Techniques for monitoring the quality (e.g., optical and mechanical properties) in optical waveguides (e.g., photonic crystal fibers) are disclosed. Additionally, techniques for detecting and localizing defects in the waveguides are also described. Pulses of light are launched into one end of an optical waveguide. The amount of light scattered out of the same end of the waveguide (i.e., a backscattered or reflected signal) is monitored at certain wavelengths specific to the spectral characteristics of the waveguide. Transmission characteristics and defect localization can be determined from the backscattered signal.

Optical waveguide monitoring

An accurate method for characterizing optical fiber using a modest enhancement to equipment that is already in place for other purposes within an optical transmission system is thereby disclosed. In particular, optical amplifier light sources already embedded in transmission equipment are used to provide accurate characterization information in addition to their conventional purpose. Therefore, the invention permits fiber characterization at little additional cost over the optical amplifier light sources already present in a system. Furthermore, the need of going out to the field, disconnecting the transmission equipment and performing the field measurements with separate test equipment is eliminated.

Out of band fiber characterization using optical amplifier light sources

The invention relates to a procedure serving to correct for intensity decrease, due to optical attenuation, of fluorescence from a liquid sample in connection with fluorometric quantitative analysis, in said procedure the liquid sample being placed in a cuvette, an excitation light beam being directed into said cuvette and the intensity of the fluorescent light produced by the excitation light beam in the liquid sample owing to the substance therein contained being determined and the concentration of the substance contained in the liquid sample being determined on the basis of this intensity, wherein the intensity distribution of the image of the fluorescent liquid sample created in the liquid sample by said excitation light beam is determined and the optical attenuation is determined from the intensity distribution that has been measured.

A procedure and apparatus for correcting intensity decrease in fluorometric quantitative analysis

The invention relates to a crystal fiber, a Raman spectrometer using the same and a inspection method thereof. The crystal fiber comprises a sapphire crystal is doped with two transition metals having different concentrations. An excitation light beam at a specific wavelength can propagate along the crystal fiber to generate a narrow-band light beam and a wide-band light beam to project on a specimen. Raman scattered light is emitted from the specimen. The wavelength of the Raman scattered light falls within the wavelength range of the wide-band light beam so that the wide-band light beam is enhanced at some characteristic wavelengths to facilitate Raman spectroscopy.

Crystal fiber, raman spectrometer using the same and detection method thereof

A system for measuring an absorption coefficient of a doped optical fiber may include: a laser source configured to transmit laser light at a selectable wavelength; a single-mode optical fiber including an end configured to splice to the doped optical fiber; two or more multimode fibers at a side of the doped optical fiber, spaced apart along the side of the doped optical fiber, configured to collect spontaneous emissions from the side of the doped optical fiber; and/or a photodiode or power meter connected to the two or more multimode fibers. A method for measuring an absorption coefficient of a doped optical fiber may include: collecting, from a side of the doped optical fiber, an emission spectrum using two or more multimode fibers; and/or calculating the absorption coefficient form using the emission spectrum and McCumber theory.

Systems and methods for measuring absorption coefficients of doped optical fibers

A method of determining optical absorption and emission spectra from a crystal or non-crystalline fiber sample includes directing a laser light source to a side of the fiber sample and measuring fluorescence intensity at various positions along the crystal fiber sample, and then directing a broadband light source through the ends of the crystal fiber sample and measuring absorption in a region of no fluorescence. The preferred apparatus for carrying out the method includes a broadband light source to generate measurable absorption outside the region of fluorescence and a laser light source for generating measurable absorption in the region of fluorescence.

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A. Martin Buonchristiani

Papers

Method and apparatus for determining optical absorption and emission characteristics of a crystal or non-crystalline fiber