Equilibrium mode distribution

About: Equilibrium mode distribution is a research topic. Over the lifetime, 928 publications have been published within this topic receiving 14939 citations.

General analysis of the mode interaction in multimode active fiber

Abstract: General analysis of the mode interaction in multimode fiber is presented in this paper. By taking local gain into consideration, the general coupled mode equations in multimode active fiber are deduced in the model and the effect of various factors can be analyzed based on the general coupled mode equations. Analytical expression of the beam quality factor is deduced for the optical field emerging from the multimode active fiber. The evolution of the mode power and M2 factor along the fiber are analyzed by numerical evaluations.

A new large-diameter optical fibre waveguide for operation in the TE01 mode

Abstract: It is shown that by using an optical fibre of 'tubular' structure, comprising a thin layer of higher refractive index sandwiched between a core and a cladding of lower refractive index, it is possible to transmit the TE01 mode in isolation with the HE11 mode virtually cut off. Possible advantages of this arrangement are discussed.

Fiber-chip edge coupler with large mode size for silicon photonic wire waveguides

Abstract: Fiber-chip edge couplers are extensively used in integrated optics as one of the key structures for coupling of light between planar waveguide circuits and optical fibers. In this work, a new fiber-chip edge coupler concept with large mode size for coupling to submicrometer silicon photonic wire waveguides is presented. The coupler allows direct coupling to conventional SMF-28 optical fiber and circumvents the need for lensed fibers. We demonstrate by simulations a 95% mode overlap between the mode at the chip facet and a high numerical aperture single mode optical fiber with 6 μm mode field diameter (MFD). We also demonstrate a modified design with 89% overlap between the mode at the chip facet and a standard SMF-28 fiber with 10.4 μm MFD. The coupler is designed for 220 nm silicon-oninsulator (SOI) platform. An important advantage of our coupler is that large mode size is obtained without the need to increase buried oxide (BOX) thickness, which in our design is set to 3 μm. This remarkable feature is achieved by implementing in the SiO2 upper cladding two thin high-index Si3N4 layers. The high-index layers increase the effective refractive index of the upper cladding layer near the facet and are gradually tapered out along the coupler to provide adiabatic mode transformation to the silicon wire waveguide. Simultaneously, the Si-wire waveguide is inversely tapered along the coupler. The mode overlap at the chip facet is studied using a vectorial 2D mode solver and the mode transformation along the coupler is studied by 3D Finite-Difference Time-Domain simulations. The couplers are optimized for operating with transverse electric (TE) polarization and the operating wavelength is centered at 1.55 μm.

Longitudinal mode structure of the two-stage Raman fiber laser

Abstract: We have performed an experimental study of the internal structure of the spectrum arising from the generation of multiple longitudinal modes in a two-stage phosphosilicate Raman fiber laser. The mode structures and their interactions have been studied by the technique of rf beating in the output intensity. It is shown that the mode structure of the first Stokes wave copies the mode structure of the multimode pump laser and the mode structure of the second Stokes wave copies the mode structure of the first Stokes wave. The dependences of the amplitude and width for the rf resonances versus the pump power are discussed.