Ultrafast femtosecond-laser-induced fiber Bragg gratings in air-hole microstructured fibers for high-temperature pressure sensing

We present fiber Bragg grating pressure sensors in air-hole microstructured fibers for high-temperature operation above 800°C. An ultrafast laser was used to inscribe Type II grating in two-hole optical fibers. The fiber Bragg grating resonance wavelength shift and peak splits were studied as a function of external hydrostatic pressure from 15 psi to 2000 psi. The grating pressure sensor shows stable and reproducible operation above 800°C. We demonstrate a multiplexible pressure sensor technology for a high-temperature environment using a single fiber and a single-fiber feedthrough. © 2010 Optical Society of America

A fiber-integrated quantum memory for telecom light

We demonstrate the storage and on-demand retrieval of single-photon-level telecom pulses in a fiber cavity. The cavity is formed by fiber Bragg gratings at either end of a single-mode fiber. Photons are mapped into, and out of, the cavity using quantum frequency conversion driven by intense control pulses. In a first, spliced-fiber, cavity we demonstrate storage up to 0.55$\mu$s (11 cavity round trips), with $11.3 \pm 0.1$% total memory efficiency, and a signal-to-noise ratio of $12.8$ after 1 round trip. In a second, monolithic cavity, we increase this lifetime to 1.75$\mu$s (35 round trips) with a memory efficiency of $12.7 \pm 0.2$ (SNR of $7.0 \pm 0.2$) after 1 round trip. Fiber-based cavities for quantum storage at telecom wavelengths offer a promising route to synchronizing spontaneous photon generation events and building scalable quantum networks.Comment: 8 pages, 7 figure

Type I and II Bragg gratings made with infrared femtosecond radiation in high and low alumina content aluminosilicate optical fibers

Aluminosilicate fibers have very low Brillouin scattering gain coefficients, making them interesting fibers for nonlinear optical applications. We manufactured Bragg gratings in high (30 mol.%) and low (4 mol.%) alumina content optical fiber using 800 nm femtosecond pulse duration radiation and a phase mask. Grating spectral characteristics and thermal behavior are presented. Index modulations >10 123 were generated for fundamental pitched Bragg gratings, and >10 124 for higher-order gratings. Gratings were annealed at temperatures up to 900\ub0C. Type II gratings written in fibers with lower alumina content showed better thermal stability than gratings written in fibers with higher alumina content. Bragg gratings in these fibers would be well suited as laser cavity mirrors in high-energy laser systems, as well as in telecommunication and sensor systems where Brillouin scattering restricts power scaling.Peer reviewed: YesNRC publication: Ye

Femtosecond laser induced fiber Bragg gratings for harsh environment sensing applications

Fiber Bragg grating sensors have been developed beyond a laboratory curiosity to become a mainstream sensing technology because of their small size, passive nature, immunity to electromagnetic interference, and capability to simultaneously measure multiple physical parameters such as temperature, strain and pressure. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This presentation will give a review of some of the more recent developments of femtosecond laser induced fiber Bragg gratings.Peer reviewed: YesNRC publication: Ye

Characterization of Er3+-doped Ti:LiNbO3 waveguides: losses, absorption spectra and near field measurements

In this paper we present some experimental results about the characterization of Er^3+-doped Ti:LiNbO_3 waveguides using nondestructive methods. We report results concerning losses, near field and absorption measurements. Waveguide losses have been measured in the 1550 nm wavelength region through an interferometric method based on two different techniques: thermal cavity tuning and wavelength sweeping. Homogeneous absorption and emission cross sections have been calculated from transmitted spectra. The near field measurements have been used to obtain the waveguide mode profile through a deconvolution algorithm to eliminate the probe effect. The resulting field profile allowed to reconstruct the refractive index distribution