Non tunables DWDM SFP+ reach

[fperezromero]

Reading the SFP + DWDM datasheet, it is not clear to me what is the reach of non-tunables SFP+ as DWDM-SFP10G-61.41=

I understand that the ditance is limited by the loss of optical fiber and chromatic dispersion but, what could be the distance in the best of cases? 40 kilometers?. 80 Km?

The same thing happens to me by reviewing the SFP DWDM's datasheet.:
https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/dwdm-transceiver-modules/product_data_sheet0900aecd80582763.html

It indicates: "When shorter distances of single-mode fiber are used, it might be necessary to insert an optical attenuator in the link". Shorter than how much?

Thanks in advance.

P.D: Sorry my poor english

[Joseph W. Doherty]

If I remember correct, up to 80 Km should be possible.

Search for attenuator recommendations in: https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/data_sheet_c78-455693.pdf

[Jafar Tavana]

you can use this SFP+ Maximum distance 80 Km, you can use it for 1 meter optical cable patch cord or 79.99 Km.

[Carl Lindahl · Accepted solution]

at 1m you will need an attenutator, but yes up to 80km and a tad bit longer if the fiber is good

[Tom Randstrom]

The same thing happens to me by reviewing the SFP DWDM's datasheet.:
https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/dwdm-transceiver-modules/product_data_sheet0900aecd80582763.html

It indicates: "When shorter distances of single-mode fiber are used, it might be necessary to insert an optical attenuator in the link". Shorter than how much?

For long reach optical transceivers, the transmitters optical output power is greater than the receiver's input power range. To use the DWDM transceiver you linked to, this module has a transmit output power of +4dBm (max) which the receiver's input range is -9 to -28dBm. 

To calculate the minimum attenuation required for this link to operate correctly:

Transmit power (+4dB) minus Receiver input power (-9dBm) = Minimum link attenuation (+13dBm).

Fiber loss is ~ 0.25dB/km (@1550nm). So, 13db / 0.25dB/km =  52km minimum link length. So if you are doing bench testing, it would be necessary to add a minimum of 13dB of attenuation to have the received power level to fall within the receiver's operating range (-9dBm to -28dBm).  

Let us know if you have additional questions.