Robert M. Atkins

Stable single-mode erbium fiber-grating laser for digital communication

In this paper we report the fabrication of a short, robust, single-mode Er/sup 3+/ fiber-grating laser. This laser is proven by the successful outcome of a long-term bit-error-rate test at the 10/sup -15/ level in a 5- G/s fiber transmission experiment. In the process we present a new pumping geometry, the elucidation of one origin of relaxation oscillations that have plagued previous lasers and the demonstration of a simple electronic feedback scheme for suppressing them. This prototype source shows real promise for use in a high-speed communications system. >

Ultraviolet laser fabrication of ultrastrong optical fiber gratings and of germania-doped channel waveguides

We report the fabrication of low loss (<0.2 dB) fiber Bragg gratings of 10 nm reflection bandwidth, and of 19 nm bandwidth lossy gratings. With this technology we also demonstrate the direct writing of channel waveguides in commercial germania‐doped wafers without the use of photoresist and etching.

Measurement of the ultraviolet absorption spectrum of optical fibers

A new technique has been developed to measure directly the UV absorption spectrum of optical fibers to wavelengths as short as 200 nm. Both the shape and the intensity of the UV absorption bands found in the fiber correspond to those measured in preforms. No bands other than those attributed to GeO (240 and 330 nm) were observed.

Photoinduced second-harmonic generation and luminescence of defects in optical fibers

Upon irradiation with laser light of specific wavelengths and intensities optical fibers can undergo a slow (minutes to hours) permanent change, which results in new optical phenomena that were not present before irradiation. These phenomena include photoinduced refractive index gratings1,2 and photoinduced second harmonic generation1-4 in doped silica fibers. Since these phenomena are the result of a photoinduced periodic modification of the optical properties of the material with a periodicity that is determined by the wavelength(s) of irradiation, they are examples of photoinduced organization in glasses. Although the physics of these phenomena is not understood in detail, there is ample experimental evidence that the presence of optically active centers in the glass is of crucial importance for the observation of these phenomena. The optically active centers are due to defects or dopants in the glass. Here we discuss photoinduced SHG in Ge-doped silica fibers and the use of luminescence spectroscopy to characterize different types of Ge-related defects in the fiber.