All-fiber spectral filter based on LP/sub 01/-LP/sub 11/ mode coupling

Abstract

Spectral filters made of singlemode identical or dissinailar core pardel fibers provide 3-dB spectral widths on the order of 1 to 10 nm. A spectral filter made of singlemode and dualmode fibers and operating based on coupling of power between LP,, and LP,, modes is proposed for applications as narrowband demultiplexers and as wideband mode converters with spectral widths on the order of fraction of 1 n m to few 10 n m , respectively. With appropriate choice of parameters, filters can be designed such that the LP, mode of the singlemode f i h r is phase matched with the LP,, mode of the dual-mode fiber at a desired wavelength, thus significant exchange of power between these two modes can occur. The coupled-mode theory of parallel didectric wavegnides is used to analyze the proposed filter. Design data and transmission characteristics for maximum power coupling at 1.33 pm and 1.55 pm are presented.

Design of Spectral Filters Based on Linear Polarized Mode Coupling of Optical Fiber

“…Many types of spectral filters are designed and analyzed such as: diffraction grating filters [1][2][3], Fabry-Perot filters [4][5][6], Mach-Zehnder interferometer filters [7][8][9], all fiber filters [9][10][11] and others. Most of all fiber wavelength selective filters which have been drawn in the published papers consist of similar or dissimilar fibers with different shaping of refractive indices [12][13][14][15][16][17][18][19][20]. These filters depend on single mode fibers supporting LP01 in their coupling operation at a range of interesting wavelengths.…”