C. Arnone

Study of Photo-Induced Thin Film Growth on Cds Substrates. * *

Photo-induced growth of ZnS on CdS has been studied using amorphous (thin film) and single-crystal substrates. The effect has been found to occur for light of wavelength shorter than the CdS absorption edge; a maximum light-induced thickness enhancement of 700 A has been obtained for the ZnS film, with a growth rate of 2000 A/min. The lightinduced growth, with its observed “memory” of several minutes is consistent with photo-desorption of an adlayer.

Fabrication and characterization of tuned Gaussian mirrors for the visible and the near infrared

A thin-film technique has been developed for vacuum fabrication of mirrors with Gaussian reflectivity profiles. Samples with diameters from 2 to 8 mm and assigned maximum reflectivities for visible or near-IR wavelengths have been made and their optical properties evaluated. By properly choosing both the geometry of the evaporation source and the masking system, one can obtain quasi-Gaussian or super-Gaussian reflectivity profiles.

Copper patterning on dielectrics by laser writing in liquid solution

A technique suitable for laser induced deposition of copper on LiNbO3 and glass is presented. Deposition is achieved from Cu salt solution mixed with glycerol, after coating the surface with a very thin metal film. High resolution and low electrical resistivity can be achieved, using laser power levels in the 20‐mW range. The technique can be used for electrode and interconnect fabrication in integrated optical devices, as well as mask repair or microelectronics applications.

Nd:YAG laser with multidielectric variable reflectivity output coupler

Abstract A gaussian reflectivity output coupler fabricated by means of a new thin film vacuum deposition technique has been experimentally tested in an unstable Nd:YAG laser resonator. High brightness, diffraction limited beams with flat top profile have been generated. The results are compared with those obtained by unstable and stable resonator configurations with uniform reflectivity mirrors.

Anisotropic laser etching of oxidized (100) silicon

Laser‐induced anisotropic chemical etching of silicon is reported, by using a 488 nm Ar+ laser in direct write mode and high‐pressure Cl2 process gas. Surface modifications directly comparable with conventional anisotropic wet etching methods have been obtained. A main role in the process is played by the masking effect due to a thin uniform SiO2 film grown on the Si substrate. An explanation of the etching mechanism is attempted.

The laser-plotter: A versatile lithographic tool for integrated optics and microelectronics

Abstract The apparatus described here represents a low cost approach to artwork generation for integrated optics and microelectronics, in the resolution range around 2 μm. Its main characteristics are given below, together with some examples of the kind of patterns it can generate.

Multilevel pattern generation by GaN laser lithography: an application to beam shaper fabrication

The new GaN lasers represent a unique combination of compactness, reliability, energy efficiency, and short wavelength. With respect to the previous state of the art in direct laser write lithography, based on gas lasers, this is resulting in a breakthrough, and is opening the way to real desktop micropatterning. The field of diffractive optics can immediately benefit by the availability of a new breed of pattern generators, based on such sources, mainly for fast turnaround device development. This paper presents the technical advantages involved in the use of 405 nm GaN lasers for one-step multilevel patterning. Beam modulation, exposure control and overall process strategy are discussed. In order to evaluate the effectiveness of the new solution, a sample fabrication of beam shapers is also presented.

Technologies for the fabrication of cylindrical fine line devices

Abstract A microlithographic process suited for metal patterning on cylindrical substrates has been developed. This includes all steps from metal coating to final etching, with resolution in the 5 μm range.

Fabrication and characterization of polymeric optical waveguides using standard silicon processing technology

We report the fabrication and characterization of a rib polymeric waveguide having a thick layer of oxidized porous silicon as an innovative solution for the lower cladding. The waveguide was fabricated using standard silicon substrates and Si-based technology. The multimodal guiding structure has a polymethylmetacrylate (PMMA) core and the innovative lower cladding was obtained by thermal oxidation of a porous silicon layer. The waveguide does not have the upper cladding. Propagation loss measurements were performed at 1.48 /spl mu/m using the cut-back method. We obtained propagation loss of about 1.7 dB/cm, confirming the possibility to use the porous silicon oxide as the lower cladding layer, for low cost waveguide applications.

Optical rectification and Photon Drag in p-type InAs at 10.6microm☆

Abstract The non-linear process of optical rectification and the Photon Drag effect occurring in p-InAs crystals at CO2 laser frequency are examined and compared, under the hypothesis that both effects are present, in a separable way, in the same crystal. Following this, experimental verification of the behaviour predicted by theory is reported for this semiconductor.