Showing papers on "Mode scrambler published in 2001"
Patent•
26 Jun 2001TL;DR: In this article, a mode transformer (100) is proposed to enable low-loss coupling between optical modes of two waveguides with different index difference, where the mode size and effective index are gradually changed between two waveguide to gradually transform the mode shape, size, and speed with minimum power loss.
Abstract: A mode transformer (100) that enables low-loss coupling between optical modes of two waveguides with different index difference. The mode size and the effective index are gradually changed between two waveguides to gradually transform the mode shape, size, and speed with minimum power loss. The mode transformer is useful for coupling the mode of an optical fiber waveguide with low index difference to the mode of a planar high index difference waveguide, and vice versa.
84 citations
Patent•
22 Mar 2001
TL;DR: In this article, the authors proposed a mode converter for converting an optical signal from a first propagation mode (e.g., LP 01 ) to a second propagation mode(i.e., LP 02 ), which includes a first waveguide supporting a first mode of propagation.
Abstract: A mode converter for converting an optical signal from a first propagation mode (e.g., LP 01 ) to a second propagation mode (e.g., LP 02 ). The mode converter includes a first waveguide supporting a first mode of propagation. The mode converter also includes a second waveguide supporting a second mode of propagation. The first and second waveguides each having a group index characteristic, wherein the first group index characteristic is matched with the second group index characteristic such that electromagnetic energy propagating through the first waveguide at the first mode couples to the second waveguide at the second mode.
84 citations
Patent•
16 Mar 2001
TL;DR: In this article, a power of at least one wavelength of the optical signal is coupled from a first mode to a second mode of the waveguide and the power of the signal is measured at a detector.
Abstract: A method of measuring a power spectrum of an optical signal. The optical signal is transmitted through an optical fiber. A power of at least one wavelength of the optical signal is coupled from a first mode to a second mode of the waveguide. The power of the optical signal coupled from the first mode to the second mode is measured at a detector.
24 citations
TL;DR: In this article, the modal intensity distribution of light at the output of an optical fiber is reconstructed by using a time-gating reference field to detect the interference of the modality distribution with the reference field, and the detected interference patterns are analyzed, providing the spatial impulse response of the fiber.
Abstract: We demonstrate a method for reconstruction of the modal intensity distribution of light at the output of an optical fiber. Spatial modes of the optical fiber are separated in time as a result of differences in group velocity and are detected experimentally by observation of the interference of the modal field distribution with the time-gating reference field. The detected interference patterns of the modal fields are analyzed, providing the spatial impulse response of the fiber. We also use interferometric correlation to determine the spatiotemporal characteristics of the fiber modes, such as pulse width, linear chirp, and group velocity, for each mode.
20 citations
Patent•
19 Jan 2001
TL;DR: In this article, a mode coupler is coupled to an optical fiber and couples a first mode to a different spatial mode in a forward direction of the optical fiber in an optical apparatus.
Abstract: An optic apparatus includes an optical fiber with a cladding surrounding a core and a core-mode blocker included in at least a portion of an interactive region of the optical fiber. A mode coupler is coupled to the optical fiber and couples a first mode to a different spatial mode in a forward direction of the optical fiber.
16 citations
Patent•
10 Dec 2001TL;DR: In this article, an operation mode switching apparatus comprising a structure for making it possible to minimize the waste of energy caused by troubles occurring in optical fiber lines and the like in order to efficiently utilize the energy consumed in an optical transmission system aimed for a long-term operation.
Abstract: The present invention relates to an operation mode switching apparatus comprising a structure for making it possible to minimize the waste of energy caused by troubles occurring in optical fiber lines and the like in order to efficiently utilize the energy consumed in an optical transmission system aimed for a long-term operation; a Raman amplifier including the operation mode switching apparatus; and an optical transmission system including the Raman amplifier. If an optical fiber line acting as an optical transmission medium breaks in the optical transmission system, the signal power detected from the optical fiber decreases, whereby it changes to a set value or less or the amount of decrease in signal power per unit time changes by a set value or more. The operation mode switching apparatus comprises a control section for monitoring such a change in signal power, thereby switching the pumping light supply operation from a communication mode to a wait mode for minimizing the waste of pumping energy in response to the occurrence of troubles.
12 citations
Patent•
06 Jul 2001
TL;DR: In this article, a pumped-fibre laser with a spatial mode converting device receiving the beam is described, which is referred to as a multimodal laser, where the doped fiber has a core with diameter greater than 30 micrometers.
Abstract: The invention concerns a pumped fibre laser comprising essentially a doped fibre (1), Said laser is mainly characterised in that the doped fibre is multimode (1) and it also comprises a spatial mode converting device (3) receiving the beam. Said multimode fibre has a core with diameter greater than 30 micrometers, even greater than 50 micrometers.
9 citations
TL;DR: In this paper, an annealed step-index fiber was used for a mode-scrambler with reproducible performance and source-launch-alignment insensitivity, and an all-fibre mode scrambler with a 10 cm length and insertion loss < 3.5 dB was demonstrated.
Abstract: A mode scrambler based on an annealed step-index fibre is shown to have reproducible performance and source-launch-alignment insensitivity. Devitrification produces scattering centres in the fibre that distribute light uniformly over both angle and radius. An all-fibre mode scrambler with a 10 cm length and an insertion loss < 3.5 dB is demonstrated.
8 citations
30 Oct 2001
TL;DR: In this paper, the authors proposed a coherent propagation method of Gaussian beam decomposition to model and describe intracavity beam shaping in a diode-end-pumped Nd:YVO 4 laser and compared to modeling of expected Hermite-Gaussian mode generation.
Abstract: Methods of shaping laser beams within the laser resonator are studied. The simplest form of shaping is the spatial modegeneration inherent in the laser cavity due to the geometry of the resonator in conjunction with gain to compensate forroundtrip losses, such as diffraction and output coupling. Typically the fundamental mode or multimode behavior isexhibited from such configurations. Passive mode shaping can be accomplished by introducing static amplitude or phasemasks. An example of an amplitude mask is provided in order to generate a higher-order spatial mode. Active mode shapingcan be accomplished by altering the optical pump distribution. This case is studied experimentally with a diode-end-pumpedNd:YVO 4 laser and compared to modeling of expected Hermite-Gaussian mode generation. Active mode shaping allows thepreferred mode distribution to be altered in real time. Additional shaping can be done following the resonator to modify aHermite-Gaussian mode into a psuedo-Laguerre-Gaussian mode. This work also shows that using the coherent propagationmethod of Gaussian beam decomposition is capable of modeling and describing intracavity beam shaping.Keywords: laser beam shaping, transverse modes, solid-state lasers, laser resonator, coherent propagation, Hermite-Gaussianmode, Laguerre-Gaussian mode
4 citations
30 Sep 2001
TL;DR: In this article, a new mode converter based on the hollow optical fiber to convert the fundamental mode to the ring shape mode is proposed to reduce the differential modal delay of multi-mode fiber (MMF).
Abstract: A new mode converter based on the hollow optical fiber to convert the fundamental mode to the ring shape mode is proposed to reduce the differential modal delay of multi-mode fiber (MMF). We report improvement of BER for 2.5Gb/s transmission at 1.31 /spl mu/m through 500 m of MMF using the proposed mode converter.
3 citations
TL;DR: In this article, a polarization scrambler was used to increase the response stability of a fiber Mach-Zehnder interferometer with respect to the Faraday effect, based on simulation results.
19 Oct 2001
TL;DR: In this article, the authors demonstrate that it is possible to derive the index profile from the desired modal characteristics, which may expedite the development of special fibers with tailored mode profile.
Abstract: Fibers with tailored mode profile may benefit special applications, for example, large mode size and low nonlinearity can improve the performance of dense wavelength-division-multiplexed systems. We demonstrate that it is possible to derive the index profile from the desired modal characteristics. The procedure may expedite the development of special fibers.
Patent•
29 Nov 2001TL;DR: In this article, a method for configuring the operating mode of an optical detector, by recognition, following an emission in a first operating mode M 1, by means of the receiving system, is presented.
Abstract: Method for configuring the operating mode of an optical detector, by recognition, following an emission in a first operating mode M 1, by means of the receiving system. The latter then confirms the detector in the first operating mode or switches it over into a second operating mode M 2 according to whether there is recognition of the first mode. Automatic validation or validation carried out by the operator confirms the recognized operating mode. Application to multimode optical detectors able to operate in barrier, reflex, proximity, background suppression proximity mode.
11 May 2001
TL;DR: In this article, a new mode converter based on a tapered hollow optical fiber (HOF) was proposed, which can convert the HE/sub 11/ mode of a single-mode fiber to the H/sub 12/ mode in a step index dispersion-compensated fiber (DCF) with a coupling efficiency of more than 80%.
Abstract: Summary form only given. We have fabricated a new mode converter based on a tapered hollow optical fiber (HOF) that can convert the HE/sub 11/ mode of a single-mode fiber to the HE/sub 12/ mode in a step index dispersion-compensated fiber (DCF) with a coupling efficiency of more than 80%. Design parameters for the HOF and the matching step index DCF have been numerically predicted and show an average chromatic dispersion of -700 psec/nmkm in the EDFA C-band.
TL;DR: In this paper, a ring-shaped single-mode field pattern at Stokes wavelengths of backward stimulated Raman scattering in a multimode fiber is reported for the first time and some other novel experimental and numerical results are presented to explain the mechanism.
Abstract: The observation of a ring-shaped single-mode field pattern at Stokes wavelengths of backward stimulated Raman scattering in a multimode fiber is reported for the first time. This phenomenon and some other novel experimental and numerical results are presented to explain the mechanism. It has been proved that self-focusing plays little role in the formation of the ring-shaped structure. The ring-shaped pattern is attributed to the refractive index profile of the fiber used in the experiment. It corresponds to the fundamental mode of the fiber and mode competition causes the Stokes waves to propagate in the fundamental mode.
Journal Article•
TL;DR: Theoretical analysis of laser transverse mode competition is investigated in this article from the perspective of the spetial overlap of modes with a transverse gain-loss distribution, where the dominant mode is the mode that is stable under small perturbations.
Abstract: Theoretical of multiple transverse mode laser oscillation involving spatially varying gain and loss are investigated. The effect of gain and loss distribution on mode competition is analyzed. A theoretical analysis of laser transverse mode competition is investigated from the perspective of the spetial overlap of modes with a transverse gain-loss distribution. The dominant mode of laser oscillation is the mode that is stable under small perturbations.
17 Oct 2001
TL;DR: Test results indicate that high-order mode technology precisely manages chromatic dispersion to enable high-capacity, long-haul and ultra long- haul optical networks.
Abstract: The following paper analyzes a dispersion management technique for improved transmission fiber performance using high-order mode optical physics technology. Test results indicate that high-order mode technology precisely manages chromatic dispersion to enable high-capacity, long-haul and ultra long-haul optical networks.