First Generation
. The first generation of lightwave systems uses GaAs semiconductor laser and operating region was near 0.8 µm. Other specification of this generation are as under :
i) Bit rate : 45 Mb/s
ii) Repeater Spacing : 10 km
Second Generation
i) Bit rate : 100 Mb/s to 1.7 Gb/s
ii) Repeater spacing : 50 km
iii) Operating wavelength : 1.3 µm
iv) Semiconductor : In GaAsP
Third Generation
i) Bit rate : 10 Gb/s
ii) Repeater spacing : 100 km
iii) Operating wavelength : 1.55 µm
Fourth Generation
Fourth generation uses WDM technique
Bit rate : 10 Tb/s
Repeater spacing : 10,000 km
Operating wavelength : 1.45 to 1.62 µm
Fifth Generation
Fifth generation uses Roman amplification technique and optical solitiors.
Bit rate : 40 – 160 Gb/s
Repeater spacing : 24000 km – 35000 km
Operating wavelength : 1.53 to 1.57 µm