The present invention concerns {HEAD ~ a multi wavelength selective switch} in the form of {TAIL ~ a directional coupler structure} 
The present invention concerns { HEAD ~ a multi wavelength selective switch } in the form of { TAIL ~ a directional coupler structure }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL