Title :
The influence of aperture size and shape on crosstalk level in free-space grating demultiplexers for WDM networks
Author :
Churin, E.G. ; Bayvel, P. ; Midwinter, J.E. ; Hill, A.M.
Author_Institution :
Dept. of Electron. & Electr. Eng., Univ. Coll. London, UK
Abstract :
A simple method is presented to calculate crosstalk caused by aberrations and diffraction at the aperture edges in free-space grating demultiplexers for wavelength-division multiplexed (WDM) communication systems. The influence of circular and square aperture sizes is described for ideal and aberrated optical systems. It is shown that aperture enlargement is not critical to aberrations whilst providing significant crosstalk reduction. The minimum crosstalk value is obtained when the dispersion plane is parallel to the diagonal of the square aperture. -60 dB crosstalk is attainable for moderately aberrated systems with 80 channels (0.5 nm spacing) in the range 1530-1570 nm.
Keywords :
aberrations; demultiplexing equipment; light diffraction; optical communication equipment; optical crosstalk; wavelength division multiplexing; 1530 to 1570 nm; WDM communication systems; WDM networks; aberrated optical systems; aberrations; aperture edges; aperture enlargement; aperture shape; aperture size; circular aperture sizes; crosstalk level; diffraction; dispersion plane; free-space grating demultiplexers; minimum crosstalk value; moderately aberrated systems; significant crosstalk reduction; square aperture size; wavelength-division multiplexed; Apertures; Diffraction gratings; Gaussian approximation; Lenses; Optical crosstalk; Optical network units; Optical scattering; Shape; Stray light; Wavelength division multiplexing;
Journal_Title :
Photonics Technology Letters, IEEE
