Topic
Mode scrambler
About: Mode scrambler is a research topic. Over the lifetime, 896 publications have been published within this topic receiving 13595 citations.
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16 Feb 2009
TL;DR: In this paper, a combination of 45°-angled cut waveguide, Y-splitter and S-bend structures was designed and fabricated for simple evaluation of multimode waveguides.
Abstract: Polymer optical waveguide devices are getting popular for optical printed circuit board and/or home-network applications. In order to accelerate the development of polymer optical waveguide devices, evaluation of waveguide characteristics should be reliable and speeded up. Polymer optical chip containing a combination of 45°-angled cut waveguide, Y-splitter and S-bend structures was designed and fabricated for simple evaluation of multimode waveguides. Input launching conditions such as mode scrambler was investigated for reliable measurement for standardization.
01 Aug 2016
TL;DR: In this article, the authors proposed a photonic crystal fiber (PCF), which can achieve single TM-like mode transmission in the C- and L-band of the optical communication wavelength bands.
Abstract: When human society entered the 21st century, the demand of high-speed and large-capacity optical communication systems is constantly increasing and at the same time photonic crystal fabrication techniques have also made great progress. Precisely because of this, optical devices for information and communication systems, which are designed by the concept of photonic crystal, have been studied attractively in the world. One important component of these devices is polarization or mode selective device, and single mode optical fibers [1–3] are advantageous over multi mode optical fibers in this component. Therefore, we design a novel photonic crystal fiber (PCF), which can achieve single TM-like mode transmission in this research. The cross section of the proposed PCF is shown in Fig. 1. It has a 5-rings actinomorphic elliptical-hole lattice core to destroy the isotropy between circumferential and radial directions of core, since the elliptical hole is effective to break the symmetry [3]. Meanwhile, we defect the center of core into a large air hole to make the HE 11 x mode guided hardly. So birefringence between TM-like and HE 11 x modes can be earned easily. We employ the vectorial finite element method (VFEM) [4] to discuss the properties of the proposed PCF. The H-field profiles of the TM-like mode and HE 11 x mode are shown in Fig. 2 at the wavelength of 1.55 µm. We can observe that HE 11 x mode is not guided, only TM-like mode can be guided in the proposed PCF. A bandwidth of 150nm (1.50 µm ∼ 1.65 µm), which covers C- and L-band of the optical communication wavelength bands, can be achieved for the single TM-like mode transmission.
14 Jun 2009
TL;DR: In this paper, a single spatial mode operation of a fiber laser was demonstrated for core diameter up to 40 µm in conventional double-clad fibers and up to 100 µm for photonic crystal fiber amplifiers.
Abstract: Single spatial mode operation of a fiber laser leads to perfect output beam quality, which is important for industry. Increasing of the effective mode area allows for achieving higher laser power at the wave field intensity lower than the limit imposed by non-linear effects. However, the large mode area (LMA) fiber lasers are open to higher order mode (HOM) appearance. Single mode operation was demonstrated for core diameter up to 40 µm in conventional double-clad fibers [1], and up to 100 µm in photonic crystal fiber amplifiers [2]. Recently, the leaky channel fiber amplifier with a core diameter up to 53 µm was demonstrated [3]. The single mode operation in all these constructions is due to the highest modal gain and smallest loss of the fundamental mode (FM). Generally, the higher small signal modal gain is insufficient condition for stable single mode operation at high powers. The spatially non-uniform gain saturation leads to HOM excitation. This effect can be eliminated if the FM has flat top profile in the gain region [4]. Flattened FM constructions of cylinder and ribbon fibers were suggested in [5] as possessing higher efficiency for inversion consumption.
29 Dec 2010
TL;DR: In this paper, a large flattened mode optical fiber with raised index ring around the outer edge of the fiber core has been fabricated through modified chemical vapour deposition process to raise the threshold for nonlinear interaction in high power laser fiber.
Abstract: Large flattened mode optical fiber with raised index ring around the outer edge of the fiber core has been fabricated through modified chemical vapour deposition process to raise the threshold for non-linear interaction in high power laser fiber. The conversion of the fundamental mode shape from a Bessel function to a top hat function, enhances the effective area of the core intersected by the mode without increasing the physical size of the core. The shape of the fundamental mode is observed to be strongly dependent on the width of the raised index ring from the modal analysis. Suitable fiber parameters have also been estimated through the modal field analysis. Fabrication process steps have been optimized to achieve the desired fiber parameters. Modal field distribution, transmission properties and bending loss of the fabricated fibers have been characterized.
TL;DR: In this paper , the inscription of multi-cascaded long-period fiber gratings (LPFGs) in a few-mode fiber using a CO2-laser was presented.
Abstract: We propose and demonstrate the inscription of multi-cascaded long-period fiber gratings (LPFGs) in a few-mode fiber using a CO2-laser. The multi-cascaded LPFGs containing three gratings were fabricated successfully. The first LPFG was used to realize the mode conversion from LP01 mode to LP11 mode, the second one was used to convert LP11 mode to LP21 mode, and the third one achieved the higher-order mode conversion from LP21 mode to LP31 mode. The second-order and third-order orbital angular momentum (OAM) modes can be generated using the cascaded LPFGs with the second and third gratings, respectively. The multi-cascaded LPFGs have the promising potential to be adopted as mode converters and mode scramblers in the mode division multiplexing system thanks to the flexible mode conversion among different higher-order modes.