Hi,
we are designing a 10Gbps optical communication board using ONET1151L , here in layout guidelines (as shown in attached image) DIN (+/-) or differential 100 ohms and Dout (+/-) are differential 50 ohms impedance matched, is that means each track of DIN is 50 ohms and DOUT is 25 Ohms impedance matched? or individual tracks of DIN is 100 ohms and Dout is 50 ohms impedance matched? Will four layer board will be a optimal one for this?