The first realization of a wavelength-selective switch (WSS) with direct integration of few mode fibers (FMF) is fully described. The freespace optics FMF-WSS dynamically steers spectral information-bearing beams containing three spatial modes from an input port to one of nine output ports using a phase spatial light modulator. Sources of mode dependent losses (MDL) are identified, analytically analyzed and experimentally confirmed on account of different modal sensitivities to fiber coupling in imperfect imaging and at spectral channel edges due to mode clipping. These performance impacting effects can be reduced by adhering to provided design guidelines, which scale in support of higher spatial mode counts. The effect on data transmission of cascaded passband filtering and MDL build-up is experimentally investigated in detail.


Electrical and Computer Engineering


The research leading to these results was partially funded by the European Community's Seventh Framework Program (FP7/2007-2013) under grant agreement n° 619732 (INSPACE), and by the IT R&D program of MSIP/IITP, Republic of Korea (10043383, Research of mode-division-multiplexing optical transmission technology over 10 km multimode fiber).

Keywords and Phrases

Optical constants; Optics, Direct integration; Few-mode fibers; Free space optics; Modal sensitivities; Phase spatial light modulator; Spectral channels; Spectral information; Wavelength-selective switches, Light modulators

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version

Final Version

File Type





© 2015 Optical Society of America (OSA), All rights reserved.

Publication Date

01 May 2015