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All,
I was asked to provide some input on component cost for 10GEPON.
The following assumptions have been made for 10GEPON
1. Upstream: Depending on assumptions, the ONU will require a DML DFB, able to meet -40 to +65C temperature requirements, with minimum average output power between +3 and +5 dBm.
2. Downstream: APD at the ONU, the Tx at the OLT will need to be an EML with
+3 dBm minimum average output power.
3. Downstream: PIN at the ONU, The Tx at the OLT will need to be an amplified EML with +8 to +11 dBm minimum average output power
4. We have been considering costs as multiples of a PIN-PD, with the assumptions a standard EML TOSA = 10 x PIN-PD and standard DML TOSA = 2 x PIN-PD.
How would the proposed components raise the relative cost?
First I need to make some corrections to the assumptions:
1. ONU temperature range will probably have to be -40°C to +85°C, unless someone (systems implementer) can confirm that it should be +65°C
4. My assumption for PIN-PD means complete ROSA (PIN-PD, TIA, Optics, electrical interface such as flex), as an example a XMD MSA compliant part.
Taking the XMD-MSA as an example for TOSA and ROSA, then I would agree that the costs for present 10Gb/s TOSA and ROSA is
PIN-ROSA = x
DML-TOSA = 2x (to 3x)
EML TOSA = 10x (to 12x)
I can not say anything on EML cost for higher power. EML suppliers need to address this.
For DML however one can assume the following:
Present power of 1310nm 10Gb/s DML is -4dBm min for cost 2x
Higher power uncooled DFB DMLs are available for 2.5Gb/s with minimum power about 1dB below the min 3dBm needed for 10Gb/s.
To reach the +3dBm min at 10Gb/s DML the lower bit rate uncooled chips need to be improved, or a cooled version of present 10Gb/s is needed. Either way the cost increase is about a factor of 2 or total cost = 2*2x=4x
(at 2.5Gb/s cooled DWDM is about 2 times cost of uncooled CWDM). Note that if the max temperature is truly 65°C, the cost may be slightly lower.
APD ROSA cost is about 2-2.5 times the PIN ROSA cost or 2.5x (this will depend on the required APD sensitivity however)
Summary:
10Gb/s PIN-ROSA = x
10Gb/s APD_ROSA = 2.5x
10Gb/s high power DML = 4x
Let’s also not forget that the optical components are not the only parts in the ONU or OLT. There are several other significant cost contributors, such as high speed ICs in transceiver, Protocol ICs (Mac, framer, FEC, …) and other. All the other ICs should be virtually independent of the optical solution and hence they don’t contribute to a cost differential between the optical solutions. Their cost do affect the relative contribution of the optics to the total ONU and OLT cost, and since we are doing relative (multiplicative) cost comparison, it is important to know the relative cost contribution of the optics as well.
As an example take the ROSA. An APD ROSA is 2.5 times as expensive as a PIN ROSA. The relative cost of an APD ONU however is much less than 2.5 times the cost of a PIN ONU.
Regards,
Design Engineering Manager
Optical Communication Products, Inc.