Last updated on 02/16/2021
CWDM transmission enables low-cost WDM transmission using uncooled laser diodes. It is often the case that the eight long-wavelength channels, from 1471 to 1611 nm, are chosen. This is because the loss of silica optical fibers are lower than the other eight short-wavelength channles. The transmission distance is, still, typically limited up to 70km, and one reason is the lack of appropreate optical amplifiers in the S-band (i.e. 1471, 1491, 1511nm CWDM channels).
FiberLabs possesses S-band amplification technology enabled by in-house fluoride fiber. It allows us to produce a fiber amplifier working from 1471nm to 1611nm. Below is a schematic of how our CWDM booster amplifier AMP-FL5701-B8 is used in the uni-directional configuration. The link budget is increased by 10 dB by the addtion of the booster amplifier, extending the maximum transmission distance up to 130 km.
Figure 1: Increasing link budget using eight-wavelength CWDM booster amplifier
In addition to the above configuration using a booster amplifier only, an in-line amplifier may be combined. Figure 2 schematically shows an CWDM tranmission scheme where our CWDM in-line amplifier AMP-FL5701-I8 is used combined with AMP-FL5701-B8. The transmission distance can be further increased by this addition.
Figure 2: Combination of booster and in-line amplifier
If you do not need such a wide bandwidth using the eight wavelengths, it may be an option to use only the four long-wavelength channels, from 1531 to 1611 nm. Below is a schematic of how our four-wavelength CWDM booster amplifier AMP-FL5701-B4 and in-line amplifier AMP-FL5701-I4 are used in the uni-directional configuration.
Figure 3: Increasing link budget using four-wavelength CWDM amplifier
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