Mode scrambler

About: Mode scrambler is a research topic. Over the lifetime, 896 publications have been published within this topic receiving 13595 citations.

Novel technique for mode selection in a multimode fiber laser

Abstract: A simple technique for transverse mode selection in a large-mode-area (multimode) fiber laser is described. The technique exploits the different spectral responses of feedback elements based on a fiber Bragg grating and a volume Bragg grating to achieve wavelength-dependent mode filtering. This approach has been applied to a cladding-pumped thulium-doped fiber laser with a multimode core to achieve a single-spatial-mode output beam with a beam propagation factor (M2) of 1.05 at 1923 nm. Without mode selection the free-running fiber laser has a multimode output beam with an M2 parameter of 3.3. Selective excitation of higher order modes is also possible via the technique and preliminary results for laser oscillation on the LP11 mode are also discussed along with the prospects for scaling to higher power levels.

Dual mode fused optical fiber couplers suitable for mode division multiplexed transmission

Abstract: We experimentally demonstrate 2 × 2 and 3 × 3 fused fiber couplers made from dual mode fiber. A unique mode dependent power transfer characteristics as a function of pulling length is obtained that support various optical functionalities. Exploiting this we demonstrate several devices of interest for mode division multiplexed data transmission including LP11 mode filter, LP11 mode tap coupler, and 50:50 power splitter for both LP01 and LP11 modes.

Scaling the effective area of higher-order-mode erbium-doped fiber amplifiers.

Abstract: We demonstrate scaling of the effective area of higher-order mode, Er-doped fiber amplifiers Two Er-doped higher-order mode fibers, one with 3800 μm2 Aeff in the LP0,11 mode, and one with 6000 μm2 effective area in the LP0,14 mode, are demonstrated Output beam profiles show clean higher order modes, and S2 imaging measurements show low extraneous higher order mode content CW and pulsed amplifier experiments are reported Nanosecond pulses are amplified to 05 mJ pulse energy with 05 MW peak power

Dual mode radio communication apparatus having function of selectively designating analog or digital mode

Abstract: A radio communication apparatus of this invention includes a mode designation switch for selectively designating and inputting a desired mode from an analog mode and a digital mode, and a mode storage circuit for storing the desired mode designated and input by the mode designation switch and has a mode setting control function, a mode comparison function, and a mode change control function. In order to establish a radio link, control is performed to set a mode for transmitting a communication signal in accordance with the desired mode stored in the mode storage circuit. After the start of transmission of the communication signal, the mode comparison function compares the mode set by the mode setting control function with the desired mode stored in the mode storage circuit. If these modes are determined not to coincide with each other by the mode comparison function, control is performed to change the mode set by the mode setting control function to the desired mode stored in the mode storage circuit in accordance with the mode change control function.

Optical Vortices in a Fiber: Mode Division Multiplexing and Multimode Self-Imaging

Abstract: The optical vortices (Dennis et al., 2009; Desyatnikov et al., 2005; Soskin & Vasnetsov, 2001) or angular harmonics exp(imφ) describe a wavefront peculiarity, or helical dislocation, when in passing around the origin of coordinates the light field phase acquires a phase shift of 2πm, where m is the optical vortex's order. The generation and propagation of the laser vortices in free space has been studied fairly well, meanwhile, the excitation of individual vortex modes and obtaining desired superpositions thereof in optical fibers present a greater challenge (Berdague & Facq, 1982; Bolshtyansky et al., 1999; Dubois et al., 1994; Karpeev & Khonina, 2007; Mikaelian, 1990; Soifer & Golub, 1994; Thornburg et al., 1994; Volyar & Fadeeva, 2002). Note that the most interesting is the excitation and propagation of pure optical vortices that are not stepor graded-index fiber modes. However decomposition of the light fields in terms of angular harmonics has a number of advantages over other bases, including modal ones, when dealing with problems of laser beam generation and analysis and mode division multiplexing. As distinct from the classical LP-modes, the angular harmonics are scaleinvariant when coupled into the fiber and selected at the fiber's output using diffractive optical elements (DOEs) (Dubois et al., 1994; Karpeev & Khonina, 2007; Soifer & Golub, 1994; Thornburg et al., 1994). This gives much freedom in choosing parameters of an optical scheme, allowing one to effectively counteract noises, as it will be demonstrated below. A term "mode division multiplexing" (MDM) is used for multimodal optical fibers when describing methods for data transmission channel multiplexing, with each spatial fiber mode being treated as a separate channel that carries its own signal (Berdague & Facq, 1982; Soifer & Golub, 1994). The essence of mode division multiplexing is as follows: laser beams as a linear superposition of fiber modes can be used to generate signals that will effectively transmit data in a physical carrier a multimodal fiber. The data transmitted can be contained both in the modal composition and in the energy portion associated with each laser mode. The MDM concept has not yet been turned to practical use because a definite mode superposition with desired between-mode energy distribution is difficult to excite. Another reason is that there is energy redistribution between modes when transmitting data in real