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Re: [802.3_GT50GBIDI] APD receiver sensitivities

Hi Frank,

I think what this comes down to is whether is there a broader ecosystem for, a -13.8dBm sensitivity APD Rx, or a TX with 5.7dBm OMA(min)?  My understanding is that the highly sensitive RX represents a SiGe APD, which is not widely available from many vendors.  The higher power EML-SOA TX, on the other hand, is being developed by many vendors to support 50G PON, and uses conventional InP technology.  Assuming the 20km application is higher volume, the choice of the using the more available APD makes sense.  

Regards,
John


On Wed, May 1, 2024 at 5:27 PM Frank J Effenberger <frank.effenberger@xxxxxxxxxxxxx> wrote:

 

All,

I wanted to prime the discussion on the BR20 and BR40 budgets. In my view, where we stand at this point is:

  1. The BR40 discussion group (for lack of a better name) is favoring -12.8 dBm as the APD sensitivity. This is based on their opinion on what is the most feasible APD sensitivity including the diplexer losses.
  2. There are a couple of commenters who would prefer -13.8 dBm as the sensitivity. The reasons are that an unamplified EAM transmitter has a hard time reaching the output level required if we use -12.8 dBm.  Also, -13.8 dBm matches the 100G MSA sensitivity (albeit that is a two fiber system).

Of interest, I would like to highlight the values from G.9806 Amd. 3. The sensitivities for the Slower class (0 to 10 dB link loss) is -12.8 dBm, and for the Blower class (10 to 20 dB) is -13.5 dBm. There is an obvious near coincidence between the two views above and the sensitivities in G.9806.

 

Therefore, I would suggest that we consider the compromise where the BR20 budget is based on a sensitivity of -12.8 dBm, and the BR40 budget is based on a sensitivity of -13.5 dB. This would put the BR40 optics within striking range (2 dB) of the Blower class, and the industry could likely benefit from commonality of specifications there. Meanwhile, BR20 would become nearly identical to the Slower class, and gain economies of scale also. 

I’d like to discuss this in our upcoming meeting. I will be preparing a contribution restating this argument, and if you would like to have inputs to this contribution, I’d be happy to entertain them. I think we are getting to the point where we’d like to nail down these budgets into a complete plan, so we can progress our draft.

Sincerely,

Frank E>

 

 

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