Claude Delisle

Shearing interferometer for phase shifting interferometry with polarization phase shifter

A cyclic interferometer can be used for both lateral and radial shearing. Being common-path this interferometer is quite stable. The use of a cyclic shear interferometer for phase shifting interferometry is discussed. The phase shifting is provided here by polarization techniques. Some useful cyclic phase shifting interferometer arrangements are discussed, and the working of a polarization phase shifting cyclic shear interferometer is demonstrated.

Bistable optical switching based on bragg diffraction

Abstract The operation characteristics of an acousto-optics nonlinear device are presented where the diffracted light is used to create a feedback leading to hysteresis and bistability. Possible application as an optically controlled two-channel switch with a response time smaller than 1 μs is given.

CdS microcrystallites‐doped thin‐film glass waveguides

Thin films of Corning 7059, glass doped with CdS (2%–4% by weight) microcrystallites, with diameters presumably larger than 6 nm, were fabricated using rf sputtering technique. Sharp optical cutoff near 500 nm is visible on the absorption spectra of the films. Both Raman and absorption spectra presumably reveal the presence of size effects. At λ=632.8 nm the refractive index of the films varies from 1.55 to 1.69 depending on rf power. Propagation losses for TE0 guided mode are about 10 dB/cm.

Nonlinear optical properties of thin‐film waveguides deposited onto semiconductor‐doped glasses

We report the fabrication procedure and properties of optical nonlinear guided wave structures consisting of a thin film of Corning 7059 glass deposited on the surface of CdSxSe1−x doped glass. The limiting action in power‐dependent prism coupling in the structures produced is described. The nonlinear prism coupling is used to evaluate both the sign and the steady‐state value of the intensity‐dependent refractive index of the substrate. For the glass used the nonlinearity is negative and its value is in the range of 10−10 m2/W.

Contrast-invariant pattern recognition using circular harmonic components

A method has been devised to accomplish contrast-invariant pattern recognition using multiple circular harmonic components. In addition to detecting targets with various contrasts in the presence of high-contrast objects, the method is shift- and rotation-invariant. A vector f is formed from the autocorrelation values for each member of a set of circular harmonic components corresponding to the target of interest. The unit vector f/f is a feature vector whose direction characterizes the target. Target detection is accomplished by comparing the corresponding cross-correlation unit vector to the vector f/f. Experimental results are shown.

Polarization Component Phase Shifters in Phase Shifting Interferometry: Error Analysis

We have investigated the influence of the errors of the retardation and azimuth angle of the polarization components of a polarization phase shifter, on the phase measurement, in phase shifting interferometry.

Tapered fused bundle coupler package for reliable high optical power dissipation

Light absorption in structural adhesives constitutes the main source of heat in tapered fused bundle (TFB) devices. Efficient heat dissipation solutions were developed by studying these thermal loads. The relative merits of transparent vs. opaque package designs were established experimentally. In the former, light escapes without being absorbed by the package walls, whereas in the latter, the spurious optical signal is directly absorbed and dissipated. The fact that heat is generated directly in the adhesive largely favors the opaque package, which offers more efficient heat extraction. By using a thermally conductive package, a temperature rise of 1.1°C per Watt of dissipated power was measured. These numbers demonstrate that passive heat sinking at 20°C is sufficient to allow reliable operation up to 45Watts of dissipated power (1kW with 0.2dB optical loss) without compromising long-term reliability.

Nonlinear optical waveguides made of thin films of glass doped with semiconductor microcrystallites

The rf sputtering technique was used to deposit thin films of CdS microcrystallite-doped glass onto standard glass substrates. The presence of the microcrystallites in the films was verified by using Raman spectroscopy. A sharp cutoff below 500 nm was visible on the transmission spectra of the semiconductor microcrystallite-doped films. The evidence of size effects was visible on both Raman and transmission spectra of the films. Power-dependent prism coupling of light into the waveguides was investigated under cw-illumination conditions. The angular variation in decoupled power becomes more asymmetric with increasing input power until switching occurs on one side of the characteristic. The nonlinearity involved is presumably of thermal origin.

Spectral modulation of two coherently separated femtosecond laser pulses

A train of 150-fs 76-MHz pulses is directed into a Michelson interferometer with a path difference larger than the pulse spatial length. A modulated spectrum with a modulation frequency that increases with the path difference is observed. The consequence is discussed.

Optical branching effect in Ti:LiNbO3 waveguides: near-field pattern studies

The paper presents a detailed study of a single optical beam splitting into several beams (the branching effect) in photorefractive sensitive Ti:LiNbO3 optical slab waveguides. The near-field patterns of the multibeam structures are presented for different values of optical power coupled into TE guided modes of different orders. The process of partial recovery of the optically damaged waveguide (the partial shrinking of the multibeam bundle created) is also described.