<title>Micro-Bragg reflectors in photorefractive 3D waveguides</title>

Optical 3-D waveguides can be fabricated by moving a focus of a strong laser beam in photorefractive materials. If Bragg reflectors as small as the waveguides can be fabricated, they can be used as spectral filters, beam splitters, or beam combiners along with the waveguides or network of waveguides. Small complex optical systems such as a very small interferometer can be made in the photorefractive media. We first demonstrate our fabrication experiments of a straight, curved and array of photorefractive waveguides. Then we present the concept of small Bragg reflector in a lithium niobate crystal and show the experimental results. We confirmed the spectral selectivity of this micro-Bragg reflector by using light from a tunable dye laser. We also confirmed that we can fabricate waveguide structures simultaneously with the micro-Bragg reflector, by using a crystal whose c-axis is directed 45 degrees off the optical axis of the microscope objectives. Unfortunately, however, the reflectivity of the micro-Bragg reflector is not large enough for the immediate use.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.