Light from a pulsed GaAs injection laser is coupled into a glass fiber via a taper coupler. The time dependence of the light backscattered within the fiber as the pulse travels down the waveguide is recorded. From these data the total loss may be determined, as well as an estimate of the scattering and mode mixing characteristics of the fiber.

By using an optical time domain reflectometer a new measurement technique which allows displaying the length dependence of the fiber attenuation by analyzing backscattered light has been developed. This paper compares the backscatter and insertion-loss techniques. In addition, results of several experiments which illustrate the versatility of an optical time domain reflectometer are described.

We propose a new transduction mechanism for fiber optic pressure sensing: pressure-induced microbending, which produces excess optical attenuation in the fiber. A simple bending transducer has been used to determine the response of a step-index multimode fiber to changes in applied pressure. The potential (low frequency) acoustic sensitivity of such a transducer, calculated from this measured response, is approximately 100 μPa into a 1-Hz detection bandwidth.

The reflectivity of single-crystal sodium nitrite has been measured as a function of temperature and crystallographic orientation over a wavelength region which spans all the eight infrared-active normal modes. The temperature-dependent dielectric response functions and oscillator parameters have been obtained both by a Kramers-Kronig analysis and by fitting the reflectivity data with a series of independent harmonic oscillators. The latter model produces a good fit to the observed reflectivity at all temperatures both above and below the phase transition. Although all observed modes are temperature-dependent, none is thought to be a ferroelectric soft mode.

Studies of high optical power density propagation in Ti-diffused LiTaO3 waveguides are described. Optical damage at room temperature involving ’’blow-out’’ of the central output spot into the m line and clean-up phenomena have been observed. Studies at elevated temperature (≈150 °C) indicate that self-annealing of the damage allows these structures to sustain optical power densities up to 11 kW/cm2 at 5145 Å without damage and power saturation. Use of high-purity LiTaO3 is required if room-temperature operation at these high optical power densities is to be achieved.