Robert B. Sargent

Experimental demonstration of thin-film dispersion compensation for 50-GHz filters

Dispersion management is critical for next-generation high-bandwidth-utilization fiber-optical networks. Square-top thin-film bandpass filters for 50-GHz dense wavelength-division multiplexing inherently have high chromatic dispersion (CD) in transmission. The imparted dispersion power penalty on the network is undesirable. However, a second thin-film filter, operating in reflection, can be designed to compensate the CD of the bandpass filter. In this paper we demonstrate experimentally the reduction of the intrinsic CD of a 50-GHz thin-film coupler from /spl plusmn/170 ps/nm to /spl plusmn/50 ps/nm over a 30-GHz passband, through the use of such a cascaded thin-film compensator. Network simulations based on filter performance confirm the reduced dispersion power penalty of the cascade over the individual filter.

Beam displacement and distortion effects in narrowband optical thin-film filters

A three-dimensional model for beam propagation through optical interference filters is presented. The model predicts a wavelength-dependent lateral beam displacement of tens or hundreds of micrometers in narrowband filters at an angle of incidence of only 3° to 5°. The effects of filter bandwidth, wavelength offset, angle of incidence, and beam size are investigated. The effect is experimentally confirmed for a 100 GHz filter at a 3.5° angle of incidence.