The substrates have a coefficient of thermal expansion that is greater than that of the dielectric layers, and the thicknesses of the substrates are selected to provide compensation for {TAIL ~ temperature dependant variations} in {HEAD ~ the center wavelength} of the filter 
The substrates have a coefficient of thermal expansion that is greater than that of the dielectric layers , and the thicknesses of the substrates are selected to provide compensation for { TAIL ~ temperature dependant variations } in { HEAD ~ the center wavelength } of the filter
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH