Acoustic-optic Modulator Research Articles

Frequency stabilized laser diode locked to acetylene gas absorption lines using fiber-pigtail-type acoustic optical modulator

The operation frequency of 1.5 mu m laser diodes can be stabilized to /sup 12/C/sub 2/H/sub 2/ and /sup 13/C/sub 2/H/sub 2/ gas absorption lines without dithering the frequency spectrum of the laser diodes. The scheme employs a fiber-pigtail-type acoustic optical modulator for the purpose of a small laser-frequency scanning. Frequency stability within 3 MHz peak-to-peak fluctuation is achieved without dithering the frequency of the laser diodes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Frequency stabilization of laser diodes using 1.51−1.55 μm absorption lines of12C2H2and13C2H2

Abstract Frequency stabilization of an 1.5 μm distributed feedback laser diode (DFB-LB) is demonstrated using a vibrational-rotational absorption of acetylene 12C2H2 and 13C2H2 molecules (VRAM). Frequency stability within 2 MHz peak-to-peak fluctuation can be achieved in the wavelength region of 1.51–1.55 μm. Frequency-stabilized distributed feedback (DFB) laser compact modules have been constructed. When the fiber-pigtail-type acoustic optical modulator was used for small laser frequency scanning, frequency stability within 3 MHz peak-to-peak fluctuation was achieved without any broadening of laser spectral linewidth. In addition, temperature and pressure dependencies of the acetylene absorption lines are characterized.

ＡＦＭの試作と回折格子の形状測定

We have succeeded in constructing AFM using an optical fibre and a lever. Our AFM has a silicon dioxide V-shaped microcantilever with sharper tip radius than a commercial pyramid shape one by the silicon processing techniques combined with newly realized not only anisotropic etching but iso-one Si(100) surfaces. One of other superior techniques is that the output laser power through the optical fibre is controlled to be constant within more or less 1.0% by use of AOM (acoustic optical modulator). We also try to observe AFM images of PMMA (polymethyl metha acrylate) gratings which is soft material and to discuss the image differences when we use both the bigger protrusion on the lever and the smaller one.

Apparatus for continuous, fast, and precise measurements of position and velocity of a small spherical particle

The position and velocity of optically levitated glass spheres (radii 10–20 μm) moving in a gas are measured accurately, rapidly, and continuously using a high-speed rotating polygon mirror. The experimental technique developed here has repeatable position accuracies better than 20 μm. Each measurement takes less than 1 μs and can be repeated every 100 μs. The position of the levitated glass spheres can be manipulated accurately by modulating the laser power with an acoustic optic modulator. The technique provides a fast and accurate method to study general particle dynamics in a fluid.

Fast acoustic diffraction-type optical waveguide modulator

A fast acoustic diffraction-type thin-film optical waveguide modulator is described. Modulation was observed for the drive signal over the 150–550-MHz frequency range. A depth of modulation of 10% per electrical watt was estimated from the diffracted spots. The scheme presented here widens the selection of materials for acousto-optic modulations in an optical waveguide and may find some useful applications in the infrared region where suitable electro-optic materials are few.