat are presented.