Fiber distributed feedback laser

Utilizing round optical fibers as communication channels in optical communication networks presents the problem of obtaining a high efficiency coupling between the optical fiber and the laser. A laser is made an integral part of the optical fiber channel by either diffusing active material into the optical fiber or surrounding the optical fiber with the active material. Oscillation within the active medium to produce lasing action is established by grating the optical fiber so that distributed feedback occurs

Efficient quantum dot single photon extraction into an optical fiber using a nanophotonic directional coupler

We demonstrate a spectrally broadband and effcient technique for collecting photoluminescence from a single InAs quantum dot directly into a standard single mode optical fiber. In this approach, an optical fiber taper waveguide is placed in contact with a suspended GaAs nanophotonic waveguide with embedded quantum dots, forming an effcient and broadband directional coupler with standard optical fiber input and output. Effcient photoluminescence collection over a wavelength range of tens of nanometers is demonstrated, and a maximum collection effciency of 6.05 % (corresponding single photon rate of 3.0 MHz) into a single mode optical fiber was estimated for a single quantum dot exciton

Optical and mechanical response of high temperature optical fiber sensors

The National Aerospace Plane (NASP) will experience temperatures as high as 2500 F at critical locations in its structure. Optical fiber sensors were proposed as a means of monitoring the temperature in these critical regions by either bonding the optical fiber to, or embedding the optical fiber in, metal matrix composite (MMC) components. Unfortunately, the anticipated NASP temperature ranges exceed the glass transition region of the optical fiber glass. The attempt is made to define the operating temperature range of optical fiber sensors from both optical and mechanical perspectives. A full non-linear optical analysis was performed by modeling the optical response of an isolated sensor cyclically driven through the glass transition region

Distributed Raman optical amplification in phase coherent transfer of optical frequencies

We describe the application of Raman Optical-fiber Amplification (ROA) for the phase coherent transfer of optical frequencies in an optical fiber link. ROA uses the transmission fiber itself as a gain medium for bi-directional coherent amplification. In a test setup we evaluated the ROA in terms of on-off gain, signal-to-noise ratio, and phase noise added to the carrier. We transferred a laser frequency in a 200 km optical fiber link with an additional 16 dB fixed attenuator (equivalent to 275 km of fiber on a single span), and evaluated both co-propagating and counter-propagating amplification pump schemes, demonstrating nonlinear effects limiting the co-propagating pump configuration. The frequency at the remote end has a fractional frequency instability of 3e-19 over 1000 s with the optical fiber link noise compensation

Quantitative sensitivity analysis of surface attached optical fiber strain sensor

Optical fiber strain sensors, in particular, the fiber Bragg grating (FBG) type, are widely applied in different applications. The most common installation method is surface-attached. In principle, the optical fiber strain sensor with adequate sampling and signal processing techniques is usually more accurate than electrical resistive strain gauge. However, the strain of the surface of structure may not transfer to the sensing element perfectly. The ratio between the measured and actual strain can be correlated by a strain transfer factor (STF). However, it depends on the material and geometrical properties of the optical fiber and adhesive. It is noneconomical and impractical to measure the STF for every installed sensor. It is desirable to identify the most of the sensitive parameters on the variation of the STF so that the quality control and assurance procedure can be performed more efficiently. In this paper, a quantitative global sensitivity analysis, called extended Fourier amplitude sensitivity test will be performed to compute the first-order and total sensitivity indexes based on a well-established semi-analytical/empirical mechanical model of three material and five geometrical parameters of both integral and optical FBG type optical fiber strain sensor with two different kinds of polymeric coating under three types of strain field in 16 different configurations. From the detail analysis, the most of the sensitive parameters on the STF are bond length, the thickness of adhesive beneath the optical fiber and the deviation of grating position, which are related to workmanship instead of the material properties of the optical fiber and adhesive

Surface nanoscale axial photonics: Robust fabrication of high quality factor microresonators

Recently introduced Surface Nanoscale Axial Photonics (SNAP) makes it possible to fabricate high Q-factor microresonators and other photonic microdevices by dramatically small deformation of the optical fiber surface. To become a practical and robust technology, the SNAP platform requires methods enabling reproducible modification of the optical fiber radius at nanoscale. In this Letter, we demonstrate super-accurate fabrication of high Q-factor microresonators by nanoscale modification of the optical fiber radius and refractive index using the CO2 laser and the UV excimer laser beam exposures. The achieved fabrication accuracy is better than 2 angstroms in variation of the effective fiber radius

Diffusion of optical pulses in dispersion-shifted randomly birefringent optical fibers

An effect of polarization-mode dispersion, nonlinearity and random variation of dispersion along an optical fiber on a pulse propagation in a randomly birefringent dispersion-shifted optical fiber with zero average dispersion is studied. An averaged pulse width is shown analytically to diffuse with propagation distance for arbitrary strong pulse amplitude. It is found that optical fiber nonlinearity can not change qualitatively a diffusion of pulse width but can only modify a diffusion law which means that a root mean square pulse width grows at least as a linear function of the propagation distance.Comment: 11 pages, submitted to Optics Communication

Optical fibers for the distribution of frequency and timing references

An optical fiber communications link was installed for the purpose of evaluating the applicability of optical fiber technology to the distribution of frequency and timing reference signals. It incorporated a 1.5km length of optical fiber cable containing two multimode optical fibers. The two fibers were welded together at one end of the cable to attain a path length of 3km. Preliminary measurements made on this link, including Allan variance and power spectral density of phase noise are reported

Optical fiber sensor review

Technology of fiber optic are widely used for its applications which mostly known for carrying information over long distances for the best efficiency. It is also used for medical diagnostics, environmental monitoring, physical parameters detection, industrial applications, food safety, and security [1]. The fiber optic technology can also be a method for sensor application which is a fiber optic sensor..